Tropical Tidbits from the Tundra

Earl approaching the Antilles Islands; Future Fiona is potential trouble for the U.S.

By: Levi32, 4:46 PM GMT on August 28, 2010

If you can, playing the video in HD makes it much easier to see things. The video will play in low quality by default. If HD quality isn't available, then it will be in a few minutes. Let me know if you have problems or questions about the video.



This is likely my last update for at least a little while. I fly out to Fairbanks tomorrow morning to attend college at UAF, and I have no idea what life will be like up there, so I don't know if I'll be able to find time to do these every morning when I get up. I will certainly try to find a way but I can't make any promises. I could be back doing these in just a few days after I am settled in up there but if it doesn't work out then it could be an even longer period of time before I can get back on duty. If I can't, then I want to thank all of you who have watched my videos and commented on my blog. I really appreciate it. If I can't come back then I hope and pray that all of you make it through this hurricane season safely.

The burst of activity continues in the Atlantic today. An interesting little low has formed just off the Louisiana coast in association with the old frontal boundary sitting in there, and although this won't be able to ramp up it will be moving inland bringing pretty gusty winds and heavy rains east of it. It appears this low stole the show from the southern center, which may not bring as much rain into Texas as the models previously thought.

Danielle is recurving out far enough east of Bermuda to avoid affecting them significantly, and she's been attempting to undergo an EWRC all night. She won't be coming back from this, and gradual weakening should continue today as the trough that is recurving her starts to shear her from the southwest, and the story is pretty much finished with her.

Behind Danielle comes Earl, now up to 60mph, marching westward, and he is now starting to enter the area where he can strengthen, west of 50-55W. That has been the story this year where conditions are more favorable for these things to blow up farther west, and thus they wait before strengthening. Right now Earl's center is becoming exposed because Danielle's outflow is shearing him from the north, pushing all the convection off to the south. As she recurves out of the way Earl will be able to rebuild and strengthen steadily as he nears the islands, which should be on the watch in case they get clipped by his southern side. I am still of the feeling that Earl will recurve somewhere between Cape Hatteras and Bermuda, but both places should be on the lookout for potential impacts, especially if Earl becomes large like Danielle.

Fiona has yet to develop behind Earl but is on her way, and will be following a similar path close to the northern Antilles islands. Fiona has the greatest potential of these 3 storms to impact the United States, and the video today again shows the pattern that could result in a landfall. The storms are coming across progressively further south and west, increasing the threat to the US. The pattern says to be on the lookout and the overall message is that the threat is there, and we should be ready for it in case it happens.

Beyond Fiona we will have to see what comes our way. the SW Atlantic Basin including the Caribbean should be gradually lighting up as well during the next couple weeks, and we may start to see some action of non-Cape Verde nature that will be far more likely to impact land no matter where it goes.

We shall see what happens!

Hurricane Danielle Visible/IR2 Satellite (click image for loop):



Hurricane Danielle Track Models:



Tropical Storm Earl Visible/IR2 Satellite (click image for loop):



Tropical Storm Earl Track Models:




Caribbean/East Pacific Visible/IR2 Satellite (click image for loop):



Central Atlantic Visible/IR2 Satellite (click image for loop):



Atlantic Tropical Surface Analysis:



200mb Vertical Velocity (green areas represent upward motion associated with the MJO):






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Danielle recurves; Earl most likely to follow; Fiona could be more ogre than princess

By: Levi32, 4:56 PM GMT on August 27, 2010

If you can, playing the video in HD makes it much easier to see things. The video will play in low quality by default. If HD quality isn't available, then it will be in a few minutes. Let me know if you have problems or questions about the video.



I really apologize for the length of the video...I had no idea I had talked for 11 minutes when I was done. I guess I'm just really trying to have some fun in the last couple days before I have to leave and then may not have the time to put as much depth into these discussions, if I can continue doing them at all. Tomorrow will be my last one for an unknown period of time.

Danielle became a major hurricane overnight and the NHC gave her Cat 4 status when her eye cleared out fully and the storm took on a classic look. Minimal Cat 4 is likely as far as she will be able to go. Already dry air entrainment which is still plaguing her is causing the eye to fill up with clouds again and the core is looking less healthy. Cat 5 is pretty much unattainable in this situation, and anything above her current intensity seems unlikely. She has likely peaked now. Danielle is currently undergoing a WNW jog today as the ridge passes by to her north while she waits for the 2nd trough to fully recurve her. This should take place east of Bermuda but she could still get close enough to affect them with strong winds and heavy rain, so they should monitor her progress for potential impacts.

Behind Danielle we find Earl, still chugging westward with no change in intensity. The northern Antilles Islands will have to monitor Earl to see how close he gets to them when he passes, but it will likely be north of the islands, not over them. Earl has the potential to get farther west than Danielle and cause more worry to people on the US east coast, but I think he is likely to follow Danielle out to sea, but a closer call than she was. Bermuda may need to watch Earl even more vigilantly than Danielle. The latest ECMWF run takes Earl directly over the island in 8 days.

Behind Earl we find the tropical wave that is likely to eventually become Fiona, currently passing south of the Cape Verde Islands. This one has the potential to come farther south and west than both Danielle and Earl, and that seems to be a pattern with each successive storm coming farther south and west. GFS nonsense has Fiona catching up to Earl and merging with him, but she will instead keep a neat distance from Earl just like he did from Danielle. Hurricanes have a certain respect for each other's personal space.

The 0z ECMWF from last night is one of the scariest runs you will ever see on that model, taking Fiona as a 921mb hurricane WNW towards Florida at Day 10. This is just one run and the model will likely flop around, but the pattern for this kind of a thing makes some sense when you look at the longwave pattern across North America. The cold PDO has been setting up the ridge south of the Aleutians with the trough over the eastern Gulf of Alaska and western Canada. This forces height rises over southeast Canada and the northeast US. The result on this ECMWF run is that the trough recurving Earl encounters more resistance and the stronger jet forces the trough to lift out, allowing the ridge to build in farther north and direct Fiona west towards the United States.

One can also notice how the models that show this solution (ECMWF, CMC), are simply replacing the homegrown mischief that they were previously hinting at in the SW Atlantic Basin with a Cape Verde storm getting drawn into the pattern. No matter what happens the SW Atlantic basin is primed for a tropical cyclone to be in the area sometime during the first week of September. If the hurricane train keeps recurving out to sea to the east then we will have to watch for something spawning up in close to home, but we could just as easily get one of the long-track storms stuck underneath the ridge and take advantage of the pattern, replacing our homegrown concerns with something much more serious. Fiona has the potential to be a real bad ogre, and not a beautiful princess. Right now everything is still a long way out and the situation will continue to be monitored.

We shall see what happens!

Hurricane Danielle Visible/IR2 Satellite (click image for loop):



Hurricane Danielle Track Models:



Tropical Storm Earl Visible/IR2 Satellite (click image for loop):



Tropical Storm Earl Track Models:




Caribbean/East Pacific Visible/IR2 Satellite (click image for loop):



Central Atlantic Visible/IR2 Satellite (click image for loop):



Atlantic Tropical Surface Analysis:



200mb Vertical Velocity (green areas represent upward motion associated with the MJO):






Updated: 5:16 PM GMT on August 27, 2010

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Where's the caboose? SW Atlantic Basin should be watched for mischief in 5-10 days

By: Levi32, 5:17 PM GMT on August 26, 2010

If you can, playing the video in HD makes it much easier to see things. The video will play in low quality by default. If HD quality isn't available, then it will be in a few minutes. Let me know if you have problems or questions about the video.



The Atlantic remains in full gear now as the train continues to roar off of Africa, and looking at the wide-view satellite across the continent I can't find the end of it, the caboose. Wave after wave looks lined up. The latest one rolling off looks promising to eventually become Fiona. Out in front we have Danielle and Earl. This is a classic Cape Verde wave train with the strongest hurricane out in front, a medium-strength storm behind and a disturbance/depression last in line coming off Africa.

Danielle is a Cat 2 now and should make a run at Cat 3 today and tomorrow before she makes it to 30N. The upper low backing away to her southwest is allowing outflow to expand, and although dry air entrainment has been wreaking havoc with her core, the eye is now becoming better-defined and if she can mix out most of the dry air she should have no problem becoming a major hurricane. It is even possible she could make it to Cat 4 if she performs well today. The longwave pattern looks to finally have revealed itself clear enough to almost guarantee recurvature of Danielle without being blocked and brought back west. The high to the NW of Danielle will be pushed eastward to the north of her by the incoming trough over the eastern seaboard, and this will keep her on a NW motion today, but once the high is pushed off to the east she will recurve right into the trough and out to sea. The models all agree on a track east of Bermuda which would spare them, though if she gets close enough they may get some nasty conditions on her western edge.

Earl is also struggling with some dry air and only gradual strengthening is likely over the next couple days at least. He appears to be keeping enough distance from Danielle to avoid getting sheared by her. It remains unclear exactly how far west Earl will be able to get before recurving, but there is a decent chance he will follow Danielle's footsteps and recurve out to sea, but he may have more a chance of slamming Bermuda, and he could also potentially become a major hurricane in that area.

If Fiona develops she will have the greatest chance of these 3 storms of coming far enough west to threaten the Caribbean or United States, but this is still a long way off and we will have to see how things progress before speculating on her track. We still have to get her to develop.

What is more interesting to me right now is the possibility of some kind of mischief brewing in the SW Atlantic basin between the end of the month and September 5th, if Earl recurves. The video today details how this pattern of hurricanes recurving out in the middle of the Atlantic could set up a situation where a piece of troughiness splits away underneath the ridging building into the northeast US, and potentially end up in some kind of a system trying to spin up in the western Caribbean, Gulf of Mexico, or far SW Atlantic. There are no specific storms being shown on the operational model runs right now, but there are strong hints from the ensemble means that the pattern will be ripe for heat to buildup in this area, southwest of the African wave train.

Right now we still have a disturbance in the western gulf that will likely not become much more than a rain event for Texas, but it should be watched for feedback just in case.

We shall see what happens!

Hurricane Danielle Visible/IR2 Satellite (click image for loop):



Hurricane Danielle Track Models:



Tropical Storm Earl Visible/IR2 Satellite (click image for loop):



Tropical Storm Earl Track Models:




Caribbean/East Pacific Visible/IR2 Satellite (click image for loop):



Central Atlantic Visible/IR2 Satellite (click image for loop):



Atlantic Tropical Surface Analysis:



200mb Vertical Velocity (green areas represent upward motion associated with the MJO):






Updated: 5:40 PM GMT on August 26, 2010

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The Train Begins: Danielle may threaten Bermuda; More storms on the way

By: Levi32, 5:28 PM GMT on August 25, 2010

If you can, playing the video in HD makes it much easier to see things. The video will play in low quality by default. If HD quality isn't available, then it will be in a few minutes. Let me know if you have problems or questions about the video.



The train is leaving the station today. This is the busiest day in the tropics so far this year but expect us to have even busier times before the season is over. We currently have Hurricane Danielle, TD 7 which will be Earl by the end of the day, and another wave behind him that may try to become Fiona in a few days. We also have threats for homegrown mischief close to the US coast.

Danielle went through another reorganization of her core last night as the CDO collapsed a 2nd time and she was forced to rebuild. Dry air entrainment will be a problem as long as she has the Bermuda High directly off to her northwest, and it may never cease to be a problem, but once the high is pushed off to her north and east she will be ventilated by the trough that recurves her, and she may have a small window where she could explode and try to become a major hurricane between 30N and 35N. While she is not a threat to the US, Bermuda still has to be on their toes as a lot of ensemble runs still get Danielle caught under the ridge for a while before finally recurving out, and getting blocked like that would result in her traveling farther west, either over or west of Bermuda, giving them quite a beating from what should be a storm at its peak. The best-case scenario for Bermuda would be Danielle following the NHC forecast east of them and out to sea.

TD 7 has developed in the eastern Atlantic and looks like a tropical storm already. This should be named Earl later today. Again I think only gradual strengthening is warranted with Earl as he comes westward, as Danielle's proximity may shear him and dry air is currently an issue. It may be a while before Earl becomes a hurricane, if he is destined to become one. It remains to be seen whether Earl will follow Danielle through the weakness she creates and right out to sea behind her, or whether he gets caught beneath the ridge and makes it farther west to become a potential problem down the road.

A well-defined tropical wave behind Earl getting ready to exit Africa will likely try to become Fiona in a few days, but we'll have to see what it looks like over the water. Looking at the wide loops you can really see the train that is now starting to roar off of Africa. We're going to have 2 named storms on the map simultaneously for the first time this year, and don't expect this to be the last time we see so much activity. This kind of a weather map should be a ruling theme through at least mid-October.

An area of low pressure developing along an old frontal trough in the western Gulf of Mexico needs to be watched by Texas to see if it tries to feedback under improving upper-level conditions during the next couple of days. I don't see anything too serious coming from this but we've had several homegrown systems develop already in the gulf this year and we wouldn't want to be caught off-guard. This will be a rain event for Texas either way as the system heads WNW and inland in a couple days.

The video today shows how, according to the models, 2005 is our best analog for the September-October-November period, and there is still quite a bit of reason to be concerned about the end-game of this season. The promised burst has already begun. Don't expect a significant break for a while.

We shall see what happens!

Hurricane Danielle Visible/IR2 Satellite (click image for loop):



Hurricane Danielle Track Models:



Tropical Depression #7 Visible/IR2 Satellite (click image for loop):



Tropical Depression #7 Track Models:




Caribbean/East Pacific Visible/IR2 Satellite (click image for loop):



Central Atlantic Visible/IR2 Satellite (click image for loop):



Atlantic Tropical Surface Analysis:



200mb Vertical Velocity (green areas represent upward motion associated with the MJO):






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Danielle significantly weakens; Earl to develop; Watching for homegrown mischief

By: Levi32, 4:22 PM GMT on August 24, 2010

If you can, playing the video in HD makes it much easier to see things. The video will play in low quality by default. If HD quality isn't available, then it will be in a few minutes. Let me know if you have problems or questions about the video.



Well Hurricane Danielle really fell apart overnight. We went from seeing a developing eye to seeing an exposed surface center this morning. When that happens you know the storm is no longer a hurricane, though the NHC was generous and gave her Cat 1 for the 11am advisory. Why did this happen? The reason is simple, but the result was a bit more extreme than anyone thought. Dry air entrainment is what killed Danielle overnight, which can be seen quite well on TPW imagery. As a result the system now appears ragged with no CDO, and a fractured convective band to the west. As soon as the CDO disappeared the surface center started to try to outrun the rest of the storm, as they tend to do when the low-level steering flow is fast. That's called speed shear, which in this case is giving the appearance of westerly shear on the system.

Now the reason for all of this is that Danielle is running straight towards the center of the Bermuda High, currently located south of Bermuda. If we look back and basic meteorology we remember that the flow on the east and southeast side of a high pressure area is confluent (air piling up), and when this happens in the mid-upper atmosphere it causes the air to sink, drying and warming it, and both of these things act to suppress convection. Indeed, one can notice the massive cloudless region out ahead of Danielle to the northwest. This is where all the dry air is that is being ingested into Danielle's circulation. If you're a hurricane you never want to be running straight towards a deep-layer high from the east or southeast, and this is precisely the reason why I thought strengthening would be more gradual with Danielle yesterday and today than the NHC thought, but I must admit I didn't foresee this kind of weakening.

Can she come back from this? I believe so, and in time she should be able to mix out the dry air, but this is a big setback that will probably lower her chances of becoming a major hurricane down the road. She will be in a better environment once she gets southeast and east of Bermuda, where she will likely strengthen, but it is now uncertain how strong she will be able to get again before the trough that recurves her starts to shear her.

That brings us to the track which requires little discussion as the ideas are still the same....she should recurve out to sea and the models still take her east of Bermuda, thankfully, but residents there should continue to watch her closely, especially now that she has weakened as that could potentially affect her track a little bit. She has had a tendency so far to drift west of the NHC forecast so Bermuda should still be on the watch.

Behind Danielle we find what will likely become Earl west of Africa over the next couple of days. We will have to see if he follows Danielle's weakness right up behind her and out to sea, or if he gets caught by the ridge and directed farther west, potentially threatening land. I have doubts about how strong Earl can get as well, and again I think only gradual strengthening once he develops will be the story.

Closer to home we have the tail-end of an old front lying across the Gulf of Mexico and with some upper ridging developing over the area this will have to be watched through the end of the week to see if anything tries to spin up and move into the Texas gulf coast. I don't see anything really serious coming out of this but we've learned our lesson so far this year that these old fronts will try to spawn tropical depressions, so the area will be monitored.

Homegrown mischief may also become an issue once again in 8-10 days as Danielle is leaving with a possible trough-split situation off the SE US coast, and with the ridge building strongly into the northeast US it is a pattern where we should watch underneath the ridge for trouble, and indeed we shall be. The GFS shows 2-3 more storms developing in the deep tropics by the end of the first week of September, so the burst is probably starting, and there may not be many days for a while now where we're not tracking a named storm.

We shall see what happens!

Hurricane Danielle Visible/IR2 Satellite (click image for loop):



Hurricane Danielle Track Models:




Caribbean/East Pacific Visible/IR2 Satellite (click image for loop):



Central Atlantic Visible/IR2 Satellite (click image for loop):



Atlantic Tropical Surface Analysis:



200mb Vertical Velocity (green areas represent upward motion associated with the MJO):






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Danielle likely to recurve; Homegrown mischief a concern next week

By: Levi32, 5:41 PM GMT on August 23, 2010

If you can, playing the video in HD makes it much easier to see things. The video will play in low quality by default. If HD quality isn't available, then it will be in a few minutes. Let me know if you have problems or questions about the video.



Danielle continues to be the only major feature of interest today in the Atlantic. Danielle has become better organized since yesterday and is currently trying to develop an eye, which should gradually become better defined as the day goes on. The pattern is still only favorable for gradual strengthening, rather than explosive, and I expect a nice smooth ride up into hurricane intensity, with perhaps a burst of more rapid intensification once she passes 50W, which won't occur for 36-48 hours. It is entirely possible Danielle could become a major hurricane at some point in her life, and a solid Cat 2 is almost guaranteed given the conditions. A trough recurving and shearing her in a few days should limit how strong she can get, but I think a Cat 3 would be a reasonable peak.

As hinted above, a trough will be recurving Danielle in a few days, and the models, ensemble members and all, have all switched to the east now and unanimously agree on recurvature east of Bermuda. While Bermuda should still keep an eye on this to see if it comes farther west than forecast, there comes a point when all the models lock on that you have to consider their opinion the dominant solution and the one most likely to occur. What I have been doing is hunting down the scenarios that could end up affecting people, and bringing those scenarios into the light so that if they occur, people will have been warned. Even if they only have a small chance of happening, I feel compelled to bring them up. Thankfully, it looks like Danielle is indeed a fish. The US coast may not be so lucky next time, if this pattern does indeed mature the way the models are adamantly suggesting.

What may try to become Earl is currently exiting the African coast behind Danielle, and the upper-level environment isn't conducive enough to guarantee development, but it has a good shot and will be monitored for development over the next few days. Given how close in succession it is following Danielle, a developing Earl may just recurve up right behind her, but we'll see how it goes.

Something I have mentioned a couple times over the past week or so is that if Danielle does recurve sufficiently far east, specifically east of 60W, we may have to watch for homegrown mischief in a potential trough-split situation off the SE US coast or the Gulf of Mexico as Danielle turns out. Now that she appears to be doing so, we turn our eyes closer to our shores to watch for such an event taking shape. Again, the pattern, although Danielle is recurving, favors a storm off the SE US coast in the near future, somehow. Danielle wasn't it, but home-brew could still fill the bill. The video goes into detail on this and gives some visuals on the potential situation as currently seen by the models.

We shall see what happens!

Tropical Storm Danielle Visible/IR2 Satellite (click image for loop):



Tropical Storm Danielle Track Models:




Caribbean/East Pacific Visible/IR2 Satellite (click image for loop):



Central Atlantic Visible/IR2 Satellite (click image for loop):



Atlantic Tropical Surface Analysis:



200mb Vertical Velocity (green areas represent upward motion associated with the MJO):






Updated: 5:43 PM GMT on August 23, 2010

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TD #6 still a potential threat, to more than just fish

By: Levi32, 6:12 PM GMT on August 22, 2010

If you can, playing the video in HD makes it much easier to see things. The video will play in low quality by default. If HD quality isn't available, then it will be in a few minutes. Let me know if you have problems or questions about the video.



As there are no immediate threat areas for development the primary focus today will be tropical depression #6. The system has developed a well-defined circulation but the surface center has become exposed this morning due to easterly shear, which has pushed most of the convection off to the west of the center. This may be a limiting factor for a while yet, and the upper pattern argues for only gradual intensification over the next several days, perhaps taking longer to make it to hurricane status than some of the models think. Once west of 60W, though, this could ramp up in a hurry and try to become a major hurricane down the road. The low-level center is pinwheeling off to the NNW in response to low pressure to the northeast of TD 6 trying to string out the circulation. The motion should eventually swing back to WNW as the guts of the system still wants to head that way and there's no way a NNW motion can continue right into the ridge. The low pressure to the northeast should eventually get wrapped into the system during the next couple days.

The track of future Danielle is still an object for much debate. The system has to negotiate two troughs on its way west. The first one won't even phase it as it will be passing too far off to the northeast. The 12z ECMWF yesterday morning recurved the system right into that trough but I condemned that run as nonsense. The trough is too far away to recurve TD 6 into it. The 2nd trough will be digging in off the eastern seaboard in 5-7 days, and this is what most of the models recurve the storm into and on out to sea. However, the consensus is not what it once was, and as I opined, although this is more likely to go out to sea than not, we have to warily watch this very closely because the pattern argues for a storm off the eastern US in 8-10 days and therefore we must watch for one, regardless of what the models say.

The problem with the trough picking this up is that if the system is still far enough south, it could get caught. The trough will not be digging in for long before the ridge builds in behind it over New England and southeast Canada. This is the pattern I have been harping on for so long, that during the heart of the season the upper pattern would mature to a point where the mean ridge is sitting over southeast Canada, and is the kind of pattern that can lead to a lot of US landfalls. A lot of the ensemble members of the ECMWF and GFS now have the storm getting caught beneath the ridge and making a run at the eastern seaboard. The 0z ECMWF operational has a major hurricane south of Bermuda in 10 days moving WNW, a scary place to have a storm. Such a situation could end up in one of those rare storms that moves northwest into the eastern seaboard north of North Carolina, affecting anyone from Cape Hatteras to Cape Cod. With SSTs the way they are such a storm would be a huge deal.

Now none of this is guaranteed and I still maintain that there is a large chance this curves out to sea, but there are opportunities, especially if this storm stays weak longer, that it could get caught beneath the building ridge and make a run at somebody before it's all over. I still think our friends in Bermuda must watch this more closely than anyone, as they are now right in the middle of the model spread that gets this caught under the ridge. A storm passing south of Bermuda would be a concern for the US east coast, and this is a situation that we should all monitor to see if this pattern does indeed deliver. It has delivered before, and has a habit of doing so a lot. Again, the pattern says that there should be a storm threatening the eastern seaboard in 8-10 days. Despite the model consensus for Danielle to recurve, we should be on the lookout for the storm having other ideas given the pattern that we are in.

We shall see what happens!

Tropical Depression #6 Visible/IR2 Satellite (click image for loop):



Tropical Depression #6 Track Models:




Caribbean/East Pacific Visible/IR2 Satellite (click image for loop):



Central Atlantic Visible/IR2 Satellite (click image for loop):



Atlantic Tropical Surface Analysis:



200mb Vertical Velocity (green areas represent upward motion associated with the MJO):






Updated: 6:15 PM GMT on August 22, 2010

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Cape Verde development and homegrown mischief concerns

By: Levi32, 5:08 PM GMT on August 20, 2010

If you can, playing the video in HD makes it much easier to see things. The video will play in low quality by default. If HD quality isn't available, then it will be in a few minutes. Let me know if you have problems or questions about the video.



The Atlantic remains mostly quiet for now, but the final week of August looks to go out with a bang. We have a developing monsoonal depression SSW of the Cape Verde Islands which should be a tropical depression by tomorrow night. For now it has been designated Invest 95L by the NHC. A tropical wave out in front of it is clearing out the dry air with a huge moisture surge and this is a classic setup for a big Cape Verde storm, and if things go well this could easily become our first major of the season.

The models, after wagging back and forth for many days, seem to have finally settled on recurvature out to sea without affecting the United States, and with the pattern over southeast Canada still in its developing stages it would make sense to have some sort of a trough dip down enough to recurve a strengthening hurricane out in the central Atlantic. However, I would still keep a wary eye on the system for the first several days if I were on the eastern seaboard, as we will want to be watching to see if the models are correct on it gaining latitude right off the bat. If it is still moving nearly due west when it passes 40W then the models will be wrong and we'll have to re-evaluate the track, but right now there is a strong consensus for recurvature.

Now despite the consensus there are still major differences in the evolution of the upper pattern, most noticeably between the ECMWF and the GFS. The GFS drops down a trough over the NE US in 7 days and digs it into the NW Atlantic, waiting for the storm to recurve into it before lifting out. The ECMWF is in agreement on the trough into the northeast US but instead lifts it out right away as the ridge builds in very strongly behind it, leaving banana-ridging over top of the hurricane. Both models recurve the storm east of the US, but with these differences in the forecasted pattern we can't forget about our friends in Bermuda. The ECMWF ensembles by Day 10 have the storm sitting just southeast of the island, and the massive disagreements amongst the models gives a large potential for error and Bermuda will have to watch this to see if it comes far enough west before recurving to affect them. With the potential for this to be a major hurricane on its way out, they would be wise over there to watch this one closely.

Closer to home here in the United States we may have a couple different opportunities to watch for homegrown mischief once again during the next two weeks, while the Cape Verde storm is stealing the headlines. Firstly in 3-4 days a trough will get cut-off near the eastern seaboard and we may have to watch off the coasts of North Carolina and Virginia for possible development of a warm-core feature, though perhaps not fully so. An interesting aspect to this would be to see the remnants of TD 5, still sitting over Alabama this morning, get entrained into the front off the North Carolina coast as this trough-split occurs, possibly giving a little boost to any possible development of a low. Also, if the tail-end of this same front drops down over the northern Gulf of Mexico we may need to watch for low pressure forming down there as well.

Further down the road, if our Cape Verde storm, likely to be Danielle, recurves sufficiently far east, say east of 60W, we may have to watch for another trough-split off the SE US or near the Bahamas in 10 days or so. With the differences of opinion on the upper longwave pattern it's hard to say for sure, but if we get a solid trough digging in to recurve the hurricane to the east then the ridge will want to build in fast behind the trough as it lifts out. Such is the tendency of the pattern, and we could once again find ourselves with the tail of the trough splitting off and sitting off the SE US, possibly causing mischief underneath the ridge. This is a long way off but the pattern supports it so we should keep an eye out. The long-range CMC does hint at trouble near the Bahamas in 10 days.

Overall, we have what could be our first really big storm forming in the eastern Atlantic, which is likely to recurve east of the United States, but could potentially be of concern to Bermuda. Several possibilities for homegrown mischief exist in close to the US coast during the next couple weeks, and the overall pattern is setting up for Atlantic to really light up soon. I know that keeps getting said, but I am confident the lid will eventually pop off.

We shall see what happens!

Invest 95L Track Models:




Caribbean/East Pacific Visible/IR2 Satellite (click image for loop):



Central Atlantic Visible/IR2 Satellite (click image for loop):



Atlantic Tropical Surface Analysis:



200mb Vertical Velocity (green areas represent upward motion associated with the MJO):






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Potentially big storm could cause problems during final week of August

By: Levi32, 4:28 PM GMT on August 18, 2010

If you can, playing the video in HD makes it much easier to see things. The video will play in low quality by default. If HD quality isn't available, then it will be in a few minutes. Let me know if you have problems or questions about the video.



If I sound a little disoriented in the video I apologize....I suddenly became pretty sick today and I'm a little out of it.

The Atlantic remains mostly quiet today. A tropical wave moving through the central Caribbean is not in a really favorable upper-level environment for development, and should be just a rainmaker for the area.

The big story by the end of this week and next week will be the potential Cape Verde storm that the models are adamant will develop during the next few days from a tropical wave getting ready to exit the African continent. The future track of this storm if it develops is still uncertain, as a lot of Cape Verde storms try to recurve, yet the pattern is one that favors long-track storms making it farther west and threatening land. The latest GFS runs have shifted farther south and have the storm affecting the northern Antilles Islands before turning north, and this kind of a track would be much more likely to threaten the United States down the road. The GFS and ECMWF operational runs still ultimately recurve the system out to sea, but the ensemble means are farther south and a lot of the GFS ensemble members have this even affecting Florida.

Speculating on the end-result of the track would be too difficult right now, but one has to be ready for the possibility that this makes it all the way west in such a pattern that is developing in our area of the world. Ridging developing over southeast Canada is the kind of situation that can lead to a lot of US landfalls, and is the signature of all big hurricane seasons. We still don't know if this storm will recurve and it hasn't even developed yet, but the moral of the story is what I have been saying that the final week of August will have to be watched for trouble off the SE US coast due to the pattern, and we should be on the lookout for trouble from the east.

We shall see what happens!


Caribbean/East Pacific Visible/IR2 Satellite (click image for loop):



Central Atlantic Visible/IR2 Satellite (click image for loop):



Atlantic Tropical Surface Analysis:



200mb Vertical Velocity (green areas represent upward motion associated with the MJO):






Updated: 4:33 PM GMT on August 18, 2010

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The 2nd coming of TD #5; Cape Verde trouble later this week

By: Levi32, 3:25 PM GMT on August 15, 2010

If you can, playing the video in HD makes it much easier to see things. The video will play in low quality by default. If HD quality isn't available, then it will be in a few minutes. Let me know if you have problems or questions about the video.



The tropical Atlantic is barren of activity this morning, but it won't remain that way for long.

The main feature of interest over the next 3 days will be the remnants of tropical depression #5 which are drifting back south towards the Florida panhandle this morning. The system still has a noticeable rotation to it and a strong band of thunderstorms is already developing out over the northern gulf waters. The upper ridge is situated directly over the system this time, and when this comes back out over the water it could start winding up nicely right away. If TD 5 comes far enough out, a good 24-48 hours over water could end up in the system looking a lot better at its second landfall than its first, and although it's not likely to become a monster like Alicia in 1983 which had the time to perform such a feat, we could be looking at the possibility of this getting named and earning a spot in the books for 2010. This should be coming back into Louisiana sometime on Tuesday or Wednesday bringing more rain to the area.

Next we turn out eyes toward the east as a tropical wave gets ready to emerge off the African coast in a couple days. This will be coming off very far north, near the latitude of the Cape Verde Islands, and although normally the air is too dry and the water too cold to allow development that far north near the coast of Africa, it has another tropical wave out in front of it that will be moistening the environment and SSTs are at record levels, so it is entirely possible this will try to start developing rather quickly after emerging. This one looks to be the real deal, as it has great model support and is the same wave I was talking to you about that was over Sudan last week.

The GFS now shows recurvature of the system and the ECMWF looks to be leaning that way as well. The ridging pattern over the northeastern US is still taking shape, but as the pattern is in its early stages of maturing one can get it developing far enough west to allow troughs to dive in east of it and recurve stuff out in the central Atlantic. Recurvature of this system is still not guaranteed, but it's awfully hard to get a wave to come off Africa this far north and then punch it into the United States. It's rarely done.

However, given the pattern, if this wave recurves then the same trough that recurves it may try to split away near the SE US coast as the ridge will tend to build in very fast behind it into the northeast, and this is a pattern where we should watch for something tropical off the SE US coast regardless of whether this wave recurves or not. If it recurves far enough east then we could be looking at another home-brew situation off the southeast US underneath the ridge in 9-12 days.

Now what comes behind this first wave could be even more trouble. What is now a tropical wave entering Chad over eastern Africa will be coming in behind our first system but farther south, and this one has a chance to get caught underneath the ridge over the northeast US and could make a run at land. The GFS is showing the start of the train as we should now be entering a period where there is little to no break between storms developing out in the Atlantic, and at times we could see a whole parade of them coming west. The pattern supports a good chunk of them coming far enough west to threaten land, and even if the first one recurves that doesn't mean they all will. The pattern for the heart of the season is still maturing. That's why the big burst hasn't come yet. Once it matures and the storm train starts, I think you'll see that most of the pre-season predictions here will come true.

All these things are of course still a long way off. Our first wave hasn't even left Africa yet, but I think we will see development with it when it does and we'll see if it recurves or not. The second coming of TD #5 will steal the headlines during the next few days, but the dark clouds coming from the east will soon be the focus of attention.

We shall see what happens!

Gulf of Mexico Visible/IR2 Satellite (click image for loop):



Tropical Depression #5 Track Models:




Caribbean/East Pacific Visible/IR2 Satellite (click image for loop):



Central Atlantic Visible/IR2 Satellite (click image for loop):



Atlantic Tropical Surface Analysis:



200mb Vertical Velocity (green areas represent upward motion associated with the MJO):






Updated: 3:39 PM GMT on August 15, 2010

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A quiet rest of the week in the tropics; Next week may heat up again

By: Levi32, 3:26 PM GMT on August 12, 2010

If you can, playing the video in HD makes it much easier to see things. The video will play in low quality by default. If HD quality isn't available, then it will be in a few minutes. Let me know if you have problems or questions about the video.



The tropics are fairly quiet today. Tropical Depression #5, which should still be classified as such, is soaking the New Orleans area as it slowly moves inland and intensifies, and it will continue to tighten on its way inland before it gets entirely cutoff from the moisture supply. The GFS is still playing around with this meandering it around the southern states and then bringing it back over the northern gulf early next week, feeding it back under a more favorable upper pattern and over the hot coastal waters. No other models show this, but the GFS has been very consistent, so we'll have to watch for such a thing to occur. Otherwise, no apparent threats for development are showing themselves for the rest of this week and into early next week.

By late next week we may have to watch for Cape Verde development off of Africa as the GFS ensembles are still adamant about our first long-track hurricane forming and tracking across the basin. The operational runs are now picking up on this as well and in the high-resolution front portion of the run. If this solution becomes consistent and marches down the timeline in a realistic manner then we will have to take this development threat seriously. Looking way down the road this has great potential to threaten the US east coast with the ridge setting up over the northeast US, but it is still a long way off and such a storm, if it tracks too far north, could still recurve. With nothing else to watch there is no harm in putting it out there. The pattern is yelling and screaming to watch underneath the ridge in 2 weeks, and regardless of what the model says, I will be looking to see if there is something sitting under there east of the United States during the final week of August.

We shall see what happens!


Caribbean/East Pacific Visible/IR2 Satellite (click image for loop):



Central Atlantic Visible/IR2 Satellite (click image for loop):



Atlantic Tropical Surface Analysis:



200mb Vertical Velocity (green areas represent upward motion associated with the MJO):






Permalink

TD 5 no big deal, at least this time; Big things may be brewing by end of the month

By: Levi32, 4:56 PM GMT on August 11, 2010

If you can, playing the video in HD makes it much easier to see things. The video will play in low quality by default. If HD quality isn't available, then it will be in a few minutes. Let me know if you have problems or questions about the video.



TD #5 as expected will not be a big deal for the north gulf coast. The system's circulation is extremely broad and elongated this morning with no focused convection. Outflow is cutoff on the northern side due to easterlies aloft on the south side of the deep-layer ridge which is steering the system, and as opined here this is keeping the system weak and no more than another rainstorm for most folks. It will be interesting to see if this tries to tighten up a bit as it comes ashore. As it rounds the western periphery of the high it will be moving from a confluent environment aloft (converging air) into a diffluent one (air spreading out) which is more conducive for thunderstorm development, and this could be trying to strengthen a little coming into the coast. We'll see if this earns a name or not.

This may not be the only time we hear from TD 5 though. The GFS has been hinting at TD 5 getting stuck and meandering around over the southeast states over the next week before finally coming back down over the extreme northern Gulf of Mexico in 6-7 days and trying to develop. In fact the GFS does a whole lot more than trying and winds this up into nearly a hurricane in the last few runs. Rapid feedback would be possible under the kind of conditions the GFS shows. With the jetstream farther south next week it presses the upper ridge down over the gulf and provides ventilation over the trough-split, instead of shearing it like it is now. In essence the GFS is depicting a nearly "perfect" homegrown mischief situation in which rapid feedback can occur and the system can blow up close to the coast, like Humberto in 2007 and Alicia in 1983 did. We'll have to keep an eye out for a 2nd coming of TD 5.

Elsewhere....Invest 93L is still generating puffs of convection east of its center out in the central Atlantic, and as it recurves it might get ventilated enough to wind up a little more, and we'll see if this impresses the NHC enough to get classified. It's been shaded red now for days on end. The area east of the Caribbean that I mentioned yesterday did get shaded yellow but remains rather unimpressive and is moving into a confluent environment aloft in the Caribbean which should continue to suppress convection, and the system isn't an immediate threat. It might have to be monitored if it remains intact to get farther west, but probably not a big deal.

The GFS ensembles continue to show a storm in the central Atlantic in 2 weeks that is still missed by the operational run for some reason. I have traced the storm back to a tropical wave just now in its formative stages over southwest Sudan in eastern Africa. A bit obsessed you say? Ya I am. This pattern setting up with the positive 500mb height anomaly over the northeast US is one where we should watch underneath the ridge regardless of what the model shows at the surface. Some big guns like the Canadian ensembles and the NAEFS are also now picking up on a storm off the SE US coast in 15 days. Seeing this on the ensemble means 2 weeks out is incredible. The models are trying very hard to tell us something and I'm relaying the message. This is a dangerous pattern, reminiscent of the 1950s when the PDO went cold and this same kind of pattern brought storm after storm into the Carolinas. Keep an eye out to the east. Big things may be brewing up for the final week of August.

We shall see what happens!

Tropical Depression #5 Visible/IR2 Satellite (click image for loop):



Tropical Depression #5 Track Models:



Invest 93L Visible/IR2 Satellite (click image for loop):



Invest 93L Track Models:




Caribbean/East Pacific Visible/IR2 Satellite (click image for loop):



Central Atlantic Visible/IR2 Satellite (click image for loop):



Atlantic Tropical Surface Analysis:



200mb Vertical Velocity (green areas represent upward motion associated with the MJO):






Updated: 5:00 PM GMT on August 11, 2010

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94L developing and will threaten Louisiana; Big trouble brewing later this month?

By: Levi32, 6:20 PM GMT on August 10, 2010

If you can, playing the video in HD makes it much easier to see things. The video will play in low quality by default. If HD quality isn't available, then it will be in a few minutes. Let me know if you have problems or questions about the video.



I apologize for the late post....I had major uploading issues this morning so satellite imagery in the video may be a couple hours old as of the time this entry was posted. Update: Youtube finally works. Video is now embedded here like it's supposed to be.

Invest 94L is developing today northwest of the Florida Keys. This looks like a tropical depression already to me with a closed 1008mb low and abundant convection near and south of the center. A recon plane is going in there right now and I expect advisories will likely be initiated on TD #5 at 5pm EDT. The steering flow for this system is rather simple around a deep-layer ridge over the SE US which will direct this system into the Louisiana area in about 48 hours. There is room for some nudging to the west if the ridge proves a little stronger, and the upper Texas gulf coast should keep an eye on this as well just in case.

As far as intensity, the forecast here is tricky. An upper low over northern Florida is not behaving as the models predicted, and is swinging by to the north of 94L, interacting with its circulation. Dry air from this upper low is inhibiting convection, especially on the north side of the system, but the upper low will be moving on to the WSW around 94L and away to the west later today and tomorrow. This should allow upper ridging to expand over the system and allow some strengthening, but then comes 94L's biggest problem. The same deep-layer high steering 94L will also be bringing easterlies aloft around its southern side which will try to shear 94L, in a similar fashion to how Bonnie got sheared.

In order for this to really blow up and try to become a hurricane, the upper low backing away would have to allow ridging to really pump northward in its wake and strong convection to be sustained over the center that would get this to feedback in a hurry. If it doesn't, the upper easterlies would likely overwhelm 94L's personal ridge and end up shearing the system like Bonnie. In other words, this needs to put on a big show today in order to have a chance to strengthen a whole lot. Regardless, I think this has a good chance to get named and should eventually become Danielle. However, I don't really see this becoming a hurricane at this point, but Louisiana and the surrounding areas should be ready for tropical storm conditions by Thursday.

Invest 93L continues to toy with tropical depression status and still needs more organized convection closer to the center. I think this still could make a run at getting named as it recurves in 2-4 days. The shortwave recurving it out will be enhancing upper divergence over the system and if it can overcome the dry air then I think it could tighten up and generate enough convection to deserve classification. If 94L develops this would become Earl if it gets named, and thus there is potential to rack up 2 more named storms before this week is out. 5 storms before August 15th isn't a lame number at all.

A tropical wave and an associated area of low pressure near 50W out in the central Atlantic is showing signs of developing a nice little circulation, and although thunderstorm activity is rather weak with the system at the moment, this is an area which I think should be hatched in yellow by the NHC (note: late post resulted in this getting shaded yellow after this writing), and I would keep an eye on this as it comes WNW over the next few days. We'll have to see what the environment is like for it when it gets to the Caribbean.

Now there are things afoot for the future that will have to be watched for. First of all a front stalling out off the eastern seaboard this weekend will have to be watched for a broad low perhaps trying to acquire subtropical or tropical characteristics on its way east in the vicinity of Bermuda. A bigger threat though may come a few days later next week closer to the tail of the same front, where homegrown mischief may try to brew up yet again either in the Gulf of Mexico or off the SE US coast. The GFS and ECMWF both hint at this.

I'm playing around with the idea that there may be something big in store for the final week of August. I've been watching the GFS ensemble means for several days now, and there have been about 6 runs in a row now where the operational run shows nothing much in 16 days but the ensemble mean shows a big hurricane tracking north of the Caribbean, evidenced by the big MSLP spread in the mean. Today it is extremely pronounced in both the MSLP and precipitation means for Day 16. You don't see this every day, and the model is really trying to tell us something.

The ensemble is also showing a big positive height anomaly at 500mb developing over the NE US in 10-16 days, and this is the pattern we have been talking about where the ridge shifts north later in the season, and when you see that ridge over the northeast you want to look underneath for tropical trouble. I show all this on the video and more. There are reasons to be keeping an eye out to the east after August 20th.

The MJO is here to stay for a while and may never really leave again. Things are cooking up and we could be up to Danielle or Earl by the time this week is over. The pattern is shifting towards where it was supposed to go during the heart of the hurricane season and has the signature of all big landfalling seasons for the United States. Be ready.

We shall see what happens!

Invest 94L Visible/IR2 Satellite (click image for loop):



Invest 94L Track Models:



Invest 93L Visible/IR2 Satellite (click image for loop):



Invest 93L Track Models:




Caribbean/East Pacific Visible/IR2 Satellite (click image for loop):



Central Atlantic Visible/IR2 Satellite (click image for loop):



Atlantic Tropical Surface Analysis:



200mb Vertical Velocity (green areas represent upward motion associated with the MJO):






Updated: 7:10 PM GMT on August 10, 2010

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Invests 93L and 94L

By: Levi32, 4:45 PM GMT on August 09, 2010

If you can, playing the video in HD makes it much easier to see things. The video will play in low quality by default. If HD quality isn't available, then it will be in a few minutes. Let me know if you have problems or questions about the video.



Colin is dead, badly forecasted by me, and although the NHC had the same idea for intensification near Bermuda that still doesn't let me off the hook. That is good news for Bermuda though that they didn't have to deal with as much bad weather.

Invest 93L out in the middle of the Atlantic is toying with TD status and needs more thunderstorm activity organized around the center in order to get classified. As proclaimed several days ago this will remain weak due to large-scale dry air in its area, and we'll have to see if we can get it classified but it has just about as good a chance of making it as not making it. Regardless, this will eventually recurve out to sea.

Invest 94L is an area of low pressure near SW Florida that is backing westward into the Gulf of Mexico, followed by an upper low. This is associated with an old frontal boundary and such things should always be watched in the gulf. The surface low will be curving up into Louisiana in 2-3 days, similar to an infamous invest earlier this year, and we'll see if this can pull a similar stunt by feeding back and trying to develop. The big deep-layer high is building back over the southern states again though so upper-level conditions may not be ideal with the easterly flow aloft to the south of the high, and 94L may have a better chance if the upper low stacks up with it and allows it to feedback off of the cold pocket aloft. If the upper low backs away then we may not get development, but threats in close to home like this should be watched meticulously.

Elsewhere....there are no other immediate threats for tropical development. The MJO is once again coming back into our area of the world. Today's video shows how the MJO archive can't produce a year with more upward motion focused in our area of the world than we have seen so far this summer. The long-range GFS continues to light up the sky with a train of storms, and eventually it will come true, probably before the end of this month. The 2nd half of August should get active. We may have to wait a week to 10 days before getting the next burst of activity, which would correlate with the SOI pulse that came across the Pacific, but don't let your guard down. The parade is coming.

We shall see what happens!

Invest 94L Visible/IR2 Satellite (click image for loop):



Invest 94L Track Models:



Invest 93L Visible/IR2 Satellite (click image for loop):



Invest 93L Track Models:




Caribbean/East Pacific Visible/IR2 Satellite (click image for loop):



Central Atlantic Visible/IR2 Satellite (click image for loop):



Atlantic Tropical Surface Analysis:



200mb Vertical Velocity (green areas represent upward motion associated with the MJO):






Updated: 4:48 PM GMT on August 09, 2010

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Colin threatening Bermuda; Watching for Danielle and possible homegrown mischief

By: Levi32, 4:28 PM GMT on August 06, 2010

If you can, playing the video in HD makes it much easier to see things. The video will play in low quality by default. If HD quality isn't available, then it will be in a few minutes. Let me know if you have problems or questions about the video.



Colin looks better than ever this morning with a well-defined circulation and healthy thunderstorm activity east of the center. It is all still east of the center due to wind shear, but convection is trying to wrap around the north side now and wind shear is weakening in the path of the storm. The concern here is that with the heat from Colin kicking out the upper low over Bermuda, the upper ridge will balloon northward during the next couple days and result in an intensifying storm approaching Bermuda, which could bring strong tropical storm force conditions and possibly hurricane-force gusts if the center passes just west of the island. It's also possible that this sneaks just east of the island which would spare them the worst of the weather, but I still think this is going over or west of them, and that will mean a very nasty weekend for those folks. This should still be a strong, high-end tropical storm by the time it gets there, and could possibly become a hurricane right after passing Bermuda, but we'll have to see how it goes. Right now nobody over there should be taking this storm lightly, and the Bermuda weather service is doing a good job of getting the word out.

A large envelope of low pressure in the eastern Atlantic may attempt to become Danielle over the next several days. Right now it has two competing centers which will need to conglomerate together to allow development. A bunch of dry air in the path of this should limit its intensity ultimately, but we'll have to see if we can at least get this named. The models look a bit too far east and this should start NW and then come WNW towards 60W, but should eventually recurve out.

Now another area in disguise that will have to be watched after this weekend is the front currently digging into the southeast US, and as the longwave trough lifts out quickly this will get left behind and try to drift over the northeast Gulf of Mexico. The upper low currently northeast of the Bahamas will be backing southwest as ridging builds back into the eastern US, and when you get an old front and a trough-split together in the Gulf of Mexico, you're looking for trouble. Remember Invest 95L? It's the same kind of thing, and you can see what can happen. This may cause another ruckus about the oil spill if something materializes, but we'll have to see how it goes. It is something to keep an eye on early next week.

Wouldn't it be something if we got Danielle and Earl named by the 10th? That's 3 storms during just the first third of August! And we're not even yet to the biggest burst of the month. This season has yet to show its true colors, but they will come out, and soon.

We shall see what happens!

Tropical Storm Colin Visible/IR2 Satellite (click image for loop):



Tropical Storm Colin Track Models:



Invest 93L Track Models:




Caribbean/East Pacific Visible/IR2 Satellite (click image for loop):



Central Atlantic Visible/IR2 Satellite (click image for loop):



Atlantic Tropical Surface Analysis:



200mb Vertical Velocity (green areas represent upward motion associated with the MJO):






Updated: 4:31 PM GMT on August 06, 2010

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Colin to threaten Bermuda; Danielle may form in the central Atlantic

By: Levi32, 3:40 PM GMT on August 05, 2010

If you can, playing the video in HD makes it much easier to see things. The video will play in low quality by default. If HD quality isn't available, then it will be in a few minutes. Let me know if you have problems or questions about the video.



Colin is alive and kicking, and is a tropical storm again. From the NHC this morning:

"...SURFACE OBSERVATIONS SUGGEST THAT IT LACKS A
WELL-DEFINED CIRCULATION..."

What? They have no buoys within 500 miles of the west side of the circulation that report wind direction, and the only buoy near the storm is in the eastern semicircle where we already know what the winds are. And what about the visible satellite this morning? How much more well-defined of a circulation can you want? It's exposed now which is allowing us to see clearly what's going on, and you can't get a more obvious WSW inflow to the south of the center coming into the thunderstorms. Why wait for the plane? This is ridiculous. Colin is a tropical storm again and stronger than he was before.

Colin will be threatening Bermuda this weekend, and will probably pass over or west of the island, which would put the worst weather over them either way. I don't expect this to get too awful strong, but this could be a strengthening tropical storm encroaching on the island. The GFS is way underestimating the strength of the upper ridge associated with Colin, and the nature of the trade wind flow piling up is that there is a whole lot more heat involved here that is getting released, and Colin is going full boar on attacking the TUTT to its northwest. The TUTT is weak and fractured into two lows, and it has nowhere to go with the jetstream to the north. Colin's ridge will be splitting the shear zone and we'll end up with a ventilated area near Bermuda for the storm to utilize, and conditions should only get better, not worse, for development over the next 3 days. There is always the chance that this weakens, but I don't think so. We'll have to see if thunderstorms can try to wrap around the center before it makes it to Bermuda, but chances are most of the weather will be weighted east of the center. They could potentially be staring down a very strong tropical storm by the time it gets there.

Invest 92L hasn't developed and as a result will be a straight pot-shot west into central America, and nothing but a light rain event for them.

A very active ITCZ in the central-eastern Atlantic is giving rise to an area of low pressure near 35W, and this has a chance to become Danielle later this week or next week if it can negotiate with the dry SAL mass to its northwest. This one looks like a candidate for recurvature but we'll have to see how things go.

After Danielle, if she develops, we may have a tiny break for about a week while the east Pacific tries to spin up a storm due to the SOI pulse coming across, but the MJO is coming back over the Atlantic and with upward motion focused in the tropics things should be really picking up by mid-month. The eastern Atlantic will have to be watched for Cape Verde waves developing and the western Caribbean will have to be watched after Day 10 due to the SOI pulse and a possible trough-split.

We shall see what happens!

Tropical Storm Colin Visible/IR2 Satellite (click image for loop):



Tropical Storm Colin Track Models:



Invest 92L Visible/IR2 Satellite (click image for loop):



Invest 92L Track Models:




Caribbean/East Pacific Visible/IR2 Satellite (click image for loop):



Central Atlantic Visible/IR2 Satellite (click image for loop):



Atlantic Tropical Surface Analysis:



200mb Vertical Velocity (green areas represent upward motion associated with the MJO):






Updated: 3:57 PM GMT on August 05, 2010

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Watching Ex-Colin for redevelopment; 92L and EATL Wave

By: Levi32, 3:51 PM GMT on August 04, 2010

If you can, playing the video in HD makes it much easier to see things. The video will play in low quality by default. If HD quality isn't available, then it will be in a few minutes. Let me know if you have problems or questions about the video.



Only had time for a quick video today, outlining the areas to watch over the next several days.

Ex-Colin is breathing once again, and is developing lots of thunderstorms under the divergent flow east of the TUTT. In many ways even a moderately sheared but divergent environment today is better that what Colin was dealing with yesterday. Because the system died yesterday, it didn't wrap in the trough to the northwest, and thus where the center would be today is now just northeast of Puerto Rico, and if it hadn't have fallen apart this would be taking my path further west towards the United States. While this is still possible, it seems likely that the center to the east under the convection will remain there, intensify, and move farther north into the weakness in the ridge, which is now being enhanced by the trough charging up there because Colin didn't wrap it in.

Thus, the storm is now probably more likely to recurve than not. Nonetheless, it still ended up west of the initial forecasts, and if it hadn't have died yesterday it would be continuing even farther west. It was the intensity forecast that undid my track this time around. This is another example of how closely related the two are. We'll have to watch to see if it tries to form the dominant center further west today, but odds look against it. We could see this reform back into a tropical storm during the next couple days, probably not too awful strong but there's a decent chance of seeing it reclassified if it can hold off the shear just enough. If this recurves out Bermuda may have to keep an eye on it for some bad weather.

Invest 92L in the central Caribbean has no circulation yet this morning and the deal with this one is that to threaten the United States it will have to develop, and develop quickly. If this waits until it's north of Honduras to develop, or just remains a tropical wave, it will likely be committed to central America and the Bay of Campeche. To get this to curve northwest into the Gulf of Mexico and threaten the US coast it would have to develop rapidly, and so far there are no signs of that occurring but the west gulf coast should keep one eye on it just in case.

A tropical wave passing SW of the Cape Verde Islands will likely try to develop over the next several days, and although dry air to its northwest may limit intensity, we'll have to see if this can become Danielle. Wouldn't it be something if this wave and 92L developed and we'd be up to the "E" storm, 3 storms in just the first week of August. Not particularly likely, but you never know. The models continue to throw hints about the pattern becoming ripe for the peak of the season, and things should start picking up in activity over the next couple weeks, and then really ramp up after mid-month.

We shall see what happens!

Tropical Storm Colin Visible/IR2 Satellite (click image for loop):



Tropical Storm Colin Track Models:



Invest 92L Visible/IR2 Satellite (click image for loop):



Invest 92L Track Models:




Caribbean/East Pacific Visible/IR2 Satellite (click image for loop):



Central Atlantic Visible/IR2 Satellite (click image for loop):



Atlantic Tropical Surface Analysis:



200mb Vertical Velocity (green areas represent upward motion associated with the MJO):






Updated: 3:55 PM GMT on August 04, 2010

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Colin remains weak; Atlantic gearing up for the main event

By: Levi32, 4:34 PM GMT on August 03, 2010

If you can, playing the video in HD makes it much easier to see things. The video will play in low quality by default. If HD quality isn't available, then it will be in a few minutes. Let me know if you have problems or questions about the video.



A lot of stuff to show you on the video today....had to go through it a little fast to stay under the time limit so hopefully it's comprehensible.

Colin remains a very ragged storm with little convection and this is all thanks to the very strong low-level flow racing this off to the WNW at 25-30mph. A flow this fast doesn't allow much surface convergence and punches dry air into the system. It also shears it because the low-level winds are much faster than the upper-level winds. Yesterday I thought this had a chance to be a strong-end tropical storm near the islands but am less excited about that today. Despite moving over warmer waters today this could remain on the weak side as a 35-40 knot TS when it nears the NE Caribbean. I could see it getting up to 50 knots but that's probably about it as far as the islands are concerned. The NHC mentioned that this could even open back up into a tropical wave today, and while I don't think it will fully open up, the circulation is barely closed and will have a hard time getting any stronger.

Beyond the islands it will be running into the TUTT and since this storm hasn't strengthened it isn't outputting much heat, and thus is at the mercy of the TUTT's shearing force. This will likely weaken the system if it hasn't already fallen apart, and then there is a chance for some restrengthening once it gets out to the other side of the TUTT. With dry air around and the small size of the system I don't see this as being a huge threat to the SE US intensity-wise, and at this time I don't think anyone there need worry about a strong hurricane closing in this weekend. This looks like a weaker system, but we'll have to see what it does north of the islands.

The track from the NHC and the model consensus still looks too far north and east. Colin is already south of the position they had it in at 50W. The GFS and CMC have the best ideas, and I think it will be somewhere in between them. This should come just north of the islands and get west of 75W, and although this could still recurve out without hitting the US coast, my forecast still stands for this to threaten and impact the SE US coast. This doesn't have to mean a full landfall, but I do think it will get at least close enough to spread its weather over land, which is what is meant by "impact". The upper pattern is very fragile with the upper trough diving down and turning this north, but the trough leaves as fast as it came, leaving a weak ridge building in and trying to hold Colin down to the south. The GFS shows a decoupling of the system with the surface energy escaping north while the 500mb low is left behind, which implies the tendency to stay to the south. This will likely meander very slowly off the southeast coast during the 5-8 day period trying to make up its mind what to do, and we'll have to see how healthy of a system it is by the time it gets there.

Elsewhere....a tropical wave in the eastern Caribbean has to be watched for possible mischief when it gets into the western Caribbean in a couple days. This may try to lift northwest into the Gulf of Mexico and will have to be monitored as it will be under upper ridging and a far more favorable environment than Colin is currently dealing with. A tropical wave coming in behind Colin may try to develop later this week and into next week.

The SOI is tanking negative in the dailies and I show in the video how the pressures have crashed in the Pacific. This is like a mini Nino burst in the middle of a La Nina pattern with a shot of westerlies coming across the Pacific. When these arrive in the east we may see the eastern Pacific try to eek out a storm (they are way overdue for one) but then given the nature of the La Nina pattern overall this burst will keep going right across into the Atlantic, and these things can cause fun and games down the road in 1-2 weeks. The westerlies when they come across focus convergence in the Atlantic and what can sometimes happen is that the burst supports a trough diving into the eastern US but then it gets kicked out really fast by the overall La Nina pattern returning, and sometimes you can get a trough-split that can cause mischief in the SW Atlantic or ventilate something coming out of the deep tropics. We'll have to watch to see what this does in our area of the world near the middle of the month.

The MJO is also coming into our area of the world during the middle part of the month and is way ahead of the model projections as expected. The Atlantic is gearing up for the main event which will be a burst of storms that may not stop from mid-August to October. 18 named storms is still very much on the table. Get ready for the show. It's coming.

We shall see what happens!

Tropical Storm Colin Visible/IR2 Satellite (click image for loop):



Tropical Storm Colin Track Models:




Caribbean/East Pacific Visible/IR2 Satellite (click image for loop):



Central Atlantic Visible/IR2 Satellite (click image for loop):



Atlantic Tropical Surface Analysis:



200mb Vertical Velocity (green areas represent upward motion associated with the MJO):








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Updated: 4:40 PM GMT on August 03, 2010

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TD 4 forms; Future still uncertain

By: Levi32, 4:51 PM GMT on August 02, 2010

If you can, playing the video in HD makes it much easier to see things. The video will play in low quality by default. If HD quality isn't available, then it will be in a few minutes. Let me know if you have problems or questions about the video.



I forgot to maximize some of the graphics in the video today....I apologize. Hopefully it's not impossible to see anything. I'd re-cut it but I don't have the time. The youtube player shows it bigger if you want to use that.

Advisories were initiated on TD #4 in the central Atlantic this morning at 11am EDT. The system has a fairly well-organized and well-defined circulation now, but in truth looks sickly to me. I looked at the floater this morning and was reminded of the eastern Pacific, where a lot of storms move into that stratocumulus field later on in life and die. Looking at the floater you can see a bunch of strato-cu northeast of TD 4, and this indicates a dry, stable airmass associated with cold water. TD 4 has moved over SSTs that are 3C colder than what it was over the last couple days, and they are now only 27C under the system with low ocean heat content, and you can see how close it is to very cold water just to its northeast. This is resulting in weak convection and is a problem for TD 4 until it can get to 50W when the water starts warming up again.

Intensity-wise the formation of the main center to the north of where the broad center was yesterday is what has put this over colder water and this was something that wasn't factored in yesterday, so this system could end up weaker by the time it approaches the islands. Dry air may also be a problem over the next few days. A tropical storm is likely, but if it takes advantage of the warmer water farther west in a hurry I can't rule out a Cat 1 hurricane approaching the northern Antilles in 3 days. This may go by north of them and spare the islands but they should keep a close eye on this, especially if it remains weaker which would tend to keep it tracking farther south than the models currently have it.

The track past 60W remains fuzzy. With more model support now for a stronger trough coming into the eastern US I'm not as confident in my forecast for this to threaten the US instead of recurving, and a recurve is still on the table but we are still not sure of anything yet. The ECMWF continues to flop around and now shows a recurve, and a good sign that things are still up in the air is when this model can't lock onto a solution. Basically, if this reaches 20N before 60W, I think it's gone. If it stays south of that point on approach to the islands it will still have a chance to impact the United States. A track like the 0z CMC could easily end up in a landfall. The GFS shows the worry that with the MJO coming back the trend is for ridging to try to build back over the eastern US and thus this trough, strong as it is, lifts out in a hurry, and you're left with a fragile ridge trying to hold Colin down. Whether it succeeds or not remains to be seen. It will be a close call, and could go either way at this point.

As far as intensity past 60W, this will be running into the TUTT and in my opinion must be a hurricane in order to release enough heat to force a bust of the TUTT. In other words, the system needs to be strong enough to cause ample resistance along the SE flank of the TUTT to force the jet out, kick the main trough northeast, and split off the tail-end of the TUTT which would become a cut-off low backing southwest away from the system. The result would be a ballooning ridge off the SE US which could ventilate the system and result in a strengthening storm north of the Bahamas. However, a weaker system doesn't release a lot of heat, as you can see it's not now due to the lack of cirrus outflow, and thus it would likely get sheared by the TUTT and remain weak.

So again, close calls and uncertainties about both track and intensity, but the likely deal right now is a gradually strengthening tropical storm passing near the northern Antilles, and probably some weakening north of Puerto Rico before it gets out on the other side of the TUTT and then perhaps some restrengthening is possible. The track is still largely up in the air. My confidence in a US landfall is lowered but I still think there's a good chance. A lot will depend on where this is tracking when it gets to 60W. The pattern favors an upset where the longwave trough loses and this gets shunted west into the coast, but this is yet another close call on recurvature that will drive forecasters nuts over the next few days. Either way, the SE US need not be overly concerned yet but should keep their eyes open.

Elsewhere....the tropical wave behind TD 4 will likely try to develop this week, and will be monitored.

We shall see what happens!

Tropical Depression #4 Visible/IR2 Satellite (click image for loop):



Tropical Depression #4 Track Models:




Caribbean/East Pacific Visible/IR2 Satellite (click image for loop):



Central Atlantic Visible/IR2 Satellite (click image for loop):



Atlantic Tropical Surface Analysis:



200mb Vertical Velocity (green areas represent upward motion associated with the MJO):








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Updated: 6:42 PM GMT on August 02, 2010

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91L likely to develop and threaten the NE Caribbean; U.S. is next

By: Levi32, 4:56 PM GMT on August 01, 2010

If you can, playing the video in HD makes it much easier to see things. The video will play in low quality by default. If HD quality isn't available, then it will be in a few minutes. Let me know if you have problems or questions about the video.



After a quiet end to July, August is kicking off with some bite. Invest 91L, a re-declaration of Invest 90L, is gradually organizing in the eastern Atlantic. A broad area of low pressure near 10N, 36W has increased in thunderstorm activity over the last 24 hours, and the most noticeable change is a kink in the ITCZ this morning that was not there yesterday, when the ITCZ looked flat from east to west. This kink indicates development, and with the low pressure center located on the portion of the ITCZ that is oriented SW to NE, it is in a very lucrative position to develop a cyclonic circulation. This is classic ITCZ development.

The low-level winds are trying to wrap in from the northwest, a strong sign that this is trying to develop. The low center remains elongated and broad, but the ASCAT pass from a few hours ago shows continued organization with sharp turning of the winds near the center and strong southwesterly monsoonal winds coming into the southern side of the system. There is a tropical wave merging with 91L from behind, and a negative from this is that the wave is helping to drive some dry air towards the system from the northwest, and this may be a limiting factor on intensification over the next few days. Regardless, this should develop and become tropical storm Colin by Tuesday. We could see a tropical depression as soon as tomorrow.

91L has been moving slowly but will now start feeling the steering influence of the subtropical ridge and will head WNW, arriving in the vicinity of the northern Antilles Islands in 4-5 days. Dry air may put a cap on initial intensification, but this should be a healthy tropical storm by the time it reaches the islands, and could even be a hurricane, though it is hard to say yet exactly how strong it could get. If I were in the northern Antilles, Virgin Islands, or Puerto Rico, I would be making preparations for a possible hurricane to affect the area later this week.

Beyond the islands both track and intensity forecasts get a little trickier. I see no sharp recurves in 91L's future, and although there will be a broad weakness in the subtropical ridge east of the US, the tendency here is for ridging to build in over the eastern US as the MJO closes back in on the Atlantic, and this should be directed WNW and threaten the SE US coast in 7-9 days. At this point the pattern is very fragile and speculating on specific landfall possibilities in the US would be unwise at this point. However, the SE coast from the Carolinas to Florida should monitor the progress of this system as it approaches the NE Caribbean islands, as it will likely threaten them next.

As far as intensity past the islands, 91L may run into the TUTT as soon as it hits the islands, which could weaken the system by shearing it, and this is reflected by the intensity models after Day 3. For a reason that escapes me for now, the 0z ECMWF continues to strengthen the system into a powerful hurricane despite entering a rather hostile upper environment. The concern here though is that the pattern is fragile and there is room for things to change. If the upper ridge balloons up out of the tropics and splits the TUTT, which won't be that strong, it could result in an upper low cutting off and backing SW away from the storm while the TUTT retracts to the northeast, resulting in an environment favorable for ventilating the storm as it approaches the Bahamas and SE US coast. Such a scenario looked possible on the 0z GFS run last night which showed a fairly favorable upper environment off the SE US coast. While I won't make a call on the long-range intensity forecast yet, it is something to hope for that the TUTT could weaken the system as it approaches our shores, but don't lock onto the idea because there is room for other things to happen. It should also be noted that if this were to eventually get into the Gulf of Mexico like the ECMWF shows, it would likely encounter a more favorable environment even if it was getting sheared east of Florida.

Overall, we have a tropical system that should develop into Colin and threaten the northeast Caribbean islands on Thursday or Friday, and will likely strengthen before getting there. The United States will be threatened next, but location and strength remain big unknowns that will have to be solved over the next few days. The models are still floppy and common-sense forecasting is what we are relying on right now, which is what we should always rely on anyway. The northeast Caribbean should be prepared for a possible hurricane, and the US with over a week before this threatens should just keep an eye on it for now and see what it does.

We shall see what happens!

Invest 91L Visible/IR2 Satellite (click image for loop):



Invest 91L Track Models:




Caribbean/East Pacific Visible/IR2 Satellite (click image for loop):



Central Atlantic Visible/IR2 Satellite (click image for loop):



Atlantic Tropical Surface Analysis:



200mb Vertical Velocity (green areas represent upward motion associated with the MJO):








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Updated: 5:44 PM GMT on August 01, 2010

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About Levi32

Levi Cowan has been tracking tropical systems since 2002, and is currently working on his bachelor's degree in physics at UAF.

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