Tropical Tidbits from the Tundra

Tomas weakens, but will likely fight back and threaten the northern Caribbean

By: Levi32, 9:57 PM GMT on October 31, 2010

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We shall see what happens!

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



Hurricane Tomas 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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Tomas lashing the Antilles; Big Caribbean Islands are next

By: Levi32, 4:56 PM GMT on October 30, 2010

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It is a very busy day in the Atlantic today with two simultaneous hurricanes on the charts right at the end of October, which is quite a feat. Shary is recurving out and weakening but Tomas is slowly strengthening as he enters the Caribbean. He is just now starting to cross the southern Antilles Islands, bringing nasty weather to St. Vincent and St. Lucia right now. The core structure still needs lots of work, as convection hasn't built tightly all the way around the center yet. Slow organization is expected with a storm this large, and overall the presentation is extremely impressive for a storm at this time of year, especially east of the islands.

Slow intensification should continue until Tomas develops a solid core with an eye, but once that happens we could see some more rapid strengthening. I believe this will eventually become a major hurricane somewhere south of Jamaica and Hispaniola. Strangely enough, none of the global models really agree. The GFS does strengthen Tomas a little bit, but the ECMWF, CMC, NOGAPS, and UKMET are rather unenthusiastic. One can hope that they are seeing something, but I believe Tomas will indeed strengthen into a powerful storm. The video illustrates some of my reasons with pattern comparisons to a time earlier this season.

The track reasoning remains exactly the same as it has been for weeks, that Tomas will continue WNW into the Caribbean, likely turning more towards the west as ridging builds north of the storm, and then stalling in the central Caribbean as a trough dives into the eastern US. This trough should eventually draw Tomas north or northeastward across the northern Caribbean islands and entrain the storm. This is a situation that the big Caribbean islands should be monitoring very closely, as there is a good possibility that they will be facing a major hurricane trying to recurve in the vicinity of eastern Cuba, Jamaica, or Hispaniola later next week. This kind of a situation loves to unfold at the end of big La Nina seasons, and folks should be preparing right now.

We shall see what happens!

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



Hurricane Tomas 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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Tomas to be a big problem for the Caribbean, possibly the grand finale of the season

By: Levi32, 3:38 PM GMT on October 29, 2010

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An active scene continues in the Atlantic this morning. The western of the two subtropical lows ended up earning the name Shary from the NHC last night. One could make an argument that since the surface low is still tucked under a portion of the 200mb low that it is still subtropical, but it matters little. This system will remain weak and recurve in the vicinity of Bermuda, with nothing more than squally weather for them that isn't too big of a deal.

What is of far greater concern is what is going on southeast of the Antilles Islands, where Invest 91L is likely already a tropical depression or storm. Unfortunately the other thing to the north stole the name Shary, so this would be Tomas if it gets named. This is an extremely impressive system coming from east of 60W for the end of October, and this is what I was talking about 2 weeks ago where this was possible that we could get one last system come from east of 60W and threaten the Caribbean, possibly as a major event.

Unfortunately, this may be true, as conditions aloft are just splendid for intensification of this puppy as it comes WNW over the next several days. The track will likely take this between Greneda and St. Vincent, affecting everywhere from Trinidad to Martinique. From there the storm will probably continue gaining latitude before curving more towards the west as the ridge builds back in temporarily north of the system. Thereafter it will likely stall somewhere south of Hispaniola or Jamaica and slowly get pulled north or northeastward out of the Caribbean by a trough digging into the eastern United States in 6-8 days.

This pattern was set up for you two weeks ago when the logic was laid out that the cooling of the SSTs off the SE US combined with SOI bursts would favor a temporary shift of tropical activity to the east of where it has been. This is not model madness and never has been, but rather a logical result of the overall pattern that has indeed turned out to be a threat. The 0z GFS has a scary-looking hurricane headed towards Haiti, and the HWRF is bombing the pressure into the 930s.

While this may or may not happen, the message is that major hurricanes can and do happen in the Caribbean in November, and it's not crazy to think that the northern Caribbeans may be threatened by one next week. This is something I've been voicing for a while and I'm not going to back down. This area of the world has to be ready for something like this at the end of the season. It very often happens that big La Nina seasons like this like to go out with a bang, with one big storm to end it all. We will see if Tomas is the grand finale, but whether he is or not, this is something that the Caribbean should be watching very closely.

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):






Updated: 3:39 PM GMT on October 29, 2010

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Potential Shary to threaten Trinidad and Tobago first, northern Caribbean after

By: Levi32, 4:48 PM GMT on October 28, 2010

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We have an unusually active day in the Atlantic for late October, with three areas of interest that are being monitored for development. A couple of cold-core subtropical lows are being painted orange and red by the NHC for potential development, and we'll see if they try to eek out a name from one of them.

The main feature is Invest 91L, a system of low pressure northeast of French Guiana that I have been tracking for several days. This is what I mentioned earlier this week would try to become Shary as it came westward and would make a run at the Caribbean. Satellite imagery this morning shows that it is definitely attempting to develop, as vigorous mid-level rotation has opened up in the last few hours. It is unclear how much of this rotation is manifesting itself at the surface, but there is a clear turning of the surface winds apparent in visible loops. This has the look of a developing tropical cyclone, and in my opinion should have more than the yellow paint that the NHC has on it right now.

As has been warned about for a long while now, this system will move into the eastern and central Caribbean trying to punch westward, but will likely be stopped in its tracks by a monster trough digging into the eastern United States in 6-8 days. This will try to tug whatever's in the Caribbean northeastward, and if we have Shary sitting down there at this time then the northern Caribbean islands will have to be watching closely. It is possible that if 91L remains weak that it will not get caught by the trough and will continue westward after stalling for a while, but conditions are favorable for 91L to develop, and I find it more likely that the system will slowly try to find its way out of the Caribbean to the north or northeast, perhaps taking several days to do so, but eventually getting out.

Overall, we have a developing tropical system north of South America that will be threatening Trinidad, Tobago, and the southern Antilles Islands in 36-48 hours, and moving on from there to potentially threaten the northern Caribbean islands next week.

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):






Updated: 4:49 PM GMT on October 28, 2010

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Be Wary of Shary next week

By: Levi32, 5:38 PM GMT on October 25, 2010

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Richard is dying now over central America after hitting Belize as a Cat 1 hurricane, though he is not stuck there. He will be moving out over the Gulf of Mexico later tonight and get slowly drawn north as a remnant low or tropical depression. He is no threat to the gulf coast, but one can see how he is recurving to the north and the overall idea that this would develop, come north, get turned west, and then drawn back to the north again was a good one. The exact track ended up too far east on my end, but this was never supposed to be a strong storm in the gulf, and overall the thinking on this storm was sound. It was interesting to see both Paula and Richard develop in the midst of large-scale sinking air, a pair of underdog storms that was intriguing to watch.

We now turn our attention to the next threat, this time farther east. For a long time now I have been warning that the eastern Caribbean may see storm development near the end of October and the first week of November that would threaten the northern Caribbean islands. This threat is still very much there, and we actually have a system to watch SSW of the Cape Verde Islands, which we will see propagate across the Atlantic over the next several days.

The video explains again why this scenario makes sense, and is not just model mumbo-jumbo. Pressures will be lowering in the central-eastern Caribbean and central Atlantic next week and there will be a lot of energy available to bundle. This is something that the northern Caribbean islands should be watching closely, as there is potential for such a system to be rather potent. With the pattern the way it is with troughs diving into the eastern seaboard, this storm may have the look of trying to punch straight west through the Caribbean gauntlet, but then may get stopped in its tracks by a trough and have to meander around trying to find out where to go, likely eventually recurving northeast, but not rapidly. A slow-mover in the Caribbean in November can be nasty, and major hurricanes do occur in the Caribbean during the end of the season. A recent pair were Hurricanes Omar and Paloma at the end of the 2008 hurricane season. The Caribbean islands should be prepared for this possibility.

After what will try to become Shary, we will be up to 18 named storms, and we will have to see whether there are any more threats left on the table. The Caribbean will remain open to more activity and possible mischief as long as wind shear doesn't get too high, as the overall pattern still favors upward motion in the tropics, the same as it did at the beginning of the season.

Elsewhere....on the video I neglected to mention a subtropical low in the eastern Atlantic, which the NHC might try to name sometime over the next few days. This is cold-core for now, but is over greater than 26C water. We'll have to see what comes of that.

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: 9:25 PM GMT on October 25, 2010

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Richard targets Belize; Shary may develop during first week of November

By: Levi32, 4:08 PM GMT on October 23, 2010

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Today's update is a true tidbit as it is just a quick one.

Richard is finally strengthening as the surface center is starting to feedback under the convection, and this will likely be a hurricane when it comes into Belize in about 36 hours. Heavy rainfall will likely be the worst worry with Richard for central America, but they should be ready for wind damage in Belize as well in case this really ramps up before landfall.

In the end I will probably end up being guilty of being too stubborn on the exact track forecast on this storm. The overall idea of Richard developing, moving north, then getting forced west, and then getting drawn north again into the Gulf of Mexico were all sound ideas, but a bit too far east. Richard, if his circulation does not completely dissipate during his crossing of Mexico, will still be drawn north into the gulf, but a bit farther west, and even if he makes it to the north gulf coast he will be no kind of a problem for anyone.

Keep in mind that the general life story of Richard was mapped out here back on October 15th, where the general track and the idea that it would weaken before hitting the U.S. were brought up, and that has seemed to verify decently, but details on the final track are what I stumbled on here. In all fairness, the computer models failed even worst, completely dropping Richard's development just a couple days in advance, and trying to punch him into Nicaragua, Panama, or even the eastern Pacific. Logic defeated the models here in terms of the overall pattern, but again the models proved their prowess once they finally get their heads out of the ground and catch onto the pattern.

Looking ahead.....we will have to watch for Shary trying to develop in the central-eastern Caribbean during the first week of November, as the pattern will next favor that area of the world for lowering pressures and upward motion. This is something the northern Caribbean islands should keep an eye on. Shary would bring us up to 18 named storms, fulfilling my seasonal forecast for this year.

We shall see what happens!

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



Tropical Storm Richard 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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Richard to threaten the Yucatan and Gulf of Mexico; Troubles from the east afterwards

By: Levi32, 4:48 PM GMT on October 22, 2010

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Tropical Storm Richard is a better-organized storm today, despite recon finding pressures way up at 1010mb. The satellites loops imply the system as a whole moving in slow westerly direction, while the last recon reports showed the surface center diving southward trying to escape out from under the convection. My suspicion is that this is indeed a weakening surface vortex that may leave the situation and let a new surface center develop underneath what appears to be a healthy mid-level center. The winds around the storm are certainly stronger than yesterday overall, and the circular convective bomb has been in place for quite some time now over the center as shear has relaxed.

The models have all generally shifted west today, but my track reasoning remains exactly the same. The trough currently over the eastern seaboard is leaving and allowing a ridge to propagate eastward over the southern U.S., and this will perhaps give Richard one last little southward push as it starts to come westward, and eventually the movement will be all west and WNW taking the storm to the Yucatan in 2-3 days as the ridge moves into a position off the SE US coast. Thereafter a shortwave trough coming out of the 4-corners region will help induce a weakness over the Gulf of Mexico that will start to draw Richard northward around the western periphery of the SE US ridge. The shortwave will lift out and weaken quickly, but a big-papa trough coming out of the Gulf of Alaska will dig in right behind it and reinforce the southerly flow out of the Caribbean, which I think will ensure Richard getting drawn out. With the models shifting southwest I am now northeast of most of them, with the track still over the eastern Yucatan and out into the eastern gulf. I could see this anywhere from eastern Louisiana to the Florida panhandle, but my feeling is still that Florida in general has the best chance to get the landfall of whatever system comes out of the Yucatan.

Intensity-wise Richard could still be quite a beast approaching the Yucatan if he can get his act together today, and this could ramp up to a Cat 1 or 2 hurricane before landfall. Land interaction will of course weaken the storm, and when he eventually moves out into the Gulf of Mexico he will likely be in a weakened state when he threatens the US. The hurricane models have dropped the worst-case Yucatan channel scenario, and although it is still on the table, having every model shift away from it of course lowers confidence in that possibility, which is a good thing here. My forecast remains generally the same as it was yesterday, that Richard will move into the Yucatan and then get drawn north towards the eastern gulf coast, likely in a weaker state and not a huge deal for the United States, but something to watch closely. The whole situation fits in with the recurving and weakening typhoon in the western Pacific as well, as those things like to teleconnect across to the Atlantic.

The video shows why our next problem next week and the week after will be the eastern Caribbean and central Atlantic as upward motion returns and pressures lower. This makes sense given the overall pattern, and we will have to watch for Shary trying to form during the first week of November. This would bring us up to 18 named storms, which was my forecast back in May.

We shall see what happens!

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



Tropical Storm Richard 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):






Permalink

Richard potentially a big problem for the Yucatan and possibly Florida as well

By: Levi32, 4:34 PM GMT on October 21, 2010

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Tropical Storm Richard was born last night. Despite all the models killing this system, the logical reasoning and the overall pattern in reality defied them. We now have a tightening center near a cluster of deep convection which is still weighted east of the center, but we will continue to see this tighten and wrap in today. Intensification should be steady, not rapid today, but once this gets farther west into the northwest Caribbean this weekend it could really go to town if it stays over water.

The track thinking remains the same as the trough over the eastern US will lift out allowing a ridge to propagate across to the north of Richard, forcing him back towards the west, north of Honduras over the next couple days. This ridge will sit itself off the SE US coast and allow another trough to come across, which is currently sitting over Arizona, and provide a weakness in the ridge over the eastern Gulf of Mexico. This will eventually draw Richard up to the north. The models have all finally come around to my idea on this, and although they are still spread out, they are finally grasping the overall pattern now that it is on top of them.

Problems arise now when we consider the exact track. A track like mine which still takes it over the NE Yucatan would result in a much weaker system coming towards Florida, but the scary possibility that this remains over water and heads through the channel is on the table. The GFDL and HWRF are known to have a strong poleward bias, but it is concerning now to see the 0z ECMWF showing the same kind of track through the channel. This kind of a track could result in a major hurricane in the NW Caribbean, weakening on its way to Florida, but still a potent storm, likely a hurricane, coming into the state next week.

I told you guys yesterday not to worry about the GFDL's insanity, and you still shouldn't, because a Cat 4-5 is not coming into Tampa Bay, but that doesn't mean you folks in Florida shouldn't be watching this closely. I have been voicing concern about the end of this season for a while now in that these land areas of the SW Atlantic Basin would get affected, and they all have in potent ways except for the eastern Gulf of Mexico. While I still think it is more likely that we see Richard interact with the Yucatan and be a weaker storm coming across into Florida, we have to be looking out for the worse option where we get a solid hurricane landfall in 5-7 days.

We shall see what happens!

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



Tropical Storm Richard 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: 4:38 PM GMT on October 21, 2010

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99L gradually developing; More mischief near the eastern Caribbean next week

By: Levi32, 4:44 PM GMT on October 20, 2010

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Invest 99L continues to steal the show this morning. The system is becoming better-defined with a pronounced, closed surface circulation, but the center is currently exposed with most of the convection focused northeast of the center. This is due to some wind shear out of the west with some dry air getting pushed in towards the circulation. This will be a hindering factor for the next couple days, but will be improving as we head into the weekend as the trough over the SE US lifts out and gets replaced by a ridge. This will put upper divergence in the path of the storm instead of upper convergence, which is what is causing the dry air.

The models are still spread out, but one can see how they are coming around to the ideas I laid out days ago based on the overall pattern and what this system should do. The models had dropped this system and adamantly insisted on no development whatsoever and a track that never took it north of 15N, having it die over central America and some models had it even developing over in the Pacific. This is obviously not the case, as we have what should be a tropical depression developing well to the north of where the models thought it would be. This may be confusing the computers, but this made logical sense to us given the weather pattern. The general thinking on the track still remains the same. We have completed the first leg where the storm gets drawn north, and now it will gradually turn back towards the west, probably in the form of a loop, though we may not see the system move all that much during the next day or two. Eventually though this should end up near the Yucatan sometime this weekend, and from there it will eventually get drawn north into the Gulf of Mexico.

As far as intensity goes, gradual organization will likely continue over the next couple days, but nothing too serious. However, steady intensification will likely set in if the system gets any kind of a convective core over the center, and at that point we would have the potential for another potent hurricane developing. Remember Paula developed in the face of worse dry air, and the pattern evolution over the next few days will be such that 99L will have to deal with less and less of it as time goes on. Land interaction will of course come into play, and the combination of interaction with the Yucatan and the subtropical jet over the gulf will mean that it will be hard to hit the U.S. with anything horridly strong if this gets drawn north by the next trough. However, the Caribbean countries in this area should be watching this closely just in case. The GFDL and HWRF go absolutely crazy on the intensity of this thing, with the GFDL taking it to Cat 5 in the Yucatan Channel. This is unrealistic and will not happen, but at the same time the models are showing you that intensification into a hurricane is very possible if this thing gets a core like Paula managed to do. The GFDL track is also likely biased poleward as usual, and is a worst-case scenario since the track is all over water. Overall, this is likely not a huge threat to the United States, but folks in the eastern gulf should keep an eye on this.

Typhoon Megi in the western Pacific is indeed trying to recurve now, defying the earlier JTWC track, and this teleconnects nicely to the idea that 99L will eventually get drawn north into the gulf.

Later next week we will have to watch the SE Caribbean and central Atlantic for possible mischief as pressures lower and upward motion returns to that area of the world.

We shall see what happens!

Invest 99L Visible/IR2 Satellite (click image for loop):



Invest 99L 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: 4:44 PM GMT on October 20, 2010

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99L likely to become Richard and threaten the Yucatan first; More trouble thereafter

By: Levi32, 4:33 PM GMT on October 19, 2010

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Invest 99L is the only attractive feature in the tropical Atlantic today. One can see the circulation near 17.5N, 83.5W, and this is already much farther north than the models have been insisting during the last couple days, which had it moving back westward into Nicaragua without coming north. However, we all know that reality leads the models, not the other way around, and as we have been talking about, the pattern makes more sense for a slow northward drift of 99L and then a turn west as the ridge builds in to the north. This should take the system towards the Yucatan, but not into Nicaragua and the eastern Pacific. I could see a looping track all the way back down to where it was yesterday, but I find it more likely that this will remain north of the Honduras coastline, with the southernmost track probably being right over it. After this point things become more uncertain, but the general thinking remains the same as it has been all along, that the system would move north initially, get turned west for a time into the Yucatan area, and then eventually get drawn out to the north by a trough digging into the central U.S. down the road. This means the eastern Gulf of Mexico, central America, and Cuba need to keep an eye on this system.

Now that this is out over water, we're going to see development, and you'll see the models start to catch onto this again now that it's out there and spinning away while pressures lower in the northwest Caribbean. This will likely acquire the name Richard at some point between now and Friday. Once it gets going, it will probably continue strengthening steadily until it encounters land, and with enough time over water this has the potential to become quite strong. We'll have to see how quickly it can get its act together. Overall, this is a situation people should continue to watch, while keeping in mind that the models are not always right, even when they are in consensus, and if this develops like I have been saying it will, then this will be a big bust for nearly all of the models.

Once again I will mention that after Richard our next threat comes from farther east, as pressures will be lowering in the eastern Caribbean and central Atlantic during the 8-15 day period. This makes good sense given the troughing pattern over the eastern seaboard, and we will have to watch for something coming into the eastern Caribbean and trying to develop by month's end, possibly into early November. The Caribbean will remain active into next month, and although it is now becoming harder to hit the United States with a hurricane, the Caribbean countries still have to be on alert for a potentially strong system before the season ends.

We shall see what happens!

Invest 99L Visible/IR2 Satellite (click image for loop):



Invest 99L 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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99L to stick around for a while; Possible threat from the east by end of the month

By: Levi32, 4:48 PM GMT on October 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.



I rewatched the video before posting it, and I have no idea what I was doing with my vocal processes lol. I was up until 2am last night writing, so my articulation this morning is rather bad. Please bear with me.

Invest 99L remains a broad area of low pressure, but the circulation is becoming increasingly recognizable with time, and one can see it currently centered just off the northeast tip of Nicaragua, where NNW winds are being reported along the coast. This system will likely drift northwestward today, perhaps popping out just north of the coast of Honduras later tonight.

The models are still surprisingly unexcited about development of this system, contrary to the almost unanimous agreement on strong development just a couple days ago. The pattern argues that development is still on the table, as conditions aloft are favorable in the western Caribbean with an anticyclone over top of the low, and the MJO will be supplying more largescale upward motion in the SW Atlantic Basin during the next 5-10 days. I don't think 99L will just go away and fizzle, but will be something to watch for several days.

Steering currents will be iffy and weak for most of this week in the western Caribbean, as although the broad upper trough to the north of the Caribbean will be tugging stuff northeastward, a ridge over central America will also be enforcing a light northerly flow, and this is what some of the models have 99L getting caught in, which would bring it into central America. Some such as the GFS even pop it out into the eastern Pacific where it tries to develop. I am still not seeing a move into the eastern Pacific as a likely one, and I think it's more sensible to expect 99L to drift around near central America and the western Caribbean for several days before really deciding what to do. Much will depend on how much time the center of the system spends over water and over land this week, as the overall organization and strength of the storm will determine both where it ends up being steered and how much chance it will have of ultimately getting named. Eventually a trough will come into the central United States, probably days 7-10, which will try to draw tropical moisture up into the Gulf of Mexico, possibly entraining 99L in the process. This will continue to be something the southeast US, central America, and the western Caribbean islands should be watching for rainfall implications and possibly more if this gets over water for a time.

Down the road we will have to watch farther east as the ITCZ lifts north over the central Atlantic and eastern Caribbean, lowering pressures as the pattern enforces upward motion in this area of the world. We will have to see if we can get one more development from the east by the end of the month or early November.

We shall see what happens!

Invest 99L Visible/IR2 Satellite (click image for loop):



Invest 99L 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: 4:51 PM GMT on October 18, 2010

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Still watching for Richard in the Atlantic; Philippines brace for Supertyphoon Megi

By: Levi32, 5:33 PM GMT on October 17, 2010

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We are continuing to watch for signs of Richard in the SW Caribbean as a monsoonal circulation cell very slowly develops east of Nicaragua. This will be a slow mover over the next 5 days, and may tangle a bit with central America. We have lost a lot of the strong model support we had over the last few days, and the models are suddenly much more skeptical. The GFS now develops Richard in the eastern Pacific, where of course it wouldn't be named Richard, and although the ECMWF ensembles still show hints of a storm moving up into the western Caribbean, there are fewer members in that camp.

However, just because the models drop a system doesn't mean this is a done deal. The pattern still supports the idea of tropical mischief in the western Caribbean, as we have been talking about the last couple days. The question we should now ask is does it make sense for no development, or development on the Pacific side. The answer is that it is possible. With the SOI burst coming across, the eastern Pacific will see the westerlies first, and thus there may be some more competition for low pressure on that side than the models were seeing before. Also, it is possible that as the upper trough moves across the eastern seaboard, the convergent flow aloft may temporarily suppress convection in the Caribbean and allow things to get more focused towards the Pacific.

However, the pattern we have been talking about is progressive, and the ridge that moves over the SE US will move along far enough to the east to allow another trough to dig in towards the Gulf of Mexico. This will be trying to draw tropical moisture out of central America and the Caribbean in 7-10 days, possibly in the form of a named storm. The general idea here remain the same, that the monsoonal low currently in the SW Caribbean will get drawn slowly north over the next few days, and then get turned west or southwest as the ridge builds in to the north. This may tangle the system with central America, but it should eventually move north again as it gets tugged out by the next trough. The exact path can't be known yet, but the general pattern hasn't changed, and we should continue to watch for mischief in this area. If we do get something to develop, it could end up being a big deal if it gets time over water.

Looking ahead, we will still have to watch farther east as pressures lower in the eastern Caribbean and central Atlantic. We may see one last storm come from east of 60W before the month is out.

Out in the western Pacific, Supertyphoon Megi is 10-12 hours from landfall in Luzon, the northernmost island of the Philippines. This is a catastrophic storm packing winds of 180mph with gusts to 220mph. Our prayers are with the people over there.

We shall see what happens!

Invest 99L Visible/IR2 Satellite (click image for loop):



Invest 99L 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: 5:41 PM GMT on October 17, 2010

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Richard likely to develop and be a threat next week; More mischief in store afterward

By: Levi32, 5:08 PM GMT on October 16, 2010

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The Atlantic is quiet for the moment with no named storms currently in progress. A small feature of low pressure in the central Atlantic is likely in too dry of an environment to develop. A developing monsoonal circulation cell near Panama will be the focus point for potential development next week as this area slowly organizes and gets drawn north with time. There is a good possibility we will see Richard develop out of this by late next week. There is logical support for this from the SOI burst currently coming across the Pacific, which argues for mischief in the Caribbean in 5-10 days.

With the strong trough into the eastern US during the next 5 days it makes sense that any developing tropical system in the SW Caribbean will get drawn northward for a time. However, days 7-10 will probably see a ridge build in over the SE US and force the trough out, directing what would be Richard towards the west for a time. This idea is supported by the models and the fact that we have a typhoon in the western Pacific moving straight west towards China, a typical teleconnection for ridging over the southeastern US.

Of course the exact track and potential intensity of Richard remain unknown at this time, but my current idea is that the system will be drawn north into the western Caribbean as it is trying to develop, and then will get forced westward for a time, possibly close to or over central America. From there I think it will eventually get drawn north by some trough coming to pick it up, as it is rather hard to stick something into central America and hold it down there at this time of year when troughs are getting pretty deep. The countries of central America, the western Caribbean islands, and the SE US all need to keep a close eye on this situation next week and the following week. The pattern is quite favorable in the Caribbean and we could get a monsoonal depression that develops quicker than most, potentially becoming a powerful hurricane in the Caribbean if it gets time over water.

Looking even further ahead....mischief may be brewing in the central Atlantic and eastern Caribbean after Richard leaves, as the perturbations in the atmosphere continue to march eastward. The upward motion argues for lowering of pressures and a drawing north of the ITCZ in the central Atlantic, possibly resulting in one last storm trying to come from east of 60W and developing in the eastern Caribbean. This is two weeks or so down the road, but is something to remember because once again, Richard may not be the very end of the game.

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):






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Potentially dangerous Richard may develop later next week and be a big threat to land

By: Levi32, 4:31 PM GMT on October 15, 2010

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Paula has finally been sheared off and her main energy is heading out to the ENE as the surface center lags behind. The center is now north of Cuba passing through the southernmost Florida Straights, a bit farther south than I thought but certainly farther north than the earlier NHC ideas, so a compromise was made here. The biggest point is that Paula is not drifting back into the Caribbean to be a threat for regeneration.

The video today looks down the road to what could be Richard developing out of the monsoon trough in the SW Caribbean later next week. The runs of the GFS are split with some taking the storm up past Jamaica and over Cuba to the east of Florida, while some take it into central America before turning it north. I favor the latter scenario more, as there are factors arguing for ridging over eastern North America during the 7-12 day period which would direct a potential storm farther west before recurving. Typhoon Megi is setting up a nice teleconnection for ridging in the eastern U.S., and the MJO is also playing a strong role in supporting the ridge, which I look at in the video.

Overall, this is still a ways out but there is plenty of model support for development in the SW Caribbean sometime next week, and this is something that Jamaica, Cuba, central American countries, and the southeast US should monitor closely. The setup right now with the focused ball of heat near Panama is one where we could get abnormally rapid development of a monsoon depression that could end up being a rather dangerous storm in the Caribbean.

Further down the road after Richard we may have to watch for one last storm coming from east of the Caribbean, as the pattern will favor lowering pressures in the central Atlantic and a drawing north of the ITCZ.

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):






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Paula weakens, mostly a rain threat; Mischief possible in the Caribbean next week

By: Levi32, 4:26 PM GMT on October 14, 2010

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In the video when I was talking about hurricane-force gusts in Cuba I was meaning to say "50kt gusts".

Paula has weakened considerably since yesterday. The falling off was a bit greater than I expected. Land interaction with Cuba by such a small storm can be partially blamed for this, and it is possible that the concentric eyewalls observed at one point by the recon yesterday also contributed to making the storm more vulnerable to the wind shear that was already over it. However, the storm's structure remains rather impressive, and strong gusts may continue to rack Cuba's coastline today along with heavy rains.

My take on the track yesterday was to skirt NW Cuba and then head out through the Florida Straights. Paula is indeed farther north than the NHC has had it in preceding forecasts, and they have continually had to adjust north. However, they still have the remains getting stuck and curving back down into the Caribbean as the remnant low dissipates. It will be interesting to see just how much of the storm escapes, as I think at least a portion of it will. At this point since the storm has weakened enough, we may see a decoupling later today with the surface center getting pushed down into Cuba while the mid-level center takes off to the ENE with the deep-layer flow. About half of the models think that the surface center will go out as well, but I can see how it may get left behind if the system decouples, which is quite possible. However, the main energy of the system will be leaving. At this point, I don't believe the remnants of Paula will be any significant threat for redevelopment in the Caribbean.

What may be more of a threat in the Caribbean is the storm that the GFS and NOGAPS develop later next week which would be named Richard, coming up out of the monsoon trough north of Panama and threatening Cuba and the Yucatan Channel. This could make sense given the recent negative burst in the SOI, which will be having implications in the Caribbean in 5-10 days in the form of westerlies coming out of the Pacific and creating convergence. The models are a little more bullish on this system than most of our recent storms, and such a development could have the potential to be a potent hurricane in the NW Caribbean. We will have to continue to keep an eye on this general area for mischief over the next couple of weeks. These land areas are still going to be threatened, as we have seen with Paula.

We shall see what happens!

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



Hurricane Paula 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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Paula threatens Cuba and south Florida; Watching for Richard down the road

By: Levi32, 4:28 PM GMT on October 13, 2010

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Hurricane Paula is the big story today. Paula is a very small storm, with a central core that fits right in the Yucatan Channel without producing particularly dangerous weather on either the Yucatan or Cuban coasts, which is pretty remarkable. Despite the NHC calls for weakening yesterday morning, saying Paula had 12 hours max to maintain hurricane intensity, she is in fact still a solid Cat 2 and we will be getting another recon plane in there later today to see how she is doing compared to last night.

The big question is where Paula is going to go. There has been a massive model spread with this system and it has been a very interesting forecast situation. Though I have not been here to say so, I have been thinking the NHC track has been too far south, and indeed they have been shifting it north bit by bit since yesterday, but they still have Paula weakening and getting stuck over Cuba by high pressure building into the Gulf of Mexico. Why would this happen when there is a trough digging into the eastern seaboard? Their reasoning is that wind shear and land interaction would weaken the storm, make it very shallow, and allow the shallow steering flow to push it back to the south.

However, the wind shear is not nearly as detrimental to Paula as the NHC believes, as she is moving aligned with the jetstream, and the idea that she doesn't have enough outflow channels to maintain herself is a bogus one. When you have a storm this small, you only need that one big exhaust vent to the northeast where the jetstream is taking air out of the top of the storm. In a bigger system you would see weakening because one outflow channel isn't enough, but for a storm like Paula, one exhaust vent is all you need. We could very well see Paula try to maintain Cat 1 intensity through the Florida Straights on her way out, with at least hurricane-force gusts still racking the waters over there. I'm going to go ahead and say that I believe this will not get stuck over Cuba but will rather pass through the Florida Straights and on out to the northeast within the deep-layer flow. Even the high-resolution models are initializing the height field way too high in the storm area based on recon data, and Paula is "taller" than some of these models may think, because her small size makes it hard for the computer to "see" the storm with their limited resolution.

Overall, this is something that the western half of Cuba and south Florida should be keeping a close eye on. The NHC was prudent in issuing a tropical storm watch for the Florida Keys due to the forecast uncertainty. If Paula's center passes right through the straights, then the small size of the core may end up sparing both Cuba and Florida any significant weather, but any deviation towards either coast could result in some nasty issues for one of them.

Looking ahead....the pattern will continue to favor mischief in the western Caribbean during the next couple weeks, and we will have to watch for Richard possibly trying to develop and move up to the north, threatening land again. We are up to 16 named storms. My forecast was for 18. We'll see how the final tallies add up, but we likely have a couple punches left in the season, and hopefully they will continue to spare the United States any big hits.

We shall see what happens!

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



Hurricane Paula 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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Otto likely to develop and recurve; Watching for Paula in the Caribbean later

By: Levi32, 3:04 PM GMT on October 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.



Note 10-7-10: This is mid-term week and thus I am too busy to do updates every day. There is not an awful lot of new stuff to talk about anyway.

The main features in the tropical Atlantic today are two cold-core upper lows stacked over surface lows in the central Atlantic. The one north of Puerto has been designated Invest 97L, and will likely try to develop into a tropical depression or tropical storm over the next couple days as convection warms the air column and weakens the upper low that is over top of it. This will be recurving out to the northeast and is not a threat to the United States. Rainfall in the Caribbean islands will be the only big effect of this system. The other system to the east will likely weaken and merge with what would be named Otto as he exits to the northeast.

The video today shows how with the AO and NAO tanking negative over the next 5-8 days, one should be worried about troughs digging in and leaving pieces behind in the tropics. Indeed the GFS illustrates this concern by leaving a piece behind in the Caribbean from this trough that Otto will be recurving into, and we may see Paula try to develop in the SW Caribbean from this trough-split during the next week or so and move up to the north. This could be a potential concern for Cuba and Florida if development does occur.

Down the road the pattern will continue to favor activity in the Caribbean through the end of this month and we are likely to knock a couple more names off the alphabet here before the season winds down. I also show in the video how the pattern is forcing the subtropical jetstream to show itself over the Gulf of Mexico and SW Atlantic, and this is the time of year when we start watching for that feature to develop in preparation for the winter. This typically sets up a wall of strong westerlies that shear any tropical system trying to make a run at the United States, but that doesn't mean they won't be making a run. What it does mean is that the storms that do make a run at us will be more likely to be weaker. We can't let our guard down as we all remember Wilma in late October of 2005, a major hurricane landfall in Florida, so they can and do happen late in the season. However, the risk of a major landfall in the United States will be decreasing as time goes on. The Caribbean still has to worry though.

We shall see what happens!

Invest 97L Visible/IR2 Satellite (click image for loop):



Invest 97L 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: 4:04 PM GMT on October 07, 2010

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97L not a threat to the U.S.; Simmerings going on in the Caribbean as pattern reloads

By: Levi32, 3:59 PM GMT on October 01, 2010

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Nicole is gone, but has left a ravaged eastern U.S. in her wake. Winds of over 60mph and historic rains bashed North Carolina last night, and this true tropical event has damaged many areas heavily.

We now look to the east as Invest 97L moves WNW in the central Atlantic. A TUTT low lifting out in the face of all the heat in the Caribbean will be providing ventilation for this system, but only the Canadian is really excited with development on this. Now that I see the center likely passing north of the Caribbean now I don't think this is a threat to the United States and will eventually turn out to sea, though it will be interesting to see if we get a storm out of it.

The pattern for the next 10 days or so will be one that deflects threats from the east, and stuff coming out of the central Atlantic will likely get recurved. However, things will not be completely dead as the troughing likes to hang back towards the Gulf of Mexico and split pieces away which ventilate the western Caribbean. Indeed the modeling is seeing low pressure in the NW Caribbean hanging back to the southwest of 97L even as it recurves out to the northeast. This will have to be watched by central America and the western Caribbean islands.

As we get out towards the mid-point of October things should start to change again and come back towards where we were before Matthew and Nicole formed, with ridging showing back up in SE Canada and the northeast US. We are in the fall now, a transition period between summer and winter that means the pattern will be dynamic as it sets up for the winter season, and changes back and forth are to be expected. As soon as the ridge shows back up south of the Aleutians with a trough into western Canada we will have to start watching for threats to the U.S. coast again. After things simmer in the Caribbean during the next week or so we may have a fairly quiet period of several days while the pattern reloads, but once it comes back around we will have to watch again for trouble in the SW Atlantic Basin that could threaten land. We still have a few more storms to get through before this season will be over.

We shall see what happens!

Invest 97L 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: 4:02 PM GMT on October 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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