Tropical Tidbits from the Tundra

91L slow to organize, should eventually develop and threaten the Puerto Rico Area

By: Levi32, 7:06 PM GMT on July 31, 2011

Please note that these tidbits do NOT reflect the official forecasts of the National Hurricane Center, and should not be taken as such. While tropical cyclones exist in the Atlantic, the official NHC forecasts will be posted in the lower part of this blog. Please refer to those when making decisions, and heed the advisories and evacuation statements of your local National Weather Service Office.

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 with the video, and please feel free to ask me any questions regarding what I talk about in these tidbits, or about the weather in general. You can post in either of my blogs or on Youtube. I will do my best to answer. Thanks for stopping by!

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The main feature in the Atlantic today remains invest 91L east of the lesser Antilles. This system has struggled to organize since yesterday due to some interesting happenings. I noted yesterday afternoon that the tropical wave which 91L was associated with has decided to leave 91L behind, racing off to the west of the low pressure area. This may be to much stronger trade winds just off to the north of 91L, pushing the wave axis out ahead of the system. A secondary low is hanging onto the southern end of this tropical wave, and is competing with the eastern circulation which is still being called 91L's center. The models all show the eastern circulation eventually becoming dominant and taking over, which would make sense given that it has the monsoonal support. However, if more a compromise occurs instead, and the western low tries to hang back and merge with the eastern one, then we may see 91L enter the eastern Caribbean a tad farther south than the models currently have it, so it will be interesting to see where the main low eventually consolidates. The hurricane hunters are in 91L now, and I have doubts that they will find this system classifiable as a tropical cyclone, given that neither of the low centers may be fully closed, and the system is extremely elongated. Development with this system was never supposed to be rapid, but gradual, so we should get Emily out of this eventually, but perhaps a bit slower than expected given the organizational issues today.

The track for this system seems pretty straight-forward for the short-term, with the models in excellent agreement on a track over the Leeward Antilles late tonight and tomorrow, and then the Puerto Rico area during the middle of the week, near Wednesday. Again, this path could be tweaked a tad depending on where the main low eventually consolidates. The track thereafter becomes more fuzzy, as we will have to worry about potential threat to the Bahamas and the United States. I show in the video how the pattern doesn't support either a straight WNW punch across Florida into the gulf, or a slow, sweeping recurve into North Carolina. Rather, the storm will likely eventually recurve sharply off to the northeast, more than likely avoiding the Carolinas when it does. The question is whether the system will get far enough west to affect Florida and the western Bahamas as it recurves. I still want to see how the system looks in the Puerto Rico area before I make a call on which scenario is most likely, as a lot will depend on the strength of the storm, and as we have seen today, some organizational issues are making it uncertain as to how strong it will be near the big island chain. We're still talking about something 6-7 days away, so we can afford to wait a little bit before nailing down the long-term track. The focus right now will be on the lesser Antilles, Puerto Rico, the Virgin Islands, and the Dominican Republic, as these areas should be preparing for a possible tropical cyclone within the next 3 days.

We shall see what happens!

Invest 91L Visible/IR2 Floater (Click for loop):



Invest 91L Track Forecast 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

91L to become Emily - will affect Leeward Islands first - may or may not recurve

By: Levi32, 6:36 PM GMT on July 30, 2011

Please note that these tidbits do NOT reflect the official forecasts of the National Hurricane Center, and should not be taken as such. While tropical cyclones exist in the Atlantic, the official NHC forecasts will be posted in the lower part of this blog. Please refer to those when making decisions, and heed the advisories and evacuation statements of your local National Weather Service Office.

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 with the video, and please feel free to ask me any questions regarding what I talk about in these tidbits, or about the weather in general. You can post in either of my blogs or on Youtube. I will do my best to answer. Thanks for stopping by!

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Tropical Storm Don vanished last night over southern Texas, as if someone blew a candle out. Unfortunately, not a lot of rain came onshore with this system as it was weakening at landfall. My forecast for Don turned out pretty well, with the 50mph landfall intensity verifying perfectly, as well as the landfall forecast for between Brownsville and Corpus Christi, closer to Corpus.

We are now moving on to invest 91L, which should become Tropical Storm Emily, probably before reaching the Antilles Islands in a couple of days. It is currently a very broad circulation, elongated west to east, with multiple surface vortices. This system will need to consolidate in order to develop. Dry air to the northwest may be a limiting issue in the short-term, but this should have no trouble developing into our 5th named storm. This system may have a chance to go on to become our first hurricane of the season later on if it doesn't run into something big like Hispaniola right away. The Leeward Antilles will be affected first, with Puerto Rico and the Virgin Islands likely next in line. What should be Emily by then will likely not be a hurricane at the Leewards, as it doesn't have enough time before then to strengthen that much, but folks should be preparing for a tropical cyclone. Puerto Rico may have to deal with a strengthening system, and there is a better chance that it could be a hurricane there if Emily develops fast. Upper-level conditions are pretty favorable, and despite some dry air in the way, this storm will be likely to steadily intensify for a while.

After the northeastern Caribbean, we will have to talk about potential impacts on Hispaniola, the Bahamas, and maybe even the southeastern U.S. or Cuba. The majority of the models currently call for recurvature, though there remains the possibility that this storm tries to come farther west. I show in the video how the pattern is fragile, just like it was when Don came across (remember it was forecasted to recurve). The steering currents will be weak north of the Bahamas during the middle of next week, and there are still a lot of open doors for future Emily here. I discuss those in the video. The track will depend a lot on 91L's intensity, because a weaker system will be more likely to track west, while a strong system like a hurricane will be more likely to recurve. For that reason, I want to see how 91L looks by the time it reaches the northeast Caribbean before I sell myself on whether it recurves east of the U.S. or not.

We shall see what happens!

Invest 91L Visible/IR2 Floater (Click for loop):



Invest 91L Track Forecast 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

Don to make landfall tonight near Corpus Christi, Texas; 91L to be watched closely

By: Levi32, 1:46 PM GMT on July 29, 2011

Please note that these tidbits do NOT reflect the official forecasts of the National Hurricane Center, and should not be taken as such. While tropical cyclones exist in the Atlantic, the official NHC forecasts will be posted in the lower part of this blog. Please refer to those when making decisions, and heed the advisories and evacuation statements of your local National Weather Service Office.

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 with the video, and please feel free to ask me any questions regarding what I talk about in these tidbits, or about the weather in general. You can post in either of my blogs or on Youtube. I will do my best to answer. Thanks for stopping by!

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Tropical Storm Don is 12-15 hours from landfall near or just south of Corpus Christi, Texas. A slight jog to the north has occurred overnight, taking Don just north of the current NHC track. Don has been maintaining a strong ball of convection west and southwest of his center throughout the night, but without any strengthening since yesterday's evening hours. The recon this morning just went in and found the pressure up to 1004mb, actually higher than it was before, indicating possible weakening. Winds reported by the plane remain lackluster and may not even support a 50mph tropical storm, which is what the current NHC intensity is. I see no reason why Don's intensity should change significantly before landfall. This will not be a big deal for Texas at all. Rainfall will make this storm much more of a benefit than a danger, and we are hoping that the big ball of convection south of Don's center will come onshore over deep south Texas if the center moves in near Corpus Christi. Some light rainbands will give some folks some showers north of where Don comes onshore, but nothing very heavy, unfortunately. Don is a small, weak storm, and is not a drought-buster, but relief will be brought to some folks in the southern portion of the state.

Looking ahead....as soon as Don is inland, all eyes turn eastward to Invest 91L, the tropical wave mentioned during the last couple days that could potentially be our next storm, named Emily. The wave has a closed low, though broad, and in proximity to dry air to the north and west. The wave looks a lot better-defined than pre-Don did over in that area, and this system may have even better conditions ahead of it west of 55W than Don had.

Steering will be the big issue to resolve with 91L. The eastern Caribbean will be the first to be affected as the wave moves WNW across the lesser Antilles in 3-4 days. After that, a trough comes off of the eastern seaboard on all of the models, and will attempt to recurve the system. The forecast problem here is similar to with Don, as that wave was forecasted to recurve into a trough as well, but that trough lifted out too fast to grab hold of it. Here, the models are showing the same kind of thing, lifting the trough out and flattening the flow across the western Atlantic within a couple days of the trough digging in. This may not be enough time to fully recurve the wave, but it is a long way off still, and either scenario is possible. If the wave does recurve, it would most likely be between Cape Hatteras and Bermuda, and a sharp turn northeast or ENE, not a sweeping rider up the length of the eastern seaboard, given that the trough is not going to be heavily amplified.

Overall, this wave is one to watch closely, and will be monitored as it transverses the central Atlantic over the weekend. I will be able to devote more attention to it after Don has made landfall.

We shall see what happens!



Official NHC TS Don Public Advisory:

000
WTNT34 KNHC 291156
TCPAT4

BULLETIN
TROPICAL STORM DON INTERMEDIATE ADVISORY NUMBER 7A
NWS NATIONAL HURRICANE CENTER MIAMI FL AL042011
700 AM CDT FRI JUL 29 2011

...DON CONTINUES MOVING TOWARD SOUTH TEXAS WITH LITTLE CHANGE IN
STRENGTH...


SUMMARY OF 700 AM CDT...1200 UTC...INFORMATION
----------------------------------------------
LOCATION...25.7N 94.3W
ABOUT 255 MI...395 KM SE OF CORPUS CHRISTI TEXAS
ABOUT 195 MI...315 KM E OF BROWNSVILLE TEXAS
MAXIMUM SUSTAINED WINDS...50 MPH...85 KM/H
PRESENT MOVEMENT...WNW OR 295 DEGREES AT 14 MPH...22 KM/H
MINIMUM CENTRAL PRESSURE...1000 MB...29.53 INCHES


WATCHES AND WARNINGS
--------------------
CHANGES WITH THIS ADVISORY...

NONE.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT...

A TROPICAL STORM WARNING IS IN EFFECT FOR...
* TEXAS COAST FROM THE MOUTH OF THE RIO GRANDE TO MATAGORDA

A TROPICAL STORM WARNING MEANS THAT TROPICAL STORM CONDITIONS ARE
EXPECTED SOMEWHERE WITHIN THE WARNING AREA...IN THIS CASE WITHIN 24
HOURS.

INTERESTS IN NORTHEASTERN MEXICO SHOULD MONITOR THE PROGRESS OF DON.

FOR STORM INFORMATION SPECIFIC TO YOUR AREA IN THE UNITED
STATES...INCLUDING POSSIBLE INLAND WATCHES AND WARNINGS...PLEASE
MONITOR PRODUCTS ISSUED BY YOUR LOCAL NATIONAL WEATHER SERVICE
FORECAST OFFICE. FOR STORM INFORMATION SPECIFIC TO YOUR AREA OUTSIDE
THE UNITED STATES...PLEASE MONITOR PRODUCTS ISSUED BY YOUR NATIONAL
METEOROLOGICAL SERVICE.


DISCUSSION AND 48-HOUR OUTLOOK
------------------------------
AT 700 AM CDT...1200 UTC...THE CENTER OF TROPICAL STORM DON WAS
LOCATED NEAR LATITUDE 25.7 NORTH...LONGITUDE 94.3 WEST. DON IS
MOVING TOWARD THE WEST-NORTHWEST NEAR 14 MPH...22 KM/H...AND THIS
GENERAL MOTION IS EXPECTED TO CONTINUE UNTIL LANDFALL LATE TODAY OR
EARLY SATURDAY.

MAXIMUM SUSTAINED WINDS REMAIN NEAR 50 MPH...85 KM/H...WITH HIGHER
GUSTS. SOME STRENGTHENING IS POSSIBLE UNTIL LANDFALL...WITH
WEAKENING LIKELY BY SATURDAY MORNING. AN AIR FORCE RESERVE
HURRICANE HUNTER AIRCRAFT IS CURRENTLY APPROACHING THE CENTER OF
DON.

TROPICAL-STORM-FORCE WINDS EXTEND OUTWARD UP TO 105 MILES...165 KM
FROM THE CENTER.

ESTIMATED MINIMUM CENTRAL PRESSURE IS 1000 MB...29.53 INCHES.


HAZARDS AFFECTING LAND
----------------------
WIND...TROPICAL STORM CONDITIONS ARE EXPECTED WITHIN THE WARNING
AREA BY LATE TODAY.

STORM SURGE...WATER LEVELS WILL RISE BY AS MUCH AS 1 TO 2 FEET ABOVE
GROUND LEVEL...MAINLY ALONG THE IMMEDIATE COAST NEAR AND TO THE
NORTHEAST OF WHERE THE CENTER MAKES LANDFALL. NEAR THE COAST...THE
SURGE WILL BE ACCOMPANIED BY LARGE AND DAMAGING WAVES.

RAINFALL...DON IS EXPECTED TO PRODUCE TOTAL RAIN ACCUMULATIONS OF
3 TO 5 INCHES FROM SOUTH TEXAS INTO EXTREME NORTHEASTERN MEXICO...
WITH POSSIBLE ISOLATED MAXIMUM AMOUNTS OF 7 INCHES.


NEXT ADVISORY
-------------
NEXT COMPLETE ADVISORY...1000 AM CDT.

$$
FORECASTER BEVEN



Tropical Storm Don Radar Loop (Brownsville, TX):



Tropical Storm Don Visible/IR2 Floater (Click for loop):



Tropical Storm Don Track Forecast 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: 1:48 PM GMT on July 29, 2011

Permalink

Don to remain a moderate tropical storm and bring some rain to Texas

By: Levi32, 1:45 PM GMT on July 28, 2011

Please note that these tidbits do NOT reflect the official forecasts of the National Hurricane Center, and should not be taken as such. While tropical cyclones exist in the Atlantic, the official NHC forecasts will be posted in the lower part of this blog. Please refer to those when making decisions, and heed the advisories and evacuation statements of your local National Weather Service Office.



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 with the video, and please feel free to ask me any questions regarding what I talk about in these tidbits, or about the weather in general. You can post in either of my blogs or on Youtube. I will do my best to answer. Thanks for stopping by!



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The main feature today is Tropical Storm Don, moving WNW across the central Gulf of Mexico towards the Texas coastline. Don was upgraded straight to a tropical storm yesterday after the recon found a respectable pressure of 1001mb and TS-force winds. During the rest of the day, Don struggled due to proximity to land, dry air entrainment, and wind shear out of the northeast due to the big southern U.S. ridge, all issues that we discussed yesterday would be negative influences on Don. These will continue to hinder the storm during its journey across the gulf. A new burst of convection is developing just to the southeast of the surface center, indicating that Don may make some recovery today and strengthen a little bit. A moderate tropical storm at peak still looks good to me, around 50mph with the possibility for 60mph if Don can fire convection over the center today or tomorrow.



With track, Don was able to become a deeper system yesterday morning and exert a strong presence at the 500mb level, allowing him to feel the mid-level steering flow and move WNW. The surface flow is still much more northerly, and keeps trying to pull the surface center out from under the convection. There is still a possibility that this could succeed in pulling Don farther up the Texas coast if he weakens before landfall, but I think he will hold together just enough to continue to be steered by the big southern U.S. ridge into southern Texas. The models have come into better agreement since yesterday, and almost all of the northerly solutions that brought Don into the Galveston area yesterday are now in line with my idea of southern Texas between Brownsville and Corpus Christi late tomorrow night or early Saturday morning. Given the shape of the coastline, I would expect landfall to be closer to Corpus than Brownsville.



Overall, Don is not a huge wind threat, though folks should still take the necessary precautions. At this point, we are hoping for Don to hold together to bring Texas some rain, more than we are worried about this blowing up into a dangerous hurricane.



We shall see what happens!

Updated: 1:47 PM GMT on July 29, 2011

Permalink

90L poised to become TD #4, and perhaps Don

By: Levi32, 3:07 PM GMT on July 27, 2011

Please note that these tidbits do NOT reflect the official forecasts of the National Hurricane Center, and should not be taken as such. While tropical cyclones exist in the Atlantic, the official NHC forecasts will be posted in the lower part of this blog. Please refer to those when making decisions, and heed the advisories and evacuation statements of your local National Weather Service Office.

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 with the video, and please feel free to ask me any questions regarding what I talk about in these tidbits, or about the weather in general. You can post in either of my blogs or on Youtube. I will do my best to answer. Thanks for stopping by!

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Invest 90L will remain the primary focus today, and likely for the next couple days. 90L looks better than it ever has this morning, with what appears to be a more well-defined center showing up partially naked on satellite imagery, now moving out of the Yucatan Channel and entering the southern Gulf of Mexico. This center may or may not be closed, and the hurricane hunters will be flying in in a few hours to see whether this system has become a tropical depression. Thunderstorm activity has been strong for over 24 hours now, which is a good sign for development, but most of the activity is confined south of the surface center. This is due to a couple of things. One is northeasterly wind shear induced by the strong upper ridge over the southern United States, pushing the thunderstorms to the south of 90L's center. The other is that 90L is actually being pulled in two different directions by the steering layers right now. The surface flow over the gulf is trying to pull 90L's surface center more northwestward towards SW Louisiana, while the mid-level flow around the U.S. ridge is pushing 90L's mid-level center more WNW. This is helping to pull the surface center out from under the convection and partially exposing it on visible satellite imagery.

The aforementioned difference in steering currents is key, as it will define where 90L will go. If 90L strengthens into a moderate tropical storm or stronger, it will likely follow the mid-level flow more, WNW towards southern or central Texas. However, if the system remains weak or falls apart, it will follow the surface flow more towards the Galveston area or SW Louisiana. The question is whether 90L will strengthen. I expect a tropical depression today, and 90L will likely make a run at becoming Tropical Storm Don at some point during its life. There is a pool of dry air in the central Gulf of Mexico, confirmed by soundings in Cancun this morning, that will likely negatively impact 90L during its crossing of the gulf, along with the wind shear that is unlikely to significantly abate during the next few days. Given these difficulties, I expect only gradual strengthening, with the possibility for a weak or moderate tropical storm. Anything stronger than that I find unlikely at this time, but things can always change on a dime, so folks should keep an eye on it as always. Given that some strengthening is possible, I expect 90L to curve slightly WNW and move into Texas somewhere between Brownsville and Corpus Christi, though this could easily shift northward to the Galveson area and SW Louisiana if the system remains weaker. Either way, some beneficial rainfall may be brought to drought-stricken Texas, which would be great for them.

We shall see what happens!


Tropical Storm Don Visible/IR2 Floater (Click for loop):



Tropical Storm Don Track Forecast 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: 1:53 AM GMT on July 28, 2011

Permalink

Invest 90L comes back to life - may have a shot at development

By: Levi32, 1:30 PM GMT on July 26, 2011

Please note that these tidbits do NOT reflect the official forecasts of the National Hurricane Center, and should not be taken as such. While tropical cyclones exist in the Atlantic, the official NHC forecasts will be posted in the lower part of this blog. Please refer to those when making decisions, and heed the advisories and evacuation statements of your local National Weather Service Office.

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 with the video, and please feel free to ask me any questions regarding what I talk about in these tidbits, or about the weather in general. You can post in either of my blogs or on Youtube. I will do my best to answer. Thanks for stopping by!

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Invest 90L has been resurrected by the NHC after being decommissioned yesterday due to very low expectations for development. We were talking about this wave as a potential trouble-maker near the eastern Caribbean last week when it was still well-defined, but the strong trade winds of the central Caribbean caused the wave to lose its circulation over the weekend and eventually all of its convection as well. Development chances over the past couple of days have not looked that great, but last night and this morning a bit of life has returned to the system, as a new ball of convection is developing south of western Cuba over the wave axis. Trade winds are now piling into the area from the ESE and forcing air to rise over the extremely warm waters of the NW Caribbean, allowing 90L to try to make another attempt at development. Upper-level conditions are only marginal, and will make 90L have to struggle hard if it's going to develop. 90L will have to overcome first an elongated upper trough over the southeastern Gulf of Mexico, and then easterly shear from the big ridge over the southern United States. If 90L can throw enough heat out of its thunderstorms into the Gulf of Mexico, it may have a chance to form a pocket of light winds aloft for itself, but it will be difficult, which is why there is no real model support for development.

The track of 90L has been continually shifting slightly farther south with time. It wasn't that long ago that the models had this system recurving out to sea east of the U.S., but the pattern was discussed here as being one that favored a more WNW track towards the Caribbean islands and SE US. The track now seems to be settled in the general direction of southern Texas or extreme northeastern Mexico as 90L moves along the periphery of the southern U.S. ridge. This track may get tweaked if 90L actually develops and becomes a "taller" system that can be steered by different layers of the atmosphere. 90L may bring some very needed rains to parts of Texas, but shower activity may be very sparse if the wave never develops. Significant rainfall will likely be confined to a situation where 90L comes into the coast as a tropical cyclone.

Given the current organization trend, invest 90L still has a small shot at development, and despite marginally unfavorable upper-level conditions, a tropical depression or a weak tropical storm cannot be ruled out as 90L crosses the rest of the NW Caribbean and the Gulf of Mexico. Chances are that if it is not already close to a tropical depression by the time it leaves the Caribbean, then it won't develop in the gulf. The feature will continue to be monitored closely.

We shall see what happens!



Invest 90L Track Forecast 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: 1:44 PM GMT on July 26, 2011

Permalink

One-two wave punch coming to the Caribbean through Florida area

By: Levi32, 2:02 PM GMT on July 22, 2011

Please note that these tidbits do NOT reflect the official forecasts of the National Hurricane Center, and should not be taken as such. While tropical cyclones exist in the Atlantic, the official NHC forecasts will be posted in the lower part of this blog. Please refer to those when making decisions, and heed the advisories and evacuation statements of your local National Weather Service Office.

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 with the video, and please feel free to ask me any questions regarding what I talk about in these tidbits, or about the weather in general. You can post in either of my blogs or on Youtube. I will do my best to answer. Thanks for stopping by!

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Bret and Cindy are leaving the scene today, and will soon be dissipated/extratropical. Our attention turns to the wave that we have been watching in the central Atlantic, which has now been tagged invest 90L. This wave will be moving a bit farther south than the models had it last week, and will pass very close to the big Caribbean islands, likely curving up towards the Bahamas and Florida early next week by Tuesday. Rains will come with this feature, but the question is whether tropical development may be an issue. The wave has a very broad circulation with it, wrapped up with some dry air, but popcorn convection going off west of the center since last night is indicating a moistening atmosphere ahead of the wave, and with an upper low backing westward ahead of it over the Caribbean, environmental conditions could favor some gradual development as it approaches the big Caribbean islands. As it moves farther north, the bit southern U.S. ridge may shear it a bit, limiting significant development until it is very close to the U.S. coastline. None of the models are appreciably excited about developing 90L, and most of them keep it open as it moves WNW. However, it is suspicious-looking enough to keep a close eye on, especially since it is aimed towards land. Notice that the pattern we were talking about last week is coming to fruition and aiming this feature towards the coast, rather than away from it.

A 2nd punch is coming from the wave behind 90L, which is also exhibiting broad turning SW of the Cape Verde Islands. The steering pattern should bring this wave into the same general area of the Bahamas, Florida, and NW Caribbean 4-6 days after 90L, making this pattern a one-two punch as we head into the first week of August. This 2nd wave may have a similar chance to develop, but again, no model currently develops it. However, with this pattern starting to aim these things at land multiple times in a row, both of these will be worth watching carefully. The pattern is going towards one in August that will favor tropical waves that have to come through the TUTT in the central Atlantic, but then find favorable conditions close to the U.S. coast and northern Caribbean islands. Such a pattern could easily get someone nailed with a potent storm sooner rather than later next month.

We shall see what happens!



Invest 90L Track Forecast 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: 2:19 PM GMT on July 22, 2011

Permalink

Bret leaving; 99L may develop; CATL wave possibly a problem down the road

By: Levi32, 3:12 PM GMT on July 20, 2011

Please note that these tidbits do NOT reflect the official forecasts of the National Hurricane Center, and should not be taken as such. While tropical cyclones exist in the Atlantic, the official NHC forecasts will be posted in the lower part of this blog. Please refer to those when making decisions, and heed the advisories and evacuation statements of your local National Weather Service Office.

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 with the video, and please feel free to ask me any questions regarding what I talk about in these tidbits, or about the weather in general. You can post in either of my blogs or on Youtube. I will do my best to answer. Thanks for stopping by!

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The Atlantic remains a fairly active place for mid-late July. Tropical Storm Bret continues to hold his own, despite being sheared and injected with dry air, and is slow to weaken as he moves northeast, though he will continue to weaken and eventually fizzle as he integrates into the mid-latitude westerlies. A passing shower or two may touch Bermuda, but he is no real threat to anyone.

A feature that I neglected to mention over the last few days is the old competing circulation that was initially just northeast of Bret along the frontal boundary that spawned them both, and this low is now quite far out to the northeast of Bret, looking very well-defined and tropical in nature, perhaps more so than Bret. This feature has been tagged invest 99L, and now has a high chance of development from the NHC. This is another random middle-of-nowhere situation where the system could have been classified a while ago, but won't be unless it persists for quite a long time, due to the fact that it is in the middle of nowhere. We may get TD 3 or Cindy out of this, but it will be a subjective decision by the NHC as to whether we do or not.

The bigger story that may develop next week is the large tropical wave in the central Atlantic. This wave, despite lacking convection, has a deceptively deep moisture field with it, and although there is dry air wrapping in from the northwest, this moisture field will have a chance to consolidate into a stronger area of low pressure once the wave gets farther west. The models are all hinting at this wave consolidating a bit more just north of the Caribbean in 5-7 days. A part of this wave may go into the Caribbean while the northern part continues north of the Caribbean, but either way, the energy will need to bundle before this wave can have a shot at development. As mentioned yesterday, a trough is forecasted to be over the western Atlantic around the time when this wave gets north of the Caribbean, which could recurve any system that tries to develop. However, as I also mentioned, this pattern is rather fragile, and the trough will not be in that position for very long before lifting out. In fact, some of the latest model runs, including the ECMWF and the CMC, show the system getting caught beneath the U.S. ridge as it builds northeastward, bringing the system westward towards the U.S. coast and the Bahamas.

With a fragile pattern like this, as always, timing will be everything. Whether we get development north of the Caribbean will also play a role in whether the wave recurves. I show in the video how one of the top analogs for the 500mb pattern coming up in 8-10 days is that of Hurricane Allen in 1980, which came across the northern Caribbean and Gulf of Mexico into southern Texas as a Cat 4. While this doesn't mean our wave will be anything like Allen, the big point is that this kind of a pattern can favor a storm coming underneath the big U.S. ridge when it makes one of its August moves northeastward. If this pattern does indeed set up this way, it is reminiscent of the pattern I have warned about that could develop at times this season and bring storms to the coast. There are a lot of ifs still to be resolved with this wave, and it may never develop, but it may also be a problem to watch next week, and thus will be monitored closely.

We shall see what happens!



Tropical Storm Bret Official NHC Track Forecast:



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



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

Bret on his way out; Tropical wave in the eastern Atlantic could kick up some trouble

By: Levi32, 1:24 PM GMT on July 19, 2011

Please note that these tidbits do NOT reflect the official forecasts of the National Hurricane Center, and should not be taken as such. While tropical cyclones exist in the Atlantic, the official NHC forecasts will be posted in the lower part of this blog. Please refer to those when making decisions, and heed the advisories and evacuation statements of your local National Weather Service Office.

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 with the video, and please feel free to ask me any questions regarding what I talk about in these tidbits, or about the weather in general. You can post in either of my blogs or on Youtube. I will do my best to answer. Thanks for stopping by!

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The main feature in the Atlantic today continues to be Tropical Storm Bret. Bret tried to intensify into a stronger tropical storm yesterday, aided by his small size, but has since weakened in the presence of strong sinking air, as was expected. Bret will now continue weakening and will soon be nearly dissipated. Some showers may be brought into Bermuda from the system, but it is no real threat to anyone.

A tropical wave interacting with an upper low just north of Puerto Rico will be warily monitored, despite none of the models showing anything coming of it.

Looking ahead...A large tropical wave near 35W in the eastern Atlantic may be something to watch carefully this weekend and early next week as it marches across the Atlantic. Dry air is currently limiting thunderstorm activity with the wave, but it has a broad spin on satellite and TPW imagery, and could potentially be an issue once it gets north of the Caribbean in about a week. The ECMWF and UKMET both hint at low pressure developing with this wave by that time, and thus the wave will be closely monitored.

The MJO is moving back into the undefined middle region for the next week or so, which is unsupportive of Atlantic development, but is forecasted to reemerge over the Atlantic basin for the beginning of August, just in time for the beginning of the main part of the Atlantic hurricane season.

We shall see what happens!



Tropical Storm Bret Official NHC Track Forecast:



Tropical Storm Bret Visible/IR2 Floater (click image for loop):



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

Tropical Storm Bret to remain weak and move out to sea

By: Levi32, 1:28 PM GMT on July 18, 2011

Please note that these tidbits do NOT reflect the official forecasts of the National Hurricane Center, and should not be taken as such. While tropical cyclones exist in the Atlantic, the official NHC forecasts will be posted in the lower part of this blog. Please refer to those when making decisions, and heed the advisories and evacuation statements of your local National Weather Service Office.

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 with the video, and please feel free to ask me any questions regarding what I talk about in these tidbits, or about the weather in general. You can post in either of my blogs or on Youtube. I will do my best to answer. Thanks for stopping by!

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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~

NHC Official Advisory for TD 2:

000
WTNT32 KNHC 181131
TCPAT2

BULLETIN
TROPICAL STORM BRET INTERMEDIATE ADVISORY NUMBER 3A
NWS NATIONAL HURRICANE CENTER MIAMI FL AL022011
800 AM EDT MON JUL 18 2011

...BRET DRIFTING NORTHEASTWARD...


SUMMARY OF 800 AM EDT...1200 UTC...INFORMATION
----------------------------------------------
LOCATION...27.4N 77.5W
ABOUT 65 MI...105 KM NNW OF GREAT ABACO ISLAND
MAXIMUM SUSTAINED WINDS...50 MPH...85 KM/H
PRESENT MOVEMENT...NE OR 50 DEGREES AT 3 MPH...6 KM/H
MINIMUM CENTRAL PRESSURE...1001 MB...29.56 INCHES


WATCHES AND WARNINGS
--------------------
CHANGES WITH THIS ADVISORY...

NONE.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT...

A TROPICAL STORM WARNING IS IN EFFECT FOR...
* GRAND BAHAMA ISLAND AND THE ABACO ISLANDS IN THE NORTHWEST BAHAMAS

A TROPICAL STORM WARNING MEANS THAT TROPICAL STORM CONDITIONS ARE
EXPECTED SOMEWHERE WITHIN THE WARNING AREA...IN THIS CASE WITHIN THE
NEXT FEW HOURS.

FOR STORM INFORMATION SPECIFIC TO YOUR AREA...PLEASE MONITOR
PRODUCTS ISSUED BY YOUR NATIONAL METEOROLOGICAL SERVICE.


DISCUSSION AND 48-HOUR OUTLOOK
------------------------------
AT 800 AM EDT...1200 UTC...THE CENTER OF TROPICAL STORM BRET WAS
LOCATED NEAR LATITUDE 27.4 NORTH...LONGITUDE 77.5 WEST. BRET IS
MOVING TOWARD THE NORTHEAST NEAR 3 MPH...6 KM/H. A TURN TOWARD THE
NORTH-NORTHEAST IS EXPECTED LATER TODAY WITH A GRADUAL INCREASE IN
FORWARD SPEED EXPECTED TONIGHT AND TUESDAY. ON THE FORECAST
TRACK...THE CENTER OF BRET WILL BEGIN MOVING AWAY FROM THE
NORTHWEST BAHAMAS LATER TODAY.

MAXIMUM SUSTAINED WINDS ARE NEAR 50 MPH...85 KM/H...WITH HIGHER
GUSTS. SOME STRENGTHENING IS FORECAST DURING THE NEXT 48 HOURS.

TROPICAL-STORM-FORCE WINDS EXTEND OUTWARD UP TO 35 MILES...55 KM
FROM THE CENTER.

THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 1001 MB...29.56 INCHES.


HAZARDS AFFECTING LAND
----------------------
RAINFALL...BRET COULD PRODUCE TOTAL RAINFALL AMOUNTS OF 2 TO 4
INCHES OVER THE NORTHWEST BAHAMAS.

WIND...TROPICAL STORM CONDITIONS ARE ONGOING OR IMMINENT IN THE
WARNING AREA. THESE WINDS ARE EXPECTED TO DIMINISH LATER TODAY AS
BRET BEGINS TO MOVE AWAY FROM THE NORTHWEST BAHAMAS.

SURF...LOCALLY HIGH SURF CONDITIONS CAN BE EXPECTED ALONG NORTHERN
AND WESTERN FACING BEACHES IN THE NORTHWEST BAHAMAS THROUGH TODAY.


NEXT ADVISORY
-------------
NEXT COMPLETE ADVISORY...1100 AM EDT.

$$
FORECASTER PASCH/STEWART


Tropical Storm Bret Official NHC Track Forecast:



Tropical Storm Bret Visible/IR2 Floater (click image for loop):



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: 1:30 PM GMT on July 18, 2011

Permalink

Tropical Depression #2 forms east of Florida

By: Levi32, 9:47 PM GMT on July 17, 2011

Please note that these tidbits do NOT reflect the official forecasts of the National Hurricane Center, and should not be taken as such. While tropical cyclones exist in the Atlantic, the official NHC forecasts will be posted in the lower part of this blog. Please refer to those when making decisions, and heed the advisories and evacuation statements of your local National Weather Service Office.

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 with the video, and please feel free to ask me any questions regarding what I talk about in these tidbits, or about the weather in general. You can post in either of my blogs or on Youtube. I will do my best to answer. Thanks for stopping by!

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Tropical Depression #2 has formed east of Florida, just north of the Bahamas. This system is the one that was mentioned last week that warranted close watching this weekend for home-grown mischief. A recon plane investigating the area found a central pressure of 1009mb, rather high, but still sufficiently lower than the 1017mb pressure of the surrounding environment. TS-force winds were discovered in the SE quadrant of the system beneath the thunderstorm cluster, but the NHC has attributed this to dry air mixing in and causing stronger winds from higher up in the atmosphere to cascade down to the surface, and are thus not reflective of the true pressure gradient associated with the storm.

The forecast track for TD 2 is fairly straight-forward. Steering currents are currently weak as TD 2 is caught between a strong ridge over the central U.S. and a trough exiting the eastern seaboard region. The central U.S. ridge is expected to build slowly eastward over the next couple of days, at the same time as a new shortwave trough dives across New England out of southern Canada and on into the northwest Atlantic. This shortwave will renew the weakness to the north of TD 2, and the building ridge from the west will help push it northeast towards that weakness. The NHC and computer models are in good agreement on this scenario as well. TD 2 should not be a significant threat to any land areas, except possibly Bermuda.

As far as intensity, TD 2 is still embedded within an old frontal zone, with a competing circulation just to the northeast. This will make it difficult for TD 2 to utilize all of the surface convergence in the area, which is needed to build deep thunderstorms. Dry air associated with the U.S. ridge is also pressing down on TD 2 from the north, and will limit thunderstorm activity for the foreseeable future. The NHC brings TD 2 up to a 60mph tropical storm, which may be possible, though I have doubts about this system being able to strengthen a whole lot. With recon winds already up near TS strength, I expect we will see this system named Tropical Storm Bret at some point in its life. Again, this system should remain weak and pose no significant threat to any land areas.

We shall see what happens!

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~

NHC Official Advisory for TD 2:

BULLETIN
TROPICAL DEPRESSION TWO ADVISORY NUMBER 1
NWS NATIONAL HURRICANE CENTER MIAMI FL AL022011
500 PM EDT SUN JUL 17 2011

...TROPICAL DEPRESSION FORMS JUST NORTH OF THE NORTHWEST BAHAMAS...


SUMMARY OF 500 PM EDT...2100 UTC...INFORMATION
----------------------------------------------
LOCATION...27.5N 78.2W
ABOUT 100 MI...165 KM NW OF GREAT ABACO ISLAND
MAXIMUM SUSTAINED WINDS...35 MPH...55 KM/H
PRESENT MOVEMENT...S OR 180 DEGREES AT 2 MPH...4 KM/H
MINIMUM CENTRAL PRESSURE...1010 MB...29.83 INCHES


WATCHES AND WARNINGS
--------------------
CHANGES WITH THIS ADVISORY...

THE GOVERNMENT OF THE BAHAMAS HAS ISSUED A TROPICAL STORM WATCH FOR
GRAND BAHAMA ISLAND AND THE ABACO ISLANDS IN THE NORTHWEST BAHAMAS.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT...

A TROPICAL STORM WATCH IS IN EFFECT FOR...
* GRAND BAHAMA ISLAND AND THE ABACO ISLANDS IN THE NORTHWEST BAHAMAS


FOR STORM INFORMATION SPECIFIC TO YOUR AREA...PLEASE MONITOR
PRODUCTS ISSUED BY YOUR NATIONAL METEOROLOGICAL SERVICE.


DISCUSSION AND 48-HOUR OUTLOOK
------------------------------
AT 500 PM EDT...2100 UTC...THE CENTER OF TROPICAL DEPRESSION TWO WAS
LOCATED NEAR LATITUDE 27.5 NORTH...LONGITUDE 78.2 WEST. THE
DEPRESSION IS DRIFTING TOWARD THE SOUTH NEAR 2 MPH...4 KM/H...AND
LITTLE MOVEMENT IS EXPECTED OVERNIGHT...FOLLOWED BY A SLOW
NORTH-NORTHEASTWARD MOTION ON MONDAY.

MAXIMUM SUSTAINED WINDS ARE NEAR 35 MPH...55 KM/H...WITH HIGHER
GUSTS. SOME STRENGTHENING IS FORECAST DURING THE NEXT 48
HOURS...AND THE DEPRESSION COULD BECOME A TROPICAL STORM TONIGHT.

THE MINIMUM CENTRAL PRESSURE REPORTED BY AN AIR FORCE RESERVE UNIT
HURRICANE HUNTER AIRCRAFT WAS 1010 MB...29.83 INCHES.


HAZARDS AFFECTING LAND
----------------------
RAINFALL...THE DEPRESSION COULD PRODUCE TOTAL RAINFALL AMOUNTS OF 2
TO 3 INCHES OVER THE NORTHWEST BAHAMAS.

SURF...LOCALLY HIGH SURF CONDITIONS CAN BE EXPECTED ALONG NORTH AND
WESTERN FACING BEACHES IN THE NORTHWEST BAHAMAS THROUGH TONIGHT.


NEXT ADVISORY
-------------
NEXT INTERMEDIATE ADVISORY...800 PM EDT.
NEXT COMPLETE ADVISORY...1100 PM EDT.

$$
FORECASTER PASCH/STEWART



Tropical Depression #2 Visible/IR2 Floater (click image for loop):



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: 9:49 PM GMT on July 17, 2011

Permalink

Watching for home-grown development; Typhoon Ma-on likely to threaten Japan

By: Levi32, 1:41 PM GMT on July 15, 2011

Please note that these tidbits do NOT reflect the official forecasts of the National Hurricane Center, and should not be taken as such. While tropical cyclones exist in the Atlantic, the official NHC forecasts will be posted in the lower part of this blog. Please refer to those when making decisions, and heed the advisories and evacuation statements of your local National Weather Service Office.

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 with the video, and please feel free to ask me any questions regarding what I talk about in these tidbits, or about the weather in general. You can post in either of my blogs or on Youtube. I will do my best to answer. Thanks for stopping by!

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There are a couple of little features to watch today. A weak circulation just east of Nicaragua will be monitored for further development, though it will be soon moving inland and likely not posing a threat for development on the Atlantic side of central America. However, it may develop in the eastern Pacific.

A 2nd feature to watch, as I have been mentioning for the past few days, is at the tail-end of a front off of the SE U.S. coastline, where an area of weak low pressure may develop during this weekend and very early next week. This area will be around for the next 3-4 days at least, and may have to be monitored for home-grown development. Environmental conditions are marginally favorable, and the setup is classic, but model support is lacking. However, features like this are not always caught by the models, and thus this area will be closely monitored due to its proximity to the coast.

In the western Pacific...Typhoon Ma-on is now a Cat 3, but still struggling wickedly with dry air being punched into his north side. The latest microwave pass shows an open eyewall with no spiral bands insulating it from the hostile, dry environment to the north. Ma-on will not be able to attain Category 4 status until that eyewall is allowed to close. It will have an opportunity to as Ma-on rounds the more diffluent SW periphery of the upper ridge that is responsible for the upper confluence which is creating the dry air. Ma-on will have this short opportunity to strengthen, but will start to weaken again before landfall in Japan. The JTWC forecasts Ma-on to be a low-end Cat 3 at landfall in southern Japan, which makes sense to me, assuming the storm reaches a Cat 4 peak. This would be a major typhoon making landfall, and hopefully folks in Japan are prepared for a storm that will be taking a little bit of time to cross the country compared to most.

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

Typhoon Ma-on struggles to strengthen; Atlantic quiet for the time being

By: Levi32, 1:41 PM GMT on July 14, 2011

Please note that these tidbits do NOT reflect the official forecasts of the National Hurricane Center, and should not be taken as such. While tropical cyclones exist in the Atlantic, the official NHC forecasts will be posted in the lower part of this blog. Please refer to those when making decisions, and heed the advisories and evacuation statements of your local National Weather Service Office.

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 with the video, and please feel free to ask me any questions regarding what I talk about in these tidbits, or about the weather in general. You can post in either of my blogs or on Youtube. I will do my best to answer. Thanks for stopping by!

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In the Atlantic...things are fairly quiet for the time being. The models continue to hint at an area of low pressure developing in the extreme southwest Caribbean during the next couple of days associated with the monsoonal circulation, perhaps trying to become a tropical depression before being quickly whisked across central America and into the eastern Pacific. I still doubt that this feature will be able to significantly develop on the Atlantic side, but it will be watched for potential classification before moving inland.

I forgot to mention in the video that we are still watching off the SE US coastline for possible home-grown mischief this weekend and early next week. Model support has been periodic and has only shown weak development since the beginning, making a significant system unlikely, but a weak area of low pressure may develop along the tail-end of a front in a few days, possibly needing to be monitored for acquiring tropical characteristics.

Elsewhere...things are quiet, despite the MJO moving into octant 1. The rest of July may still see some activity, though things likely won't heat up in earnest until August.

In the Pacific...Typhoon Ma-on continues to struggle with dry air, and has yet to develop a solid core or closed eyewall. As long as the storm is on the southern side of the deep-layer ridge to the north, it will continue to have this issue. Once on the SW periphery of this high, though, Ma-on may find himself under more favorable conditions, and could strengthen into a Category 4 typhoon. I don't see Category 5 being very likely at this time. Unfortunately, with the steering pattern being fairly locked down hemispherically right now, Ma-on will likely move in on Japan in 5-6 days, likely weakening some right at landfall, but probably still a major typhoon. In the absence of a strong longwave trough, the storm's movement would also be slow over the island country, bringing very heavy rainfall and prolonged exposure to strong winds, which would not be a good situation. Hopefully it will not turn out as bad as that, but the models seem to have high confidence in this right now. We will hope and pray that the storm spares them the worst.

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

Typhoon Ma-on could be a big problem for Japan; A look at Pacific-Atlantic connection

By: Levi32, 3:17 PM GMT on July 13, 2011

Please note that these tidbits do NOT reflect the official forecasts of the National Hurricane Center, and should not be taken as such. While tropical cyclones exist in the Atlantic, the official NHC forecasts will be posted in the lower part of this blog. Please refer to those when making decisions, and heed the advisories and evacuation statements of your local National Weather Service Office.

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 with the video, and please feel free to ask me any questions regarding what I talk about in these tidbits, or about the weather in general. You can post in either of my blogs or on Youtube. I will do my best to answer. Thanks for stopping by!

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The video ran a bit longer than usual today, but there is a lot of stuff in there that is worth giving attention to. If you stick around until the end, I talk about another teleconnection between the NW Pacific and the Atlantic regarding the mid-latitude longwave pattern.

*Update: During this writing, the NHC issued a special tropical outlook for newly-designated invest 97L in the southwestern Bay of Campeche. 97L is a small area of low pressure, basically an extension of the monsoon low. The compact nature of the system is making it fairly well-defined on satellite and radar imagery, however, it will move inland before significant development can occur. It is possible that the NHC will classify it as TD #2 right before landfall, but I doubt we will get a random name (Bret) out of it. It will bring some heavy showers to Mexico and that's about it.

In the Atlantic, all is quiet for now. Monsoonal mischief will be going on near Central America, mostly on the Pacific side, over the next several days, mainly bringing lots of rain to those countries, and possibly another named storm to the eastern Pacific. The Caribbean, as expected, should lose the battle here and be unable to generate a storm, although the GFS insists on one developing east of Nicaragua before immediately moving inland. We will monitor the area regardless.

Models have backed off a bit on the strength of a home-grown tropical low near the SE US coast this weekend, and fluctuations in the model solutions are expected. They may drop the system altogether if the front ends up being too elongated to support a consolidated feature, but it is hard to say at this point whether we will actually get something to try to develop. The situation will continue to be monitored as long as the possibility of mischief remains.

Typhoon Ma-on in the western Pacific is expected to gradually strengthen into a major typhoon over the next few days, and may be a big problem for Japan. I offer a little analysis of the storm in the video, and show the ECMWF forecast. The concerning thing here is that no big longwave trough is present to pick up the storm, meaning that although Ma-on will move north through a weakness in the ridge, it will not be accelerating northeastward like most recurving typhoons do, which usually move at 30-40mph by the time they're moving northeastward over northern Japan. Here, the ECMWF has Ma-on taking 48-72 hours to transverse most of the southern half of Japan, which would be an ugly situation for them if it comes to pass. We can hope that the storm avoids Japan, as it is still several days away, but the steering pattern puts them right in the potential target area. This would certainly be something that Japan wouldn't need to deal with after everything else that has happened over there recently. Our thoughts and prayers are with them.

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

Possible home-grown tropical development off the SE US coast this weekend

By: Levi32, 1:41 PM GMT on July 12, 2011

Please note that these tidbits do NOT reflect the official forecasts of the National Hurricane Center, and should not be taken as such. While tropical cyclones exist in the Atlantic, the official NHC forecasts will be posted in the lower part of this blog. Please refer to those when making decisions, and heed the advisories and evacuation statements of your local National Weather Service Office.

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 with the video, and please feel free to ask me any questions regarding what I talk about in these tidbits, or about the weather in general. You can post in either of my blogs or on Youtube. I will do my best to answer. Thanks for stopping by!

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The tropical Atlantic remains fairly quiet today. The nice-looking tropical wave east of Nicaragua yesterday moved inland before being able to start developing, as expected. We will still be watching a tropical wave over western Africa as it comes out over the eastern Atlantic during the next few days, though it is likely not a threat for significant development. However, the African wave train will have to start to be monitored more closely in the coming weeks as we get towards that time of year when we must start looking to the east as well for development.

A new area that will be the focus of attention this week and early next week is an area of possible home-grown mischief off the SE US coastline in 4-6 days. An upper trough is forecasted to stall east of New England, and with the big ridge over the central U.S. building northeastward behind it, the tail-end of that trough will likely be trapped off the southeast U.S. coast for a few days. With high pressure building in to the north of it, this is a classic setup for home brew tropical development. The GFS and ECMWF are both forecasting a weak area of low pressure to develop either this weekend or very early next week, which will likely follow the ridge westward and inland, though details like that may change as the situation becomes clearer in time. The other global models are dropping hints as well, so to have this kind of agreement on home-grown mischief means that it is something we should be watching seriously, and will be very relevant to many folks by this weekend if it comes to pass. I will monitor this situation closely as it develops.

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

Watching the Caribbean and a couple tropical waves

By: Levi32, 1:10 PM GMT on July 11, 2011

Please note that these tidbits do NOT reflect the official forecasts of the National Hurricane Center, and should not be taken as such. While tropical cyclones exist in the Atlantic, the official NHC forecasts will be posted in the lower part of this blog. Please refer to those when making decisions, and heed the advisories and evacuation statements of your local National Weather Service Office.

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 with the video, and please feel free to ask me any questions regarding what I talk about in these tidbits, or about the weather in general. You can post in either of my blogs or on Youtube. I will do my best to answer. Thanks for stopping by!

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Somehow I erased this written entry while creating the next day's. I apologize. Please refer to the video for my thoughts from this day.



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: 1:43 PM GMT on July 12, 2011

Permalink

96L not a threat; Interesting things happening in the global tropics

By: Levi32, 1:53 PM GMT on July 08, 2011

Please note that these tidbits do NOT reflect the official forecasts of the National Hurricane Center, and should not be taken as such. While tropical cyclones exist in the Atlantic, the official NHC forecasts will be posted in the lower part of this blog. Please refer to those when making decisions, and heed the advisories and evacuation statements of your local National Weather Service Office.

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 with the video, and please feel free to ask me any questions regarding what I talk about in these tidbits, or about the weather in general. You can post in either of my blogs or on Youtube. I will do my best to answer. Thanks for stopping by!

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Invest 96L seems to have lost its surface circulation this morning, and has degenerated into a weak surface trough with limited convection. This, as expected yesterday, is due to the wind shear being imposed on the system by an upper low over the northern Gulf of Mexico that will be responsible for not allowing 96L to develop significantly. This system will be just a rain-maker for Florida, which is generally good news for all concerned. The track should take 96L into the Florida panhandle and eventually curving northeastward towards the eastern seaboard.

A tropical wave interacting with Trinidad and northeastern Venezuela will be watched later next week as it gets into the western Caribbean to see if it interacts with the monsoon trough near central America, but at this time none of the global models are excited about this wave. Regardless, it will be monitored.

The video today mentions a massive reduction in vertical instability world-wide in the tropics that I have not seen before. Given the global tropical activity drought that we are currently in, to suddenly see punch of stability show up in the tropics is very interesting, and worthy of research into the issue.

Enjoy the quiet in the Atlantic while it lasts, as it won't be long until we hit the meat of the season.

We shall see what happens!

Invest 96L Model Tracks:





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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Invest 96L; Tropical Wave east of South America

By: Levi32, 1:34 PM GMT on July 07, 2011

Please note that these tidbits do NOT reflect the official forecasts of the National Hurricane Center, and should not be taken as such. While tropical cyclones exist in the Atlantic, the official NHC forecasts will be posted in the lower part of this blog. Please refer to those when making decisions, and heed the advisories and evacuation statements of your local National Weather Service Office.

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 with the video, and please feel free to ask me any questions regarding what I talk about in these tidbits, or about the weather in general. You can post in either of my blogs or on Youtube. I will do my best to answer. Thanks for stopping by!

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There a couple of areas of interest to mention in the Atlantic today. Just recently at 12z, invest 96L was labeled west of Key West, Florida, in the eastern Gulf of Mexico. An area of low-level vorticity, or spin, has developed over the last few hours in this area, and convection is developing on its northeast side. Convection will likely remain confined to the north and east of the system due to southwesterly wind shear being imposed on it by an upper low over the northern Gulf of Mexico that will not be moving very much over the next two days. Any surface low pressure that tries to develop will likely remain weak, and move north into the Florida Panhandle without significant development. This system will bring tropical rains farther north into the SE US, which should be welcome to most people.

The other feature worth watching this morning is the tropical wave that was mentioned yesterday east of South America, now near 50W. Vorticity is pronounced with this wave up through the 500mb level, and an ASCAT pass last night revealed a well-defined area of surface convergence and decent cyclonic turning about the wave axis. This wave will likely be running at least partially into northeastern South America, namely Venezuela and Trinidad. It is unclear how much this interaction may disrupt the wave's organization, but any dance with land will only be short-lived, as steering currents should lift this wave into the Caribbean Sea shortly after it encounters the continent. The wave will then travel WNW across the breadth of the Caribbean, posing as a feature to be watched through next week, despite no models showing any tropical development with it. Conditions will be decent once it gets into the western Caribbean, and thus this system will be monitored through its life cycle.

We shall see what happens!

Invest 96L Model Tracks:





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: 1:36 PM GMT on July 07, 2011

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Tropics fairly quiet, though pattern supports activity for the next 10 days

By: Levi32, 3:01 PM GMT on July 06, 2011

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. Please feel free to ask me any questions regarding what I talk about in the video, or about the weather in general. You can post in either of my blogs or on Youtube. I will do my best to answer.

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The tropical Atlantic (and really the global tropics) remain fairly quiet today. As expected, despite all the thunderstorm activity near and just north of the Caribbean over the 4th of July holiday, the area of energy was too broad to allow anything significant to develop out of it. The only feature I would watch for any possibility of development would be a disturbance within the ITCZ, currently in the central Atlantic near 40W, which will be moving towards the Trinidad area in about 3 days, and into the Caribbean from there. Right now it is at a fairly low latitude, and will thus have a hard time gaining significant spin, but once it starts to gain latitude, it may be worth watching. Such features following behind tropical waves can be sneaky at times. It is not an immediate threat, but may be worth watching next week in the Caribbean, as conditions could allow something to brew.

Other than that, there are no other current threats. The Atlantic will be favored for activity by the MJO for about the next 10 days before the models show this current upward motion pulse moving on into the Indian Ocean, allowing a greater portion of sinking air to return to the Atlantic, suppressing activity for the latter portion of July. This month should be a fairly quiet month overall, though I could see us getting one development out of it. Folks should keep in mind that June and July are generally not great indicators of what the peak of the hurricane season (August-October) will be like. Last year, we had a deadly quiet July, with only Tropical (Rainstorm) Bonnie forming, and yet we went on to have 19 named storms when it was all said and done. A quiet July should be no reason to let down your guard for this hurricane season. We have a long way to go, so let's enjoy the quiet while it lasts.

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: 3:09 PM GMT on July 06, 2011

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Tropics active but not a significant threat; June historical comparison concerning

By: Levi32, 5:56 PM GMT on July 03, 2011

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The tropical Atlantic has a little bit of activity today, especially in the Caribbean and SW Atlantic, where scattered areas of showers and thunderstorms have been persisting for the last few days, due to the presence of an upper trough strung out along the southeast U.S. coastline, which is providing upper divergence and promoting shower activity. A tropical wave in the central Caribbean is advancing northwestward towards this upper trough, and will be warily watched, but the area of energy in the Caribbean and SW Atlantic is so broad that it will be hard to get anything consolidated going, and consolidation is what we need for tropical development. Therefore, significant organization is not expected with any of the little features running around the SW Atlantic Basin over the next few days.

Looking ahead...The MJO is forecasted to remain in octant 1 for the next 10-15 days, providing upward motion to the Caribbean area. Thus, this area will continue to be watched during these first two weeks of July for any possible opportunities for tropical mischief, though the models show nothing right now.

In today's video I took this quieter period in the tropics to bring to your attention the similarities that this June exhibited to the Junes of past hurricane seasons that had many U.S. hurricane landfalls. The pattern comparision is strikingly similar, and if this year continues to follow the evolution of those years, it will set up a pattern during the peak of this hurricane season that could bring multiple hurricanes into the United States coastline. Hopefully everyone is prepared for whatever may come.

We shall see what happens!

I probably won't have a blog tomorrow, so Happy Independence Day!



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: 5:58 PM GMT on July 03, 2011

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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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