Watching for Lee to develop in the gulf; Katia may need to be watched by Bermuda

By: Levi32 , 4:49 PM GMT on August 31, 2011

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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 biggest threat to land areas right now is the area of disturbed weather in the NW Caribbean and southern Gulf of Mexico as a tropical wave interacts with a frontal boundary. A surface low may be trying to form in its embryonic stages NNW of the Yucatan Channel. This low will be moving NW over the next couple of days, being steered by a high over the southeastern U.S., and will likely try to deepen in the northwest Gulf of Mexico this weekend. Waters are very warm in here, and there is no competition from the eastern Pacific, which means that there is a lot of energy available that this system will be able to hog all to itself. There is some wind shear over the central gulf, associated with an elongated upper trough over the northern gulf, but this will eventually have to shift north or split as the heat surge from the Caribbean muscles its way northwest. I believe we have a good chance of seeing a tropical depression develop in the box from 25N-30N and 90W-95W, likely during this weekend.

This system will be moving northwest for the next 2-3 days, but as an upper shortwave trough which is currently moving into the Pacific Northwest comes across the mid-west in a few days, the Texas ridge will re-strengthen over northern Texas and the 4-corners region, which should block the system's progress before it quite reaches the Texas coast. The shortwave trough may then dig in over the Great Lakes region and exert a northeastward tug on our gulf system, trying to pull it into Louisiana. It may succeed in doing this, and the GFS shows a similar solution by bringing a storm into the Florida Panhandle, but I think this may be overdone due to the typical GFS bias of strengthening troughs too much over the eastern seaboard this season. Chances are that our system will stall out for a while over the NW gulf and then eventually find a way to the north gulf coast, closer to the ECMWF solution.

Overall, what we're hoping for here is a weak Lee to develop and bring Texas some rain. Chances are that even if the storm moves into Louisiana, given its location of development, it is likely to give at least a few showers to coastal Texas anyway. The bad news is that the pattern favors it having to sit down there for a while over very hot water, and that could turn it into a potent system if atmospheric conditions allow. We'll have to monitor it closely, as home-grown development in the western gulf is notorious for meaning business. The central gulf coast all the way down to northern Mexico should keep an eye on this system this weekend and next week.

Tropical Storm Katia continues to chug along WNW. Dry air is present from the north to the west of the system, but she seems to be doing a good job keeping it out of her core. I have no big issues with the NHC forecast here, and Katia should be a major hurricane early next week in the central Atlantic north of the Antilles islands. I feel pretty confident that she will avoid the Antilles due to a weakness in the Bermuda High ahead of Katia which is great news for the islands. While she's still a long way out, I'm leaning towards the idea that she will miss the U.S. and recurve out to sea a bit west of Bermuda. The models are targeting Bermuda strongly today, and although I think they will shift a bit west eventually, Bermuda may need to keep a very close eye on this storm for early next week.

We shall see what happens!

Official NHC Forecast for Tropical Storm Katia:



Tropical Storm Katia Model Track Forecasts:



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 Potential (green areas represent upward motion associated with the MJO):






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30. WaterWitch11
11:19 PM GMT on September 01, 2011
.
Member Since: August 11, 2008 Posts: 3 Comments: 1988
29. Levi32
6:13 AM GMT on September 01, 2011
Quoting BrockBerlin:
Levi could you explain to me the reasons why the multi-decadal cycles in hurricane activity occur? Is there any reason why every 20-30 years wind shear (which if I remember right is linked to an enhanced West African monsoon) seems to decrease basin-wide and SST's increase slightly.

I think I have a decent idea of "what" the multi-decadal cycle is, but I am confused why it occurs and what would trigger it every several decades?



We don't know. They are one of the mysteries of the climate that we don't fully understand. We don't even fully understand what governs ENSO yet, and that is the shorter-term manifestation of the Pacific multidecadal signal. To figure out what causes these cycles would be a huge breakthrough in our understanding of the Earth's climate.
Member Since: November 24, 2005 Posts: 635 Comments: 26775
27. Levi32
1:43 AM GMT on September 01, 2011
Katia looks like a chickling still in its egg, or a gerbil sleeping, or a shrimp. Whatever it is, it's a sign of steady strengthening.

Member Since: November 24, 2005 Posts: 635 Comments: 26775
26. Levi32
12:46 AM GMT on September 01, 2011
We have Hurricane Katia:

AL, 12, 2011090100, , BEST, 0, 148N, 436W, 65, 987, HU,
Member Since: November 24, 2005 Posts: 635 Comments: 26775
25. AtHomeInTX
12:04 AM GMT on September 01, 2011
Thank you Levi and Tom. :) I need to write this down. :)
Member Since: August 24, 2010 Posts: 0 Comments: 435
24. Levi32
12:02 AM GMT on September 01, 2011
The NHC is worried...


000
ABNT20 KNHC 312341
TWOAT

TROPICAL WEATHER OUTLOOK
NWS NATIONAL HURRICANE CENTER MIAMI FL
800 PM EDT WED AUG 31 2011

FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...

THE NATIONAL HURRICANE CENTER IS ISSUING ADVISORIES ON TROPICAL
STORM KATIA...LOCATED ABOUT 1285 MILES EAST OF THE LEEWARD ISLANDS.

A LARGE AREA OF DISORGANIZED CLOUDINESS AND THUNDERSTORMS OVER THE
SOUTHEASTERN GULF OF MEXICO IS ASSOCIATED WITH A TROUGH OF LOW
PRESSURE. UPPER-LEVEL WINDS ARE CURRENTLY UNFAVORABLE FOR
DEVELOPMENT...BUT ARE FORECAST TO BECOME MORE CONDUCIVE ON
THURSDAY...AND THIS SYSTEM COULD BECOME A TROPICAL DEPRESSION
DURING THE NEXT DAY OR SO. THIS SYSTEM HAS A HIGH CHANCE...60
PERCENT...OF BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS

AS IT MOVES SLOWLY NORTHWESTWARD. INTERESTS ALONG THE ENTIRE
NORTHERN GULF OF MEXICO COAST SHOULD MONITOR THE PROGRESS OF THIS
DISTURBANCE.

ELSEWHERE...TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE
NEXT 48 HOURS.

$$
FORECASTER BROWN
Member Since: November 24, 2005 Posts: 635 Comments: 26775
23. TomTaylor
11:55 PM GMT on August 31, 2011
Quoting Levi32:


Well honestly the only really good, college-level textbook that I have is called "Meteorology Today" by C. Donald Ahrens. I've had it since I was 11, eight years ago, but it's been through several new editions so the latest edition should be up to date.
That was it, thanks. I had heard you recommend it to somebody else before, but I forgot what it was called lol
Member Since: August 24, 2010 Posts: 19 Comments: 4358
22. katzanddogz
10:46 PM GMT on August 31, 2011
Thanks Levi!! Sitting on pins and needles begging for rain. Even my dogs are looking stressed!! LOL
Member Since: February 10, 2009 Posts: 0 Comments: 44
21. Levi32
10:07 PM GMT on August 31, 2011
Quoting TomTaylor:
Levi, do you know of any good weather/meteorology books or textbooks you could recommend me?

Thanks in advance


Well honestly the only really good, college-level textbook that I have is called "Meteorology Today" by C. Donald Ahrens. I've had it since I was 11, eight years ago, but it's been through several new editions so the latest edition should be up to date.
Member Since: November 24, 2005 Posts: 635 Comments: 26775
20. Levi32
10:05 PM GMT on August 31, 2011
Quoting FLGatorCaneNut:
Levi.... thanks for the update...

Question...... Katia and the beginings of Hurricane Andrew in "92 are almost in the same position. I remember how forcaster were saying not to worry that it was headed to the fish grave yard...... as they did not forsee the high moving in as it did.... and we all know what happened after that.......

What are the chances that a high builds in and pushes this further west as the high seems to be moving back and forth alot this season....

Thanks


Well tracks like Andrew and Dora in 1964 can and do happen. Here, a straight west track into the gulf like Andrew is pretty unlikely given that the ridge will still be hanging out near Texas, with a weakness in the ridge near the eastern seaboard. Could Katia get close enough to threaten the east coast? Sure - it's still on the table. I'm leaning more towards unlikely right now, but that doesn't mean it can't happen, for the reasons that I talked about in Monday's video.
Member Since: November 24, 2005 Posts: 635 Comments: 26775
19. Levi32
10:03 PM GMT on August 31, 2011
Quoting TomTaylor:
Hey AtHome

I'm not levi, but I've seen you post the euro model runs lately on the blog from the ECMWF site itself, so I am assuming you are talking about this type of image




In this case, it is showing winds for meters per second. 1 Meter per Second (m/s) is equal to about 2.2 Miles per Hour (MPH). So in other words, 1 m/s = 2.2 mph, 40 m/s = 90 mph, 20 m/s = 45 mph.


I forgot that she might be referring to that one. Thanks. I've seen Maue's maps posted far more often on the blogs, so my mind immediately jumped to that map.
Member Since: November 24, 2005 Posts: 635 Comments: 26775
18. TomTaylor
10:00 PM GMT on August 31, 2011
Quoting AtHomeInTX:
One more question? On the EURO 850 wind model, do they use knots or mph? I may have missed where it said? Just trying to find out how much wind it's showing. Thanks if ya have the time. :)
Hey AtHome

I'm not levi, but I've seen you post the euro model runs lately on the blog from the ECMWF site itself, so I am assuming you are talking about this type of image




In this case, it is showing winds for meters per second. 1 Meter per Second (m/s) is equal to about 2.2 Miles per Hour (MPH). So in other words, 1 m/s = 2.2 mph, 40 m/s = 90 mph, 20 m/s = 45 mph.
Member Since: August 24, 2010 Posts: 19 Comments: 4358
17. TomTaylor
9:54 PM GMT on August 31, 2011
Levi, do you know of any good weather/meteorology books or textbooks you could recommend me?

Thanks in advance
Member Since: August 24, 2010 Posts: 19 Comments: 4358
16. FLGatorCaneNut
9:41 PM GMT on August 31, 2011
Levi.... thanks for the update...

Question...... Katia and the beginings of Hurricane Andrew in "92 are almost in the same position. I remember how forcaster were saying not to worry that it was headed to the fish grave yard...... as they did not forsee the high moving in as it did.... and we all know what happened after that.......

What are the chances that a high builds in and pushes this further west as the high seems to be moving back and forth alot this season....

Thanks
Member Since: July 26, 2009 Posts: 0 Comments: 203
15. Levi32
9:22 PM GMT on August 31, 2011
A decent chunk of the 12z ECMWF ensemble members (purple/pink colors) show Katia approaching the northern Bahamas in 10 days, illustrating how the potential threat to the U.S. isn't over yet given the overall pattern, but a miss seems a little bit more likely for now.

Member Since: November 24, 2005 Posts: 635 Comments: 26775
14. Levi32
7:12 PM GMT on August 31, 2011
Quoting AtHomeInTX:
One more question? On the EURO 850 wind model, do they use knots or mph? I may have missed where it said? Just trying to find out how much wind it's showing. Thanks if ya have the time. :)


It depends on who's giving the data and what units they chose in their computer program for processing the data. If you're talking about Ryan Maue's ECMWF 850mb wind plots, then his scale is in knots.
Member Since: November 24, 2005 Posts: 635 Comments: 26775
13. AtHomeInTX
7:01 PM GMT on August 31, 2011
One more question? On the EURO 850 wind model, do they use knots or mph? I may have missed where it said? Just trying to find out how much wind it's showing. Thanks if ya have the time. :)
Member Since: August 24, 2010 Posts: 0 Comments: 435
12. AtHomeInTX
6:56 PM GMT on August 31, 2011

Quoting Levi32:
From the NHC 2pm TWO:

A LARGE AREA OF DISORGANIZED CLOUDINESS AND SHOWERS OVER THE
NORTHWESTERN CARIBBEAN SEA...THE EASTERN GULF OF MEXICO...AND THE
ADJACENT LAND AREAS IS ASSOCIATED WITH A TROPICAL WAVE. THIS
SYSTEM IS EXPECTED TO MOVE GENERALLY WEST-NORTHWESTWARD AT 10 TO 15
MPH. ALTHOUGH UPPER-LEVEL WINDS ARE NOT FAVORABLE FOR SIGNIFICANT
DEVELOPMENT DURING THE NEXT DAY OR TWO...THERE IS SOME POTENTIAL
FOR TROPICAL OR SUBTROPICAL CYCLONE DEVELOPMENT
OVER THE CENTRAL OR
WESTERN GULF OF MEXICO IN A FEW DAYS. THIS SYSTEM HAS A MEDIUM
CHANCE...30 PERCENT...OF BECOMING A TROPICAL OR SUBTROPICAL CYCLONE
DURING THE NEXT 48 HOURS.

Oh gee here we go with the possibility for "subtropical" development over the Gulf of Mexico during the first week of September over 31C water. Here's the big, big problem with that statement. There is already an anticyclonic wind flow at 200mb above the tropical wave, which implies warm-core throughout the entire tropospheric column. There is nothing subtropical about it, and if there isn't now, there certainly isn't going to be when it's developing and pumping even more heat into the atmosphere.

Lol.Thank you Levi.  I think we may get our rains. We are all hoping for the best. Everyone, including our locals are pulling their hair out. At least that's what they said last night. I can't wait to see what our lead met on our local ABC affiliate says about the last couple of EURO runs. Lol.

Haven't seen all of the 12z but what I have seen looks like a sit and spin system for a few days anyway but deeper. And there is the biggest fear. Water right off our coast is 91 with 90 about 300 miles out and a bunch of 88's. We are hoping for the rains. Actually we might be heartbroken without. Lol. I'd love to discount the GFS. BUT if you'll notice on the EURO there's a NE tug at the beginning that wasn't there before. Sigh. C'MON RAIN HERE AT LEAST! K done putting in my order. :)
Member Since: August 24, 2010 Posts: 0 Comments: 435
11. Levi32
6:36 PM GMT on August 31, 2011
We have Invest 93L as low pressure develops northwest of the Yucatan Channel:

AL, 93, 2011083118, , BEST, 0, 240N, 860W, 25, 0, DB,

Member Since: November 24, 2005 Posts: 635 Comments: 26775
10. Levi32
6:06 PM GMT on August 31, 2011
Quoting LakeWorthFinn:
When is the best time to visit Alaska? We would love to take a trip up there, but when it's not very cold. You know I'm from Finland and they have wonderful warm summers there, I hate cold and would want to pick the warmest weeks you get.


In the interior our warmest months are June and July, while down south near the coast they are July and August. Anywhere in there would be in the middle of our summer season. It's not as short as some believe lol. Here in the interior we hit 70s in May and we keep those 70s until early September. Down in the southern part of the state and along the coastline, 70s are rarer, though our largest city, Anchorage, gets 70s fairly often during the summer. That's darn hot for me, but I think it's just about warm enough for you lol.
Member Since: November 24, 2005 Posts: 635 Comments: 26775
9. LakeWorthFinn
6:01 PM GMT on August 31, 2011
When is the best time to visit Alaska? We would love to take a trip up there, but when it's not very cold. You know I'm from Finland and they have wonderful warm summers there, I hate cold and would want to pick the warmest weeks you get.
Member Since: October 6, 2005 Posts: 69 Comments: 7669
8. LakeWorthFinn
5:51 PM GMT on August 31, 2011
Thanks again, your videos and weather analysis, which everybody can understand, are fabulous :)

11 C, oh my you're cold up there :(
Member Since: October 6, 2005 Posts: 69 Comments: 7669
7. Levi32
5:46 PM GMT on August 31, 2011
From the NHC 2pm TWO:

A LARGE AREA OF DISORGANIZED CLOUDINESS AND SHOWERS OVER THE
NORTHWESTERN CARIBBEAN SEA...THE EASTERN GULF OF MEXICO...AND THE
ADJACENT LAND AREAS IS ASSOCIATED WITH A TROPICAL WAVE. THIS
SYSTEM IS EXPECTED TO MOVE GENERALLY WEST-NORTHWESTWARD AT 10 TO 15
MPH. ALTHOUGH UPPER-LEVEL WINDS ARE NOT FAVORABLE FOR SIGNIFICANT
DEVELOPMENT DURING THE NEXT DAY OR TWO...THERE IS SOME POTENTIAL
FOR TROPICAL OR SUBTROPICAL CYCLONE DEVELOPMENT
OVER THE CENTRAL OR
WESTERN GULF OF MEXICO IN A FEW DAYS. THIS SYSTEM HAS A MEDIUM
CHANCE...30 PERCENT...OF BECOMING A TROPICAL OR SUBTROPICAL CYCLONE
DURING THE NEXT 48 HOURS.

Oh gee here we go with the possibility for "subtropical" development over the Gulf of Mexico during the first week of September over 31C water. Here's the big, big problem with that statement. There is already an anticyclonic wind flow at 200mb above the tropical wave, which implies warm-core throughout the entire tropospheric column. There is nothing subtropical about it, and if there isn't now, there certainly isn't going to be when it's developing and pumping even more heat into the atmosphere.

Member Since: November 24, 2005 Posts: 635 Comments: 26775
6. Levi32
5:46 PM GMT on August 31, 2011
Quoting JGreco:
So just to be sure, no threat from Lee for the Western Florida Panhandle region right?


Not impossible, but in my opinion more unlikely at this point.
Member Since: November 24, 2005 Posts: 635 Comments: 26775
5. JGreco
5:45 PM GMT on August 31, 2011
So just to be sure, no threat from Lee for the Western Florida Panhandle region right?
Member Since: September 22, 2005 Posts: 0 Comments: 322
4. BEENE
5:38 PM GMT on August 31, 2011
thanks Levi- we'll keep our fingers crossed here in Texas.
Member Since: June 16, 2011 Posts: 0 Comments: 52
3. InTheCone
5:09 PM GMT on August 31, 2011
Thanks Levi, great update! Just hoping Texas can get some rain.
Member Since: September 1, 2007 Posts: 0 Comments: 1990
2. 2xRitaEvacuee
5:06 PM GMT on August 31, 2011
Thanks Levi!
Member Since: October 20, 2005 Posts: 0 Comments: 143
1. whitewabit (Mod)
5:00 PM GMT on August 31, 2011
thanks for the video Levi ...
Member Since: August 17, 2005 Posts: 375 Comments: 35448

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Masters student in tropical meteorology at FSU. Raised in Alaskan blizzards, but drawn toward tropical cyclones by their superior PGF.

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