Don closing in on Texas; 91L a potential threat to the Lesser Antilles

By: Dr. Jeff Masters , 3:22 PM GMT on July 29, 2011

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Tropical storm warnings are flying along the coast of Texas from Brownsville to Matagorda as Tropical Storm Don closes in on the Texas coast. Don remains a disorganized, moderate strength tropical storm, and appears unlikely to cause major damage or bring much-needed drought-busting rains to Texas. A hurricane hunter plane is in Don, and found highest surface winds of 55 mph at 11:06am EDT. Don continues to have trouble with moderate wind shear of 10 - 20 knots, which is injecting dry air to the northwest into the storm. Water vapor satellite images show this region of dry air to the northwest of Don. Visible satellite imagery from this morning shows little change to Don so far today, with most of the heavy thunderstorms on Don's south side, and the cloud pattern elongated, the sign of a storm struggling with wind shear. Radar out of Brownsville, Texas shows the main rain areas are on the south of Don's center, and bands of heavy rain are now very close to the Texas/Mexico border.


Figure 1. Morning image of Tropical Storm Don from the Brownsville, Texas radar.


Figure 2. The latest drought map for Texas shows that over 75% of the state is in exceptional drought--the highest category of drought. Image credit: U.S. Drought Monitor.

Forecast for Don
The wind shear and dry air affecting Don will continue until landfall, and it is unlikely Don will intensify to more than a 60 mph tropical storm. With most of the heavy thunderstorms displaced to the south side of the storm, Mexico will be the primary beneficiary of Don's expected rains of 3 - 5 inches. South Texas will see modest rains of 1 - 2 inches over a few isolated areas, but Don is going to do very little to bring drought relief to the state. Most of Don's rains in Texas will be concentrated in the extreme southern portion of the state near Brownsville. This portion of Texas is experiencing only moderate drought, and the extreme to exceptional drought areas of the state will miss the bulk of Don's rains.

For those of you wondering about your odds of experiencing tropical storm force winds, I recommend NHC's wind probability forecast. The 11 am version of this forecast shows that Corpus Christi Texas has the highest chance of tropical storm-force winds (39+ mph): 48%. The primary threat from Don will be heavy rain, which will caused localized flooding problems. An isolated tornado is also a possible concern.


Figure 3. Morning satellite image of 91L.

African wave 91L a potential threat to the Lesser Antilles
A well-organized African wave near 9°N 44°W (Invest 91L) is headed west-northwest at 15 - 20 mph, and could arrive in the vicinity of the Lesser Antilles Islands as early as Monday night. Residents of the Lesser Antilles should pay careful attention to this system, as it has the potential to organize into a tropical storm before reaching the islands. While visible satellite loops currently show only minimal heavy thunderstorm activity and no signs of a surface circulation, there is a pronounced large-scale rotation to the cloud pattern. Water vapor satellite loops show that a large area of dry air from Africa lies just to the north of 91L, and this dry air is inhibiting development. The SHIPS model is diagnosing low shear, 5 - 10 knots, over 91L, but the University of Wisconsin CIMSS analysis shows that moderate shear, 10 - 20 knots, is affecting 91L. Sea surface temperatures are 27.5° - 28°C, which is 1° above the 26.5°C threshold usually needed to support a tropical storm.

Forecast for 91L
Low to moderate wind shear of 5 - 15 knots is predicted along 91L's path over the coming three days, which should allow the storm to steadily organize, assuming it can shut out any incursions of dry air that might intrude. The latest 06Z run of the GFS model does show 91L developing into a tropical storm by Monday, but the other three most reliable models for forecasting formation of a tropical storm--the ECMWF, NOGAPS, and UKMET models--show little or no development of 91L in their latest runs. On Monday, when most of the models predict that squalls of rain from 91L will begin affecting the Lesser Antilles, wind shear is expected to rise to the moderate or high range, which should act to interfere with development. The latest runs of the GFDL and HWRF models show 91L developing into a hurricane by Monday, but these models are not to be trusted for systems that have not developed into a tropical depression yet. The long-range path of 91L could take it through the Caribbean or towards the U.S. East Coast; it is too early to know with path might be more probable. NHC is giving a 30% chance that 91L will develop into a tropical depression by Sunday morning.

Iran records its hottest temperature of all-time
Omidieh, Iran and Shoshtar, Iran hit a scorching 52.6°C (126.6°F) on July 27, the hottest temperatures ever recorded in the country. The previous record was 52.5°C (126.5°F) set in Hamidiyeh on August 4, 2001. If confirmed by the Iranian weather service, these readings would rank as the third hottest undisputed temperatures ever measured in Asia. There have been only two Asian readings matching or exceeding Wednesday's new Iranian record of 52.6°C that are undisputed that I am aware of. Both of these occurred last year, and were recognized by their respective country's meteorological services as new official records for their country:

53.5° (128.3°F) in Moenjodaro, Pakistan on May 26, 2010
52.6°C (126.7°F) in Abdaly, Kuwait on June 10, 2010

Iran is the third nation this year to set a new all-time heat record (no nations have set an all-time coldest temperature record this year, or did so in 2010.) The Democratic Republic of the Congo, the world's 12th largest country, set a new all-time extreme heat record on March 8, 2011, when the temperature hit 39.2°C (102.6°F) at M'Pouya. Congo's previous all-time hottest temperature was 39.0°C (102.2°F) at Impfondo on May 14, 2005.

Also this July, a 50.2°C temperature was measured at Aydyngkol Lake, China--the highest temperature on record at any official Chinese weather station. Next week, our weather historian, Christopher C. Burt, will report on this record. Credit for researching these records goes to weather records researcher Maximiliano Herrera, who maintains a comprehensive set of world extreme temperature records on his web site.

Vacation
I'm taking some time off today through August 9 for a family celebration and vacation, and don't plan on blogging again until August 10 unless a major hurricane develops. In my absence, Angela Fritz will be handling most of the blogging duties, and she will have a post on the latest for Don this afternoon. Angela is on Pacific time, so her posts will be later in the day than I make them.

Jeff Masters

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Quoting yonzabam:


You know, I'm sick of hearing about this continual bickering about what constitutes a 'fish storm'.

If it recurves out to sea and knocks a chimney pot down in Ireland do we not call it a 'fish storm'?

If it causes some damage as a tropical storm in the Antilles, but recurves before it hits a continental land mass as a hurricane, it's understandable that people living in the US would call that a 'fish storm'. Personally, I don't have a problem with that, but some folk seem to have a need to appear as more caring human beings and be seen to be more sympathetic towards those islanders. I wonder why that is.



+1
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when Hugo was near 41.6W (close to where 91L is now) it wasnt much further north (near 12.8)...biggest difference is by this time Hugo was only 4mph away from being a hurricane...and hugo also went thru Herbert's box (yes, i know it is a bad word) but he did
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594. DFWjc
CBS 11 Weather
Made it to 100 degrees again at DFW. Streak now at 28 days.

Will the streak ever end???
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Quoting Stormchaser2007:
For now this is a threat to PR and the islands. Anyone who says that this is a "fish" is simply uneducated.



You know, I'm sick of hearing about this continual bickering about what constitutes a 'fish storm'.

If it recurves out to sea and knocks a chimney pot down in Ireland do we not call it a 'fish storm'?

If it causes some damage as a tropical storm in the Antilles, but recurves before it hits a continental land mass as a hurricane, it's understandable that people living in the US would call that a 'fish storm'. Personally, I don't have a problem with that, but some folk seem to have a need to appear as more caring human beings and be seen to be more sympathetic towards those islanders. I wonder why that is.

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Quoting tiggeriffic:


DC or state? if that high lifts to DC...southern East coast could be toast
Yeah I live in the city of D.c.the high is forecasted to move over here.Not so good for the folks down south.
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What the hell is this?? this isn't even a storm anymore, lol

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589. yoboi
Quoting Stormchaser2007:
For now this is a threat to PR and the islands. Anyone who says that this is a "fish" is simply uneducated.




fish storm
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okay then drop it before landfall with just enough time so that it will not be able to redevelope and if there not pricey (which they probably would be) just drop a few on it.
Member Since: July 25, 2011 Posts: 0 Comments: 453
Pre Emily might take Bertha'96 path
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Invest 91L is starting to look very scary gang! A BEAST in the making it appears!
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Quoting GHOSTY1:


I already said there would be no radiation, this invention hasn't been made or probably hasn't been thought of but if they do i am sure they will not include radiation unless there completely stupid.


You need to read up on nuclear physics... a nuclear based bomb can never be made without the release of radiation. That's where it gets it's energy from in the first place.

In my mind, there's no artificial way of disrupting a hurricane. Besides, hurricanes regulate sea surface temperatures, so we need them.
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Radiation-cane? lol...better not..might turn all those florida alligators into godzillas...how would FEMA manage THAT? Is there a policy that covers godzilla attacks?
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Quoting ncstorm:


Jason, wasnt you on here just yesterday when I posted model runs of pre 91L and said it was going out to sea??


Yes, Jason was saying fish last night.
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Oz is currently live. Go to my WU blog for the link!
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Quoting GHOSTY1:
Can someone post a picture of alex i dont remember how large he was.
Member Since: October 9, 2008 Posts: 0 Comments: 8436
OOooooooooooooohhhh....Yeeeahh, he was a biggy, was he bigger than Texas?
Member Since: July 25, 2011 Posts: 0 Comments: 453
some of the models inialised a stronger trough, and responded with 91L going further north. looking at thr multi layer dteering the next 4 days, 91L will move wnw for the next 12-24 hrs and then resume a west track there after taking it through the central lesser antilles and into the caribbean sea.the strengh is not quite known as the disturbance is slowly getting it's act together.
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Quoting GHOSTY1:


I already said there would be no radiation, this invention hasn't been made or probably hasn't been thought of but if they do i am sure they will not include radiation unless there completely stupid.


You might be able to disperse the clouds for a little while, but the energy would already be there and it would not be long before the storm would reconfigure itself. Your theory is similar to that of destroying an asteroid with a nuke. Some asteroids are composed of loose rocks bound together by gravity. if you separate them, they would just get back togehter after a short period of time.
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Quoting GHOSTY1:
Can someone post a picture of alex i dont remember how large he was.




Covered roughly half of the GOMEX.
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Can someone post a picture of alex i dont remember how large he was.
Member Since: July 25, 2011 Posts: 0 Comments: 453
575. red0
What is the high pressure ridge of doom forecast to do? That is going to dictate what 91L does. It's been on vacation for the last few days in Georgia/Alabama for the last few days. I wouldn't mind if it decided to stay there.
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My blog entry:

http://www.wunderground.com/blog/louisianaboy444/ show.html
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Quoting washingtonian115:
Dammmit all!!!!.Damn it!!.


How about Earl?
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Quoting washingtonian115:
Dammmit all!!!!.Damn it!!.


Thats some pretty language coming from a blog with a pretty picture :P
Member Since: July 25, 2011 Posts: 0 Comments: 453
I wouldn't doubt this getting as big, or bigger, than Alex of last year.

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Quoting Stormchaser2007:
For now this is a threat to PR and the islands. Anyone who says that this is a "fish" is simply uneducated.


yes
Quoting jasonweatherman2011:
that trough will not tune invest 91L OUT TO SEA AT ALL!! THE TROUGH is going to move fast and lets invest 91L KEEP MOVING WNW!!
MOVING WWW AND SLIGHT WNW SO ITS A WWNW
Member Since: June 13, 2009 Posts: 2 Comments: 12818
Quoting jasonweatherman2011:
that trough will not tune invest 91L OUT TO SEA AT ALL!! THE TROUGH is going to move fast and lets invest 91L KEEP MOVING WNW!!


Jason, wasnt you on here just yesterday when I posted model runs of pre 91L and said it was going out to sea??
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Quoting washingtonian115:
Ahhh!! looks like the U.S sheild is up and running again.The east coast will be protected by a trof once again.And the high in the south is pushing storms into Mexico.although that high is going to weaken and move over to my area.Noooo!!!!!


DC or state? if that high lifts to DC...southern East coast could be toast
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Quoting Hurricanejer95:



No models are supporting a Danielle-like path
Dammmit all!!!!.Damn it!!.
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Quoting CaneHunter031472:


Not to mention the addition of radiation to the Hurricane. That would be something a radioactive Katrina


I already said there would be no radiation, this invention hasn't been made or probably hasn't been thought of but if they do i am sure they will not include radiation unless there completely stupid.
Member Since: July 25, 2011 Posts: 0 Comments: 453
Ahhh!! looks like the U.S sheild is up and running again.The east coast will be protected by a trof once again.And the high in the south is pushing storms into Mexico.although that high is going to weaken and move over to my area.Noooo!!!!!
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Quoting washingtonian115:
Pre Emily is coming back for revenge against us..well Mexico for that matter.Let's hope she takes a hurricane Danielle path like in 2010.



No models are supporting a Danielle-like path
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...
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Don nearing landfall:

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the heat wouldn't matter because all the clouds would of been blown away, im not talking about the heat the shockwave
Member Since: July 25, 2011 Posts: 0 Comments: 453
Quoting aspectre:
Even big nukes are extremely mini compared to the energy contained in any dangerous TropicalCyclone.
And I don't see how adding heat-energy into a heat-engine is gonna slow things down.


Not to mention the addition of radiation to the Hurricane. That would be something a radioactive Katrina
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anyway I have this to get us in the mood
Link
Link
Member Since: June 13, 2009 Posts: 2 Comments: 12818
91-L's circulation is 10 degree wide in long and 10 degrees tall in lat. Wow. Just a massive circulation!

If this Storm does go on to be as powerful as some of the models show its ACE will be off the charts.

Link

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For now this is a threat to PR and the islands. Anyone who says that this is a "fish" is simply uneducated.

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Pre Emily is coming back for revenge against us..well Mexico for that matter.Let's hope she takes a hurricane Danielle path like in 2010.
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NHCpositions(dots&2dumbbells) superimposed on the (NHCre-evaluated&altered)ATCFstormtrack

Copy&paste 21.7n86.2w-22.0n86.8w, 22.0n86.8w-22.4n87.5w, 22.4n87.5w-22.9n88.4w, 22.9n88.4w-23.6n89.5w, 23.6n89.5w-24.3n90.7w, 24.3n90.7w-24.6n91.9w, 24.6n91.9w-25.1n93.0w, 25.1n93.0w-25.8n94.3w, 25.8n94.3w-26.5n95.6w, tam, mam, bro, kpil, kbks, isj, 22.2n87.0w, 22.8n88.1w-22.6n88.2w, 23.0n88.7w, 24.0n89.8w, 24.1n90.1w, 24.6n90.7w, 24.9n91.3w-24.7n91.8w, 24.7n92.5w, 25.0n93.0w, 25.3n93.6w, 25.7n94.3w, 26.2n94.9w, 26.5n95.6w into the GreatCircleMapper for more info, and to view a clearer separation between the ATCF dots (which have line segments through their middles) and the NHC dots.

The 2 dumbbells were included as egregious examples of the "scent-hunting" in the NHCtrack:
The rightmost projecting TS.Don SouthSouthWest into a Yucatan landfall.
The leftmost projecting TS.Don WestSouthWest into a (near)Tampico landfall.

Except for a late jaunt toward Brownsville, the ATCF coordinates kept landfall projections between (north of) PortIsabel and (south of) formerMatagordoIslandAirForceBase... even without the track-smoothing by NHC re-evaluations&alterations.
And the "scent-hunting"behaviour of the NHCtrack doesn't derive only from its 3hours-between-reports vs the ATCF's 6hours-between-reports. Comparing consecutive NHC 6hour-tracks, ya still get relatively large variations in NHC-derived headings --
eg the largest being a projected landfall near Galveston, then a projected landfall in Mexico --
showing up consecutively on different sides of the ATCF-derived headings.



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Quoting GHOSTY1:


I know and even if we did figure out a way God would throw us a curveball and then we would have to start all over. What about an idea for using lightning as a source of energy, i don't here too many people looking for that with all this renewable energy. There is never gonna be no lightning and it contains so much power it would perfectly. JMO :P Just trying to think of ways to improve the future


Harvesting Lightning
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Angiest, i understand what your talking about but my idea was more a concussion or percussive explosion that would cause a shockwave to disperse the cloud, this "bomb" wouldn't be blown up close to the ground but in the air above the storm because shockwaves extend in spheres. I don't believe in the chemicals the russians tried chemicals to prevent snowfall and i dont think it worked well for them
Member Since: July 25, 2011 Posts: 0 Comments: 453
Quoting Baybuddy:


It does seem to have that "vibe" doesn't it?
Quoting BDAwx:
Good afternoon blog!
there are a couple of interesting convectionless swirls to the north and northeast of Bermuda :)

Tropical Storm Don kinda looks like a hook on radar. I can't see any reason why Don's intensity would change too much before landfall. I hope rain goes where its needed/wanted from this storm.

91L is quite impressive... ya know, for an invest. I hope everyone is prepared for any potential storm to come from it, and for the Western Pacific tropical storms/typhoons.


91L Resembles a WP storm, or a thypoon. It's pretty big.
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550. JLPR2
Quoting ProgressivePulse:


3/4 days out for you guys. Focus will turn to 91L..


Been keeping both eyes on it with occasional glimpses of Don.
Member Since: September 4, 2007 Posts: 7 Comments: 8748
Is it just me or is 91L looking pretty good for its timeline?
Member Since: August 13, 2007 Posts: 0 Comments: 655
Even big nukes are extremely mini compared to the energy contained in any dangerous TropicalCyclone.
And I don't see how adding heat-energy into a heat-engine is gonna slow things down.
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91L seems to be taking shape pretty quickly. Anyone know what the main impediments to development are?
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Quoting CaneHunter031472:
I can't recall a storm that big forming that far south in the CATL. 91L will be impressive if it put it's act together and I am convinced it is doing just that.

Member Since: October 9, 2008 Posts: 0 Comments: 8436

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Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.

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