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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Well just our luck here in ole CC, finally get a rain event to come close enough to us and all the "normal" aspects don't exist. Like the NE quadrant having the majority of the moisture..... Oh well i guess we can enjoy the minimal breeze and the cloud cover, but for crying out loud will someone please send us some rain!
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Don about to make landfall in less than 3 hours? anyone have any live cams from texas?
Member Since: July 25, 2011 Posts: 0 Comments: 1102
720. thewindman 8:49 PM GMT on July 29, 2011 +0
91L is already a FISH STORM per GFS model. I woudn't be surprised

you are WRONG
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Quoting PrivateIdaho:


Tropical13 beat you by 2 minutes....you must be getting old...;^)
LOL. Back and forth between the computer and grandchildren.
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Quoting barbados246:
Thank you so very much for mentioning that to him. Sometimes i believe some people on here just see the USA as small as our islands are "PEOPLE" still live on them!!!


I am pretty sure that the majority of posters know that the islands are inhabited by humans. FISH STORM is a term and while it may not be at all true, its going to be used.
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Looks like us In south Florida needs to watch 91L very closely, look at what the NWS Miami posted


.EXTENDED FORECAST...
THE LATEST LONG RANGE MODELS ARE THE HIGH PRESSURE TO REMAIN OVER
THE SOUTHERN GULF COAST STATES EXTENDING BACK INTO NORTH CENTRAL
FLORIDA...AS A TROUGH OF LOW PRESSURE DEVELOPS IN THE EASTERN
ATLANTIC STATES. THIS WILL KEEP THE WIND FLOW OVER SOUTH FLORIDA
IN A EASTERLY DIRECTION AND FOCUS THE HIGHEST POPS OF THE SHOWERS
AND THUNDERSTORMS OVER THE INTERIOR AND LAKE OKEECHOBEE AREA FOR
MOST OF NEXT WEEK.

THERE IS ALSO A LARGE TROPICAL WAVE OVER THE CENTRAL ATLANTIC
WATERS EAST OF THE LESSER ANTILLES. THIS SYSTEM IS FORECAST BY THE
LONG RANGE MODELS TO MOVE GENERALLY WESTWARD THROUGH NEXT WEEK. AT
THIS POINT IT IS TO EARLY TO TELL WHAT IMPACT IF ANY THIS SYSTEM
WILL HAVE ON LOCAL WEATHER. WE WILL CONTINUE TO MONITOR THIS
SYSTEM IN THE COMING DAYS.
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Quoting wunderkidcayman:

I was off island as well just a few hours ago I got back




you don't even know what that means do you? cause if you did you wouldn't be using it for this system


Welcome home WKC.Looks like a busy season from here on!
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Quoting MiamiHurricanes09:
He's one of the first 5 people I have on my ignore list...ignorance at its finest. LOL.


207 for me.



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Quoting Jedkins01:


Nope, pride is what ruins are society, pride keeps people from accomplishing things. Humility, honesty, respect, diligence, honor, peace, love, confidence, and faith. Those are the things that lead people to accomplish great things.

I'm not gonna argue on a computer, but I tried to help :)


I think you may be a little off on this one Jedkins. I work in the family business. While at times it is a a real pain dealing with family at work, it is the pride that keeps the job fun. Pride in knowing that I am doing what my grandfather did. Pride in the fact that the business was built by people with my last name. Pride in the fact that we run our business to the highest standards, with American workers and with a tremendous level of ethics. I take great pride in my job.
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Quoting MississippiWx:


How is it a fish storm when it goes through the Greater and Lesser Antilles? A lot of people live on those islands. The US isn't the only place where people live.
Thank you so very much for mentioning that to him. Sometimes i believe some people on here just see the USA as small as our islands are "PEOPLE" still live on them!!!
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alright guys and gals, im outta here and i enjoyed the military tech part i gotta have 2 of my 3 favorite things in one blog, military and hurricanes
Member Since: July 25, 2011 Posts: 0 Comments: 453
Quoting MiamiHurricanes09:
He's one of the first 5 people I have on my ignore list...ignorance at its finest. LOL.


Yeah, probably about to be added to mine as well.
Member Since: July 15, 2006 Posts: 17 Comments: 10160
Quoting stormpetrol:


Kman lives just under 1 mile from me and come to think of it I haven't seen him on the road in about 2 weeks, though I know Kman is a very busy man!Probably off Island!

I was off island as well just a few hours ago I got back



Quoting thewindman:
91L is already a FISH STORM per GFS model. I woudn't be surprised

you don't even know what that means do you? cause if you did you wouldn't be using it for this system
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Quoting thewindman:
91L is already a FISH STORM per GFS model. I woudn't be surprised

91L imo will track similar to Don, probably just a tad south if anything, a Caribbean Cruiser I would venture to say!
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twc cone does not look like a fish
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Quoting MississippiWx:


How is it a fish storm when it goes through the Greater and Lesser Antilles? A lot of people live on those islands. The US isn't the only place where people live.
He's one of the first 5 people I've put on my ignore list...ignorance at its finest. LOL.
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18z NAM shows Emily/TD5 coming through the Lesser Antilles at a much lower latitude:

Member Since: July 15, 2006 Posts: 17 Comments: 10160
"The MOAB's blast is equivalent to around 11 tons of TNT, whereas the Hiroshima blast was equivalent to 15,000 tons of TNT; modern nuclear missiles are far more powerful than the atomic bomb used against Hiroshima. However, the MOAB bomb's yield is comparable to the smallest of nuclear devices, such as the M-388 Davy Crockett."
Then there's the Father of All Bombs.
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Quoting P451:


LOL!


If hurricanes really were male then we wouldn't need model runs. XTRP would suffice for every storm.



Lol.
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jedkins, No argument intended, but if some people didn't have pride i bet things would have of totally different in a negative way. You gotta take pride in your work. But since it seems that this topic has brought on bad feelings im officially ending my part in this topic.
Member Since: July 25, 2011 Posts: 0 Comments: 453
Quoting JLPR2:


Including Puerto Rico and the US Virgin Islands that in a way are part of the US. :\

To me a storm that hits land either in Spain, Bermuda, Africa, US, Caribbean in conclusion anywhere were people live is not a fish storm.

Saying a storm is a fish when it killed people in another country makes you wonder what happened to human sympathy.
Yes. Sorry. When I said US I only meant the mainland.
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Quoting thewindman:
91L is already a FISH STORM per GFS model. I woudn't be surprised


How is it a fish storm when it goes through the Greater and Lesser Antilles? A lot of people live on those islands. The US isn't the only place where people live.
Member Since: July 15, 2006 Posts: 17 Comments: 10160
723. j2008
Quoting stormpetrol:
I think 9.2N/44W is the vort of 91L, though I see another near 10N/41WLink

9.8/44 I think, its even got a blob of convection growing over it now. Ill say 40-50%, they will want to look for more persistiance in convection.
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721. HCW
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91L is already a FISH STORM per GFS model. I woudn't be surprised
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Quoting GHOSTY1:
Jedkins, it it wasnt for our human pride we wouldn't have gone anywhere so that pride is what keeps up innovative and great, so i hope that pride continues


Nope, pride is what ruins are society, pride keeps people from accomplishing things. Humility, honesty, respect, diligence, honor, peace, love, confidence, and faith. Those are the things that lead people to accomplish great things.

I'm not gonna argue on a computer, but I tried to help :)
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Quoting CanesfanatUT:


I have been here a yr and a half and have never driven in the District. Too many streets that are at weird directions and just the parking/traffic in general.

I Metro or walk. Love the Metro!


It wasn't any better in the 70's. My dad rode his bike to the Pentagon nearly everyday for 6 years. Lol.
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Quoting catastropheadjuster:
Hey this is off subject, but was just wondering if anyone has heard from KMan or talked to him? Usually u see him around and I haven't.

sheri


Kman lives just under 1 mile from me and come to think of it I haven't seen him on the road in about 2 weeks, though I know Kman is a very busy man!Probably off Island!
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Artificial weakening was experimented with Debbie in 1969



However, the storm quickly downgraded, and by August 19 it was once again at minimal hurricane force. At roughly the same time, it turned more to the west, although it maintained a general northwesterly path.[1][4] The abrupt weakening may have been the result of a seeding experiment carried out on the storm in an attempt to deteriorate it.[5] By later in the day, Debbie had begun to restrengthen. It resumed Category 3 intensity on August 20, despite a minor oscillation in magnitude during the day. At this point, the cyclone acquired peak winds of 120 mph (195 km/h); shortly thereafter, its lowest recorded barometric pressure fell to 951 millibars.[1]

And im seeing an uptick in bad words (692, 646, 627), im getting frowned
Member Since: August 30, 2008 Posts: 1 Comments: 224
i've gotten so far off topic but i like a good debate. :P
Member Since: July 25, 2011 Posts: 0 Comments: 453
I think 9.2N/44W is the vort of 91L, though I see another near 10N/41WLink
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711. jpsb
Quoting metwombly:
Call me batty, whatever, but I think that is why the storms get names. For scientists, a numerical designation is sufficient for tracking purposes. But one gets the feeling that by them having names, they also will behave more like a human, difficult to predict, even when forecasters are armed with the most sophisticated technology, a set of avgs, and years of experience.
Hurricanes are supposed to be named after woman, completely unpredictable and highly destructive ;)
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Quoting CanesfanatUT:


I have been here a yr and a half and have never driven in the District. Too many streets that are at weird directions and just the parking/traffic in general.

I Metro or walk. Love the Metro!
The streets here are weired and in some cases small and crowded.
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Quoting stormpetrol:
I wouldn't be surprised to see 50-60% at 8/7cst for 91L

With you on that orange/red alert 50-60% at 8pm
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Jedkins, it it wasnt for our human pride we wouldn't have gone anywhere so that pride is what keeps up innovative and great, so i hope that pride continues
Member Since: July 25, 2011 Posts: 0 Comments: 453
Hey this is off subject, but was just wondering if anyone has heard from KMan or talked to him? Usually u see him around and I haven't.

sheri
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As lame as Don might look, that deep convective burst will hammer Brownsville. Convection with tropical cyclones is always much more intense than it appears on radar, remember that. Its too complicated to explain why, but processes in tropical convection is actually quite different from processes in Mid-Latitude type convection.

Of course, tropical convection can occur in Mid-Latitudes too if the atmosphere so permits. But, you get my point.

Interestingly enough though, the convective core appears to be weakening now quite a bit as it approaches the coast, so we will see.
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Quoting stormpetrol:
I wouldn't be surprised to see 50-60% at 8/7cst for 91L


It's looking good no doubt.
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91L IR Floater

Link
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Quoting angiest:


They have been further north:



Never saw all of her track before. Yeah it happens. The weirdest one I saw like that formed off of NC went sw over FL then into Tx. I can't remember what storm. I'm linkless right now.
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Quoting jpsb:
If you want bigger then an H-Bomb, don't fool around with a carbon or oxygen bomb, go straight for an anti-matter bomb. 100% efficiency and no harmful long lasting radiation :)


Well there are those harmful, extremely high energy, gamma rays that are released. :)
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I wouldn't be surprised to see 50-60% at 8/7cst for 91L
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Quoting CanesfanatUT:


I have been here a yr and a half and have never driven in the District. Too many streets that are at weird directions and just the parking/traffic in general.

I Metro or walk. Love the Metro!


Yeah the spoke and wheel system, extremely confusing.
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Quoting Jedkins01:
lol people are silly, a weapon wouldn't stop a hurricane, it might temporarily disrupt a portion of it, but a low pressure area with air wrapping around it at over 100 mph will quickly fill in that little dent that it took millions and millions of dollars to produce. Waste of money, waste of time. Oh and not too mention its just stupid. Hurricanes are there for a reason. This Universe was designed along with the Earth no matter how much people want to deny it. We already have stupidly done enough damage to the nature and the environment, trying to stop hurricanes is just another big step of human pride and foolishness.


+1
Member Since: July 6, 2010 Posts: 113 Comments: 31548
jpsb got the right idea, and when the MOAB was created it was largest ordinance bomb, but like i said earlier times change guns get deadlier, bombs more effective, etc. etc. etc.
Member Since: July 25, 2011 Posts: 0 Comments: 453

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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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