Intensifying Hermine closes in on the Texas/Mexico coast

By: Dr. Jeff Masters , 9:47 PM GMT on September 06, 2010

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Steadily intensifying Tropical Storm Hermine is closing in on the coast near the Texas/Mexico border, and should move ashore late tonight. Hermine became a tropical depression at 11pm last night, and could become a minimal hurricane by 11 pm tonight. Hermine's rate of intensification from nothing to a strong tropical storm is one of the fastest on record. It turns out that the extreme southwestern Gulf of Mexico's Bay of Campeche, where Hermine formed, is prone to these sort of rapidly intensifying tropical storms. The curvature and topography of the land help induce a counter-clockwise spin to the air over the region, which helps get tropical storms spinning up unusually quickly. Helping the spin-up process are the very warm 30°C waters, low 5 - 10 knots of wind shear, and moist atmosphere. Hermine promises to be a very wet storm, and latest long range radar out of Brownsville, Texas shows a large area of heavy rain has been drenching southern Texas and northern Mexico all afternoon, with radar estimated rainfall amounts exceeding two inches in a few areas along the coast. Radar loops show that an eyewall is attempting to form, but a region of dry air from over land spiraled into Hermine's core between 4 - 5pm EDT, disrupting eyewall formation. However, it now appears that Hermine has closed off its eye from this dry air, which should aid in intensification. Satellite imagery shows Hermine has vigorous thunderstorms with very cold tops, and improving low-level spiral banding.

Forecast for Hermine
Hermine doesn't have much time over water before it comes ashore, which is a good thing. The storm is steadily organizing, and has a shot at reaching hurricane strength before the center moves ashore late tonight, near midnight. Heavy rain will be the main threat from Hermine, though isolated tornadoes may also cause damage, particularly over South Texas. Hermine is expected to accelerate through Central Texas Tuesday and Wednesday, and the storm's rains will help alleviate moderate to severe drought conditions affecting Central Texas.


Figure 1. Late afternoon radar image of Tropical Storm Hermine. Note the band of dry air spiraling into the core of the storm from the north.

Gaston continues to suffer from dry air
An Air Force Hurricane Hunter aircraft spent the afternoon in Gaston's remains, and found a weak 1012 mb center of low pressure with only a limited region of westerly winds on the south side of the center of circulation. Top surface winds uncontaminated by heavy rain seen by their SFMR instrument were in the 30 - 35 mph range. The airplane found plenty of dry air in the storm's environment, and there are not enough heavy thunderstorms in ex-Gaston's circulation for it to qualify as a tropical depression. The remains of Gaston are now approaching the northern Lesser Antilles, and residents can expect a few heavy rain showers and wind gusts up to 40 mph beginning early this evening and continuing into the night. Latest radar out of Martinique doesn't show much in the way of heavy rain, and satellite imagery confirms that the thunderstorm activity associated with Gaston's remains is quite sparse. A large amount of dry air surrounds Gaston's remains on all sides, as seen on water vapor satellite loops.


Figure 2. Afternoon satellite image of the remains of Gaston, approaching the Lesser Antilles Islands.

Forecast for Gaston
There is little change to the forecast for Gaston's remains. Dry air will continue to be the major impediment to development, and the system is unlikely to become a tropical depression today. However, wind shear, which is currently a moderate 10 knots, is forecast by the latest SHIPS model run to fall very low, 0 - 5 knots, tonight through Wednesday. With almost no wind shear affecting it, Gaston will a better chance of keeping the moisture from its heavy thunderstorms near its core on Tuesday. This will insulate the storm from the dry air surrounding it. The atmosphere is also moister in the eastern Caribbean, further increasing the chances of development. I believe it is probable Gaston will become a tropical depression again on Tuesday. NHC is currently giving Gaston a 70% chance of developing into a tropical depression by Wednesday, which is a reasonable forecast.

Heavy rain showers and gusty winds from the storm will affect Puerto Rico Tuesday morning through Wednesday afternoon. This activity will spread to the Dominican Republic Tuesday afternoon through Thursday morning. Assuming dry air and an encounter with Hispaniola's high mountains do not destroy Gaston, heavy rain from the storm should move over Haiti, eastern Cuba, and Jamaica Wednesday night and Thursday morning. The models don't give much support for Gaston surviving past Wednesday. The ECMWF, GFS, NOGAPS, Canadian, and HWRF models all dissipate Gaston. However, two models--the GFDL and UKMET--predict that Gaston will survive the dry air and an encounter with Hispaniola, and pass far enough south of the island to find a favorable environment in the Central Caribbean for development on Wednesday. Wind shear will be low, water temperatures will be hot, and the atmosphere will be plenty moist. Gaston could intensify into a hurricane in the Western Caribbean by the end of the week, as predicted by the latest run of the GFDL model.

Elsewhere in the tropics
The models are fairly unanimous in predicting development late this week of a tropical wave expected to emerge from the coast of Africa on Tuesday or Wednesday. The next storm will be called Igor.

Next post
I'll have an update in the morning.

Jeff Masters

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Levi: How far north? Tx/Mx border?
Member Since: Posts: Comments:
285. JLPR2
Quoting weatherman12345:
POLL TIME!
Ex Gaston at the 8:00PM TWO
A. 50%
B. 60%
C. 70%
D. 80%
E. 90%


I'll say they keep it the same, C.
Member Since: September 4, 2007 Posts: 7 Comments: 8747
If all we get along the TX Gulf Coast this year is these outer bands of Hermine--I'll take it! It's raining right now and we need the rain.
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This is the Caribbean in two days:


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Ouch, some nasty thunderstorm activity headed my way over here. Loads of thunder and lightning all over the place.

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Poll: D 80 percent
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Quoting weatherman12345:
POLL TIME!
Ex Gaston at the 8:00PM TWO
A. 50%
B. 60%
C. 70%
D. 80%
E. 90%


Member Since: Posts: Comments:
Quoting weatherman12345:
POLL TIME!
Ex Gaston at the 8:00PM TWO
A. 50%
B. 60%
C. 70%
D. 80%
E. 90%

C. or D. The environment is forecast to be much more favorable, but it may pass too close to PR.
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Quoting weatherman12345:
POLL TIME!
Ex Gaston at the 8:00PM TWO
A. 50%
B. 60%
C. 70%
D. 80%
E. 90%


I originally was thinking 60%, but after seeing several well-respected people say; including the NHC say conditions will be much better for development tomorrow; I will go with C - 70%
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276. iahwx
Quoting weatherman12345:
POLL TIME!
Ex Gaston at the 8:00PM TWO
A. 50%
B. 60%
C. 70%
D. 80%
E. 90%


A.

He's got a chance but I give him 50/50
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275. 7544
Quoting futuremet:
Gaston will be in less dry air and no wind shear tomorrow.



yeap tomorow might be his day

also notice the new model runs take him further north this run he still needs to be watch no rip just yet imo so for the poll ill say 70%
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Here we go with the frictional effects keeping Hermine offshore and moving more northerly for the moment. This is how storms like Dolly in 2008 snuck into Texas even though they were bound for Mexico. Now this is too close to avoid Mexico now, but it is trying to stay over water and come farther north.

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Quoting MiamiHurricanes09:
C.
Quoting weatherman12345:
POLL TIME!
Ex Gaston at the 8:00PM TWO
A. 50%
B. 60%
C. 70%
D. 80%
E. 90%
D.
Convection is over the coc now and has been basically all afternoon. He is not looking that bad right now imo.
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.
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.
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If something can move over that TCHP slowly, I'm willing to bet that it would rival Wilma's intensity. Especially if it was already a Hurricane.

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Quoting CycloneUK:

A lot of convection in Westernmost Africa.
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Quoting weatherman12345:
POLL TIME!
Ex Gaston at the 8:00PM TWO
A. 50%
B. 60%
C. 70%
D. 80%
E. 90%
C.
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Quoting Eugeniopr:

Thank You for the correction Weathernerd, you are right.

No problem.
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Gaston will be in less dry air and no wind shear tomorrow.

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Thank You for the correction Weathernerd, you are right.
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261. JLPR2
Quoting TropicalAnalystwx13:


This is where I just ignore and move on.


And I admire that :D
Member Since: September 4, 2007 Posts: 7 Comments: 8747
Quoting ozzyman236:
it doesnt have to turn nne for you guys to get some really heavy rains and flooding conditions...a north movement would bring hermine very close to you all in houston...


It looks like it took a west hook actually..., but it did stall so who knows. I just havent seen any steering currents pushing it north.
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Quoting StormW:


Hey thel,

They did overnight, while you weren't looking! LOL!

How are ya this evening?


Senior Chief, I am doing wonderful thanks for asking! :) And yourself?

Appears that Herm is floundering, not moving much......

I could see some erratic motion..... but not sold on Houston just yet! LOL
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251. TropicalAnalystwx13 7:19 PM EDT on September 06, 2010

good ty
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And do not forget the US Virgin Island too. They received some winds and rain a 100 miles south of Earl. Earl impacted USA like 20 times.
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Quoting RitaEvac:
Same location from when Masters posted





Looks N to me.
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Quoting sammywammybamy:
Whats Going On Over Florida?


East coast seabreeze front lit everything up.
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Quoting hurricanealley:


For some reason this sentence gave me a headache.


You're not the only one.....
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Quoting will40:


i know what bashing is yungan


This is where I just ignore and move on.
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Quoting skkippboo:
All that water that flooded Monterrey from Alex and TD2 finally exited the interior floodways on the US side just 2 weeks ago. We have never seen that amount of water inside the levee system here in S. TX. It took a full month and a half for that water to finally flow back into the ocean. I hate to imagine what the flooding would have been like here along the border region of S. TX. and Mexico if we hadn't put in place the flood control infrastructure we have now, including Amistad Dam, Falcon Dam, Marte Gomez res. in Mex., Anzalduas Dam, and the interior floodway system built by the Army Corp of Engineers here in S. TX. All that flooding was pretty much a non-event thanks to all that infrastructure other than a little inconvenience of having to find another route over the floodway levees, and some crop losses inside the floodway. Monterrey got hammered pretty bad though, they don't need that again.

Nuevo Leon (The Mexican State were Monterrey is) had 1.35 billion dollars in damage. They got hammered.
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Definitely strong storms moving to Corpus.

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Quoting dmaddox:
amazing how it was racing NNW then just nearly stalled! wow dont think i have ever seen that before!!!

Its probably feeling the coastline. It is not uncommon for storms coming into a coastline at a shallow angle to "bounce" off the coast a bit.
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Quoting futuremet:


The longer it stalls, the slower it will strengthen. It is upwelling the waters below it. Then again if it moves too fast, it is going to hit land sooner. Die-die situation I guess...


Could be slowing cause of this? Although it shouldnt slow it for long.
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Quoting futuremet:



It will continue to strengthen, but it will not go through tropical bombogenesis.


lol.

Is that a fancy word for intensification?
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Quoting Eugeniopr:
Guys, Ladies and Others:

Earl impacted Puerto Rico with 30KT winds and some rain while cruising 120 miles north. Remember Puerto Rico is also USA, so please consider another impact.

35Knots in the North-Eastern Part of PR. But it's the same pretty much.
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Quoting will40:


sure you was wont be to go find it?


For some reason this sentence gave me a headache.
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Quoting Eugeniopr:
Guys, Ladies and Others:

Earl impacted Puerto Rico with 30KT winds and some rain while cruising 120 miles north. Remember Puerto Rico is also USA, so please consider another impact.


Yeah I was going to mention that but didnt know if official TS conditions were experienced.
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Quoting TropicalAnalystwx13:


I'd rather he hype it then downcast it.

I guarantee Bastardi knows more than about 80% of you in here.

I get sick and tired when people bash other people. (Ex. Someone Vs. Bastardi)

Just stop.

(Directed to the whole Wunderground community as a whole.)


TV Mets hype, shoot they need the ratings. My poor brother on Central L.I had to call me to get the REAL forecast on Earl. He said if he had to listen to the local Mets he thought he was gonna get blown away!!..LOL I told him he wouldnt even get TS Force winds and he didnt.
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Quoting leo305:


so you're telling me it uses up that energy in mere hours? That's..not right



It will continue to strengthen, but it will not go through tropical bombogenesis.
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Quoting WeatherNerdPR:

Mexico would get flooded. AGAIN.
All that water that flooded Monterrey from Alex and TD2 finally exited the interior floodways on the US side just 2 weeks ago. We have never seen that amount of water inside the levee system here in S. TX. It took a full month and a half for that water to finally flow back into the ocean. I hate to imagine what the flooding would have been like here along the border region of S. TX. and Mexico if we hadn't put in place the flood control infrastructure we have now, including Amistad Dam, Falcon Dam, Marte Gomez res. in Mex., Anzalduas Dam, and the interior floodway system built by the Army Corp of Engineers here in S. TX. All that flooding was pretty much a non-event thanks to all that infrastructure other than a little inconvenience of having to find another route over the floodway levees, and some crop losses inside the floodway. Monterrey got hammered pretty bad though, they don't need that again.
Member Since: Posts: Comments:

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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.