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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Quoting will40:


sure you was wont be to go find it?


Bashing: The act or process of attacking or abusing, as with blows or, esp., with words
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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.
Member Since: August 1, 2010 Posts: 0 Comments: 251
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...


so you're telling me it uses up that energy in mere hours? That's..not right
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Quoting SETexas74:


Just wondering, why do you think Hermine will turn NNE?


Because in stormtop's mind all TC's are attracted to LA if they are worth a darn.
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230. Vero1
Quoting sammywammybamy:
Whats Going On Over Florida?




We are creating our own weather...should we name it??
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Same location from when Masters posted



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Quoting sammywammybamy:
Whats Going On Over Florida?




Is TD5 about to make another pass?
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Quoting sammywammybamy:
Whats Going On Over Florida?



A lot of rain.
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Quoting TropicalAnalystwx13:


No, I wasn't bashing Hurricanes101.


sure you was wont be to go find it?
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http://tidesonline.nos.noaa.gov/plotcomp.shtml?station_info=8779770+Port+Isabel%2C+TX#

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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!!!


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...
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Quoting ozzyman236:
txnovice keep and eye on hermine it could be heading up your way..


Just wondering, why do you think Hermine will turn NNE?
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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!!!

That is amazing.
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Quoting will40:
200. TropicalAnalystwx13 7:07 PM EDT on September 06, 2010

i think you was bashing someone on here earlier


No, I wasn't bashing Hurricanes101.
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Quoting Hurricanes101:


you rang? lol


lololol
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Quoting will40:
200. TropicalAnalystwx13 7:07 PM EDT on September 06, 2010

i think you was bashing someone on here earlier


you rang? lol
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Quoting RecordSeason:
I saved the 2300 Radar and the 2245 Dvorak of Gaston so we can see how pathetic he looks right now, just in case the nightmare CHIPS scenario later pans out...

Then we can see how dramatic a difference there might be.

lol
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amazing how it was racing NNW then just nearly stalled! wow dont think i have ever seen that before!!!
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200. TropicalAnalystwx13 7:07 PM EDT on September 06, 2010

i think you was bashing someone on here earlier
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Quoting weatherman321:
H. has definatly stalled for the time being, This storm wants to be hurricane so badly right now... =0

2 comments in 2 years? Are you a super lurker?
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Hermine would have to change an awful lot to head my way :)
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Quoting StormW:


Hey thel,

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

How are ya this evening?


Evening Storm,

I still have the baby powder if you need to slap a troll this evening lol!
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They have'nt shown the next vortex point yet... its not clear... but I am pretty sure it went that way




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Quoting IKE:


Agree....but, Earl came no closer than 75 miles from a USA landfall. About the same with Alex. If he's gonna play the game that way, then I quit playing his prediction.
To me, the eye must cross over the land before it makes landfall.
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H. has definatly stalled for the time being, This storm wants to be hurricane so badly right now... =0
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Funny, the wind is blowing and it's raining pretty heavily here and I'm up here near Houston.
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Quoting Krycek1984:


Bastardi is just like almost the rest of Accuweather...gets his panties all in a bunch and hypes everything up to the umpteenth degree at the nearest sign of tropical development/impact (or, in the winter, snow events). The only two guys on there I can stand are Brett Anderson and Joe Lundberg, neither of which blow things out of proportion, and both are reasonable in forecasts, especially Brett Anderson.


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.)
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In the absense of strong steering currents, the frictional force created by the proximity of the center of Hermine to the coast will impart a northerly movement to the system.
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198. JeffM
Quoting PtownBryan:


Between all of us and some others we got texas covered lol. Where are you San Antonions and Austinites? lol


San Antonio here. Waiting for the rain to make it up this way.
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Quoting IKE:
Brownsville,TX airport had a 48 mph wind gust on June 30th from Alex. You get that much wind in a severe thunderstorm.




He said on the Florida Network News(radio), back in August of 2005 that Katrina was headed for the Florida panhandle. Then when the models switched west to Louisiana he said, on FOX news, that his track was to Louisiana all along.

He stretches the truth.


That I was five years ago. I wonder if he still does that. I don't visit AccuWeather much.
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Quoting btwntx08:
pressure steadly falling here
Brownsville / South Padre Island Intl Airport
Lat: 25.9 Lon: -97.43 Elev: 19
Last Update on Sep 6, 5:53 pm CDT


Fair

81 °F
(27 °C) Humidity: 88 %
Wind Speed: NE 10 MPH
Barometer: 29.71" (1005.8 mb)
Dewpoint: 77 °F (25 °C)
Heat Index: 88 °F (31 °C)
Visibility: 10.00 mi.


A
Are you getting rain yet?
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193. xcool
boy i tell you ike good memories for be old.lol ha
Member Since: September 26, 2009 Posts: 2 Comments: 15620
Quoting MiamiHurricanes09:
Did he say landfall? No, he said impact. Both Earl and Alex impacted the US by bringing tropical storm conditions to both of the areas both of those storms impacted.


Don't or he'll ignore you as a troll as well. Argument with IKE simply begets nothing.
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191. JLPR2
I see Gaston doesn't look good, not good at all, so that's good. :D

The movie, well... I cant say it was good. :|
Member Since: September 4, 2007 Posts: 7 Comments: 8499
Gaston will be moving into favorable conditions soon.
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Quoting JLPR2:


Not really, Alex had stronger convection before his landfall in the Yucatan peninsula, but it is intense and organized, no doubt about that. :| Lots of rain for areas that doesn't need it.


he also had a lot more time over the Gulf too and was already a TS when he got there
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Quoting skkippboo:
Why don't you like Bastardi?


Bastardi is just like almost the rest of Accuweather...gets his panties all in a bunch and hypes everything up to the umpteenth degree at the nearest sign of tropical development/impact (or, in the winter, snow events). The only two guys on there I can stand are Brett Anderson and Joe Lundberg, neither of which blow things out of proportion, and both are reasonable in forecasts, especially Brett Anderson.
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187. JLPR2
Quoting angiest:
Anyone else impressed with the strength of Hermine's convection?


Not really, Alex had stronger convection before his landfall in the Yucatan peninsula, but it is intense and organized, no doubt about that. :| Lots of rain for areas that doesn't need it.
Member Since: September 4, 2007 Posts: 7 Comments: 8499
Hey Guys!

So that area to the south and southwest of Hermine was a Dry slot. I though it was about 1-3 hours ago, but didn't mention it.
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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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