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 pottery:

A trifle warm, what?


You gonna get wet again... there is a Blob sneaking up on you.
Member Since: October 1, 2007 Posts: 81 Comments: 26511
I think its peak intensity (now because of landfall) is 75-80 mph
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Quoting pottery:

A trifle warm, what?


I think we could go diving in your neck of the ocean and find the crabs already boiled... LOL

How ya doing Pottery?
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Quoting CybrTeddy:
Looking at radar, surface obs, and recon reports from earlier Hermine made landfall at 9:26 pm EDT as a 65 mph Tropical Storm with a pressure of 991 mb.
It hasn't made landfall yet. Give it another 10 minutes or so.

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Quoting CybrTeddy:
Looking at radar, surface obs, and recon reports from earlier Hermine made landfall at 9:26 pm EDT as a 65 mph Tropical Storm with a pressure of 991 mb.


I dont think it has made landfall yet
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Quoting btwntx08:
hydrus i live on the north side of brownsville...also that was a stupid question greyelf said to u lol he is lying i dont get mad
Thanx...I would say you are in for a pretty long night...Wish ya the best..:)
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Quoting tomas5tex:
Good evening everyone


Good evening!
Member Since: July 5, 2010 Posts: 0 Comments: 170
Looking at radar, surface obs, and recon reports from earlier Hermine made landfall at 9:26 pm EDT as a 65 mph Tropical Storm with a pressure of 991 mb.
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Quoting earthlydragonfly:
Holy Hot Batman!! Stay out of the water...


A trifle warm, what?
Member Since: October 24, 2005 Posts: 0 Comments: 24239
Quoting stormpetrol:
My 25th Wedding Anniversary is tomorrow(Silver)and I love my wife more today than I did yesterday but not as much as tomorrow. Catch up with you all Wednesday, hopefully :)
Well, happy anniversary! Have a great day!
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Quoting SirTophamHatt:
The only way I could consider Gaston dead is when the low totally dissipates. With the THCP of the Carribean, all somebody has to do is fart in the water to generate a tropical system


lol
Member Since: July 5, 2010 Posts: 0 Comments: 170
Quoting Stoopid1:
Do those scans show sustained winds or gusts, and is it showing sea level or at a set elevation? Either way, that's impressive.


that is radar height or in this case 3000 ft
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Quoting thunderblogger:
Wi dosome pepole on her not nohow to spoklen r spill kerrectly.?...?? lol
Maybe texting language syndrome has overcome the masses.
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Quoting Stoopid1:
Do those scans show sustained winds or gusts, and is it showing sea level or at a set elevation? Either way, that's impressive.


You're looking at a slice through the system at a particular angle of elevation of the radar, meaning higher up the further out you get.
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762. thunderblogger 1:25 AM GMT on September 07, 2010

*Checks his stats*

Oh look, people who laughed at this "joke"

1

hmmmmm imagine that
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Quoting pottery:

You are correct in that.
In fact, Gaston has been a real enigma.
He SHOULD have become a much stronger system.
What a peculiar year 2010 has been, so far.
Dry air?
That was not in the recipe at all...........
Thanks to the SAL. However, the back half of the season can be more deadly than the CV portion. As can the back half of a hurricane.
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My 25th Wedding Anniversary is tomorrow(Silver)and I love my wife more today than I did yesterday but not as much as tomorrow. Catch up with you all Wednesday, hopefully :)
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The only way I could consider Gaston dead is when the low totally dissipates. With the THCP of the Carribean, all somebody has to do is fart in the water to generate a tropical system
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Quoting KoritheMan:


It is. Not only for the reason you stated, but because I'm tired of forecasting him. lol
I thought I was the only one that got frustrated....
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Quoting Stoopid1:
Do those scans show sustained winds or gusts, and is it showing sea level or at a set elevation? Either way, that's impressive.


that is radar height or in this case 3000 ft
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Quoting skkippboo:
It was back when he posted that.


Gotcha. I was gonna say lol.
Member Since: July 5, 2010 Posts: 0 Comments: 170
Good evening everyone
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Quoting btwntx08:
hydrus i live on the north side of brownsville...also that was a stupid question greyelf said to u lol he is lying i dont get mad
How was that last little cell that came through? Looked short but nasty...
Member Since: August 28, 2005 Posts: 0 Comments: 112
Holy Hot Batman!! Stay out of the water...

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When it makes landfall, the NHC will come out with a special statement regarding the intensity, usually, when there is no recon investigating the system, they tend to use radar estimates. Based on that, I wouldn't be surprised that they raise the winds another couple mph, whether or not it becomes a hurricane is up in the air, although it doesn't seem as likely as before.
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Do those scans show sustained winds or gusts, and is it showing sea level or at a set elevation? Either way, that's impressive.
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Quoting Thundercloud01221991:


no but I want one


Annoying not seeing the coastline south of the River.
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757. xcool
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Quoting angiest:


Do you know of a placefile that will show Mexico?


no but I want one
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Quoting PtownBryan:


The sun is still out there?
It was back when he posted that.
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Newbie question....pressure is rising here in Corpus. Isn't that a good thing? I am sure that i have heard that storms gravitate to lower pressure and away from higher ones. Is this correct? TIA
Member Since: July 28, 2010 Posts: 0 Comments: 276
753. IKE
Looks like she's(or part of her), touching the coast....

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Quoting skkippboo:
Ahh,, finally,, some differnt f5 ads. And no, I'm not gonna pay to get rid of ads.


Not having the ads is nice but I paid to support the site.
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Quoting Thundercloud01221991:
this is from the last scan you can see the peak winds on the right hand side



Do you know of a placefile that will show Mexico?
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Latest scan shows 83 knts
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We're about 15-30 minutes away from landfall.

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Quoting angiest:
Hmmm, radar may support hurricane strenght. May. the 0.5 degree base velocity scan has some ~65kt winds east of the eye.
A hurricane is still possible.
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Gaston is dead , they just ain't buried him yet!Hope I don't have to eat my words "There is no indigestion as bad as having to eat your own words"
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Quoting duckhookag:
Hello all. Longtime lurker and rare poster. Located here in Harlingen, TX. Looks like we're getting ready to get pounded. Ugly looking clouds to my southeast. I'll post some tonight if I get a chance.


The sun is still out there?
Member Since: July 5, 2010 Posts: 0 Comments: 170
I'm out. Gonna go watch Hermine in person with my own eyes, not on the computer. Good Night.
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Quoting Nolehead:
very true Potter...but i'm just saying it don't take much this time of year for anything to form...

You are correct in that.
In fact, Gaston has been a real enigma.
He SHOULD have become a much stronger system.
What a peculiar year 2010 has been, so far.
Dry air?
That was not in the recipe at all...........
Member Since: October 24, 2005 Posts: 0 Comments: 24239
742. IKE
The 34 knot winds only extend out 50 miles to Hermine's NW. See...I knew that Levi, before I posted the Brownsville observation that showed a wind at 9 pm....

MAX SUSTAINED WINDS 50 KT WITH GUSTS TO 60 KT.
50 KT....... 30NE 30SE 0SW 20NW.
34 KT....... 90NE 90SE 20SW 50NW.
........................................

Wind gust now of...Wind Gust: 22 mph
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this is from the last scan you can see the peak winds on the right hand side

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740. xcool
GRlevel3 79.99$
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Quoting MiamiHurricanes09:
Where do you find that information?


Grlevel3 is what I use, too.
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738. xcool
GRlevel3 100%best rader
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I think my post was eaten the other night because I can't find it. Can someone explain the difference between the computer spaghetti models and the ensemble models?
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Quoting Hurricanes101:


you sure about that?

Pressure was 1015mb with Andrew and the LLC completely disintergrated
lol.. I said LOOKED better.
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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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