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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FLdewey what!?!?!?!?

I think you watch too much Greenzone
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Quoting MiamiHurricanes09:
Hermine seems to have picked up in speed (slightly) as it heads generally towards the N/NNW.



Now see, you zoom in on WU radar and the coastline is absolutely perfect.
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Quoting Hurricanes101:


Texas, Mexico whatever

the point is people are following these storms on radar, how could they not have the coastline shaped properly?
Good question. I dn't know. And there is a big difference in MX and TX.
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Quoting skkippboo:
That aint TX. And nobody's perfect.


good catch..was thinking that was weird but have not lived there for over 20 years
Member Since: August 19, 2007 Posts: 0 Comments: 2974
Quoting Hurricanes101:


There is no island there
There is. It is off the Mexican coast. Why did yousay its not there??WWWWWWWHHHHHHYYYYYYYY?/....jk.101:)
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Quoting Hurricanes101:


There is no island there

Not any more. Wow Hermine means business!
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Quoting leo305:
looks like miami beach may flood..

a line of heavy storms stalled over miami beach
Tell me about it. I'm not in Miami Beach but the streets are beginning to flood here.
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Quoting beell:
Special exemptions for Post's 601 and 609.


LOL thanks! Momma always told me I was special!

How bout b
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Quoting IKE:
Brownsville, Texas (Airport)
Updated: 9 min 57 sec ago
Heavy Rain
81 °F

Heavy Rain Mist
Humidity: 89%
Dew Point: 77 °F
Wind: 9 mph from the NE
Pressure: 29.68 in (Steady)
Heat Index: 87 °F
Visibility: 2.0 miles
UV: 0 out of 16
Pollen: 6.80 out of 12
Pollen Forecast new!
Clouds:
Few 1700 ft
Mostly Cloudy 2700 ft
Overcast 8000 ft
(Above Ground Level)
Elevation: 20 ft



Give it time. The core is small and the storm is immature.
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Hermine seems to have picked up in speed (slightly) as it heads generally towards the N/NNW.

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expecting to get what doesnt drench miami to come "flood" me in key west. our form of drainage is called evaporation
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Quoting docrod:


Time to move in close

Link


Excellent link...Thank you...My original post referred to a Family Guy episode.
Member Since: September 10, 2007 Posts: 0 Comments: 11513
Quoting skkippboo:
Wow, getting tired of Bill White's ad every time I F5!!


You and me both!! lol
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Quoting FLdewey:
Not even a good MD going yet...

SPC

...MIDDLE TX COAST TONIGHT...
TROPICAL STORM HERMINE IS FORECAST TO APPROACH HURRICANE STRENGTH JUST PRIOR TO LANDFALL ALONG THE LOWER TX COAST LATE TONIGHT /SEE LATEST NHC ADVISORIES FOR DETAILS/. DEEPENING OF THE CYCLONE WILL RESULT IN A CORRIDOR OF INCREASING LOW-LEVEL FLOW/SHEAR TO THE RIGHT OF THE CYCLONE CENTER...WHICH WILL OVERSPREAD THE MIDDLE TX COAST OVERNIGHT. THE CORRIDOR OF INCREASING LOW-LEVEL SHEAR WILL ALSO COINCIDE WITH MID-UPPER 70S BOUNDARY LAYER DEWPOINTS AND AT LEAST WEAK SURFACE-BASED INSTABILITY. GIVEN THESE ENVIRONMENTAL FACTORS...WILL INTRODUCE A SLIGHT RISK AND 5% TORNADO PROBABILITIES FOR OUTER BAND SUPERCELLS DURING THE OVERNIGHT PERIOD.


MCD posted on page one of this blog was pretty good. imo
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had to get my game face on!
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sorry CaneWarning not yet plz don't put it in that wording you are making it sound like gaston is my brother thanks
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People will figure it out Magellan.
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looks like miami beach may flood..

a line of heavy storms stalled over miami beach
Member Since: April 17, 2010 Posts: 0 Comments: 1753
how do I find the recon tracker when I open google earth?? I though I had it place marked but I guess I didnt!
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617. IKE
Brownsville, Texas (Airport)
Updated: 9 min 57 sec ago
Heavy Rain
81 °F

Heavy Rain Mist
Humidity: 89%
Dew Point: 77 °F
Wind: 9 mph from the NE
Pressure: 29.68 in (Steady)
Heat Index: 87 °F
Visibility: 2.0 miles
UV: 0 out of 16
Pollen: 6.80 out of 12
Pollen Forecast new!
Clouds:
Few 1700 ft
Mostly Cloudy 2700 ft
Overcast 8000 ft
(Above Ground Level)
Elevation: 20 ft
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616. beell
Special exemptions for Post's 601 and 609.
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Quoting hydrus:
I wonder what the name of that large island is SSE of Brownsville. They are gettin a whippen.


There is no island there
Member Since: March 10, 2010 Posts: 1 Comments: 7874
Quoting Levi32:


Um B, but, it would be funny if she crossed the Rio Grande and then made a second landfall north of near Corpus Cristi lol. That is unlikely, but you never know.
I would go with B also. If it goes due north, it would go in right where I am predicting and then come back out in Laguna Madre just west of south Padre (only 40 miles on land) and then its 120 miles of open water (barrier islands excluded) to Corpus.
Member Since: August 28, 2005 Posts: 0 Comments: 113
Quoting Col15thTex:
"Was it 2005 when they ran out of names? What do they do if that happens again I forget?"

They start using the Greek alphabet.
Storm "Alpha" etc
I wonder what the name of that large island is SSE of Brownsville. They are gettin a whippen.
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Wow, getting tired of Bill White's ad every time I F5!!
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Quoting skkippboo:
That aint TX. And nobody's perfect.


Texas, Mexico whatever

the point is people are following these storms on radar, how could they not have the coastline shaped properly?
Member Since: March 10, 2010 Posts: 1 Comments: 7874
Quoting Hurricanes101:
wow WU does fail, there is no lsland there near that part of Texas, why is it there?
That aint TX. And nobody's perfect.
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Quoting beell:
B.

Anybody don't vote is a chicken!

We usually try to nail a landfall from 3 days out. This one is a little closer.

Just kiddin', yall.


Can I do C! At the mouth of the rio grande?
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Hey all,
I know most of you are occupied with Hermine and Gaston, but can you take a look at the data for the area between S. Fla and Bahamas? Do you think something could develop there?
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Port Isabel conditions

Link
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Here's a good radar loop with the proper coastline overlay. If the average heading shown in this loop (the last 2 hours) continues for the next 12 hours, it's going to be a nasty night for south Texas.
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Interesting to observe Hermine and environs on WVL. click for 24 hr loop. (Flash) The ridge lay along the coast yesterday eve.

Image from 0907 0015GMT
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Quoting PrivateIdaho:


Yes!


LOL.
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Quoting StormW:


That's my thinking...something like that.


Allowing further strengthening?
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Quoting Levi32:


For better landfall reference use this:



Exactly
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Quoting beell:
EZ Poll.

Hermine Landfall:

A. North of the Rio Grande?
B. South of the Rio Grande?


Yes!
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I'm getting a little tired of everyone screaming "Gaston is dead!" every time it goes through a d-min cycle.

Give it time. It's about to head into a much higher-moisture environment, and wind shear will be almost nothing. The big question should not be whether it has a bunch of thunderstorms at any given time, but rather what the health of the LLC is. If the LLC survives, it will fire up quickly once it gets into the Caribbean.
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599. beell
B.

Anybody don't vote is a chicken!

We usually try to nail a landfall from 3 days out. This one is a little closer.

Just kiddin', yall.
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wow WU does fail, there is no lsland there near that part of Texas, why is it there on the WU radar?

also the shape of the coastline is wrong, how do you expect to follow a system on WUs radar when the coastline is not shaped correctly?
Member Since: March 10, 2010 Posts: 1 Comments: 7874
Quoting breald:
Was it 2005 when they ran out of names? What do they do if that happens again I forget?


I think they went to Greek letters for the last few.
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Quoting Levi32:


Ya that is true....I always wonder why it displays that way on WU radar.


For better landfall reference use this:

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I was poking around and found this, just can't fathom all of these models showing Gaston getting quite strong, very interesting....


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Quoting GeoffreyWPB:


Bird Is The Word.


Time to move in close

Link
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live Ob data Eugeniopr I really don't find them there much unless you can show me


sorry stormpetrol not yet let us see what happens by morning if in any case are you ready for when it comes (if it comes)
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Where is the coc of ex-Gaston located as of 8 pm?
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Quoting houstongator:
When you look at this radar, remember that the Northern coast of Mexico looks nothing like what is pictured. It is much, much smoother, and there is no huge island.


Ya that is true....I always wonder why it displays that way on WU radar.
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"Was it 2005 when they ran out of names? What do they do if that happens again I forget?"

They start using the Greek alphabet.
Storm "Alpha" etc
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Quoting beell:
EZ Poll.

Hermine Landfall:

A. North of the Rio Grande?
B. South of the Rio Grande?
b
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Quoting pilotguy1:


1999 or 2005?
bret of 2005 was a short lived minimal ts that went straight into mex from boc
Member Since: August 22, 2009 Posts: 0 Comments: 691
586. xcool
a
Member Since: September 26, 2009 Posts: 2 Comments: 15684

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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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