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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1136. leo305
well the steering layers are calling for this thing to move NNW/NW soon
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Quoting texascoastres:
pottery

no sir, just that they were concerned about them

and to F4PHANTOM
i don't remember them saying Earl was coming to TX


They didn't, he is just being a smart guy tonight. He is probably not in the path of this storm so he doesn't really care.
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hold on I'll rewind. TGIF TIVO
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1133. pottery
Quoting txsweetpea:

You dont have to be sorry...YOU are entitled to your opinion and what you THINK you see, and you still MAY be right. That is how you learn.

Very True!
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BE.....
Quoting PrivateIdaho:


NICE!
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1130. RTLSNK
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1129. lparky
Link

definitely north bound and down...
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Quoting fatlady99:

Well, she won't yet. :)


NICE!
Member Since: August 29, 2010 Posts: 0 Comments: 5236
1127. pottery
Quoting texascoastres:
pottery

no sir, just that they were concerned about them

and to F4PHANTOM
i don't remember them saying Earl was coming to TX

OK.
Strange thing to say, without saying something about the direction...
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The weather on the east coast is agreeable to us Idahoans.... ;^)
Member Since: August 29, 2010 Posts: 0 Comments: 5236
1125. leo305
Quoting Hhunter:
the weather or not bit on the weather channel is a pile of cr(* but i dig the gal...


yea they've been doing it every hour, and the sad thing is that it's live and they say the same things ... it's like they're getting payed to do it over and over again..
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Quoting want2lrn:
SORRY..the east thing came from me in a question for pottery. It was just my UNTRAINED eye looking at radar loops. I do stand corrected

You dont have to be sorry...YOU are entitled to your opinion and what you THINK you see, and you still MAY be right. That is how you learn.
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1123. JLPR2
Quoting btwntx08:
breif power outage got a gust of 56 mph got vid of it probably last comment b4 the power goes out as the eyewall nears see ya soon


Take care and I hope to see you soon again. :D
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1122. Hhunter
the weather or not bit on the weather channel is a pile of cr(* but i dig the gal...
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1121. JLPR2


Not intimidating at all, pfft, I think 92L looked scarier than this.

Let me see if I find one of 92L to compare.

here we go, it did look scarier XD
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Quoting GeoffreyWPB:
And please don't say the fat lady sings...

Well, she won't yet. :)
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Quoting fatlady99:


Um... does that mean it's time for a song?

Not yet fatlady... things can happen, let's sit and watch.
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Quoting GeoffreyWPB:


What would you like to hear?


I can't decide between Zydeco/Cajun Blues, or Rocky Horror. Any suggestions?
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pottery

no sir, just that they were concerned about them

and to F4PHANTOM
i don't remember them saying Earl was coming to TX
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And please don't say the fat lady sings...
Member Since: September 10, 2007 Posts: 0 Comments: 11159
Quoting leo305:
the "eye wall" of TS hermine is probably going to slam to brownsville.. 60 + mph gusts are likely within that..


Hmmmm.... NOT time for a song...
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1113. leo305
wow, blinding rain fall, with extreemly high winds going to hit brownsvillle
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Quoting fatlady99:


Um... does that mean it's time for a song?


What would you like to hear?
Member Since: September 10, 2007 Posts: 0 Comments: 11159
SORRY..the east thing came from me in a question for pottery. It was just my UNTRAINED eye looking at radar loops. I do stand corrected
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Quoting Hhunter:


is that neil frank?


who?
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Quoting GeoffreyWPB:
Hermine is inland. Case Closed!


Um... does that mean it's time for a song?
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1108. leo305
the "eye wall" of TS hermine is probably going to slam to brownsville.. 60 + mph gusts are likely within that..
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1107. pottery
Quoting texascoastres:
Channel 11 in Houston just said "they are concerned with these wobbles and will be monitoring them."

Did they say what direction the wobbles are taking?
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1106. Hhunter
Quoting TexasHurricane:


hmmmmm, that is interesting....


is that neil frank?
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1105. GBguy88
Quoting 1992Andrew:
btwntx08

Where in texas do you live? You must be appalled by all these sneak attacks from the bay of campeche.


Apalled? If his behavior toward any previous storm is any indication, he'd prefer this to be threatening to take Brownsville off the map. Incidentally, I don't think he holds the responsibility of filing insurance claims.
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KSPL reporting 44 mph sustained and gusts to 52 mph.
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Hermine is inland. Case Closed!
Member Since: September 10, 2007 Posts: 0 Comments: 11159
That was from Gene Norman. Dr. Neal Frank said earlier that these kinds of storms can spring up very quickly this time of year
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1099. pottery
Quoting c150flyer:
Just measured a 1-min sustained wind of 28mph in Brownsville and a gust to 38mph. The eye-wall is getting close... I expect the gusts will occasionally top 60 in the next hour or so...

Wind direction?
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Quoting TexasHurricane:


hmmmmm, that is interesting....

very...
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Quoting texascoastres:
Channel 11 in Houston just said "they are concerned with these wobbles and will be monitoring them."


hmmmmm, that is interesting....
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Quoting pottery:

I dont see east at 1042 either.

Neither did I.
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Quoting pottery:

I dont see east at 1042 either.

I do in the last movement...ALTHOUGH I could be wrong.It could have been a wobble. Dont know
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Just measured a 1-min sustained wind of 28mph in Brownsville and a gust to 38mph. The eye-wall is getting close... I expect the gusts will occasionally top 60 in the next hour or so...
Member Since: September 12, 2008 Posts: 0 Comments: 74
Hermine has not eastward component to her whatsoever
Member Since: March 10, 2010 Posts: 1 Comments: 7726
Channel 11 in Houston just said "they are concerned with these wobbles and will be monitoring them."
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Quoting txsweetpea:

Look at post 1042


Nothing east in that loop.
Member Since: September 10, 2007 Posts: 0 Comments: 11159
1090. pottery
Quoting txsweetpea:

Look at post 1042

I dont see east at 1042 either.
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Quoting GeoffreyWPB:
Where is all this east nonsense coming in from:


Well that looks pretty clear...
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Quoting GeoffreyWPB:
Where is all this east nonsense coming in from:


Look at post 1042
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Quoting GeoffreyWPB:
Where is all this east nonsense coming in from:



Not sure...good question.
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1086. pottery
Quoting ShenValleyFlyFish:
If you want a bunch of choices on how to approach viewing a weather event just open a second tab to nws.gov and follow your nose. I tend to bounce back and forth between there and WU when something is going on.

Good Advice there...
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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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