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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1436. JLPR2
Quoting tornadodude:


he is in raymondville, heading back north


Impressive looking system even inland.
Member Since: September 4, 2007 Posts: 7 Comments: 8499
Should be interesting. Always expect the unexpecte. This year has been wacky as ever. Who knows what is going to last or where it's going.
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1434. xcool
CoopNTexas . no more out sea storms hmmm
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1433. JLPR2
Quoting MoltenIce:
RIP Gaston, after a week long of struggle with dry-air, he finally succumbed.

RIP


Maybe we misunderstood Gaston's true dream, he didn't want to be a monster, just a little rain maker for the Antilles. :]
Member Since: September 4, 2007 Posts: 7 Comments: 8499
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Could that be the ghost of Gaston in the Carib?
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1430. xcool
CoopNTexas yeah .
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he is in raymondville, heading back north
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yep...something trying to brew in carib there too.
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RIP Gaston, after a week long of struggle with dry-air, he finally succumbed.

RIP
Member Since: August 11, 2010 Posts: 0 Comments: 772
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1424. xcool
CoopNTexas about getting active
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1423. xcool
wow
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1420. xcool
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1419. xcool
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1418. JLPR2
Quoting cirrocumulus:


Apparently, the ants were the first to go to meteorological classes.


True. LOL!
Member Since: September 4, 2007 Posts: 7 Comments: 8499
1417. xcool
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Quoting JLPR2:


And the ants agree, lol! They are still moving around normally so I'll say PR will feel squat from Gaston. For Earl and Fiona the ants took cover, watching ants is interesting sometimes. :P


Apparently, the ants were the first to go to meteorological classes.
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1415. xcool
Ex-Gaston dead,,,
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1414. xcool
JRRP, nhc just put 10% on that wave.shows by you images
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1413. JLPR2
Ex-Gaston on radar.


There's actually something there, earlier there wasn't, maybe I'll get some rain afterall. XD
Member Since: September 4, 2007 Posts: 7 Comments: 8499
1412. xcool
Kowaliga ,no
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1411. JRRP
see you...
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Wow I refreshed the NHC page and two new blobs appeared.
Member Since: August 11, 2010 Posts: 0 Comments: 772
1409. xcool
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Quoting GBguy88:


I agree, the chain tornado phase of Ivan was nerve-wracking, to say the least. I can't even describe that sound...like a jetliner taking off on top of a train. And the roar of the eye wall between midnight and 2AM was just incredible. The surge missed us by a couple of hundred yards, at best. I'm not sure I'd stick around for anything much stronger, though curiosity and a general lack of common sense would probably detain me.


Lack of common sense??? LOL At least your are honest. I think I would probably fall victim to that too.
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1407. xcool
here come 91L & 92L
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Quoting JLPR2:
Well to change the mood a little which I see is a little tense, lets see the amazing thunderstorm complex Gaston has developed (sarcasm) LOL!

Is that a pinhole eye? :O
Member Since: August 11, 2010 Posts: 0 Comments: 772
Gaston is down to 20% and no wonder as it enters the graveyard of hurricane development. After that...
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Quoting xcool:


Have you noticed this model keeps wanting to break off a low off the coast of NC from the mega-trof thats due this weekend?

...last 3 runs.
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Quoting BreadandCircuses:




XD
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1402. GBguy88
Quoting traumaboyy:


LOL.....that lack of common sence thang gets me every time!!


Where were you at during Ivan, just out of curiosity? I was at the west end of Gulf Breeze, Florida.
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Quoting GBguy88:


I agree, the chain tornado phase of Ivan was nerve-wracking, to say the least. I can't even describe that sound...like a jetliner taking off on top of a train. And the roar of the eye wall between midnight and 2AM was just incredible. The surge missed us by a couple of hundred yards, at best. I'm not sure I'd stick around for anything much stronger, though curiosity and a general lack of common sense would probably detain me.


LOL.....that lack of common sence thang gets me every time!!
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1399. xcool
A SMALL LOW PRESSURE AREA LOCATED ABOUT 300 MILES WEST OF THE
NORTHERNMOST CAPE VERDE ISLANDS IS PRODUCING DISORGANIZED SHOWERS
AND THUNDERSTORMS. ENVIRONMENTAL CONDITIONS ARE EXPECTED TO REMAIN
UNFAVORABLE FOR DEVELOPMENT DURING THE NEXT COUPLE OF DAYS AS THIS
SYSTEM MOVES WESTWARD AT ABOUT 10 MPH. THERE IS A LOW CHANCE...10
PERCENT...OF THIS SYSTEM BECOMING A TROPICAL CYCLONE DURING THE
NEXT 48 HOURS.

A LARGE AREA OF CLOUDINESS AND THUNDERSTORMS LOCATED BETWEEN THE
CAPE VERDE ISLANDS AND THE WEST COAST OF AFRICA IS ASSOCIATED WITH
A TROPICAL WAVE. DEVELOPMENT...IF ANY...OF THIS SYSTEM IS EXPECTED
TO BE SLOW TO OCCUR AS IT MOVES WESTWARD AT 10 TO 15 MPH DURING THE
NEXT COUPLE OF DAYS. THERE IS A LOW CHANCE...10 PERCENT...OF THIS
SYSTEM BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS
Member Since: Posts: Comments:
Quoting OceanMoan:


The big swooshes of air down the chimney freaked me out.


Yess!...I forgot about those.....and the sound of something HUGE hitting something.....but you don't know what it was or what it landed on!!
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1397. GBguy88
Quoting traumaboyy:


IVAN THE TERRIBLE.....We were feeling very full of ourselves....the electricity was out....the BRAND NEW Diesel generator was running we were enjoying the tv and the AC.....and then the stinking tornadoes started coming through.......we were scared nearly breathless with the thundering sound....with the lights ON!!


I agree, the chain tornado phase of Ivan was nerve-wracking, to say the least. I can't even describe that sound...like a jetliner taking off on top of a train. And the roar of the eye wall between midnight and 2AM was just incredible. The surge missed us by a couple of hundred yards, at best. I'm not sure I'd stick around for anything much stronger, though curiosity and a general lack of common sense would probably detain me.
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1396. xcool


damm
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1395. xcool
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1394. JLPR2
Quoting KoritheMan:
000
ABNT20 KNHC 070558
TWOAT

DISORGANIZED SHOWERS AND A FEW THUNDERSTORMS OVER THE LEEWARD
ISLANDS AND ADJACENT WATERS ARE ASSOCIATED WITH THE REMNANTS OF
GASTON. THE CIRCULATION REMAINS POORLY DEFINED AND THE ENVIRONMENT
SURROUNDING THE SYSTEM IS EXPECTED TO BE ONLY MARGINALLY CONDUCIVE
FOR DEVELOPMENT DURING THE NEXT COUPLE OF DAYS. THEREFORE...THERE
IS A LOW CHANCE...20 PERCENT...OF THIS SYSTEM BECOMING A TROPICAL
CYCLONE AGAIN DURING THE NEXT 48 HOURS.


ELSEWHERE...TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE
NEXT 48 HOURS.

$$
FORECASTER BROWN


And the ants agree, lol! They are still moving around normally so I'll say PR will feel squat from Gaston. For Earl and Fiona the ants took cover, watching ants is interesting sometimes. :P
Member Since: September 4, 2007 Posts: 7 Comments: 8499
Reports coming in of 3,000+ people without power already. My lights just keep flickering, haven't gone out, but we're about to get a decent squall right about now...
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1391. 789
Quoting tornadodude:


CycloneOz is getting close to Harlingen right now

link
you gonna call oz with the 2
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1390. xcool
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Quoting KoritheMan:
2AM intermediate advisory out. Winds are still 60 mph, and the pressure still 991 mb. I'm impressed.


That is impressive!
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1388. JRRP
Quoting SunnyDaysFla:
Tell me those are future FISH please JRRP

lol
we will see
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Quoting GBguy88:


I remember that during Ivan. You have a sense of comfort when the power is on, and then everything goes out (happened around 8PM for us, and the worst was between midnight and 3AM). It feels very finalizing when the power goes, like a "this is really it" feeling.


IVAN THE TERRIBLE.....We were feeling very full of ourselves....the electricity was out....the BRAND NEW Diesel generator was running we were enjoying the tv and the AC.....and then the stinking tornadoes started coming through.......we were scared nearly breathless with the thundering sound....with the lights ON!!
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000
ABNT20 KNHC 070558
TWOAT
TROPICAL WEATHER OUTLOOK
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
200 AM EDT TUE SEP 7 2010

FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...

THE NATIONAL HURRICANE CENTER IS ISSUING ADVISORIES ON TROPICAL
STORM HERMINE...LOCATED ABOUT 10 MILES SOUTH-SOUTHWEST OF
HARLINGEN TEXAS.

DISORGANIZED SHOWERS AND A FEW THUNDERSTORMS OVER THE LEEWARD
ISLANDS AND ADJACENT WATERS ARE ASSOCIATED WITH THE REMNANTS OF
GASTON. THE CIRCULATION REMAINS POORLY DEFINED AND THE ENVIRONMENT
SURROUNDING THE SYSTEM IS EXPECTED TO BE ONLY MARGINALLY CONDUCIVE
FOR DEVELOPMENT DURING THE NEXT COUPLE OF DAYS. THEREFORE...THERE
IS A LOW CHANCE...20 PERCENT...OF THIS SYSTEM BECOMING A TROPICAL
CYCLONE AGAIN DURING THE NEXT 48 HOURS.

A SMALL LOW PRESSURE AREA LOCATED ABOUT 300 MILES WEST OF THE
NORTHERNMOST CAPE VERDE ISLANDS IS PRODUCING DISORGANIZED SHOWERS
AND THUNDERSTORMS. ENVIRONMENTAL CONDITIONS ARE EXPECTED TO REMAIN
UNFAVORABLE FOR DEVELOPMENT DURING THE NEXT COUPLE OF DAYS AS THIS
SYSTEM MOVES WESTWARD AT ABOUT 10 MPH. THERE IS A LOW CHANCE...10
PERCENT...OF THIS SYSTEM BECOMING A TROPICAL CYCLONE DURING THE
NEXT 48 HOURS.

A LARGE AREA OF CLOUDINESS AND THUNDERSTORMS LOCATED BETWEEN THE
CAPE VERDE ISLANDS AND THE WEST COAST OF AFRICA IS ASSOCIATED WITH
A TROPICAL WAVE. DEVELOPMENT...IF ANY...OF THIS SYSTEM IS EXPECTED
TO BE SLOW TO OCCUR AS IT MOVES WESTWARD AT 10 TO 15 MPH DURING THE
NEXT COUPLE OF DAYS. THERE IS A LOW CHANCE...10 PERCENT...OF THIS
SYSTEM BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS.

ELSEWHERE...TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE
NEXT 48 HOURS.

$$
FORECASTER BROWN
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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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