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 F4PHANTOM:
Link
Ex-gaston has dry air on three sides now. getting harder on the little guy. will he or won't he make it?
Looks like he is going straight in to the Caribbean and no dry air there. Looks like as he approaches the dry air backs away from him but IDK.
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Quoting mcluvincane:
Atlantic reminds me of June not September. Where the hell is that chart?



dont get that thing started
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Quoting F4PHANTOM:
Link
Ex-gaston has dry air on three sides now. getting harder on the little guy. will he or won't he make it?

Wont!
He is Doom.
Member Since: October 24, 2005 Posts: 0 Comments: 24402
Quoting F4PHANTOM:
12z and 18z GFS have that scenario; both recurve


I only look at the 5 day then I use my imagination.

That aside WOW I looked at the long range GFS and it has IGOR storming towards New England like the halloween storm before verring slightly and CRASHING into Halifax, Nova Scotia like Juan.

That is a pretty scary looking long range and Northeast could be in for some monumental surf like Felix in '96 with that track. Also well within margin of error.
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Atlantic reminds me of June not September. Where the hell is that chart?
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Quoting Tazmanian:



99L was bust see post 955
Hoos on first.
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Quoting btwntx08:
eyewall getting closer to here
Eye seems to be sneaking up towards you-hope you don't float away! Good luck to you and your family!
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GO VT!!!! GO ACC!!!1
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Quoting HurricaneGeek:


Is this it?
Thanks.


woops my mistake

the area west of 30W and north of 15N is what was 99L, and is firing up heavy convection again.

The area east near africa is a new Large Tropical wave merging with another one, and has a chance of developing, but I say the remnant 99L should be watched
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Anyways Guys & Gurls have a good night! I am out!
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000
WTNT35 KNHC 070233
TCPAT5
BULLETIN
TROPICAL STORM HERMINE ADVISORY NUMBER 5
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL102010
1000 PM CDT MON SEP 06 2010

...HERMINE MADE LANDFALL AS A STRONG TROPICAL STORM...PRODUCING
HEAVY RAINS OVER NORTHEASTERN MEXICO AND SOUTH TEXAS...


SUMMARY OF 1000 PM CDT...0300 UTC...INFORMATION
-----------------------------------------------
LOCATION...25.5N 97.5W
ABOUT 30 MI...45 KM S OF BROWNSVILLE TEXAS
ABOUT 120 MI...190 KM N OF LA PESCA MEXICO
MAXIMUM SUSTAINED WINDS...60 MPH...95 KM/HR
PRESENT MOVEMENT...NNW OR 330 DEGREES AT 14 MPH...22 KM/HR
MINIMUM CENTRAL PRESSURE...991 MB...29.26 INCHES


WATCHES AND WARNINGS
--------------------
CHANGES WITH THIS ADVISORY...

THE GOVERNMENT OF MEXICO HAS DISCONTINUED THE HURRICANE WATCH FOR
THE COAST OF MEXICO AND THE TROPICAL STORM WARNING SOUTH OF BAHIA
ALGODONES MEXICO.

THE HURRICANE WATCH FOR THE COAST OF TEXAS HAS BEEN DISCONTINUED.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT...

A TROPICAL STORM WARNING IS IN EFFECT FOR...
* BAHIA ALGODONES MEXICO NORTHWARD TO PORT OCONNOR TEXAS

FOR STORM INFORMATION SPECIFIC TO YOUR AREA IN THE UNITED STATES
...INCLUDING POSSIBLE INLAND WATCHES AND WARNINGS...PLEASE MONITOR
PRODUCTS ISSUED BY YOUR LOCAL NATIONAL WEATHER SERVICE FORECAST
OFFICE. FOR STORM INFORMATION SPECIFIC TO YOUR AREA OUTSIDE THE
UNITED STATES...PLEASE MONITOR PRODUCTS ISSUED BY YOUR NATIONAL
METEOROLOGICAL SERVICE.


DISCUSSION AND 48-HOUR OUTLOOK
------------------------------
AT 1000 PM CDT...0300 UTC...THE CENTER OF TROPICAL STORM HERMINE WAS
LOCATED NEAR LATITUDE 25.5 NORTH...LONGITUDE 97.5 WEST. HERMINE IS
MOVING TOWARD THE NORTH-NORTHWEST NEAR 14 MPH...22 KM/HR. A GRADUAL
TURN TOWARD THE NORTH AND NORTHEAST IS EXPECTED OVER THE NEXT
COUPLE OF DAYS. ON THE FORECAST TRACK...HERMINE WILL CONTINUE TO
MOVE INLAND OVER NORTHEASTERN MEXICO TONIGHT...AND MOVE INTO
SOUTHERN TEXAS ON TUESDAY AND INTO CENTRAL TEXAS EARLY ON
WEDNESDAY.

MAXIMUM SUSTAINED WINDS HAVE DECREASED TO NEAR 60 MPH...95 KM/HR
...WITH HIGHER GUSTS. ADDITIONAL WEAKENING IS FORECAST AND HERMINE
IS EXPECTED TO WEAKEN INTO A TROPICAL DEPRESSION BY TUESDAY
AFTERNOON.

TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 105 MILES...165
KM...MAINLY TO THE NORTHEAST OF THE CENTER. A NATIONAL OCEAN SERVICE
OBSERVING SITE IN MALAQUITE BEACH TEXAS RECENTLY REPORTED A
SUSTAINED WIND OF 41 MPH...66 KM/HR...AND A PEAK GUST TO 47 MPH...
76 KM/HR.

THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 991 MB...29.26 INCHES.


HAZARDS AFFECTING LAND
----------------------
WIND...TROPICAL STORM CONDITIONS ARE OCCURRING IN THE WARNING AREA
AND ARE EXPECTED TO CONTINUE OVERNIGHT.

STORM SURGE...STORM SURGE WILL RAISE WATER LEVELS BY AS MUCH AS 2 TO
4 FEET ABOVE GROUND LEVEL ALONG THE IMMEDIATE COAST NEAR AND TO THE
NORTH OF WHERE THE CENTER MAKES LANDFALL.

RAINFALL...HERMINE IS EXPECTED TO PRODUCE RAINFALL ACCUMULATIONS OF
4 TO 8 INCHES OVER NORTHEASTERN MEXICO...AND FROM SOUTHERN INTO
NORTH CENTRAL TEXAS WITH ISOLATED MAXIMUM AMOUNTS OF 12 INCHES
POSSIBLE. THESE RAINS COULD CAUSE LIFE-THREATENING FLASH FLOODS.

TORNADOES...ISOLATED TORNADOES ARE POSSIBLE ALONG THE LOWER AND
MIDDLE TEXAS COAST THROUGH TUESDAY MORNING.


NEXT ADVISORY
-------------
NEXT INTERMEDIATE ADVISORY...100 AM CDT.
NEXT COMPLETE ADVISORY...400 AM CDT.
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Quoting HurricaneGeek:


what was 99L?



99L was bust see post 955
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Quoting want2lrn:
TOUCHDOWN VT......


Yes!!...Beamer-Ball!!
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29-26 Va Tech, well or 27-26 pending the 2 point
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quite a bit north of alex... and is heading nnw instead of nw... so even tho hermine is way weaker than alex was, stx is likely to get much worse weather than it did from alex.
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Quoting leo305:


99L was a large wave that came off africa, that split in two, and fell apart. As of right now, what was 99L seems to be re strehgthening tonight a little bit at least.. heavy convection is forming over the remnant spin around 17N 15.1W in the central atlantic


Is this it?
Thanks.
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Taz, 955.
Nice one, man!
Member Since: October 24, 2005 Posts: 0 Comments: 24402
TOUCHDOWN VT......
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Quoting stormwatcherCI:
Not quite. I think I saw earlier 65-70 mph winds.

Oh darn, that would've been 4! And I just ate my last post as Va Tech just scored.
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Quoting HurricaneGeek:


what was 99L?


99L was a large wave that came off africa, that split in two, and fell apart. As of right now, what was 99L seems to be re strehgthening tonight a little bit at least.. heavy convection is forming over the remnant spin around 17N 15.1W in the central atlantic
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taz 955...

wow good list! =)
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Quoting btwntx08:

no 90L became hermine


what was 99L?
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Quoting kramus:


Hay, I resembel that remarc.


lol...true....there is plenty of intelijent people in here and they got lots of intelesting thing to say about them hurricanders!!
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round 1


90L bust


91L bust


92L bust

93L be comes Alex

94L bust

95L bust

96L be come TD 2

97L be comes BONNIE

98L bust

99L bust


round 2



90L bust

91L be comes .COLIN

92L bust

93L bust

94L be comes TD 5

95L be comes Danielle

96L be comes Earl

97L be comes FIONA

98L be comes Gaston

99L bust


round 3


90L be comes hermine
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Quoting GTcooliebai:

Umm I wasn't on here much this afternoon, did she make Hurricane strength?


nope, she peaked at 65MPH/991MB
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Quoting traumaboyy:


Deal.....but I may refer any non medical questions to the truly intelligent people in the blog......IF I EVER MEET THEM......LMFAO!!


Now thats funny right there...i dont care who you are lol
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btwntx08 , c150flyer.

your welcome and stay safe.

it looks like it makes landfall North of Alex, no?
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Quoting GTcooliebai:

Umm I wasn't on here much this afternoon, did she make Hurricane strength?
Not quite. I think I saw earlier 65-70 mph winds.
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Quoting GTcooliebai:
I take dat back! That QB is like Michael Vick!

Yes he is Micheal Vick'ish although the pitbulls aren't following him.
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Quoting HurricaneGeek:


isn't 99L hermine?



nop 99L is long gone this was 90L that came hermine
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Quoting leo305:
brownsville is getting ambushed with rain...

and hermine is slowly creeping N/NW..

Umm I wasn't on here much this afternoon, did she make Hurricane strength?
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Quoting HurricaneGeek:


isn't 99L hermine?
No, 99L was off Africa. Hermine was 90L.
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Quoting HurricaneGeek:


isn't 99L hermine?


hermine was 90L

99L is in the central atlantic ! Around 17n 15w
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Quoting HurricaneGeek:
Good evening.

I see we have no circle on the new African wave. That's a little surprising and non surprising at the same time.
I think we'll see a yellow circle tomorrow if it stays with convection.

Best of luck to those being affected by Hermine tonight, stay safe!


so far it's downright boring in b-ville... though in the next 2 to 3 hours that should be changing...
Member Since: September 12, 2008 Posts: 0 Comments: 75
Is Hermine the record for the shortest lifespan of a system? 12 hours from birth to death?
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brownsville is getting ambushed with rain...

and hermine is slowly creeping N/NW..
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Quoting traumaboyy:


...to the truly intelligent people in the blog......IF I EVER MEET THEM......LMFAO!!


Hay, I resembel that remarc.
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Quoting leo305:
99L should be making a comeback.. afterall models did pick up on that and not gaston


isn't 99L hermine?
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I take dat back! That QB is like Michael Vick!
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Quoting want2lrn:


great....now i am confused all over again. lol i guess it is back to the books for me!

Storms are steered by several things....
The location of high and low pressure areas being important too.
And right now, even if Gaston was a powerfull hurricane, he would tend to go west.

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About

Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.