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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might be moving due north on radar
Member Since: April 17, 2010 Posts: 0 Comments: 1753
Basically, an average heading of 345 or greater is going to be nasty for south Texas tonight.
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If I may ask, what is this D-max?
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Quoting BDADUDE:
what does poof mean?


I think he was a magic dragon.
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480. 7544
gaston trying another come back for dmax tonight
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Blog update on Hermine and Gaston.
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Orca: Wobble or a true change in direction
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Quoting aislinnpaps:


Not a good side for Raymondville to be on.
Water tends to kinda collect there doesn't it?
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Quoting StormW:


What it looks like may be happening, is the flow, if you look right around Oklahoma, given the orientation of things, may be going a little more zonal (west to east)


what does that mean? I cannot find the question you were referring to
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Quoting Orcasystems:


You mean like this?

Now why do I think this next Vortex fix is going to give some people fits?






Well it is, lol. These storms love to do that, and most always try at least once. Even Alex tried but failed. Dolly in 2008 was one that succeeded. The frictional effects always try to pull them north when they try to hit northern Mexico. This time, we'll see how it goes, but Hermine could still take a mean track if she heads an average of NNW over the next 12 hours.

Now if she's really naughty and keeps going due north, well, that's not going to be very fun, but she likely won't stay on this particular heading for too awful long. They are often wobbles due to the frictional effects.
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Quoting Stormchaser2007:


Centers dont "reform" in well-defined systems.

They simply move around.


that is why I said reformed/moved
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Quoting StormW:


What it looks like may be happening, is the flow, if you look right around Oklahoma, given the orientation of things, may be going a little more zonal (west to east)


Thanks, And I thought I had learned something lol!
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Quoting Thundercloud01221991:
I think the center has reformed/moved further south as the eyewall is trying to reform larger


Centers dont "reform" in well-defined systems.

They simply move around.
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Quoting StormW:


What it looks like may be happening, is the flow, if you look right around Oklahoma, given the orientation of things, may be going a little more zonal (west to east)


Agree.
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ok guys just because they bumped it % down doesn't mean gaston is dead as I say wait for the next 24 hours things can change between then and I expect it to and gaston will likely be come a TD by tomrrow
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Stalled, then moved NNE.

FULL IMAGE

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466. beell
Hermine-NWS Local Statements
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Quoting F4PHANTOM:
Please enlighten us with the storms you have seen do this.
Hurricane Brett was one of them
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Quoting skkippboo:
Looks like you think the center will pass right over Harlingen and San Benito, and possibly Santa Rosa.


Not a good side for Raymondville to be on.
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Quoting Levi32:
What could be a problem here is that the envelope of low pressure could potentially allow Hermine to move NNW for the next while and prolong the process of moving inland. In that situation we could have the storm up at 27.5N 98W in 12 hours just west of Corpus Cristi, and then southeast Texas is still getting a major beating from the spiral bands rotating onshore, and with the center close enough to the water to still cause issues with strong winds and excessive rainfall.


FWIW Tropical Storms Charley and Frances in 1998 hit in the Corpus area and gave Houston a lot of rain, with Frances causing significant flooding of some Houston area roadways. I thought it was bad until Allison 3 years later.
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462. Wots
Quoting Chavalito:

Is dead.


Try it here, Java or Gif

Link
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I think the center has reformed/moved further south as the eyewall is trying to reform larger
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Thanks Levi32 and beell for posting alternative steering maps, bookmarked. :-)
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According to the most recent vortex messages, Hermine has slowed down quite a bit.
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Product: Air Force Vortex Message (URNT12 KNHC)
Transmitted: 7th day of the month at 00:03Z
Aircraft: Air Force Aircraft (Last 3 digits of the tail number are 301)
Storm Number & Year: 10L in 2010
Storm Name: Hermine (flight in the North Atlantic basin)
Mission Number: 2
Observation Number: 20
A. Time of Center Fix: 6th day of the month at 23:33:00Z
B. Center Fix Coordinates: 24°49'N 97°08'W (24.8167N 97.1333W)
B. Center Fix Location: 80 miles (129 km) to the SSE (164°) from Brownsville, TX, USA.
C. Minimum Height at Standard Level: 1,346m (4,416ft) at 850mb
D & E. Estimated (by SFMR or visually) Maximum Surface Wind: Not Available
F. Maximum Flight Level Wind Inbound: From 137° at 52kts (From the SE at ~ 59.8mph)
G. Location of Maximum Flight Level Wind Inbound: 32 nautical miles (37 statute miles) to the NNE (27°) of center fix
H. Minimum Sea Level Pressure: 991mb (29.26 inHg) - Extrapolated
I. Maximum Flight Level Temp & Pressure Altitude Outside Eye: 16°C (61°F) at a pressure alt. of 1,524m (5,000ft)
J. Maximum Flight Level Temp & Pressure Altitude Inside Eye: 20°C (68°F) at a pressure alt. of 1,525m (5,003ft)
K. Dewpoint Temp & Sea Surface Temp (collected at same location as temp inside eye): Not Available
L. Eye Character: Not Available
M. Eye Shape: Not Available
N. Fix Determined By: Penetration, Radar, Wind, Pressure and Temperature
N. Fix Level: 850mb
O. Navigation Fix Accuracy: 0.02 nautical miles
O. Meteorological Accuracy: 2 nautical miles
Remarks Section:
Maximum Wind Outbound: 61kts (~ 70.2mph) in the east quadrant at 23:35:30Z
Maximum Flight Level Wind: 61kts (~ 70.2mph) in the east quadrant at 23:35:30Z
Sea Level Pressure Extrapolation From: 850mb
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Quoting btwntx08:
guys ignore ozzyman236 hes seriously doesnt know about this so dont agrue with him just move on

Stormtop again.
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what does poof mean?
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Quoting Levi32:
What could be a problem here is that the envelope of low pressure could potentially allow Hermine to move NNW for the next while and prolong the process of moving inland. In that situation we could have the storm up at 27.5N 98W in 12 hours just west of Corpus Cristi, and then southeast Texas is still getting a major beating from the spiral bands rotating onshore, and with the center close enough to the water to still cause issues with strong winds and excessive rainfall.


You mean like this?

Now why do I think this next Vortex fix is going to give some people fits?




Member Since: October 1, 2007 Posts: 81 Comments: 26511
453. IKE
Brownsville, Texas (Airport)
Updated: 5 min 22 sec ago
Light Rain
81 °F
Light Rain
Humidity: 84%
Dew Point: 75 °F
Wind: 12 mph from the NNE
Pressure: 29.70 in (Steady)
Heat Index: 86 °F
Visibility: 10.0 miles
UV: 0 out of 16
Pollen: 6.80 out of 12
Pollen Forecast new!
Clouds:
Scattered Clouds 1300 ft
Mostly Cloudy 2000 ft
Mostly Cloudy 3100 ft
(Above Ground Level)
Elevation: 20 ft
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Quoting sammywammybamy:


And What Have you Been Smoking today?
and he's yelling at us!
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It's not like this couldn't allow NNW movement right here. Southeast Texas may still be in for a long night if the center takes longer to make its way inland and stays close enough to the water to be a bugger.

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I have pushed F5 so much my fingers hurt. I'll check in after I get some little people into bed and a drink into my hand. Have they revised the time of landfall? I read somewhere that it was supposed to be between 5 and 6 pm (which has passed), but to be honest, I don't remember where I read that.
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Quoting Stormchaser2007:


Drifting N?
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Quoting WeatherNerdPR:

True. But nearing depression status followed by waning convection over and over again is kind of annoying.


Not to tropical meteorologists. As I've stated several times thoughout the year, a storm that doesn't develop as predicted tells scientists as much about the errors of their forecasting methodologies as one that does develop when it shouldn't. It's all part of cyclogenesis, and it's all good... ;-)
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Quoting ozzyman236:
what im saying if hermine paralells the texas coast brownsville will get some rain and some wind but the brunt of hermine will be offshore...this could very easily happen with no steering currents in that part of the gom...


a black hole could very easily form in the central gulf and suck up the entire body of water later tonight but i doubt it
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Quoting Levi32:
What could be a problem here is that the envelope of low pressure could potentially allow Hermine to move NNW for the next while and prolong the process of moving inland. In that situation we could have the storm up at 27.5N 98W in 12 hours just west of Corpus Cristi, and then southeast Texas is still getting a major beating from the spiral bands rotating onshore, and with the center close enough to the water to still cause issues with strong winds and excessive rainfall.


Glad it's still "could". We need rain, but not all at once.
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What could be a problem here is that the envelope of low pressure could potentially allow Hermine to move NNW for the next while and prolong the process of moving inland. In that situation we could have the storm up at 27.5N 98W in 12 hours just west of Corpus Cristi, and then southeast Texas is still getting a major beating from the spiral bands rotating onshore, and with the center close enough to the water to still cause issues with strong winds and excessive rainfall.
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Quoting StormW:


No...just went to 232...not your post.


I'm sorry 292. lol
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North/NNE
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437. DDR
Quoting Stormchaser2007:
If by tomorrow ex-Gaston doesn't pull off some sort of spontaneous bout of organization, I think that will be pretty much the end of it.


I agree
OTH he's pulling a moisture surge behind him,this shoud bring some needed rainfall for the islands.
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Quoting Relix:
50% lol. Gaston fail


Is dead
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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.