Hurricane watches for Mexico and Texas as Hermine suddenly develops

By: Dr. Jeff Masters , 4:15 PM GMT on September 06, 2010

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Hurricane watches are up for the Texas/Mexico border region as fast developing Tropical Storm Hermine steams towards the coast at 13 mph. Hermine was a tropical depression twelve hours ago, got its name just six hours ago, but already is a threat to intensify into a hurricane by tonight. It's remarkable how fast Gulf of Mexico disturbances can blow up into strong tropical storms, when the right mix of warm waters and low wind shear develops. Indeed, water temperatures are a very warm 30°C, wind shear is a low 5 - 10 knots, and the atmosphere is very moist in the Gulf--ideal conditions for a tropical storm. 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 moved ashore over southern Texas and northern Mexico, with radar estimated rainfall amounts already exceeding two inches in a few areas along the coast. Radar loops show that an eyewall may be beginning to form, and I expect this process will continue through the afternoon and early evening. Satellite imagery shows that Hermine is getting more organized, with vigorous thunderstorms with very cold tops building, low-level spiral bands developing, and improving upper-level outflow occurring on all sides except the west. There is some dry air to the west of Hermine over land that is restricting the storm's development there.

Forecast for Hermine
Hermine doesn't have much time over water before it comes ashore, which is a good thing. Hermine is organizing rapidly, and has a shot at reaching hurricane strength before the center moves ashore late tonight, near midnight. Neither the GFDL or HWRF models develop Hermine into a hurricane, but the HWRF model does predict that tropical storm force winds of 39+ mph will affect the coast as far north as Corpus Christi, Texas. 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. Early afternoon radar image of Tropical Storm Hermine.

Gaston continues to suffer from dry air
The remains of Tropical Storm 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 late this afternoon and continuing into the night. A pass from the ASCAT satellite this morning at 9:03 am EDT showed a large region of 25 mph winds on the north side of Gaston's circulation, and these winds will move into the northern Lesser Antilles late this afternoon. 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. Gaston does have developed a well-organized surface circulation, but not enough heavy thunderstorm activity to be considered a tropical depression. A large amount of dry air surrounds Gaston's remains on all sides, as seen on water vapor satellite loops.


Figure 2. Morning satellite image of the remains of Gaston, approaching the Lesser Antilles Islands.

Forecast for Gaston
Dry air will continue to be the major impediment to development for Gaston, 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 it 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. The models don't give much support for Gaston surviving past Wednesday, since many of them have the storm hitting the rugged island of Hispaniola, disrupting the storm.

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, the Turks and Caicos Islands, and Jamaica Wednesday night and Thursday morning. Though none of the global dynamical computer models are showing this, should Gaston survive the dry air and its coming encounter with Hispaniola, the storm will find itself in a very favorable environment for development in the Western Caribbean late in the week, and could intensify into a hurricane by next weekend.

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, and let's hope it doesn't live up to its fearsome-sounding name!

Next post
There will be an update by early this evening.

Jeff Masters

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Quoting Skyepony:


But then they turned around & flew home...Either the something scared them or something was broke.


someone mentioned earlier about radar probs but i didnt see a resource
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Quoting extreme236:
We need some recon in this thing.


which thing and why?


I just got on, wondering what you are talking about

I know we have Hermine
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Quoting leo305:
looks to me like gaston is finally organizing a bit

Your avatar is, cute-ish and creepy. lol
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104. Skyepony (Mod)
ASCAT pass of Gaston is not as tight as lastnight.
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looks to me like gaston is finally organizing a bit
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98. IKE
Igor pulling a Danielle on the 12Z GFS...

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96. Skyepony (Mod)
Quoting RecordSeason:
82:

they must have seen some sort of small scale cyclone at flight level on radar and went to investigate. Maybe a supercell or something...


But then they turned around & flew home...Either the something scared them or something was broke.
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Is that IGOR look to be a scary name for you?
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Quoting CoffinWood:


Hmm, it has a certain "buzzsaw" look to it.



yeah, it does...
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We need some recon in this thing.
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Quoting Relix:


Link?


Sorry for the delay. Here is the link
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Quoting TexasHurricane:

That is scary looking. Hermine is a monster.
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Quoting TexasHurricane:


Hmm, it has a certain "buzzsaw" look to it.
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82. Skyepony (Mod)
Quoting PintailKiller:
Did recon have problems? I see it is headed back to Biloxi without having made it to Hermine.


Had to run out there a bit. Just getting in & noticed that. AF303 looks to have flown down to 26.3N 93W turned around & started flying back. Chucked a dropsonde a little north of where they then turned around..bazaar.. especially since the mission identifier is Hermine & not some untasked mission. Look at the winds from the dropsonde..

Significant Wind Levels...
Level Wind Direction Wind Speed
1014mb (Surface) 130° (from the SE) 17 knots (20 mph)
1009mb 135° (from the SE) 22 knots (25 mph)
984mb 130° (from the SE) 23 knots (26 mph)
971mb 130° (from the SE) 22 knots (25 mph)
964mb 185° (from the S) 14 knots (16 mph)
961mb 105° (from the ESE) 47 knots (54 mph)
959mb 95° (from the E) 157 knots (181 mph)
957mb 95° (from the E) 146 knots (168 mph)
954mb 105° (from the ESE) 51 knots (59 mph)
951mb 125° (from the SE) 24 knots (28 mph)
948mb 140° (from the SE) 21 knots (24 mph)
931mb 145° (from the SE) 25 knots (29 mph)
915mb 145° (from the SE) 21 knots (24 mph)
850mb 160° (from the SSE) 25 knots (29 mph)
790mb 145° (from the SE) 23 knots (26 mph)
736mb 155° (from the SSE) 21 knots (24 mph)
706mb 135° (from the SE) 17 knots (20 mph)
691mb 150° (from the SSE) 14 knots (16 mph)
677mb 135° (from the SE) 14 knots (16 mph)
633mb 160° (from the SSE) 12 knots (14 mph)
579mb 125° (from the SE) 2 knots (2 mph)
488mb 350° (from the N) 10 knots (12 mph)
426mb 295° (from the WNW) 11 knots (13 mph)
393mb 295° (from the WNW) 17 knots (20 mph)

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Ok, I am invisible today. Have a nice day if you can read this. Out for now.
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Quoting CycloneUK:


That looks like an awful strong La Nina.
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Quoting reedzone:


I just realized, but again, not too far behind.

Yeah, if the wave train continues, it shouldn't be too long until we equal or surpass 2004.
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Quoting TOMSEFLA:
recon flying to gus about a hour to fly.


Hi Tom, what's that you're holding in your arms in your avatar?
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Helloooooo!!! I dont know if the blog is eating my posts :-(


Quoting Prgal:
From the previous blog: Good afternoon! Is Gaston a TD? Link
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Quoting StormW:


You're funny! Ever think of going into comedy?


he didnt say anything bad about you in any way... why start something storm?
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Quoting 1900hurricane:

We had Ivan as well though, so we're actually slightly behind.


I just realized, but again, not too far behind.
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Actually I expect Igor to be named in 24-48 hours.
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recon flying to gus about a hour to fly.
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Quoting StormW:


You're funny! Ever think of going into comedy?


I have the drum lick down lol!
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Quoting reedzone:
Just noticed something. we are AHEAD of 2004.. We were still tracking Frances at this time.

We had Ivan as well though, so we're actually slightly behind.
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Quoting WeatherNerdPR:

Hermine looks good.
It is going through a exposive period of development here...ItLink seems like it will go in south of Texas.
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Quoting StormW:


You're funny! Ever think of going into comedy?
Thank you. I have made a few bucks writing over the years.
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Quoting WeatherNerdPR:

Not good.


Scratch that, 2004 is still ahead by one storm... We are not too far behind though.
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From the previous blog: Good afternoon! Is Gaston a TD? Link
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Quoting reedzone:
Just noticed something. we are AHEAD of 2004.. We were still tracking Frances at this time.

Not good.
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Quoting MiamiHurricanes09:

Hermine looks good.
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Looks like Gaston will pass just north of the islands and Puerto Rico. It looks like it is getting a little better organized.
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Looks like she's going east of her next tropical point. What's the steering in the Gulf?
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That was fast development.
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Just noticed something. we are AHEAD of 2004.. We were still tracking Frances at this time.
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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.