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 scott39:
Its hard to tell that there is a West component to the motion.


very hard to see looks generally N motion to me
for now anyway.
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Quoting SETexas74:
Hermine almost looks like its moving NNE in the long range brownsville radar but thats probably just a wobble in the circulation. A really strong outer band just came through southeast houston with some pretty gusty

We are fixing to get it in Conroe
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Really surprised there hasn't been a Tornado Watch issued for SE Texas yet. Gonna be watching that band approaching Brownsville and Corpus Christi very closely. Seems like there could be some weak rotation in the storms within the band.
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Tropical shower at house. I can put up the hose. It pours heavy for one minute than stops just as fast as it started. I love it and pray it does not cause issues down the road.
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gaston has no shot, dry air looming land masses. fuggetabouttit
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Quoting CaribBoy:
I give up with gaston lol!
It will strengthen now...:)
Member Since: September 27, 2007 Posts: 1 Comments: 22712
Centex, hang around the blog more.....you'll see that everyone is guilty of that to some degree. i don't see the Texas Bloggers as much until there is something threatening them. It is the nature of the blog. However, many of us are following both systems and developments away from the CONUS, GOM, or carib..no matter where we live.

Quoting centex:
I want to thank all the Texans for tolerating the G storm folks, they could care less about H. Keep it up and make us proud. We wouldn’t want to be like Fl bloggers. Cream comes to the top in tropics and Football.
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Quoting JBirdFireMedic:


I have been following recon since they started and have seen nothing like that, and when I view those coordinates in the recon, I see 15mph.


guess you need to stay alert and search the archive my good chap
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Quoting ginajo:
I am here in Matagorda County, (Texas) and we have had about 1/4 of an inch since 8:30 am. No wind to speak of.
Not far from you-we've had 1 1/2 inch of rain -last time I looked-no wind either
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798. Relix
Gaston is just a strong wave at the moment. Borderline DT status if not DT.
Member Since: August 3, 2006 Posts: 0 Comments: 2741
I give up with gaston lol!
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I'm starting to think that the ULL and the TUTT moving in tandem to Gaston's west has been steadily robbing it of convection, pulling moisture off to the northwest of the system. It may have been serving to "ventilate" the system, but it may have also kept it from maintaining any moisture field over its coc and getting the tropical engine going, recycling that moisture. That has allowed dry air to continue to entrain the core of the system and serve as an inhibitor to development.

Either the system is going to have to distance itself from the TUTT/ULL, or it will have to get over more fuel conducive to producing more moisture, quicker - and in less shear.

It's all going to depend on the energy remaining in Gaston's LLC, and whether or not it can hold on until it gets enough moisture over the coc, finally filtering out all the dry air - then, tightening its core and getting the moisture engine running.
Member Since: July 9, 2006 Posts: 184 Comments: 29610
With tropical systems in a position similar to Tropical Storm Hermine, I really get concerned about possible widespread flooding the Rio Grande Valley region and Southern Texas. With the storm poised to make landfall south of the Rio Grande and since it has a large circulation, there will a persistent SE flow coming ashore into the region bringing constant moisture. Wouldn't surprise me to see double digit rainfall totals in several areas once the storm is all said and done.
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If Gaston stays as is, it will enter the extreme Northern Caribbean Sea in about 48 hours.What is causing the flooding in that picture? And where?
Member Since: September 27, 2007 Posts: 1 Comments: 22712
I am here in Matagorda County, (Texas) and we have had about 1/4 of an inch since 8:30 am. No wind to speak of.
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yeah trying to find a long (time wise) loop of the brownsville radar because i saw that little NE wobble
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Sorry I was just trying to spice up the blog and couldn't resist. The FL knock is nothing new, I guess you guys just in a dry spell. I'll keep to more science oriented post.
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Send some of that Tx rain next door...we could use it.
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Quoting Hhunter:
Link

RECON DECODER LINK


I have been following recon since they started and have seen nothing like that, and when I view those coordinates in the recon, I see 15mph.
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Hermine almost looks like its moving NNE in the long range brownsville radar but thats probably just a wobble in the circulation. A really strong outer band just came through southeast houston with some pretty gusty winds about an hour or two ago.
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Quoting bohonkweatherman:
Texas is such a big state alot of the time a Hurricane hits this state I get little rain, the path almost has to go over your head to get good rains.


yea and this is pretty good size storm..half of state will get rain
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Any updated coordinates on COC for Hermine?
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Quoting centex:
I want to thank all the Texans for tolerating the G storm folks, they could care less about H. Keep it up and make us proud. We wouldn’t want to be like Fl bloggers. Cream comes to the top in tropics and Football.


Only Texas bloggers lol
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Quoting txjac:



LOL ...I think that we are all happy to have the rain!
Texas is such a big state alot of the time a Hurricane hits this state I get little rain, the path almost has to go over your head to get good rains.
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Just noticed something in looking at satellite imagery for Tropical Storm Hermine. It seems like there is a defined wall marking the boundary between the deep dry air over Mexico and Texas and Hermine's moisture.
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Quoting Hhunter:
Link

LONG RANGE BROWNSVILLE RADAR. IMPRESSIVE
Its hard to tell that there is a West component to the motion.
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Outflow boundaries on the NE of the circulation clearly indicate that Gaston continues to struggle with dry air intrusion which is causing the thunderstorms to collapse.

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HECK HERE IN TEXAS WE KNOW GASTON COULD BE OURS ALSO THE WAY THIS YEARS GOING...
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HECK HERE IN TEXAS WE KNOW GASTON COULD BE OURS ALSO THE WAY THIS YEARS GOING...
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Quoting centex:
I want to thank all the Texans for tolerating the G storm folks, they could care less about H. Keep it up and make us proud. We wouldn’t want to be like Fl bloggers. Cream comes to the top in tropics and Football.


Seriously? I don't see any Fl bloggers talking more about Gaston than Hermine. I'm monitoring Hermine much closely due to its proximity to land. The animosity towards FL bloggers is laughable and silly
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Quoting centex:
I want to thank all the Texans for tolerating the G storm folks, they could care less about H. Keep it up and make us proud. We wouldn’t want to be like Fl bloggers. Cream comes to the top in tropics and Football.


Huh? I'm a Florida blogger and have been following Hermine the entire time. I posted on her last night before anyone was paying attention to her.
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I searched the name meaning and history of Hermine. Here's the results that I got.

The girl's name Hermine \he-rmi-ne, her-mine\ is a variant of Erma (Old German), Herminia (Spanish) and Hermione (Greek), and the meaning of Hermine is "complete, universal; messenger; earthly".
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Quoting scott39:
Its a great thing that Hermine is close to land! She is fired up!
I agree, this would be a powerful hurricane if it had more time, fortunately it does not.
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http://www.esl.lsu.edu/webpics/goes/Storm/AOI0/latest_wv_loop.gif
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772. txjac
Quoting centex:
I want to thank all the Texans for tolerating the G storm folks, they could care less about H. Keep it up and make us proud. We wouldn’t want to be like Fl bloggers. Cream comes to the top in tropics and Football.



LOL ...I think that we are all happy to have the rain!
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Link

LONG RANGE BROWNSVILLE RADAR. IMPRESSIVE
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8 3 2

we are running above average for sure
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I want to thank all the Texans for tolerating the G storm folks, they could care less about H. Keep it up and make us proud. We wouldn’t want to be like Fl bloggers. Cream comes to the top in tropics and Football.
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Link

RECON DECODER LINK
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1011mb is the highest since ex-Gastons conception.
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anyone have a long loop of the Brownsville radar?
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I like the UKMET: More rain for the desert should help with the drought...
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Quoting mtyweatherfan90:
Here at Monterrey it's bright and sunny but some building cumulus can be sighted to the east. Maybe in a couple of hours we could have a 180° different sky. That's the best thing of all, you never get bored about weather!! It will always give you a surprise even when you don't expect anything to happen!

I haven't seen you since Alex! How ya doing!
Member Since: July 7, 2010 Posts: 0 Comments: 5725
Quoting KanKunKid:


....and I WASN'T looking in Chicklit's Kitchen window!
But you were listening awfully closely to the description of the guy standing on your shoulders.
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Quoting kmanislander:


Hi there.

Gaston still seems to have a closed circulation but the lowest pressure is fairly high at 1011 mbs and the winds and convection are marginal. If the HH sticks around long enough to find a pressure fall and some stronger winds the NHC may go with an upgrade at 5 IMO. The real problem is that Gaston has not demonstrated sustained convection for very long .

We'll know soon enough what the NHC think of the obs from the aircraft.

Hi. I think you're right, but he's proven to be a fighter, those are the ones I don't like. I think he's finally on his way to getting his name reinstated.
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Quoting Dennis8:


YES dry August here after 18.09" Rain in July.

I want this Hurricane threat fro Houston gone by the time I leave for Europe on vacation September 22..USUALLY I am not worried after that time each year. We went to Europe after Ike ( September 12-13, 2008). It has been MY experience the past 48 years we have been okay but who knows.


I know early summer was crazy with rainfall. But after Alex and td 2 I believe it was, man it has been dry! I think you are right not much usually happens here after mid September. Have a safe and great vacation!
Member Since: July 5, 2010 Posts: 0 Comments: 170
Here at Monterrey it's bright and sunny but some building cumulus can be sighted to the east. Maybe in a couple of hours we could have a 180° different sky. That's the best thing of all, you never get bored about weather!! It will always give you a surprise even when you don't expect anything to happen!
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you thinks that after swimming the whole Atlantic he is going to die close to shore? He got something in mind!
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Quoting Hhunter:
67MPH WINDS

19:34:00Z 23.500N 96.883W 843.5 mb
(~ 24.91 inHg) 1,520 meters
(~ 4,987 feet) - - From 271° at 18 knots
(From the W at ~ 20.7 mph) 14.5°C*
(~ 58.1°F*) -* 19 knots
(~ 21.8 mph) 62 knots
(~ 71.3 mph) 53 mm/hr
(~ 2.09 in/hr) 58.7 knots (~ 67.5 mph)
Tropical Storm 326.3%



LINK?
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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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