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 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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THE REMNANTS OF TROPICAL STORM GASTON WILL CONTINUE TO MOVE
WEST TOWARDS THE NORTHERN LEEWARD ISLANDS THIS EVENING. THE
POTENTIAL FOR THIS SYSTEM TO REDEVELOP INTO A TROPICAL CYCLONE
REMAIN HIGH...EITHER LATER TONIGHT OR ON TUESDAY. THEREFORE...LOCAL
RESIDENTS AND TOURISTS ARE URGED TO CONTINUE TO REMAIN ALERT TO
ANY CHANGES IN THE DEVELOPMENT OF THIS SYSTEM...AS RAIN BANDS AND
GUSTY WINDS WILL LIKELY IMPACT THE LOCAL ISLANDS TOMORROW
AFTERNOON THROUGH WEDNESDAY.

...this was from the national weather service of san juan
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Its a great thing that Hermine is close to land! She is fired up!
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Quoting stormpetrol:
I think ex Gaston is in the process of reorganizing. I think ex Gaston will be one these storms that is full of surprises when all is said and done, jmo.


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.
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Look at all that Gatorade for Gaston in the Carribean!
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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%


They could bump it up to 70mph off that but we shall see.
Member Since: September 6, 2009 Posts: 2 Comments: 3784
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I think that Hermine has walled of the dry, continental air and will be a 'cane at landfall. Gaston has refused to die so far and I see nothing to kill him off before he gets in the Carribean. If he could talk it he would say "rumours of my demise have been greatly exaggerated". And I'm out!
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IS Hermine going to strike where Alex did?
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Quoting Sfloridacat5:


The balcones escarpment (rise in elevation from the coastal plains to the Edwards Plateau)really increases the rainfall potential in tropical systems moving island over South Texas.
True and we need to be careful because these type of systems can create extreme events. One of the max events in our countries history took place with just this type of system.

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745. xcool
Hhunter .i think time for hurricane warning jmo.
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744. xcool
Gaston try so hard.
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gaston Name Meaning and History
French: from the Old French oblique case of a Germanic personal name, originally probably a byname from gasti ‘stranger’, ‘guest’, ‘host’. Compare Guest. The surname is also found in England and Ireland, where it is probably a Huguenot importation.
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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%
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hey everyone.. its been awhile.. been busy working and hanging out with the fam with the labor day weekend.. Probably won't be on long b/c im going to watch a movie and watch the big game tonight with Boise state vs Virginia Tech..
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Quoting LemieT:
Why is everyone calling Hermine a he? Wouldn't that be Hermon? Somewhere else I've been seeing Gaston referred to as a she. Talk about global gender identity crisis.


Its like Pee Wee Hermine. You don't really know what it is.
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I think ex Gaston is in the process of reorganizing. I think ex Gaston will be one these storms that is full of surprises when all is said and done, jmo.
Member Since: April 29, 2007 Posts: 0 Comments: 8134
Quoting Hurricanes101:


yea it appears to take ex-Gaston into Belize and never develops it; when ex-Gaston is near Jamaica a new wave comes into the islands and that is what the ECMWF develops and brings into the Yucatan Channel
lets see if it sticks?
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I'll be back later guys.

Going to play Tornado Jockey :)
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Quoting xcool:
Hurricanes101 i think you're rigth.


yea it appears to take ex-Gaston into Belize and never develops it; when ex-Gaston is near Jamaica a new wave comes into the islands and that is what the ECMWF develops and brings into the Yucatan Channel
Member Since: March 10, 2010 Posts: 1 Comments: 7874
Quoting KanKunKid:


....and I WASN'T looking in Chicklit's Kitchen window!


Tell it to the judge.
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From my local NWS office:

"FUTURE ISSUANCES MAY NEED
TO INTRODUCE CB/TS OR CATEGORICAL PRECIP."

TS Precipitation possible and I live in N TX...

Kinda Weird...
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731. xcool
Hurricanes101 i think you're rigth.
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694

URNT12 KNHC 061936 CCA

VORTEX DATA MESSAGE AL102010

A. 06/19:09:40Z

B. 24 deg 11 min N

096 deg 46 min W

C. 850 mb 1385 m

D. 47 kt

E. 046 deg 26 nm

F. 149 deg 48 kt

G. 045 deg 24 nm

H. EXTRAP 995 mb

I. 18 C / 1525 m

J. 19 C / 1525 m

K. 16 C / NA

L. NA

M. NA

N. 12345 / 8

O. 0.02 / 0 nm

P. AF301 0210A HERMINE OB 05 CCA

MAX FL WIND 48 KT NE QUAD 19:01:50Z

SLP EXTRAP FROM 850 MB

MAX FL TEMP 20 C 020 / 6 NM FROM FL CNTR

;
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729. xcool
scott39 hey .long time
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Quoting centex:
Updated there graphics after post timestamp. I guess think we are not watching that close.



The balcones escarpment (rise in elevation from the coastal plains to the Edwards Plateau)really increases the rainfall potential in tropical systems moving island over South Texas.
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looking at the 12Z ECMWF, it does not develop Gaston, but the system behind it
Member Since: March 10, 2010 Posts: 1 Comments: 7874
hey storm ,levi... :)
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I think Gaston is taking all these insults personal on Satellite he is looking much better this afternoon. Looks like is is excited to get to StormW's 60 west.
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Quoting xcool:


Gaston
Thats where Fredric went over in 1979!
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Quoting NOSinger:


Your right...the NHC gives 70% on just about anything that pops up in the ATL. I'll go with Storm W on this one...but thanks for all of those "facts"...lol


its been at 70% every single day for the last 4 days; still does not mean its going to develop

recon information is the most factual thing we can have and they show a weak circulation

no need to get snappy at me, I am just telling you what I see in recon;
Member Since: March 10, 2010 Posts: 1 Comments: 7874
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Quoting PtownBryan:


Hey Dennis Pearland here! Just had that storm earlier. Was nice! I am ready for more!


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.
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24 hr
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I made this yesterday...Its my Winter 2010/2011 forecast. The oranges mean it will be a relatively warm winter, Blues mean it will be cold, and Pink means frigid. California should be blue, but PSP08 didn't agree with me.

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Updated there graphics after post timestamp. I guess think we are not watching that close.

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Why is everyone calling Hermine a he? Wouldn't that be Hermon? Somewhere else I've been seeing Gaston referred to as a she. Talk about global gender identity crisis.
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Quoting SouthALWX:

thanks :)
Also, Im wondering if what the euro is showing is Gaston??
I havent had time to see if it fits the timeline but I dont see what else it could be?? If the Euro is on board with not killing him off then it's game on.



Dunno. I don't do models. But, I will say this - seems something is out-of-whack with development. 72-hr sfc chart only shows a westwards moving Low, not a "possible TS", etc. In that water? So, they're either expecting it to fizzle, get sheared or dry air to choke it before it can muster any more organization.

I don't like these "under the radar" systems that hang on and on. Either the NHC is seeing something we don't, or they're missing something and Gaston is likely to surprise a few folks. Low shear, more moisture in the Caribbean, high TCHP, fairly vigorous circ still - all elements for development. It may be just be the size of the system and any longevity to hang on until all the pieces fit together. We'll see, right! ;)
Member Since: July 9, 2006 Posts: 184 Comments: 29610
Just been reviewing the Hurricane Hunter data from both Tropical Storm Hermine and ex-Gaston.

Not at all surprised that they didn't find a strong tropical storm or minimal hurricane in Hermine. Even though some disagree, I do believe dry air has been impeding the storm strengthening some this afternoon and continues to be as water vapor imagery shows dry air over Mexico really limiting convection on the western side. I will admit radar imagery does look rather impressive with a solid core, but it does show some dry air getting into the system as well with gaps with in the core.

I'm more surprised about what Hurricane Hunters have found, or haven't found in ex-Gaston. Visible satellite imagery appears to show a still well defined low level circulation as evident in the lower cloud motions, but Hurricane Hunters barely found any west winds in the system. In fact, the data collected by the Hurricane Hunters show a very weak, very disorganized system that really needs some work.
Member Since: April 14, 2007 Posts: 8 Comments: 5169
Quoting PrivateIdaho:


Well I like your little weather nerd dude. ;^)

lol So do I.
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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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