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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Holding my breath for 2-3 more weeks..hopefully the fronts will start to move in & the northern gulf coast will be just about done with the 2010 season..
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Quoting leo305:


I disagree, it has the night and much warmer waters, and more moist environments for it to re develop
If Gaston stays as is, it will enter the extreme Northern Caribbean Sea in about 48 hours.
Member Since: September 27, 2007 Posts: 1 Comments: 22712
Quoting StormW:


MLC,
No. The TUTT is backing away as shown by the peach arrow. Right now, the way both it and ex Gaston are moving, the TUTT is aiding in ventilation. As the TUTT keeps moving away, the forecast from the 700mb charts this morning, call for a good increase in moisture in the Caribbean...and wind shear next to zilch.






Terrific explanation, and picture to boot! Exactly the info I was looking for - appreciate it.

Then that can only mean the likelihood for Gaston's further development, especially if he finds a path just south of the Hispaniola.
Member Since: July 9, 2006 Posts: 184 Comments: 29610
Quoting leo305:


well it has a more moist environment ahead of it


That dry air entrained into its circulation doesn't bode well for it.

Also the latest SHIPS text does not show a dramatically different environment than its currently in once it enters the Caribbean.
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652. IKE
Day 10 ECMWF...

Member Since: June 9, 2005 Posts: 23 Comments: 37860
Quoting StormW:


MLC,
No. The TUTT is backing away as shown by the peach arrow. Right now, the way both it and ex Gaston are moving, the TUTT is aiding in ventilation. As the TUTT keeps moving away, the forecast from the 700mb charts this morning, call for a good increase in moisture in the Caribbean...and wind shear next to zilch.





only thing is there may not be anything left of Gaston by that time, to me it appears he is weakening fast, recon observations thus far are very unimpressive.
Member Since: March 10, 2010 Posts: 1 Comments: 7874
Quoting leo305:


I disagree, it has the night and much warmer waters, and more moist environments for it to re develop


I highly believe that this will not get classified today.
Member Since: July 6, 2010 Posts: 113 Comments: 32860
Does it look like Hermine is now heading more north than northwest? It looks to me like it might travel right up the coast of Texas, after looking at satellite images on weather.com. We could use the rain...
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Port Isabel

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It's making it's final attempt. Glad we have a plane inside to document it.
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Quoting Skyepony:
SOLOLA, Guatemala -- The death toll from multiple landslides in Guatemala rose to 44, officials said Monday, as rescue crews took advantage of a brief window of good weather to search for victims and survivors.

At least 16 people were still missing after a series of landslides, mudslides and wall collapses that followed weeks of heavy rain in the impoverished Central American nation, emergency officials said.

There are "43,043 people at risk, 11,495 have been evacuated, 9,160 are in shelters and 56 people have been injured," a statement from Guatemala's National Coordination for Disaster Reduction (Conared) said.

"It's a national tragedy," President Alvaro Colom said as he visited a site where up to 40 people were thought to have been buried alive in a mudslide.

"This weekend alone we have seen damage comparable to what we experienced with Agatha," he added, referring to a tropical storm in May that killed 165 Guatemalans and left thousands homeless.





Dang, Skye! Too tragic. That's story isn't getting the proper attention this season, imo. With all the flooding, mudslides - deaths, misplaced, etc, it's been a growing and continuing tragedy, slowing unfolding.

With the sinkholes, volcanoes, earthquakes, etc, I'm starting to wonder if parts of Guatemala may simply just fall off into the Pacific. UGH! Tough down there for those folks! Thanks for the reports. :)
Member Since: July 9, 2006 Posts: 184 Comments: 29610
644. xcool
ike . going in land
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643. JLPR2
Quoting Stormchaser2007:




The west side is a desert. XD
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Recon about to make a center pass.

FULL IMAGE

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Quoting Stormchaser2007:




well it has a more moist environment ahead of it
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Quoting Stormchaser2007:




Gaston may be on its last stand for real this time

he needs to pull some magic quick
Member Since: March 10, 2010 Posts: 1 Comments: 7874
#596 MoonlightCowboy, I only see the ULL that is just West of Haiti moving WNW. It looks to be moving faster then Ex-Gaston so conditions should improve over time.
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Very impressive
Member Since: September 16, 2007 Posts: 0 Comments: 9395
19:06:30Z 24.333N 96.700W 842.6 mb
(~ 24.88 inHg) 1,497 meters
(~ 4,911 feet) 999.3 mb
(~ 29.51 inHg) - From 130° at 33 knots
(From the SE at ~ 37.9 mph) 19.5°C
(~ 67.1°F) 16.0°C
(~ 60.8°F) 34 knots
(~ 39.1 mph) 43 knots
(~ 49.4 mph) 8 mm/hr
(~ 0.31 in/hr) 41.7 knots (~ 48.0 mph)
Tropical Storm 126.5%
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Hey MLC haven't crossed paths. Seen some of your posts but wasn't sure you were on. Is the H storm headed your direction?
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Quoting leo305:


I disagree, it has the night and much warmer waters, and more moist environments for it to re develop


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Navy Site....http://www.nrlmry.navy.mil/tc_pages/tc_home.html
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633. nw5b
Quoting centex:
Hermine is rather large weather system. We are getting weather change here in Austin which is over 400 miles from center.


Yep...Austin here too. Rather enjoying the change.

But...I have some friends on Labor day holiday down on the coast, just North of Matagorda Bay, between Port Lavaca and Palacios. I've been on the phone with them several times this morning. One of them is a weather geek like me, and I've been supplying them with NHC and NWS info and radar interpretation. Most of them will be coming home tonight, but the people that own the vacation house on Caranchua Bay are going to stay and do some pre-emptive battening down for Hermine and possibly Gaston.

Hope Hermine takes it easy on the Rio Grande valley. They've had it rough this year!
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Quoting Stormchaser2007:
Quite a blow-up.



looks like it quit sucking so much dry air from Mexico into the COC.
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Quoting StSimonsIslandGAGuy:
Looks like Hermine is trying to pull a Humberto.


Yep, a little right of track would/could make a huge difference....and it does look like the heading is pretty close to 350 or so...
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Quoting TropicalAnalystwx13:
Gaston is building some convection right now, but its that time of day for him to do it anyway. This batch of convection will likely die out like all the others, and I believe he will not get reclassified until tomorrow at the earliest.



I disagree, it has the night and much warmer waters, and more moist environments for it to re develop
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Quoting MiamiHurricanes09:


Pretty sure thats a weak Category 1 HUrricane right now.
Member Since: July 6, 2010 Posts: 113 Comments: 32860
Quite a blow-up.

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Recon confirms Hermine is not near hurricane strength yet, but is a healthy tropical storm.
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Quoting MiamiHurricanes09:
I'd say cat 1.
Member Since: August 14, 2010 Posts: 10 Comments: 17834
624. IKE
Hermine looks like she's getting close to landfall.
Member Since: June 9, 2005 Posts: 23 Comments: 37860
999 mb, getting closer to the center.

190630 2420N 09642W 8426 01497 9993 +195 +160 130033 034 043 008 00
Member Since: July 8, 2005 Posts: 259 Comments: 24579
Link

8-14 day Temperature anomaly forecast from NAEFS...Summer is over except for the tropical Atlantic, Gulf, and Caribbean.
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621. Skyepony (Mod)
SOLOLA, Guatemala -- The death toll from multiple landslides in Guatemala rose to 44, officials said Monday, as rescue crews took advantage of a brief window of good weather to search for victims and survivors.

At least 16 people were still missing after a series of landslides, mudslides and wall collapses that followed weeks of heavy rain in the impoverished Central American nation, emergency officials said.

There are "43,043 people at risk, 11,495 have been evacuated, 9,160 are in shelters and 56 people have been injured," a statement from Guatemala's National Coordination for Disaster Reduction (Conared) said.

"It's a national tragedy," President Alvaro Colom said as he visited a site where up to 40 people were thought to have been buried alive in a mudslide.

"This weekend alone we have seen damage comparable to what we experienced with Agatha," he added, referring to a tropical storm in May that killed 165 Guatemalans and left thousands homeless.


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Quoting Neapolitan:
Found this and posted it on the earlier blog; I'll do so again now since more people are logged in:

Nice. Glad you did, as I am one of those you are referring to.. Thanks.
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recon obs tell me Ex-Gaston is a very weak system now
Member Since: March 10, 2010 Posts: 1 Comments: 7874
Quoting CycloneUK:


Wow! Cool graphic! Got a link for that?
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Quoting Wariac:
I just saw the navy site an it has Gaston back up again....09LGaston...is it a TD or TS again?


link?
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Quoting MiamiHurricanes09:


Looks like a lower end Cat 1 to me.
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Quoting KEEPEROFTHEGATE:
big time rain event coming even after land fall with track ending OK.

Historicaly we've only had extreme event if stalls once inland. Hopefully it picks up north and does not over stay it's welcome. btw can comment on issues they may have in valley.
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Member Since: September 2, 2009 Posts: 130 Comments: 21194
Hi StormW how's your labor day going? Working hard on the tropics I see.
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612. IKE
ECMWF shows a SE GOM low/system, on the end of the run....Link
Member Since: June 9, 2005 Posts: 23 Comments: 37860
Quoting KEEPEROFTHEGATE:
big time rain event coming even after land fall with track ending OK.

Some of us won't mind a drenching rain on our dry cracked ground.
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Quoting Neapolitan:
Found this and posted it on the earlier blog; I'll do so again now since more people are logged in:


OH no, now Im hook in Gaston's tragic life, is a soap opera, feeling sorry for him already. Would love to know how that "epic" story ends...
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609. Vero1


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Two comments on Hermine looks like she is just what Texas ordered for their drought. And thank God it's forming so close to the coast. Remain amazed no matter how many times I have seen this, but the Gulf and Bay of Campeche in particular are just explosive areas for TC development.
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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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