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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Quoting Tazmanian:

round 1


90L bust


91L bust


92L bust

93L be comes Alex

94L bust

95L bust

96L be come TD 2

97L be comes BONNIE

98L bust

99L bust


round 2



90L bust

91L be comes .COLIN

92L bust

93L bust

94L be comes TD 5

95L be comes Danielle

96L be comes Earl

97L be comes FIONA

98L be comes Gaston

99L bust


round 3


90L be comes hermine


Interesting. Glad to see somebody is keeping that scorecard.
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1035. xcool
boring hurricane season haha
Member Since: September 26, 2009 Posts: 2 Comments: 15672
1034. lparky
get out there and get video! :)
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1033. Halyn
sorry .. that was for wonderkidcayman ..
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1025...1st...you stretched the blog
2nd...I was just going by the preponderance of the evidence. More than 50%.
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1030. lparky
Quoting want2lrn:
ok...no stick throwing. But as i look at the BR, TX radar, the eye is moving what looks like NNE, like she is trying to get back to the water...thoughts. not a wish,fish or downcaster, just a NEWBIE!


Just got on here after looking quickly at the radar and I gotta concur with you...
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1029. Halyn
Well .. alrighty then .. I guess we know how you feel about this situation .. :) I think I would, too ..
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Quoting pottery:

Agree.


I apologize personally to my WU family and take full responsibility for getting off track from solely discussing the tropics....I will try to be good in the future!!
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1027. Skylink
It does look like its moving to the North now, should stay over land though, might mean a shift to the right, so that just means more flooding to the right. Winds are done.
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Quoting btwntx08:
appears thats shes hugging up the coast

Stay safe...I was wondering which direction she was going.
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1023. pottery
Quoting txjac:


I think that the blog has gone flat line too pot ...

Better the Blog, than me LOL!
Member Since: October 24, 2005 Posts: 0 Comments: 24314
1021. pottery
Quoting want2lrn:
Pottery, would you take a look at 1001 and chime in. From what i have seen, you have a pretty good grasp of things. TIA

Can you link that radar?
Member Since: October 24, 2005 Posts: 0 Comments: 24314
1019. Halyn
Quoting txjac:


I think that the blog has gone flat line too pot ...
The other night it "froze" for several hours ..:/
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1018. txjac
Quoting pottery:

UhOh!!
The ITCZ has gone flat-line.......
Does that mean it's dead?


I think that the blog has gone flat line too pot ...
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Pottery, would you take a look at 1001 and chime in. From what i have seen, you have a pretty good grasp of things. TIA
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1016. pottery
Quoting stormwatcherCI:

UhOh!!
The ITCZ has gone flat-line.......
Does that mean it's dead?
Member Since: October 24, 2005 Posts: 0 Comments: 24314
1015. KYDan
Quoting stormwatcherCI:
It seems like when the dry air reaches the islands it dissipates. Maybe enough moisture there to overcome the dry air.


It is likely that I am wrong, as I am a rank amateur at this, but I do not see the Carib as being "moist" right now, and that pesky ULL is still hanging around
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Quoting CosmicEvents:
People....I'm not one of those who run off reporting posts, plusing and minusing, and generally acting like they're still in junior high, 20 years later.......nor do I like to come across as "blog police"......BUT, a word to the wise.......in previous years I've seen wholesale banning for talking back and forth about something completely unrelated...like football. I'm into the game as well, but this isn't the place to keep a running update ala gameday. Dr. Master's doesn't like that on HIS tropical weather blog. He does provide an area where you can talk all you want about most anything. Your own blog. But the last thing he wants is for someone new to the site to see 1/2 weather talk, 1/2 football score updates.....on the main blog.

I click the - icon on the stuff that has nothing to do with weather, and the + icon for this post.
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Member Since: Posts: Comments:
Quoting CosmicEvents:
People....I'm not one of those who run off reporting posts, plusing and minusing, and generally acting like they're still in junior high, 20 years later.......nor do I like to come across as "blog police"......BUT, a word to the wise.......in previous years I've seen wholesale banning for talking back and forth about something completely unrelated...like football. I'm into the game as well, but this isn't the place to keep a running update ala gameday. Dr. Master's doesn't like that on HIS tropical weather blog. He does provide an area where you can talk all you want about most anything. Your own blog. But the last thing he wants is for someone new to the site to see 1/2 weather talk, 1/2 football score updates.....on the main blog.


Point taken and respected. As a newbie, dont want to get a ban in my infancy!
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1010. pottery
Quoting CosmicEvents:
People....I'm not one of those who run off reporting posts, plusing and minusing, and generally acting like they're still in junior high, 20 years later.......nor do I like to come across as "blog police"......BUT, a word to the wise.......in previous years I've seen wholesale banning for talking back and forth about something completely unrelated...like football. I'm into the game as well, but this isn't the place to keep a running update ala gameday. Dr. Master's doesn't like that on HIS tropical weather blog. He does provide an area where you can talk all you want about most anything. Your own blog. But the last thing he wants is for someone new to the site to see 1/2 weather talk, 1/2 football score updates.....on the main blog.

Agree.
Member Since: October 24, 2005 Posts: 0 Comments: 24314
Quoting F4PHANTOM:
if he can overcome all that dry air around him and survive the mts. and still have circulation left AND strengthens to a Cat3, then we're all doomed.
I really don't think he is going to pass far enough north to interact with the mountains of Hispaniola.
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Quoting wunderkidcayman:
gaston will the3 little storm that will


You wish to much.
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1003. leo305
winds down to 60MPH
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Quoting F4PHANTOM:
dry air was only to his east and north earlier.now also to his south. may end up surrounding him before it's all over.
I understand what you are saying but look at the dry air to his south as it reaches the islands. It is not passing through there. Maybe too moist ? I still think he is going to pass south of the northern islands and still has a good chance to develop if he does.
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ok...no stick throwing. But as i look at the BR, TX radar, the eye is moving what looks like NNE, like she is trying to get back to the water...thoughts. not a wish,fish or downcaster, just a NEWBIE!
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gaston will the3 little storm that will
Member Since: June 13, 2009 Posts: 2 Comments: 12035
i WANT POST # 1000
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Quoting F4PHANTOM:
long ways out. we just have to wait and see what develops.


It almost, according to GFS, looks like Igor merges with a low off of New England and forms a clone of the 1991 storm... will be interesting!
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Quoting stormwatcherCI:
Looks like he is going straight in to the Caribbean and no dry air there. Looks like as he approaches the dry air backs away from him but IDK.

Dr. Masters says the models show it will fall apart in the mts. of Hisp. But what if the COC stays in the hot waters below? Cat 3 fast, IMO.
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People....I'm not one of those who run off reporting posts, plusing and minusing, and generally acting like they're still in junior high, 20 years later.......nor do I like to come across as "blog police"......BUT, a word to the wise.......in previous years I've seen wholesale banning for talking back and forth about something completely unrelated...like football. I'm into the game as well, but this isn't the place to keep a running update ala gameday. Dr. Master's doesn't like that on HIS tropical weather blog. He does provide an area where you can talk all you want about most anything. Your own blog. But the last thing he wants is for someone new to the site to see 1/2 weather talk, 1/2 football score updates.....on the main blog.
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The "eye-wall" of Hermine is already starting to erode as it gets further inland in Mexico... though it appears it has resumed it's N/NNW track. If that track holds, the eye-wall (or it's weakening TS equivalent) will pass over or very near to Brownsville. 50-60mph winds (with higher gusts toward 70mph) in the next 3 or 4 hours are still in order...
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AVE MARIA, AVE MARIA, AVE MARIA
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AVE MARIA, AVE MARIA, AVE MARIA
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Quoting stormwatcherCI:
Looks like he is going straight in to the Caribbean and no dry air there. Looks like as he approaches the dry air backs away from him but IDK.
It seems like when the dry air reaches the islands it dissipates. Maybe enough moisture there to overcome the dry air.
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27-26 VT end of 3
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987. code1
Quoting pottery:

Wont!
He is Doom.


We can hope!
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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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