Hermine drenching Texas; Gaston's remains less organized
Tropical Storm Hermine hit the Mexican coast 40 miles south of the Texas border at 9:30 pm EDT last night, with 60 mph sustained winds. Top winds observed in Texas from the storm were 50 mph with gusts to 59 mph at Port Isabel near the Mexican border, and winds at Brownsville hit 45 mph, gusting to 69 mph. Harlingen had the highest gust observed from Hermine, 72 mph, and local storm reports indicate that half of the city lost power and a roof caved in on an apartment complex, with no injuries. Heavy rains have fallen along a 30-mile wide stretch of the Mexican and Texas coast, with 1.41" reported thus far in Harlingen, 3.71" at Brownsville, and 2.00" at Corpus Christi. Radar estimated rainfall amounts (Figure 3) exceed four inches along most of the Lower Texas coast, with maximum amounts near eleven inches twenty miles north of Brownsville.
Figure 1. Radar image of Hermine at landfall.
Figure 2. MODIS satellite image of Hermine at 12:45pm EDT Monday September 6, 2010. Image credit: NASA.
Hermine became a tropical depression at 11pm Sunday night, and intensified into a 65 mph tropical storm in just 21 hours, an extremely fast intensification rate. It turns out that the southwestern Gulf of Mexico's Bay of Campeche, where Hermine formed, is prone to these sort of rapidly intensifying tropical storms. This region produced two similar rapidly intensifying storms in 2007, Humberto and Lorenzo. Since 6-hourly position records of Atlantic hurricanes began in 1970, Hurricane Humberto holds the record for fastest intensification from first advisory issued to hurricane strength--18 hours. (Actually, Humberto did the feat in 14 1/4 hours, but this was rounded off to 18 hours in the final data base, which stores points every six hours). The curvature and topography of the land surrounding the Bay of Campeche 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 yesterday for Hermine were the very warm 30°C waters, low 5 - 10 knots of wind shear, and moist atmosphere.
Figure 3. Morning radar-estimated rainfall for Hermine.
Forecast for Hermine
Heavy rain and isolated tornadoes will continue across southern and central Texas today and tomorrow. Hermine is expected to accelerate northward today, limiting the potential for damaging floods along its future path. The storm's rains will help alleviate moderate to severe drought conditions affecting Central Texas.
Gaston's remains less organized
Dry air has significantly disrupted the remains of Tropical Storm Gaston, which are now over the northern Lesser Antilles Islands and Puerto Rico. Morning visible satellite imagery shows that Gaston's remains no longer have a well-defined surface circulation, though there is still some spin. Latest radar out of Martinique and Puerto Rico show a few heavy rain showers moving through the islands, but no organization to the showers. A large amount of dry air surrounds Gaston's remains on all sides, as seen on water vapor satellite loops. None of the computer models show Gaston redeveloping, and NHC has downgraded the odds of development to 10%. I think the odds should be higher than this, perhaps 30%. Gaston's remains will be disrupted some on Wednesday, when they will encounter the high terrain of Hispaniola.
Elsewhere in the tropics
There are two tropical waves off the coast of Africa that NHC is giving a 10% chances of developing into tropical depressions by Thursday. The models are fairly unanimous in predicting development of one or more tropical waves off the coast of Africa 3 - 7 days from now. The next storm will be called Igor.
Eastern Pacific Tropical Depression 11E kills 44 in Guatemala
In the Eastern Pacific, heavy rains from Tropical Depression 11E killed at least 44 people in Guatemala over the weekend. At least 56 are injured, and 16 missing. The heavy rains triggered fifteen landslides that hit portions of the Inter-American Highway, burying a number of vehicles and a bus. Guatemala is still recovering from the impacts of Tropical Storm Agatha, which killed 287 people in the country and did over $1 billion in damage.
Figure 4. Satellite image from Friday, September 3, 2010, showing Tropical Depression 11E over Guatemala. Image credit: NASA.
"Hurricane Haven" airing again this afternoon
Tune into another airing of my live Internet radio show, "Hurricane Haven", at 4pm EDT today. Listeners will be able to call in and ask questions. The call in number is 415-983-2634, or you can post a question to broadcast@wunderground.com. Be sure to include "Hurricane Haven question" in the subject line.
Today's show will be about 30 minutes, and you can tune in at http://www.wunderground.com/wxradio/wubroadcast.h tml. The show will be recorded and stored as a podcast.
Next post
I'll have an update Wednesday morning.
Jeff Masters
Reader Comments
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Its heading of (10.2degrees west of) WestSouthWest has already taken exGaston a lot farther south into the Carribbean than anyone had anticipated. M' s'spects mischief's afoot.
AL09 exGaston
06Sep . 12pmGMT - - 17.4n55.5w - - 30knots - - 1010mb - - NHC-ATCF
06Sep . 06pmGMT - - 17.5n57.2w - - 30knots - - 1011mb - - NHC-ATCF
07Sep . 12amGMT - - 17.5n59.0w - - 30knots - - 1011mb - - NHC-ATCF
07Sep . 06amGMT - - 17.1n61.0w - - 25knots - - 1010mb - - NHC-ATCF
07Sep . 12pmGMT - - 16.8n62.4w - - 20knots - - 1011mb - - NHC-ATCF
30knots=~34.5mph __ 25knots=28.8mph __ 20knots=~23mph
Copy and paste 17.4n55.5w-17.5n57.2w, 17.5n57.2w-17.5n59.0w, 17.5n59.0w-17.1n61.0w, 17.1n61.0w-16.8n62.4w, nbw, pos into the GreatCircleMapper for a look at the last 24hours.
Its nothing if not persistent.
AOI
AOI
AOI
AOI
AOI
TS BUSTED FORECAST ALIBI
Just as they lower Gaston's chances a high sets up right overhead LOL
Let's see if that helps any.
Numbers are your friend :)
That does not seem the case. If the conditions are right, all tropical cyclones can develop upper level anticyclones. Tropical Storm Hermine (and many others) developed its own upper level anticyclone. When a tropical cyclone has strong surface convergence with virtually no wind shear above it, it will positively create its own upper level ridge. Sometimes mere intense convection activity at the surface can generate an upper level anticyclone.
A tropical cyclone's upper level ridge can also be enhanced by diffluent flow aloft from the eastern side of an upper level low. The curving diffluent air increases winds at the periphery of the upper level high. If a tropical cyclone is under too much shear, the upper level high will be negligible or displaced from the center. Overall, upper level anticyclogenesis depend on the environment.
This what we can expect with virtually no wind shear above it. Dry will still be a problem today, however.
Perhaps, but convection building again.
ACE is simply the best metric yet devised for measuring the accumulated energy spent over he course of a season, and as such it is very effective at detailing overall activity. I suppose that, for some, body counts and dollar amounts are a more effective measure, but from a meteorological point of view, ACE works quite well. To put it another way, while the devastating impact of a short-lived and powerful storm like Camille means more to the general population--that is, normal folks, journalists, insurance adjusters, and the like--its relatively low ACE says nothing much about the overall power of a particular season.
(Yes, ACE-wise, 2007 was low-normal...but half its total ACE came from one storm--Dean. This year's short-lived Alex was more energetic than 12 of that year's 14 mostly weak systems. When making year-to-year comparisons on which a season's "bustedness" is based, ACE works.)
Everyone is feeling a little sorry for his long naked journey.
He's been on a quest, that's for sure. I still don't trust him to dissipate though. This is the first system in the Caribbean for weeks which makes him a threat down the road if he survives to reach the Western Caribbean.
I will be back later to see how he is getting on LOL
I was just thinking of you and the 63W position of Gaston(John Hope rule). I'll keep an eye on him too.
You need to repost your eulogy for him in case he forgets to die... (again) :/
I RIP-ed him when the NHC downgraded him. I'm like Kman...he's worth following.
Most models still take him toward the Yucatan...Link
yeah but if anyone stirs their coffee counter-clockwise he will probably revive!
Kman...how might a high over him aid in development?...sorry if that's a dumb question...learning..TIA
Hi StormW,
What do you think are the chances that Hermine starts spinning up tornado's as she goes through the midwest
Thanks alot....Even I can understand that....LOL!
FEMA has great free classes online that link with COMET for any of those that are interested in some MET/Hurricane 101.
n '57 she began with a roar
No one knew she was comin' ashore
Most people were asleep in bed
Not knowing they should have fled.
After the fury of the storm's huge eye
Families cried for members who did die
Lady Audrey would long be remembered
As the fateful day that Cameron surrendered
Hopefully that does it - these are the ones we have to watch in our neck of the woods!
"poor Gaston" is drenching us here on St. Croix. If the wind don't get you the rain will...
Lots of thunder and heavy squalls, wind about 20kts with higher gusts.
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