Intensifying Hermine closes in on the Texas/Mexico coast
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
Reader Comments
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Updated: 5 min 22 sec ago
Light Rain
81 °F
Light Rain
Humidity: 84%
Dew Point: 75 °F
Wind: 12 mph from the NNE
Pressure: 29.70 in (Steady)
Heat Index: 86 °F
Visibility: 10.0 miles
UV: 0 out of 16
Pollen: 6.80 out of 12
Pollen Forecast new!
Clouds:
Scattered Clouds 1300 ft
Mostly Cloudy 2000 ft
Mostly Cloudy 3100 ft
(Above Ground Level)
Elevation: 20 ft
You mean like this?
Now why do I think this next Vortex fix is going to give some people fits?
Stormtop again.
Transmitted: 7th day of the month at 00:03Z
Aircraft: Air Force Aircraft (Last 3 digits of the tail number are 301)
Storm Number & Year: 10L in 2010
Storm Name: Hermine (flight in the North Atlantic basin)
Mission Number: 2
Observation Number: 20
A. Time of Center Fix: 6th day of the month at 23:33:00Z
B. Center Fix Coordinates: 24°49'N 97°08'W (24.8167N 97.1333W)
B. Center Fix Location: 80 miles (129 km) to the SSE (164°) from Brownsville, TX, USA.
C. Minimum Height at Standard Level: 1,346m (4,416ft) at 850mb
D & E. Estimated (by SFMR or visually) Maximum Surface Wind: Not Available
F. Maximum Flight Level Wind Inbound: From 137° at 52kts (From the SE at ~ 59.8mph)
G. Location of Maximum Flight Level Wind Inbound: 32 nautical miles (37 statute miles) to the NNE (27°) of center fix
H. Minimum Sea Level Pressure: 991mb (29.26 inHg) - Extrapolated
I. Maximum Flight Level Temp & Pressure Altitude Outside Eye: 16°C (61°F) at a pressure alt. of 1,524m (5,000ft)
J. Maximum Flight Level Temp & Pressure Altitude Inside Eye: 20°C (68°F) at a pressure alt. of 1,525m (5,003ft)
K. Dewpoint Temp & Sea Surface Temp (collected at same location as temp inside eye): Not Available
L. Eye Character: Not Available
M. Eye Shape: Not Available
N. Fix Determined By: Penetration, Radar, Wind, Pressure and Temperature
N. Fix Level: 850mb
O. Navigation Fix Accuracy: 0.02 nautical miles
O. Meteorological Accuracy: 2 nautical miles
Remarks Section:
Maximum Wind Outbound: 61kts (~ 70.2mph) in the east quadrant at 23:35:30Z
Maximum Flight Level Wind: 61kts (~ 70.2mph) in the east quadrant at 23:35:30Z
Sea Level Pressure Extrapolation From: 850mb
Try it here, Java or Gif
Link
FWIW Tropical Storms Charley and Frances in 1998 hit in the Corpus area and gave Houston a lot of rain, with Frances causing significant flooding of some Houston area roadways. I thought it was bad until Allison 3 years later.
Not a good side for Raymondville to be on.
FULL IMAGE
Agree.
Centers dont "reform" in well-defined systems.
They simply move around.
Thanks, And I thought I had learned something lol!
that is why I said reformed/moved
Well it is, lol. These storms love to do that, and most always try at least once. Even Alex tried but failed. Dolly in 2008 was one that succeeded. The frictional effects always try to pull them north when they try to hit northern Mexico. This time, we'll see how it goes, but Hermine could still take a mean track if she heads an average of NNW over the next 12 hours.
Now if she's really naughty and keeps going due north, well, that's not going to be very fun, but she likely won't stay on this particular heading for too awful long. They are often wobbles due to the frictional effects.
what does that mean? I cannot find the question you were referring to
I think he was a magic dragon.
Actually as much as I would like to watch the panic of some on the Blog.... I would assume she is almost on track, if these were the standard two hours fixes... she would be on Track.
you think she could ride the coast for a bit and if so how far north?
What? October and November storms are MOST LIKELY to strike Florida, rather than any other state. ESPECIALLY if they form in the Caribbean due to the troughs.
Way to premature to say that.
when there's a lot of moisture available for a cyclone to feed from, it happens when the sun goes down, the temperatures tend to also go down in the tropics, and the dew point tends to get closer to the temperature, when that happens the amount of humidity the air can hold drops, so that moisture has to go somewhere, hence the amount of moisture available to a storm increases causing it to develop further and faster.
Check 488
Wasn't she already supposed to make landfall by now?
Does that mean this NNE movement is still just a wobble of the center or a real change in direction?
It's several things. Yes the shortwave over the plains has something to do with it because the ridge hasn't yet built in strongly in that area. Also affecting Hermine's track though are frictional effects and the envelope of low pressure extending to her north which is what took her north of the model consensus in the first place, and what could still pull her NNW for a while and give Texas a bad night.
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