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
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Correct. This is from wiki
Landfall
See also: List of notable tropical cyclones and Unusual areas of tropical cyclone formation
Officially, landfall is when a storm's center (the center of its circulation, not its edge) crosses the coastline.[56] Storm conditions may be experienced on the coast and inland hours before landfall; in fact, a tropical cyclone can launch its strongest winds over land, yet not make landfall; if this occurs, then it is said that the storm made a direct hit on the coast.[56] As a result of the narrowness of this definition, the landfall area experiences half of a land-bound storm by the time the actual landfall occurs. For emergency preparedness, actions should be timed from when a certain wind speed or intensity of rainfall will reach land, not from when landfall will occur.[56]
Kinda amazing how Hermine was moving tail earlier, 3 hours was a whole degree in latitude, yet as soon as she nears land she slows up entirely. She doesn't like it.
Like an anti-Fay.
To PTowBryan - Not really....this is NOT what the Dr. ordered. This is a very bad place for this storm to hit. Not sure why this is being thought of in this way.
000
URNT12 KNHC 062149
VORTEX DATA MESSAGE AL102010
A. 06/21:20:20Z
B. 24 deg 36 min N
097 deg 03 min W
C. 850 mb 1350 m
D. 50 kt
E. 180 deg 28 nm
F. 277 deg 38 kt
G. 180 deg 30 nm
I. 17 C / 1523 m
J. 21 C / 1523 m
K. NA / NA
L. NA
M. NA
N. 12345 / 8
O. 0.02 / 2 nm
P. AF301 0210A HERMINE OB 11
MAX OUTBOUND AND MAX FL WIND 57 KT NE QUAD 21:22:30Z
SLP EXTRAP FROM 850 MB
;
Technically you are wrong. Bonnie made landfall in S Florida as a 40mph thunderstorm.
Not good. :(
I had considered that possibility.
I see a jog west accompanied by very slow movement and some wobbling of the center.
You missed a Fix somewhere... Pressure is constant on the last two runs.
cyclogenesis exists over the eastern Caribbean Sea. This area, known colloquially by
forecasters as the “hurricane graveyard,” is located within the belt of tropical easterlies
during most of the Atlantic hurricane season, which lasts from June through November.
Tropical easterly waves emerging from the African continent usually follow a path
through the Lesser Antilles and into the eastern Caribbean. GOES infrared satellite
imagery shows that easterly waves frequently exhibit warming cloud tops and decreasing
convection in an area bounded by the islands to the north and east, Venezuela to the
south, and roughly 75 degrees longitude to the west. QuikSCAT derived surface winds
during clear-sky conditions frequently show the presence of accelerating easterlies in the
central Caribbean as part of the Caribbean Low-Level Jet (CLLJ). Analysis of the NCEP
global reanalysis wind fields suggests the presence of an area of persistent low-level mass
divergence in the eastern Caribbean. This implies a subsident regime that would weaken
convection. Climatologically, this phenomenon reaches peak intensity in July, then shifts
towards the east and weakens in the latter half of the Atlantic hurricane season. This is
reflected by the local minimum of tropical cyclogenesis points in the National Hurricane
Center’s best track data in the early part of the season. El Niño directly affects the
strength of the CLLJ, and hence, is related to the intensity of the low-level divergence in
the eastern Caribbean. The local minimum of tropical cyclogenesis in this region has
important implications to operational forecasting, since the vast majority of tropical
cyclones in the Caribbean eventually affect surrounding landmasses.
---It seems like Gaston would be less affected by this climate pattern now that it is later in the season.
Looking from the first advisory, she's approximately 10 to 12 hours ahead of schedule.
Considering how fast she's organised, that's quite important.
Oh, sorry for the misunderstanding.
Well it is not good where it is going in that is for sure. It's Mexico that really needs to worry. But most of Texas needs the rain so while it is a bad thing for others, it is a blessing for some like me. Tropical systems are how we get most of our rain during the yr in se Texas. It's better for this to be a 60 mph ts than an Ike or Rita or Katrina. I pray for the people that go through the bulk of it! I am not a cold hearted guy I promise! I will reword next time!
Looks like it's moving a little easterly. Maybe a Fujiwhara dance with Gaston is coming up.:)
negative...... WNW..... certainly not DUE west.......
Oh I understand totally, I am just south of you on the coast. I totally misunderstood the post earlier and I apologize to you.
I really wonder what people look at when they look at information lol
I think maybe some just chose to see what they want to see lol
Bingo.
No need to I kinda rethought my wording and I should have said something different. Sorry s Tx and Mexico we love you!
when I said that they were not exactly at the center yet.. it appeared due west but yes that is WNW... I was just pointing out that this was not moving NNW anymore... a lot of people are talking about NNW when it is clearly turning more westward
The problem is the wrong sized glass.
Ike, Gaston is Asexual. A friend just called from St. Barth and is blowing 12Kt and some soft rain.
No worries....take care and enjoy the rain
Batten down the hatches!
I ment Hermine is going to make landfall in Mexico just south of Brownsville. He's definately not going NE like some have mentioned.
You in Brzoria County too Angiest?
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