Gaston still a threat to redevelop

By: Dr. Jeff Masters , 3:17 PM GMT on September 05, 2010

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For the first time since August 22, when Danielle became a tropical storm, there are no named storms active in the Atlantic. An extratropical storm absorbed Tropical Storm Earl last night, bringing an end to the 11-day life of the 2010 season's longest-lived storm. While Earl was mostly a non-event for North Carolina and New England, the storm gave Nova Scotia a solid pounding, reminding us of what could have easily happened to New England had the forecast track deviated slightly to the left. Kudos go to the computer models and NHC, who successfully predicted the path of Earl very accurately four days in advance. As we approach the climatological peak of Atlantic hurricane season, which occurs on September 10, there are no indications that today's break in the action represents a beginning of an extended quiet period in the Atlantic. Indeed, we have two systems that could become tropical depressions in the next day, and we also have model predictions of another storm to come late in the week.


Figure 1. Morning satellite image of the remains of Gaston, approaching the Lesser Antilles Islands.

Gaston near tropical depression status again
The remains of Tropical Storm Gaston, located about 700 miles east of the Lesser Antilles Islands and moving west at about 13 mph, are close to reaching tropical depression status again. Recent satellite imagery shows that Gaston's remains 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. This dry air will continue to be a major impediment to development. The latest SHIPS model forecast predicts shear will remain moderate, 10 - 15 knots, for the next three days, then fall to the low range. The winds creating the shear are coming from the east, where a tongue of dry air has intruded. These easterly winds will be able to drive the dry air into Gaston's core, disrupting it, unless the storm can find a moister environment, or moisten its environment on its own by generating enough heavy thunderstorms. Gaston has managed to develop more heavy thunderstorms near its center of circulation late this morning, but the amount of dry air it is battling is formidable. Even if Gaston does manage to become a tropical depression today, development will be slow over the next few days, due to the dry air. When Gaston passes over or just to the northeast of the Lesser Antilles Islands early Tuesday morning, the storm is unlikely to have more than 50 mph winds. More significant development is possible later in the week, as the atmosphere should be moister for Gaston. Gaston may threaten Puerto Rico on Wednesday, the Dominican Republic on Thursday, and Haiti, Jamaica, and/or the Turks and Caicos Islands by Friday, depending upon the storm's interaction with a trough of low pressure expected to move off the U.S. East Coast later this week. The earlier Gaston develops into a tropical storm, the more likely it is to "feel" the upper-level winds of the approaching trough, and curve more to the northwest. The HWRF model predicts Gaston will develop by Monday, and pass just northeast of the Lesser Antilles Islands Tuesday morning. The GFDL model, on the other hand, delays development until Wednesday, keeping Gaston in the Caribbean. The GFDL has Gaston hitting Jamaica as a strong tropical storm on Friday morning. However, the GFDL forecast is dubious, because on Wednesday and Thursday, Gaston may have an encounter with the high mountains of the island shared by the Dominican Republic and Haiti, Hispaniola, which could easily destroy a system as fragile as Gaston. Gaston has a 70% chance of developing into a tropical depression by Tuesday, according to NHC.

Gulf of Mexico disturbance 90L
A concentrated area of heavy thunderstorms (90L) has developed over the extreme southwestern Gulf of Mexico, in the Bay of Campeche. Satellite imagery shows that this disturbance is disorganized, but has some modest spin to it. The disturbance is under a moderate 10 - 15 knots of wind shear, and has a 60% chance of developing into a tropical depression by Tuesday, according to NHC. The disturbance is headed northwest at 5 - 10 mph, and should bring heavy rains to the Texas/Mexico border region on Monday, according to the latest run of the GFS model. The main impediment to development will be the limited time 90L has over water; the storm will be ashore by Tuesday, which doesn't give it much time to develop.

Elsewhere in the tropics
The GFS and NOGAPS models are predicting development on Thursday of a tropical wave that will emerge from the coast of Africa on Tuesday or Wednesday.

Next post
I'll have an update Monday morning.

Jeff Masters

Sunrise Surf was cranking (RIWXPhoto)
Sunrise Surf was cranking
Post Hurricane Earl surf photos at Newport, RI (RIWXPhoto)
Post Hurricane Earl surf photos at Newport, RI

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2035. IKE
The GFS has also been doing little to nothing with Gaston the last several runs...and it looks correct on it...for now.
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Quoting centex:
While trop models may have shown somthing, they did not show Hermine. The trop model guys need to explain this. Don't claim showed days ago beause they did not.


I'm going to have to say they showed it a few days ago, because they did. The GFS at least and STILL shows it.
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2033. IKE
The GFS has been showing a system in the SW GOM for at least 2 days...on every run.
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Quoting KoritheMan:


Thank you kind sir,Heres what crown weather said yesterday concerning the disturbance in the gulf.Now for the potential future track of this system, the latest GFS and European model forecast a track that would take it inland into northeast Mexico on Tuesday. The NAM model, on the other hand, looks way too extreme. It forecasts a strong tropical storm or low end Category 1 hurricane making landfall on the Texas coast near Matagorda Bay on Tuesday morning. The NAM model looks way overdone and will be discounted.
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2031. centex
While trop models may have shown somthing, they did not show Hermine. The trop model guys need to explain this. Don't claim showed days ago beause they did not.
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There are 4 recons scheduled for today.

2 on ex-Gaston, 2 on Hermine.

First flight is scheduled for 1300 UTC, or 8 AM for Hermine I believe.
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Quoting victoria780:
Would someone post the track of Hurricane Brett in 1999 would be interesting to compare..


Member Since: March 7, 2007 Posts: 552 Comments: 19871
Morning all - coffee on the sideboard, and as a nod to hint of fall (65) I woke up to - apple cinnamon bread.

I see we have Hermine - and in a part of the hemisphere that really does not need any more flooding.
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Quoting KoritheMan:


Ugh. I wish he would just make up his mind already. I'm tired of trying to forecast him.
Would someone post the track of Hurricane Brett in 1999 would be interesting to compare..
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Good Morning. Hermine, eh? Cool!
Member Since: July 7, 2010 Posts: 0 Comments: 5625
Quoting IKE:
Gaston chugs along...lol....



Ugh. I wish he would just make up his mind already. I'm tired of trying to forecast him.
Member Since: March 7, 2007 Posts: 552 Comments: 19871
Quoting CybrTeddy:


Wasn't someone on here earlier hoping SE Texas would get loads of rain from Hermine?


As posted above with the comparison between Bonnie and Hermine, they may get more than they wished for.
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TropicalStormHermine's heading had turned northward to dueNorth
from its previous heading of (1.8degrees north of) NorthEast
TD.10's average speed moving between its last 2 reported positions was ~16mph(~25.8km/h)

Invest90L -- 6hour intervals between positions
05Sep . 06amGMT - - 19.1n95.6w - - 20knots - - 1007mb - - NHC-ATCF *19.2n95.7w
05Sep . 12pmGMT - - 19.5n95.7w - - 25knots - - 1005mb - - NHC-ATCF *19.4n95.6w
05Sep . 06pmGMT - - 19.9n95.7w - - 25knots - - 1004mb - - NHC-ATCF *95.9w
06Sep . 12amGMT - - 20.4n9.54w - - 25knots - - 1003mb - - NHC-ATCF
TD.10 -- 3hour intervals between positions (including the previous one and the next)
06Sep . 03amGMT - - 20.7n95.2w - - 30mph - - 1003mb - - NHC.Adv.#1
06Sep . 06amGMT - - 20.9n95.0w - - 35mph - - 1003mb - - #1A
TD.10 becomes TS.Hermine
06Sep . 09amGMT - - 21.6n95.0w - - 40mph - - 1001mb - - #2

20knots=~23mph __ 25knots=~28.8mph __ ~26.1knots=30mph

Copy and paste 19.1n95.6w, 19.5n95.7w, 19.9n95.7w-20.4n95.4w, 20.4n95.4w-20.7n95.2w, 20.7n95.2w-20.9n95.0w, 20.9n95.0w-21.6n95.0w, mid, bro into the GreatCircleMapper for a look at the last 15^hours.

* Before NHC reevaluated&alterered the ATCF numbers.
^ The last three line-segments between the last 4 coordinates individually span 3hours each.
The line-segment preceeding the last three spans 6hours.
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Hermine:

RAINFALL...HERMINE IS EXPECTED TO PRODUCE RAINFALL ACCUMULATIONS OF
4 TO 8 INCHES OVER NORTHEASTERN MEXICO INTO SOUTH TEXAS WITH
ISOLATED MAXIMUM AMOUNTS OF 12 INCHES POSSIBLE. THESE RAINFALL
AMOUNTS MAY CAUSE LIFE-THREATENING FLASH FLOOD AND MUDSLIDES...
ESPECIALLY OVER THE HIGHER TERRAIN OF NORTHEASTERN MEXICO.

Bonnie:

RAINFALL...BONNIE IS EXPECTED TO PRODUCE TOTAL RAIN ACCUMULATIONS OF
2 TO 4 INCHES OVER SOUTH FLORIDA...WITH POSSIBLE ISOLATED MAXIMUM
AMOUNTS OF 6 INCHES. RAINFALL AMOUNTS OF 3 TO 5 INCHES ARE EXPECTED
OVER THE CENTRAL AND NORTHWEST BAHAMAS...WITH POSSIBLE ISOLATED
AMOUNTS OF 5 TO 7 INCHES.
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Quoting Cotillion:
However, even if it is a tropical storm, the convection is very intense. The winds won't necessarily be the problem, it'll be the rain.


Wasn't someone on here earlier hoping SE Texas would get loads of rain from Hermine?
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2020. IKE
SYNOPSIS FOR CARIBBEAN SEA AND TROPICAL N ATLC FROM 07N TO 22N
BETWEEN 55W AND 65W
530 AM EDT MON SEP 06 2010

.SYNOPSIS...THE REMNANT LOW PRES OF GASTON NEAR 17N54W 1008 MB
IS EXPECTED TO CONTINUE MOVING WESTWARD...POSSIBLY AS A TROPICAL
CYCLONE...AS IT MOVES W ALONG 17N TO NEAR 17N57W THIS
AFTERNOON...NEAR 17N60W TONIGHT...ACROSS THE LEEWARDS TO NEAR
17N63W TUE AFTERNOON...PASSING S OF PUERTO RICO NEAR 16N66W TUE
NIGHT INTO WED MORNING...AND PASSING S OF HISPANIOLA ALONG 17N
WED NIGHT THROUGH THU NIGHT...AND S OF JAMAICA FRI NIGHT.

..............................................

SYNOPSIS FOR THE GULF OF MEXICO
430 AM CDT MON SEP 06 2010

.SYNOPSIS...TROPICAL STORM HERMINE AT 21.6N 95.0W AT 4 AM CDT
1001 MB MOVING N AT 7 KT. MAXIMUM SUSTAINED WINDS 35 KT GUSTS 45
KT. THE IS FORECAST TO STRENGTHEN AS IT MOVES TO NEAR 22.9N
95.8W THIS AFTERNOON...NEAR 24.9N 97.2W TONIGHT AND INLAND NEAR
26.8N 98.4W TUE AFTERNOON...CONTINUING NW AS A REMNANT LOW PRES
ACROSS N MEXICO. HIGH PRES WILL BUILD ACROSS THE GULF WATERS TUE
THROUGH FRI.
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However, even if it is a tropical storm, the convection is very intense. The winds won't necessarily be the problem, it'll be the rain.

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2018. IKE
Gaston chugs along...lol....

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Quoting Cotillion:


Yes, it is a pretty good rate of intensification, already. The difference is that Hermine is a bit bigger than the pair of them and still sort of disorganised.

NHC give it a 7% chance of a hurricane by 06Z tomorrow.

I'll say 60-65mph is a pretty good ballpark at the moment. It has good conditions to work with in the time it has on water.


Correct.

VERY deep convection going off in Hermine.
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Quoting CybrTeddy:


Actually, that kind of intensification is not out of the question given the conditions and the low barometric pressure (1001 mb)... that being said it has very little time to waste. But up to 60 mph in 24 hours is actually a pretty good rate of intensification.


Yes, it is a pretty good rate of intensification, already. The difference is that Hermine is a bit bigger than the pair of them and still sort of disorganised.

NHC give it a 7% chance of a hurricane by 06Z tomorrow.

I'll say 60-65mph is a pretty good ballpark at the moment. It has good conditions to work with in the time it has on water.
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Hermine goes NNE.
Will have a lot of time to become stronger.
Does not look good.Could easily become CAT2.
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The true question is how many people today are going to misspell / mispronounce 'Hermine' as 'Hermione'.
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Actually, 2007 was also 8-3-2 with the H storm (though a week later).
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Quoting Cotillion:
What's the over/under on mentions of Humberto/Lorenzo today?


Actually, that kind of intensification is not out of the question given the conditions and the low barometric pressure (1001 mb)... that being said it has very little time to waste. But up to 60 mph in 24 hours is actually a pretty good rate of intensification.
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What's the over/under on mentions of Humberto/Lorenzo today?
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8-3-2,
We are ahead of 2009 (with 5-1-1)
2007 (6-2-2)
2006 (6-1-0)
2002 (7-1-0)
2001 (5-1-0)
2000 (5-2-1)
1999 (4-2-2)
1998 (5-3-1)
1997 (5-1-0)
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Thought they'd up it to 50kts.
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2006. HadesGodWyvern (Mod)
24 HRS: 24.9N 97.2W - 50 knots (Tropical Cyclone)
48 HRS: 28.0N 99.7W - 25 knots (Low Pressure Area)
72 HRS: 33.2N 99.6W - 20 knots (Low Pressure Area)

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2005. Titoxd
Welcome Hermine...

000
WTNT25 KNHC 060848
TCMAT5
TROPICAL STORM HERMINE FORECAST/ADVISORY NUMBER 2
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL102010
0900 UTC MON SEP 06 2010

CHANGES IN WATCHES AND WARNINGS WITH THIS ADVISORY...

A TROPICAL STORM WARNING HAS BEEN ISSUED FOR THE COAST OF SOUTH
TEXAS FROM THE MOUTH OF THE RIO GRANDE TO BAFFIN BAY.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT...

A TROPICAL STORM WARNING IS IN EFFECT FOR...
* THE COAST OF MEXICO FROM TAMPICO TO THE MOUTH OF THE RIO GRANDE
* THE COAST OF TEXAS FROM THE MOUTH OF THE RIO GRANDE TO BAFFIN BAY

A TROPICAL STORM WARNING MEANS THAT TROPICAL STORM CONDITIONS ARE
EXPECTED SOMEWHERE WITHIN THE WARNING AREA...IN THIS CASE WITHIN
ABOUT 24 HOURS.

TROPICAL STORM CENTER LOCATED NEAR 21.6N 95.0W AT 06/0900Z
POSITION ACCURATE WITHIN 30 NM

PRESENT MOVEMENT TOWARD THE NORTH OR 360 DEGREES AT 7 KT

ESTIMATED MINIMUM CENTRAL PRESSURE 1001 MB
MAX SUSTAINED WINDS 35 KT WITH GUSTS TO 45 KT.
34 KT....... 90NE 60SE 0SW 0NW.
12 FT SEAS.. 60NE 30SE 0SW 0NW.
WINDS AND SEAS VARY GREATLY IN EACH QUADRANT. RADII IN NAUTICAL
MILES ARE THE LARGEST RADII EXPECTED ANYWHERE IN THAT QUADRANT.

REPEAT...CENTER LOCATED NEAR 21.6N 95.0W AT 06/0900Z
AT 06/0600Z CENTER WAS LOCATED NEAR 21.1N 94.8W

FORECAST VALID 06/1800Z 22.9N 95.8W
MAX WIND 45 KT...GUSTS 55 KT.
34 KT... 75NE 60SE 0SW 0NW.

FORECAST VALID 07/0600Z 24.9N 97.2W
MAX WIND 50 KT...GUSTS 60 KT.
50 KT... 25NE 20SE 0SW 0NW.
34 KT... 75NE 60SE 30SW 30NW.

FORECAST VALID 07/1800Z 26.8N 98.4W...INLAND
MAX WIND 35 KT...GUSTS 45 KT.
34 KT... 60NE 60SE 0SW 0NW.

FORECAST VALID 08/0600Z 28.8N 99.7W...INLAND
MAX WIND 25 KT...GUSTS 35 KT.

FORECAST VALID 09/0600Z 33.2N 99.6W...POST-TROP/REMNT LOW
MAX WIND 20 KT...GUSTS 25 KT.

EXTENDED OUTLOOK. NOTE...ERRORS FOR TRACK HAVE AVERAGED NEAR 250 NM
ON DAY 4 AND 325 NM ON DAY 5...AND FOR INTENSITY NEAR 20 KT EACH DAY

OUTLOOK VALID 10/0600Z...DISSIPATED

REQUEST FOR 3 HOURLY SHIP REPORTS WITHIN 300 MILES OF 21.6N 95.0W

NEXT ADVISORY AT 06/1500Z

$$
FORECASTER BROWN
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...DEPRESSION BECOMES THE EIGHTH TROPICAL STORM OF THE 2010 ATLANTIC HURRICANE SEASON...TROPICAL STORM WARNING ISSUED FOR SOUTH TEXAS...
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ESTIMATED MINIMUM CENTRAL PRESSURE 1001 MB
MAX SUSTAINED WINDS 35 KT WITH GUSTS TO 45 KT.
34 KT....... 90NE 60SE 0SW 0NW.
12 FT SEAS.. 60NE 30SE 0SW 0NW.
WINDS AND SEAS VARY GREATLY IN EACH QUADRANT. RADII IN NAUTICAL
MILES ARE THE LARGEST RADII EXPECTED ANYWHERE IN THAT QUADRANT.
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Good morning! I see we have Hermine.
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2000. xcool
lmao
Member Since: September 26, 2009 Posts: 2 Comments: 15620
Quoting btwntx08:
get ready with those f5 keys


Very true...many people off work today for Labor Day and a storm brewing close to home. Could be a zoo later :)
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1997. xcool
f5f5 ready go
Member Since: September 26, 2009 Posts: 2 Comments: 15620
1995. xcool
Member Since: September 26, 2009 Posts: 2 Comments: 15620
Will be nice to see a visual of xGaston once it becomes available, if nothing else he is a persistent little storm
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1993. xcool
haha
Member Since: September 26, 2009 Posts: 2 Comments: 15620
1991. xcool
lol
Member Since: September 26, 2009 Posts: 2 Comments: 15620
1989. xcool
Member Since: September 26, 2009 Posts: 2 Comments: 15620
1987. xcool
NAM 06Z out
Member Since: September 26, 2009 Posts: 2 Comments: 15620
1985. xcool
63k wo
Member Since: September 26, 2009 Posts: 2 Comments: 15620

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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.