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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Is Hermine still headed North? I'll readily admit that I am far from an expert to say the least, but it looks like she's headed more NW to me?
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Quoting Stormchaser2007:
12z SHIPS get ex-Gaston up to 112 knots.

V (KT) LAND 30 31 32 35 38 47 58 69 76 83 91 101 112

Shear drops to around 3 knots in 24 hours.
Yup. The mid-level dry air should slowly back off too, however, the environment won't be too moist for another 60 hours or so.

700-500 MB RH 41 40 41 41 45 48 49 55 57 59 56 55 53
Member Since: September 2, 2009 Posts: 130 Comments: 21032


Hermine is a classic Tehuantepec cross-over storm that I had been predicting before the season and that the GFS model had depicted for a while. Likely to become the third tropical cyclone to make landfall near the US/Mexico border this season. Luckily this system is not expected to become a hurricane.
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2680. Bielle
Quoting alaina1085:

Hahahaha!!!


There has been an attempt to include not only male and female names on the hurricane lists, but also names from all the nations and cultures served by the NHC. French, Spanish and English are all there. I am surprised by the pronunciation given for "Virginie" as it is a French name more usually pronounced with a "zh" sound for the "g", like the "s" in "casual".
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2679. SaoFeng
http://www.drought.unl.edu/dm/drmon.gif

Current drought index
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12z SHIPS get ex-Gaston up to 112 knots.

V (KT) LAND 30 31 32 35 38 47 58 69 76 83 91 101 112

Shear drops to around 3 knots in 24 hours.
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Quoting stillwaiting:
Hmmmm,i wonder what oz is doing tomorrow????,word is he'll be live in port isabel,TX covering hermine ,you can email me and i'll give a link for those interested,junky'll be on soon with a update im sure:)


Whats with you guys... you know Dr Masters has permanently banned Oz, yet you insist on babbling about him on here and posted links to his website?

Respect is something some of you appear to have problems with.
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Quoting Patrap:
Off to Lite da Grill..


Have a Good Holiday everyone.

Thanks, you too, Pat!
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2673. HCW
Recon is having radar problems and headed home now
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1 knots = 1.15077945 miles per hour.

The following approximate distance calculations are relatively simple, but can produce distance errors of 10 percent of more. These approximate calculations are performed using latitude and longitude values in degrees. The first approximation requires only simple math functions:

Approximate distance in miles:

sqrt(x * x + y * y)

where x = 69.1 * (lat2 - lat1)
and y = 53.0 * (lon2 - lon1)

You can improve the accuracy of this approximate distance calculation by adding the cosine math function:

Improved approximate distance in miles:

sqrt(x * x + y * y)

help!
where x = 69.1 * (lat2 - lat1)
and y = 69.1 * (lon2 - lon1) * cos(lat1/57.3)


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Quoting 850Realtor:
Pensacola Doug-do you know what time Oz is estimated to be in Brownsville?


He's gonna try to go live from Port Isabell at 5 am tomorrow morning.
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2670. shawn26
Gaston is starting to get it's act together.
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2668. luigi18
Quoting Chicklit:

yup

MoonlightCowboy = voice of reason

Even the agencies here in PR are saying gaston is going to bring rain if he is not already dead
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Quoting Cotillion:
These sorts of conditions where models and model reliance will have trouble.

Speed was underestimated, a storm that wasn't even picked up by most except the GFS which had this going far slower than it is, and intensity underestimated. The nautical mile differential between prediction and reality is not so bad in the middle of the Atlantic, but confined between land, every difference could be huge.

Even with the correct information fed in, it would take 2-3 hours for it to be released. By which, the circumstances could have changed or the storm might have already made landfall, particularly in the case of the twice daily models.

Trust your eyes and your noggin.


Well said!
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2666. Hhunter
15:06:00Z 27.333N 91.800W 392.5 mb
(~ 11.59 inHg) 7,755 meters
(~ 25,443 feet) - 439 meters
(~ 1,440 feet) From 134° at 15 knots
(From the SE at ~ 17.2 mph) -14.8°C*
(~ 5.4°F*) -* 20 knots
(~ 23.0 mph)
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Quoting StormW:


Thanks Pat.

For giggles and grins everyone, the DSHP intensity model is better at long range.


Did you see the CHIPS ensembles?

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.
Member Since: October 5, 2007 Posts: 20 Comments: 4970
Quoting markot:
knock off the rip stormchaser, hurricane 23, you 2 rip.

Never said he was dead.


Gaston should not be considered dead until that LLC dissipates.
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2661. Patrap
Off to Lite da Grill..


Have a Good Holiday everyone.
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These sorts of conditions where models and model reliance will have trouble.

Speed was underestimated, a storm that wasn't even picked up by most except the GFS which had this going far slower than it is, and intensity underestimated. The nautical mile differential between prediction and reality is not so bad in the middle of the Atlantic, but confined between land, every difference could be huge.

Even with the correct information fed in, it would take 2-3 hours for it to be released. By which, the circumstances could have changed or the storm might have already made landfall, particularly in the case of the twice daily models.

Trust your eyes and your noggin.
Member Since: August 23, 2008 Posts: 7 Comments: 5300
Update
HerMean is getting meaner.
Gaston is a lot of things.. dead isn't any of them.



AOI

AOI

AOI

AOI

AOI

AOI


TS BUSTED FORECAST ALIBI
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2656. Patrap
Quoting Kristina40:
Exactly Patrap! Glad to see you back, was worried about you after you said you had the concussion and then I didn't see you for a couple days. Glad you are OK.


God graced me with a very Hard Head thankfully.

But the Stars were very colorful one could say.

Thanx
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So Recon had to head home, huh? The next one is scheduled for 2am EDT tomorrow morning. Meh.
Member Since: September 2, 2009 Posts: 130 Comments: 21032
2654. Hhunter
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2650. Patrap
12z Early Cycle NHC model tracks
Gaston
Statistical/Simple Models (CLIPER,BAMs,LBAR,other Statistical Models)






Dynamic Models (More sophisticated models)





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Quoting CajunTexan:
Any idea when Gaston is forecast to reach 60W??

It's moving west about 10-15 knots.
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Hermine only 8 mbs from a cane. I saw a model that projects a low a-la Gaston S of Cuba by 9/12??
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2647. markot
no, you dont know anyting about weather.....
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Gaston should not be considered dead until that LLC dissipates.


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Exactly Patrap! Glad to see you back, was worried about you after you said you had the concussion and then I didn't see you for a couple days. Glad you are OK.
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Any idea when Gaston is forecast to reach 60W??
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2643. JeffM
Hermine should be a good indicator of just how bad it's going to be if Gaston or any other system eventually gets into the Gulf.

As far as Hermine, we in the San Antonio/Austin area or eagerly awaiting some much needed rainfall.
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Impressive

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2640. Thaale
Quoting TXCaneCrasher:


haha....cleaned this discussion up pretty quick....

IMO the official pronunciation guide just added to the confusion. It says e-GOR, which I would have assumed means long E. But then a little below it is has Lisa as LEE-sa, using double E to denote long E and suggesting e-GOR is pronounced eh-GOR, though as it's an unstressed sylalble I guess the point is that it's a schwa.

In any case, since when is Igor by any pronunciation a common name in any of the cultures / languages of the Atlantic basic, which I thought was the rule they went by? It's not common in American or Canadian English. Is it popular in any of the French speaking locales in the region? I don't think so. The Spanish speaking ones? I've lived in Miami for decades I've and never met or heard of any Igor who wasn't Russian or Ukrainian.

Next year they're pulling out Katia, which I would also have thought was more common in Eastern Europe than in Atlantic hurricane country, and is usually pronounced KAH-tcha. But they have come up with ka-TEE-ah. Who the heck is named ka-TEE-ah, anywhere? Where do they come up with this stuff?
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2639. Hhunter
Quoting Chicklit:

yup



like i said rip or cat 4 in 4 days..maybe more toward the later...
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2638. Patrap
One never discounts a closed circ in the Tropical Atlantic,,esp with conducive conditions downstream in time with model support.


Tropical Met 101
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Quoting KanKunKid:


Yes, I'm sure the NHC is on board with you.



LOL!
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One interesting thing that I've noticed is that it seems like Gaston, as he moves forward, seems to draw the dry air in behind him? Is this possible or am I making stuff up?
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About JeffMasters

Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.