94L a threat to the Lesser Antilles; Gordon a hurricane; Helene hits Mexico

By: Dr. Jeff Masters , 3:24 PM GMT on August 18, 2012

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A large tropical wave that emerged from the coast of Africa Thursday night (Invest 94L) is located a few hundred miles southwest of the Cape Verde Islands off the coast of Africa, and is headed west at 15 - 20 mph. This storm is a threat to develop into a tropical storm that will affect the Lesser Antilles Islands as early as Wednesday. The storm is under moderate wind shear of 10 - 20 knots, and is over waters of 27.5°C. A large area of dry air lies just to the north of 94L, as seen on the latest Saharan Air Layer (SAL) analysis. This morning's 8:15 am EDT ASCAT pass caught the east side of 94L, and showed a partial surface circulation. Satellite images show just a modest amount of heavy thunderstorm activity, and I expect the earliest that 94L could develop into a tropical depression would be Sunday.


Figure 1. Morning satellite image of Invest 94L.

Forecast for 94L
The latest 8 am EDT run of the SHIPS model predicts that wind shear will be low, 5 - 10 knots, and ocean temperatures will gradually warm from 27.5°C to 28.5°C over the next four days, as 94L tracks westwards towards the Lesser Antilles. As is typical with storms making the crossing from Africa to the Antilles, dry air to the north will likely interfere with development. However, with shear expected to be low, dry air may be less of an issue for 94L than it was for Ernesto or TD 7. The storm should maintain a nearly due west track through Monday night, to a point near 50°W, about 700 miles east of the Lesser Antilles. At that point, a trough of low pressure passing to the north of 94L may be able to pull the storm more to the northwest, as suggested by the latest 06Z (2 am EDT) run of the NOGAPS model, and by three members of the GFS model ensemble forecast (Figure 2.) However, the models have been trending more towards a solution where this trough is not strong enough to influence 94L's path. This scenario will be more likely if 94L takes its time to develop, since a weaker storm will be smaller and shallower, and less likely to respond to the trough passing to the north. Our two best performing models, the GFS and ECMFW, both take 94L through the Lesser Antilles. The ECMWF, which predicts that 94L will stay weak and not develop, is faster, bringing the storm through the Lesser Antilles on Wednesday. The GFS model is slower, bringing 94L to the Lesser Antilles on Thursday as a hurricane. The models have shown poor run-to-run consistency in both the timing and the track of 94L, so it is difficult to assess which land areas might be most at risk, and when. A database of historical probabilities of storms in the same location as 94L maintained by Dr. Bob Hart of Florida State University reveals that historically, 45% of storms in this location have eventually hit land, with Canada (13% chance) and North Carolina (15% chance) the most likely targets. In their 8 am EDT Tropical Weather Outlook, NHC gave 94L a 40% chance of developing into a tropical depression by Monday morning.


Figure 2. The 00Z (8 pm EDT) run of the GFS model from August 17, 2012, was done 20 different times at low resolution using slightly different initial conditions to generate an ensemble of forecasts (pink lines.) The high-resolution operational GFS forecast is shown in white.

Gordon becomes a hurricane
Hurricane warnings are flying for the central and eastern Azores Islands as Hurricane Gordon heads eastwards at 18 mph. Gordon became the third hurricane of the 2012 Atlantic hurricane season at 5 am Saturday morning, and is sporting an impressive-looking eye on visible satellite loops. Gordon should be able to maintain hurricane status until Sunday, when wind shear will rise steeply to 30 - 40 knots, and ocean temperatures will drop to 25°C. The combined effects of high wind shear, dry air, and cooler waters will likely act to weaken Gordon to a strong tropical storm by the time it arrives in the Azores Islands Sunday night, but the storm will be strong enough to bring damaging winds and heavy rain to the Azores Islands. Gordon is not a threat to any other land areas, and the extratropical remnants of Gordon will not bring any strong winds or significant rain to Europe. The last time the Azores were affected by a tropical storm was in 2009, when Tropical Storm Grace brought 65 mph winds on October 4. No significant damage was reported. Ironically, the last hurricane to affect the Azores was the 2006 version of Hurricane Gordon, which caused minor damage in the Azores, consisting of mostly fallen trees and power outages. However, after Gordon became an extratropical low, four injuries due to falling debris from high wind were reported in Spain, and Gordon brought high winds and rain that affected practice rounds at the Ryder Cup golf tournament in Ireland. About 126,000 homes were without power after the storm in Northern Ireland and one injury was reported.


Figure 3. Morning satellite image of Hurricane Gordon.

Helene makes landfall in Mexico
Tropical Storm Helene made landfall near 10 am EDT as a tropical storm near Tampico, Mexico, with 40 mph winds. Helene's formation on August 17 ties 2012 with 1933 for the 2nd earliest appearance of the Atlantic's eighth tropical storm. Helene's rains should remain south of Texas, but moisture from Helene may feed into a stalled frontal system over the northern Gulf of Mexico and bring heavy rains to the northern Gulf Coast early next week.

I'll have a new post this afternoon, giving a quick global weather summary for July, the 4th hottest July in Earth's history.

Jeff Masters

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GFS is showing
1- A weaker system approaching lesser antilles trends more to the west and late recurve
2- A strong System approaching the lesser antilles trend more to WNW and early recurve
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Quoting LargoFl:
Round 2 getting ready to come ashore Jed, i can hear the boomers out in the gulf already.............



Well really it looks like things are starting to die down now somewhat, the air has stabilized some near us additional, storms have weakened as they reach the coast. we'll see what happens a little later. My street is flooded pretty good so we've had our share, almost 3 inches here.
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Quoting kmanislander:


Shower curtain time LOL

lol
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174. 7544
landfalll so fl ?
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Riding up the coast?

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204 hrs...1004 mb. being shredded by Cuba's mountains
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Moving up into SC by 288 hours.
Member Since: June 9, 2007 Posts: 4 Comments: 15875
Quoting MAweatherboy1:
This is just another of about a million scenarios that could happen:

..really dont want that run to play out, south florida would be under the gun
Member Since: August 6, 2011 Posts: 4 Comments: 37981
Quoting TropicalAnalystwx13:
Don't show Janiel.

and me lol. i dont care bout the exact track. west trends again cods
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My Gut and MY HEAD says 94L could pull a Gustav or Fay (08) track after Hispaniola
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Quoting TropicalAnalystwx13:
Don't show Janiel.



Shower curtain time LOL
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I guess I should have held my comment till the end of the model run...on the 8th day it takes a left-hand turn and goes right over Haiti after drifting around over or near land for nearly a whole day...

That would not be good at all, and I absolute HATE slow moving Hispaniolan Tropical Storms because they tend to kill a lot of people. They'd literally be better off with a fast moving cat 1 or cat 2...
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I'd say Gordon looks pretty good.

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Tampa got it good too after us...........
Member Since: August 6, 2011 Posts: 4 Comments: 37981
This is just another of about a million scenarios that could happen:

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Quoting WeatherNerdPR:

Gross.
Worse than Jose.
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Really wouldn't put any stock into the model runs past 120 hours. I don't think though it will run headlong into the islands like the GFS is predicting, still leaning on going just north of the islands imo, similar to the UKMET/CMC track.
Member Since: July 8, 2005 Posts: 259 Comments: 23882
Don't show Janiel.

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1002 mb @ 180 hrs
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Redeveloping in the southern Bahamas by 228 hours.

Off of SE Florida by 240.
Member Since: June 9, 2007 Posts: 4 Comments: 15875
Quoting 954FtLCane:


174 hrs...Hispaniola totally disrupts it


Not good for the conus tho, if it weakens it it has a better chance of hitting the u.s.
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Round 2 getting ready to come ashore Jed, i can hear the boomers out in the gulf already.............
Member Since: August 6, 2011 Posts: 4 Comments: 37981
Quoting redwagon:

Or when gas prices come down lol!

We need a new ascat for 94L, it looks to be finally consolidating.


New pass for Ascat will not happen until early this evening.
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Quoting Tropicsweatherpr:


Why is that?


Have no idea. Thats what showed up previosuly.

Here's the corrected 168
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Oscat will miss 94L this morning. Too bad.

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Quoting VAbeachhurricanes:


6 hours old taz



oh oops
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Quoting 954FtLCane:


174 hrs...Hispaniola totally disrupts it

Looks like it might run Cuba after that.
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Quoting 954FtLCane:


lol...168 makes no sense... hmmmm?


Why is that?
Member Since: April 29, 2009 Posts: 75 Comments: 14213
Quoting bappit:

My flight plan would be to check back in a few days when the system is within range.

Or when gas prices come down lol!

We need a new ascat for 94L, it looks to be finally consolidating.
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Member Since: July 15, 2006 Posts: 170 Comments: 53528
I guess one good thing about the new GFS is that it has the storm being much weaker, and making landfall on the Dominican side of the island, so at least Haiti would be spared the worst of the rains.

With all the crap they've suffered the past few years, I wouldn't want to see another disaster from rain runoff there.


BTW...

Are there any attempts to re-plant trees, or at least grass or shrubs in Haiti to preserve what's left of the environment, or is it pretty much just doing nothing and being all swept away?!
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Quoting Tazmanian:
18/1200 UTC 13.2N 30.0W T1.0/1.0 94L -- Atlantic
18/1145 UTC 21.9N 97.6W T1.0/1.0 HELENE -- Atlantic
18/1145 UTC 33.8N 39.4W T4.0/4.0 GORDON -- Atlantic


6 hours old taz
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Moves off of Hispaniola to make landfall in Western Cuba.

Another system developing to the east of the islands.
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174 hrs...Hispaniola totally disrupts
looking like bahamas and maybe FL..
westward trend def happening with GFS though
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Quoting Stormchaser2007:
Gets caught up in Hispaniola for a while.

Significantly weaker.


That would be a big disaster if that occurs.
Member Since: April 29, 2009 Posts: 75 Comments: 14213
18/1200 UTC 13.2N 30.0W T1.0/1.0 94L -- Atlantic
18/1145 UTC 21.9N 97.6W T1.0/1.0 HELENE -- Atlantic
18/1145 UTC 33.8N 39.4W T4.0/4.0 GORDON -- Atlantic
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lanfall santo domingo
sat 12z aug25

this will and can change

Member Since: July 15, 2006 Posts: 170 Comments: 53528
I. ATLANTIC REQUIREMENTS
1. NEGATIVE RECONNAISSANCE REQUIREMENTS.
2. OUTLOOK FOR SUCCEEDING DAY.....NEGATIVE.
3. REMARKS: ADDITIONAL DAY OUTLOOK--PSBL LOW LEVEL
INVEST NEAR 14N AND 50W ON 21/1800Z.
Member Since: June 9, 2007 Posts: 4 Comments: 15875


lol...168 makes no sense... hmmmm?
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Deep tropical moisture is feeding northward from tropical depression Helene towards the slowing front in the deep south adding to already high moisture levels, this will lead to areas of intense rainfall from Louisiana through Florida the next several days.
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Quoting stormwatcherCI:
Why did you have to go and say that ? IDK, but I just have a bad "feeling" about this and not because it would be another I storm.


Sorry but that is what the model shows and the runs all the way to 168 hrs still show a blocking high. At 174 the hurricane is interacting with Hispaniola over Haiti so none of this is for sure anyway. I usually do not look out beyond 144 hrs with a model run but this looks like the Eastern Caribbean for now.
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that wont be good if it heads for Hispaniola
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Gets caught up in Hispaniola for a while.

Significantly weaker.
Member Since: June 9, 2007 Posts: 4 Comments: 15875
Quoting wunderkidcayman:
Well as I said my Gut said Caribbean Hurricane 94L will be


Your gut always says a strengthening system in the NW Caribbean. Stop listening to your gut so much and start listening to your head. Your head usually makes great predictions wunderkid but you always let your gut's bias get in the way.

I'm saying this as constructive criticism buddy, it is something we have all noticed.
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Quoting redwagon:

Huh? not sure how the HHers entered the conversation, but...OK...

If you were a HHer and I handed you this map and said find the center of 94L, what coords would you use for your initial flight plan?


My flight plan would be to check back in a few days when the system is within range.
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i will wait for the 18z
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994mb @ 162 hrs
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Quoting kmanislander:


Did you see where the Western periphery of the steering high is though ?. Across Fla and into the central GOM. If that verifies big trouble ahead. Same set up we had in 2004 for the "I" hurricane.
Why did you have to go and say that ? IDK, but I just have a bad "feeling" about this and not because it would be another I storm.
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1 week out... Getting ripped to shreds:

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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.

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