Tropical Storm Helene arrives; 94L a potential threat to the Lesser Antilles

By: Dr. Jeff Masters , 10:41 PM GMT on August 17, 2012

After a long path across the Atlantic that mirrored the track of Hurricane Ernesto, Tropical Depression Seven finally got its act together enough over the Bay of Campeche tropical storm breeding grounds to earn the name Helene. Helene's formation on August 17 ties 2012 with 1933 for the 2nd earliest appearance of the Atlantic's eighth tropical storm. Only 2005 had an earlier formation date of the season's eighth storm. Most of this year's storms have been weak, though, so the total Accumulated Cyclone Energy (ACE) of 21 is not that much higher than the normal year-to-date ACE of 15, based on a 1981 - 2010 ACE climatology. The normal yearly ACE for the Atlantic is 104. Helene doesn't have much room to work with before landfall, but has the potential to be a prodigious rainmaker for Mexico, with NHC predicting 5 - 10 inches for portions of Northeast Mexico. This part of the coast is not in drought, so will be prone to heavy flooding. Fortunately, Ernesto's main rains fell to the south of where Helene's rains are falling. Helene's rains should remain south of Texas, though we can't rule out a few thunderstorms bringing 1 - 2 inches of rain to extreme South Texas on Saturday and Sunday.


Figure 1. Afternoon satellite image of Helene.

94L a potential threat to the Lesser Antilles
A large tropical wave emerged from the coast of Africa Thursday night, and was designated Invest 94L by NHC this Friday morning. The models have been impressed this system, and develop it into a tropical storm by the middle of next week. The latest set of 12Z (8 am EDT) model runs are divided on how far west 94L will make it before curving more to the northwest. The ECMWF model keeps 94L weak for the next 5 - 6 days, and has progressively been bringing the storm closer to the Lesser Antilles Islands with each successive run. The ECMWF predicts 94L will pass very close to the northern Lesser Antilles August 24 - 25 as a weak tropical storm. The 12Z GFS model predicted recurvature of 94L well to the east of the Lesser Antilles and Bermuda, but the latest 18Z run has the storm plowing through the Lesser Antilles on Thursday, August 23, as a strong tropical storm, then becoming a hurricane in the Eastern Caribbean. Given that our two top models for forecasting hurricane tracks are increasingly showing a threat to the Lesser Antilles, residents of the islands should pay close attention to the progress of 94L. The eventual track of 94L will depend on the strength of the storm over the next seven days, which is difficult to forecast, since 94L will have the usual trouble with dry air to the north from the Saharan Air Layer (SAL.) With the models changing their tune drastically from run to run, its tough to say what land areas might be most at risk from the storm in the long term. In their 2 pm EDT Tropical Weather Outlook, NHC gave 94L a 10% chance of developing into a tropical depression by Sunday afternoon.


Figure 2. MODIS satellite image of Invest 94L taken at 8 am EDT August 17, 2012, off the coast of Africa. Image credit: NASA.

Jeff Masters


The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.

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Quoting sar2401:


There's a chance 94L could affect the Lesser Antilles, Northern Antilles, PR, Cuba, Florida, Georgia, SC, NC, and on up the coast. There's also a chance it could recurve out to see and only threaten Bermuda. Regardless of all the models runs being thrown about here, 94L is still an invest, and models are notoriously bad about forecasting both track and intensity at this stage of the game. It's hurricane season. You should be prepared for any type of tropical storm, and now's the time to start, if you haven't already. 94L will develop into something and go somewhere, but it's far too early to give anything more than a chance guess. Keep an eye on the storm and models over the five days. We should have a much better idea of what's going to happen then. Until then, take any post in all caps and with lots of exclamation points with a grain of salt, especially if it includes WOW!. :)


One thing I look for in the models... Consistency. If a model is constantly showing development and strong development over many runs, watch for the other models coming into agreement.
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Quoting washingtonian115:
Pay attention to the animals as they could be the first one to tell you a storm is coming.Micheal Laca sent me a video of his chase in PR,and he showed how the hoarse's were running to higher ground to get to safety.
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As I said last night on the blog by the time future Isaac reaches the U.S it will probably be by Labor day weekend.As we all know people have major plans/vacations.Hopefully he recurves before the U.S.Or it is going to get really ugly for millions of people..
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1523. Gorty
Does any models develop the next wave ready to leave Africa?
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ATCF says Helene is now a TD.
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1521. LargoFl
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Don't be surprised if Helene reforms its center more in the boc.
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Evening all.

To me this is a scary scenario



That looks like a Cat 4 or Cat 5 of the coast of NC.

btw I know it's a long way out but....
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Quoting sar2401:


There's a chance 94L could affect the Lesser Antilles, Northern Antilles, PR, Cuba, Florida, Georgia, SC, NC, and on up the coast. There's also a chance it could recurve out to see and only threaten Bermuda. Regardless of all the models runs being thrown about here, 94L is still an invest, and models are notoriously bad about forecasting both track and intensity at this stage of the game. It's hurricane season. You should be prepared for any type of tropical storm, and now's the time to start, if you haven't already. 94L will develop into something and go somewhere, but it's far too early to give anything more than a chance guess. Keep an eye on the storm and models over the five days. We should have a much better idea of what's going to happen then. Until then, take any post in all caps and with lots of exclamation points with a grain of salt, especially if it includes WOW!. :)


Duly Noted
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Quoting islandgirls:
Good morning all. I see there's much excitement re: 94L
where the Lesser Antilles comes into focus. What are the chances of it affecting the Northern Antilles, more particularly Guadeloupe to Anguilla?

Anticipating a response

Thanks
It's possible. Currently some models are bringing it your way. I'd say this is a good time to give a little more attention to NHC website.

Which one of the Leewards are u in... [Antigua???]
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Quoting SLU:


Very high.


o.k. heads up on this one
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18August06amGMT's 21.3n96.5w has been re-evaluated&altered
18August12pmGMT's 21.5n96.8w-22.2n97.8w are now the most recent positions
(Vectors and straightline projections have been corrected from the previous mapping)
Derived from (NHC) ATCF data for TropicalDepressionHelene for 18August12pmGMT
MinimumPressure increased from 1007millibars to 1008millibars
MaxSusWinds decreased from 35knots(40mph)65km/h to 30knots(35mph)56km/h
Vector changed 317.0*NWest@11mph(17.7km/h) to 307.0*NWest@13.4mph(21.5km/h)

CVM-CiudadVictoria
TAM-Tampico :: MMNU-Nautla :: VER-Veracruz :: VER-Ciudad del Carmen :: CPE-Campeche

The westernmost dot on the kinked line is where exTD.7's became a TropicalDepression again
The next dot NNWest of that dot is where TD.7 became TropicalStormHelene
The final dot is where TS.Helene became a TropicalDepression again at landfall

The longest line is a straightline projection thru exTD.7's 2 most recent positions to the coastline
17August6pmGMT: exTD.7 had been headed toward passage over LaPesca (nearCVMdumbbell,bottom)
18August12amGMT: exTD.7 had been headed toward passage over El Porvenir (nearCVMdumbbell,top)
18August6amGMT: exTD.7 had been headed toward passage over Altamira (TAMdumbell,top)
18August12pmGMT: exTD.7 made landfall near Tampico

Copy&paste 23.9n97.75w-24.575n97.661w, cvm, tam, mmnu, ver, cme, cpe, pcm, 19.2n90.7w- 19.3n92.6w- 19.3n94.2w- 19.7n95.2w- 19.9n95.7w, 19.9n95.7w-20.3n95.9w, 20.3n95.9w-20.8n96.1w, 20.8n96.1w-21.5n96.8w, 20.8n96.1w-22.546n97.86w, 21.5n96.8w-22.2n97.8w into the GreatCircleMapper for a larger-scale map and other information
The previous mapping for comparison
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1514. LargoFl
wow lightning and boomers and my street is like a river.............
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Quoting SFLWeatherman:
8Am not good for S FL!!


No dis-respect to persons in the Greater Antilles but, the good thing is that there are a lot of mountains along 94L's way to SFL.
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1512. LargoFl
Quoting GTcooliebai:
Tampa shields about to get knocked down, starting to flood in my location, we really hit the jackpot, Largo.
whoohoo this is a real good one alright GT
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1511. LargoFl
MARINE WEATHER STATEMENT
NATIONAL WEATHER SERVICE TAMPA BAY AREA - RUSKIN FL
919 AM EDT SAT AUG 18 2012

GMZ830-850-853-873-181415-
919 AM EDT SAT AUG 18 2012

...STRONG THUNDERSTORMS OVER THE WATERS...

AT 913 AM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED
THUNDERSTORMS...PRODUCING STRONG WINDS UP TO 33 KNOTS FROM 10 NM
NORTHEAST OF HILLSBOROUGH BAY TO 31 NM WEST OF EGMONT KEY...MOVING
NORTHEAST AT 20 KNOTS.

MARINERS CAN EXPECT GUSTY WINDS UP TO 33 KNOTS...LOCALLY HIGHER
WAVES...AND DEADLY CLOUD TO WATER LIGHTNING STRIKES. BOATERS SHOULD
SEEK SAFE HARBOR IMMEDIATELY UNTIL THIS STORM PASSES.

LAT...LON 2751 8264 2746 8265 2737 8255 2742 8345
2808 8339 2820 8278 2787 8285 2781 8278
2784 8275 2772 8269 2770 8265 2783 8261
2793 8273 2804 8269 2800 8256 2784 8254
2783 8248 2792 8250 2796 8243 2785 8235

$$
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Dont see a reason why this one wont become a significant cyclone treking towards the islands next week.
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Quoting LargoFl:
Tampa put the shields up, you got a good one about to hit you folks...............
Tampa shields about to get knocked down, starting to flood in my location, and frequent cloud-to-ground lightning, we really hit the jackpot, Largo.
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Quoting LargoFl:
Hmmmm the weather here by me is getting very interesting, dark clouds all around, but not a drop of rain yet by my house..i see a good one gearing up to come onshore shortly..might get some bad weather here in pinellas..............
Is this from the front that's supposed to be pulling Helene???

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Quoting SFLWeatherman:
8Am not good for S FL!!
Still not that close to FL. Bahamas could be in cone. Although Floyd caused a lot of uneasiness in 1999.
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1506. sar2401
Quoting SFLWeatherman:
8Am not good for S FL!!


From what I can see, there is exactly one model that takes this storm into SFL. There about as many models that want to recurve it out to sea as want to take it west. Until 94L actually become at least a TD, it seems prudent not to get too excited about what any individual modesl are showing.
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Quoting Grothar:
Another one ready to go for a swim. Hey, who was the guy who wrote that there wouldn't be much of a Cape Verde season this year. That the Atlantic would shut down?

This one looks ready to give the CVIs a really good soaking on the way out...

Quoting stoormfury:
ISLANDERS 6 DAYS TO ISAAC ARRIVAL. BARRING A MIRACULOUS RECURVE.
Wouldn't be that miraculous, IMO. Miraculous is Irene missing New Providence by 50 to the east instead of 50 to the west, as had originally been forecast. 7 days out, just about anything could happen...
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Quoting hurricane23:


A threat to the islands is looking increasingly probable as what will be issac should really intensify as it approaches them. After that this far out its really anyones guess.

Here's a look at the 00z GFS esembles...



Hi Adrian. You think there will be no troughs to recurve it before the NE Caribbean islands?
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Pay attention to the animals as they could be the first one to tell you a storm is coming.Micheal Laca sent me a video of his chase in PR,and he showed how the hoarse's were running to higher ground to get to safety.
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Quoting Tropicalupdate:
Could Helene regenerate in The Gulf again by the look at track? Is HH in Helene yet?


Some models have been regenerating it the entire time, or else re-developing something else...

I think it needs to finish ejecting the old mid-level circulation before it can start re-intensifying.

It should only take another 6 to 12 hours to get it out of the way, I guess...


Some of the convection blobs over the BoC are far enough away from the mid-level rotation so that they may be able to form a new circulation entirely. Perhaps that's what the models are developing.
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GFS morning esembles hint at recurve in terms of US which i might add is still very much on the table. Problem is might not be in time to spare the islands. Plenty of time to watch this one.
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Morning everyone, not surprised to see Gordon a hurricane and Helene barely a TS.

Hurricane Chris:


Hurricane Gordon:
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Quoting hurricane23:


A threat to the islands is looking increasingly probable as what will be issac should really intensify as it approaches them. After that this far out its really anyones guess.

Here's a look at the 00z GFS esembles...




Morning Adrian.

Good to see ya.
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Quoting hurricane23:


A threat to the islands is looking increasingly probable as what will be issac should really intensify as it approaches them. After that this far out its really anyones guess.

Here's a look at the 00z GFS esembles...

Becoming increasingly likely that this will affect the US.
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Been thundering all morning In youngsville, la. But not a drop of rain yet.
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1496. Walshy
Some wild deer roaming around this morning here in north-west North Carolina.



Good morning.
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Quoting islandgirls:
Good morning all. I see there's much excitement re: 94L
where the Lesser Antilles comes into focus. What are the chances of it affecting the Northern Antilles, more particularly Guadeloupe to Anguilla?

Anticipating a response

Thanks


1430. ProgressivePulse 1:11 PM GMT on August 18, 2012 +2
Assuming it develops as modeled, 94L will be a major threat to the Antilles as outlined in Dr. Masters blog writing, maybe both the Lesser and the Greater.

Just keep a wary eye for now. Chances are it develops eventually. Still a lot of questions to be answered. I would personally be angling towards getting ready in your location.
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Quoting LargoFl:
its about to hit you guys,stay safe
Roger that. Working so cant keep a good eye on those storms rolling threw
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PR mets just watching this one for now but I'm just beginning to prepare. I have a second home in Rincon and the main one in Bayamon so I need to left both hurricane ready. What would be a better place as a shelter is this thing decides to make an unwelcome visit: Rincon which is located to the west of the island or Bayamon just SW of San Juan?
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1492. mati
Quoting NEFLWATCHING:

just kidding! I am almost as old as you. In other words, i was around when they invented dirt...


BAH I survived Hurrican Hazel :)

Link
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Quoting gugi182:
There still not talking in the local newspapers here in Puerto Rico about 94L must be waiting until a couple of days now to alarm the citizens of PR or other Caribbean islands. This looks like our first MAJOR HURRICANE. Crossing my fingers for it to go out to sea. But that scenario looks to be fading away as every advisory comes up.
Really not much to talk about for now, as the storm is still just in the beginning stages. I'd expect it to get more attention by Monday.

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Quoting ProgressivePulse:
But, I do agree with Levi's prior assessment on a re-curve between 65-80. Personally think it will be closer to the 75-80 mark.


A threat to the islands is looking increasingly probable as what will be issac should really intensify as it approaches them. After that this far out its really anyones guess.

Here's a look at the 00z GFS esembles...

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1489. LargoFl
FINALLY..skies real dark, winds up and its pouring rain!!! yessss. after nine days of this humid heat wave..we finally get rain..and BOOMERS too..have to watch this one here now..tree's are swaying some
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Wouldn't be surprise to see Gordon become a 85-90mph storm.
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Wow radar is just lit up! Hard to predict when it will rain in your spot no matter what kind of charts you put up, mother nature dictates it all.

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Quoting dartboardmodel:
Quick question for you guys… I have just recently moved to Charleston S.C. and I was wondering if I should be worried about 94L??? I have never lived by the ocean before and I obviously have never experienced a tropical storm or hurricane before. The funny thing is I always wanted to experience what one would be like but I don’t want to be blown away by a Cat. 3 or higher. I guess I have mixed feelings about it.
information and deve

I am also from Charleston. If your are new to the area and never lived in a Hurricane proned area I would go the the Charleston County website and read up on the Hurricane Preparedness information and get some basic supplies lined up. Also plan a course of action and where you would go if needed to evacuate.

In the event of a land falling Cat 3 or higher, anything east of highway 17 could be under water depending on the angle of approach to the coast and location of the center.
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1485. sar2401
Quoting islandgirls:
Good morning all. I see there's much excitement re: 94L
where the Lesser Antilles comes into focus. What are the chances of it affecting the Northern Antilles, more particularly Guadeloupe to Anguilla?

Anticipating a response

Thanks


There's a chance 94L could affect the Lesser Antilles, Northern Antilles, PR, Cuba, Florida, Georgia, SC, NC, and on up the coast. There's also a chance it could recurve out to see and only threaten Bermuda. Regardless of all the models runs being thrown about here, 94L is still an invest, and models are notoriously bad about forecasting both track and intensity at this stage of the game. It's hurricane season. You should be prepared for any type of tropical storm, and now's the time to start, if you haven't already. 94L will develop into something and go somewhere, but it's far too early to give anything more than a chance guess. Keep an eye on the storm and models over the five days. We should have a much better idea of what's going to happen then. Until then, take any post in all caps and with lots of exclamation points with a grain of salt, especially if it includes WOW!. :)
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Quoting unknowncomic:
Ridge does not look as strong as earlier in the season, unless it get a big reinforcement.
Agree 100% with this... but also have been noting relatively few interruptions since it started to weaken a couple weeks ago. Also, it's been building back and bridging into the GoM with speed and alacrity after these breaks.

[Really got to find that link.]
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1483. LargoFl
Quoting severstorm:
I see what your talking about. I'm just north of the airport windy and very dark out. not much rain yet
its about to hit you guys,stay safe
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Quoting LargoFl:
..whew we must watch THIS one closely, wow
Could Helene regenerate in The Gulf again by the look at track? Is HH in Helene yet?
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Quoting Thing342:
Could Gordon be turning annular?
Looking Good!!
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Quoting RTSplayer:


Yeah.


I gave it some thought, and it's possible the storm was weak enough to be under the radars from Baton Rouge and Nola, if the circulation wasn't especially deep, because that was Spring in 2003, but how would I know, since I was inside the house.

We opened the door to look at it since it was obviously not strong enough to tear down the house, but it was so strong it would yank the door back out of your hand.

We had floodlights and flashlights, so we could see the rain.

Obviously they didn't have Dual-Pol radars then, and the updates online were nowhere near as fast or accurate. A lot of improvements have been made since the 2005 hurricane season.
Yes your are right in the middle.

Now the slidell radar is strong enough to see all the way to br
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1479. LargoFl
Tampa put the shields up, you got a good one about to hit you folks...............
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Quoting TampaBayStormChaser:

If you play the velocity radar for tampa...you will see the storm pulse up and create an area of light green that is consistent of 60 mph aloft which would be 40-55 mph surface wind gusts with the cell over the bay that just moved into hillsborough
Link
You can see the pulse of light green = 55 kt aloft so 40-50 kt surface right over the bay which then propagated northwards into NE st.pete but near the bay, winds rapidly die down as it moves inland
I see what your talking about. I'm just north of the airport windy and very dark out. not much rain yet
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Quoting Thing342:
Could Gordon be turning annular?

Dang that's a beautiful cane.
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Quoting Grothar:
I don't like working the morning shift on here. We post all the models, post all the images, see all the trends. Then everyone comes on later and starts writing, "Hey look what I found" LOL


Yes, but it also tends to be more troll free.
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Cat 6 lead authors: WU cofounder Dr. Jeff Masters (right), who flew w/NOAA Hurricane Hunters 1986-1990, & WU meteorologist Bob Henson, @bhensonweather