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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Hello everyone.I have been a member here reading everyone's posts and lurking here for a long time. I have been a member here since at least 2002.Last time I posted here was in 2008 when Hurricane Gustav was about to hit my area. Now I think it is time to start posting with you guys here again. Look like Tropical Storm Helene is starting to feel that strong Trough and Ridge to the north and is starting to pull her like a magnet to the NNE. what do you guys think.
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Quoting JLPR2:


Haha, yeah and I wouldn't expect it to come back for awhile.
Ah... the suffering! XD


By the way,today yes Deborah did it again. She said there is nothing to worrie about.
Member Since: December 31, 1969 Posts: Comments:
Quoting TropicalAnalystwx13:

It did not move inland...recon was in the storm. The center is moving north...over water.


I'm aware of what recon claims, but there's just nothing whatsoever in the satellite presentation to suggest the storm is anything other than a decoupled piece of remnant garbage.

Regardless of where the CoC is, it's obvious all the convection and mid level circulation wen west to WSW a long time ago...
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Quoting JLPR2:


94L is expected to be huge! Would be awful if it did take the 18z track as its damaging winds would probably cover a rather large area. :\


Look at the GFS new path... passing S into RD....
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Quoting Chicklit:

Helene is inland imho.


The blob over N TX looks better
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Best analogue I can find for pre- Isaac. David 1979. I think it will recurve a little east of there though, so shift the track north of Hispaniola about 100 miles east.
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Quoting sar2401:


Helene is dead. She's already onshore in Mexico and rapidly becoming a remnant low.

Incorrect!
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368. JLPR2
Quoting Tropicsweatherpr:


And there goes the power off.


Haha, yeah and I wouldn't expect it to come back for awhile.
Ah... the suffering! XD
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Quoting evilpenguinshan:
Recon disagrees (see my post #158).
The LLC seems to have decoupled from the mid level spin for the time being...remember, Ernesto taught us not to run solely on satellite presentation =p


figures there is some unseen force at work...but do not see how that can regenerate.
sorry, just stating the obvious but often things don't work out that way.
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Quoting Chicklit:

I fail to see how Helene is going to do anything except make landfall.

Which appears she already has.
I agree, looks like it already has, I have been at work and didnt even know it formed til now, doesnt look like much of anything anyways, but I dont really know much of anything about the tropics anyways, I just come on here and lurk and read what some of the vets have to say
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and now we get 1 person after another saying the system is moving onshore when recon obs and satellite LOOPS clearly show the circulation over water
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Quoting JLPR2:


94L is expected to be huge! Would be awful if it did take the 18z track as its damaging winds would probably cover a rather large area. :\


And there goes the power off.
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Lol! She hasn't made landfall! Not even close!!
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Quoting RTSplayer:


Yeah, I don't know what NHC is callnig the CoC, but all appearances to me are that the storm actually made landfall some time between 3 and 6 hours ago.

There is no apparent convection or cyclonic rotation near the official CoC. It's all over land.

If it was moving north, why is there less rain on the Brownsville long range radar than there was 6 hours ago?!?

It did not move inland...recon was in the storm. The center is moving north...over water.
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Quoting AtHomeInTX:


Well that was quick. lol
Yeah probably the center was eject more to the west.
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I saw the 00z Best Track for 94L but I have not seen the 00z Bams updated.
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359. JLPR2
Quoting sunlinepr:


94L is expected to be huge! Would be awful if it did take the 18z track as its damaging winds would probably cover a rather large area. :\
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Quoting scott39:
Does Helene want to play?


Helene is dead. She's already onshore in Mexico and rapidly becoming a remnant low.
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Quoting clwstmchasr:


Looks to be that way.

'cept for her tailfeathers ;-)
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Recon disagrees (see my post #158).
The LLC seems to have decoupled from the mid level spin for the time being...remember, Ernesto taught us not to run solely on satellite presentation =p

Quoting Chicklit:

Helene is inland imho.
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hey guys, what the hell! I come back to check in and I find that people are saying 94L will be a carib cane...

...well, hmm... ok I'll go with that.
NO! I will not say anything till 94L reaches 40W

and TD-7 becomes TS ok that is expected...

Gordon will be a spain storm...

ok I'll be gone, back to vacation. I may check back in later.
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Quoting JrWeathermanFL:

I said that earlier and the ATCF disagrees


so does every loop you run, its clear the circulation is still offshore

cant judge by a picture sometimes
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Looks like Texas is getting some rain!
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Quoting Chicklit:

I fail to see how Helene is going to do anything except make landfall.

Which appears she already has.


Yeah, I don't know what NHC is callnig the CoC, but all appearances to me are that the storm actually made landfall some time between 3 and 6 hours ago.

There is no apparent convection or cyclonic rotation near the official CoC. It's all over land.

If it was moving north, why is there less rain on the Brownsville long range radar than there was 6 hours ago?!?
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Quoting Chicklit:

Helene is inland imho.

I said that earlier and the ADT disagrees
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Hugo or Georges?

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Quoting Chicklit:

Helene is inland imho.


Well that was quick. lol
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Quoting Chicklit:

I fail to see how Helene is going to do anything except make landfall.

Which appears she already has.


I agree. I don't know what the models are seeing, but it sure looks like Helene lived a short and not too glorious life.
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Quoting clwstmchasr:


The NHC on Don....

POST-TROPICAL CYCLONE DON DISCUSSION NUMBER 11
NWS NATIONAL HURRICANE CENTER MIAMI FL AL042011
400 AM CDT SAT JUL 30 2011

THE DON IS DEAD. THE CYCLONE LITERALLY EVAPORATED OVER TEXAS ABOUT
AS FAST AS I HAVE EVER SEEN WITHOUT MOUNTAINS INVOLVED. DON HAS NO
CONVECTION...MEAGER RAINFALL...AND ONLY A SLIGHT SIGNATURE IN
SURFACE OBSERVATIONS AND RADAR DATA. THEREFORE...THIS IS THE LAST
ADVISORY ON THIS SYSTEM. DON SHOULD OPEN UP INTO A TROUGH LATER
TODAY AS IT MOVES TO THE WEST-NORTHWEST AND IS NOT EXPECTED TO POSE
A RAINFALL THREAT.

Who wrote that discussion?
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Helene is inland imho.
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Quoting TropicalAnalystwx13:

Uhm, why not?


Have you read their discussions? They would have simply never named a naked swirl.
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Quoting KEEPEROFTHEGATE:
Now that looks serious.
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338. TXCWC
Quoting RTSplayer:
GFS likes Corpus.




I think most people in Texas would celebrate if that track was to verify.


I would think the NHC will have to update their track given the model and track shifts...but hey what do I know right. :)
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I fail to see how Helene is going to do anything except make landfall.

Which appears she already has.
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Just had a near X class solar flare:



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Cmon Gordon.. you're just 4mph short of Category 1 again, you can do it.
AL, 08, 2012081800, , BEST, 0, 342N, 431W, 60, 990, TS
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Quoting RTSplayer:
GFS likes Corpus.




I think most people in Texas would celebrate if that track was to verify.



Centex people will.. Lake Travis has had two consecutive years of drought and is 40ft low.
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Quoting zillaTX:


she is falling into pieces.

I think you are lol...jk give it time!
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Freaking serious....


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If Helene can get a little further away from land it can sufficiently organize... otherwise due to it being very close to the coast, land interaction is hurting it.
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Quoting clwstmchasr:


That was really bizarre the way that storm "poofed" as soon as it hit the coast.


"poof" is an understatement.

It disappeared into the void or something.
Member Since: December 31, 1969 Posts: Comments:
326. etxwx
Good news from Hong Kong but apparently there are no international boundaries on wishcasting...note bolded line.

Typhoon Kai Tak lightly brushes city over night
China Daily Updated: 2012-08-18 06:34

Excerpt: Typhoon Kai-Tak brushed by Hong Kong giving the city barely a nudge on Thursday night and Friday morning. The Hong Kong Observatory replaced the No 8 Southeast Storm Signal, issued at 10:15 pm on Thursday, with a No 3 Strong Wind Signal at 6:20 am on Friday morning. The typhoon disrupted public transportation services in the New Territories.

Major bus company operators Citybus & New World First Bus cancelled their services at about 1 am on Friday. However, by 5 am, they announced five special routes to the airport were open and other routes began operations from 6:30 am. Ferry service between Hong Kong and Macao, which was halted after the No 8 signal was issued, also resumed service at about 6:30 am. The MTR resumed normal operations. Other public transport gradually resumed normal.

Many employees woke up this morning disappointed as they found Typhoon Kai Tak moving away from Hong Kong faster than expected. Some of them had to hurry to get to work on time.

There were six reports of tree damage but none of flooding or landslides.
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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