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.

Reader Comments

Display: 0, 50, 100, 200 Sort: Newest First - Order Posted

Viewing: 476 - 426

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | 32 | 33 | 34 | 35 | 36Blog Index

476. JLPR2
Quoting pottery:

Check the wind-barbs there.
That's a really big system anticipated.


Even passing that far the GFS shows PR covered with hurricane force winds.

Member Since: Posts: Comments:
Quoting gustavcane:

Grothar, 94L passes right thru the first Hebert Box. this may be bad for South Florida if it takes this route.Link
http://upload.wikimedia.org/wikipedia/commons/a/a 7/Hebert_boxes.jpg


Be careful, I live in South Florida. :)
Member Since: December 31, 1969 Posts: Comments:
UW - CIMSS
ADVANCED DVORAK TECHNIQUE
ADT-Version 8.1.3
Tropical Cyclone Intensity Algorithm

----- Current Analysis -----
Date : 18 AUG 2012 Time : 011500 UTC
Lat : 20:48:07 N Lon : 96:23:14 W


CI# /Pressure/ Vmax
2.5 /1009.2mb/ 35.0kt


Final T# Adj T# Raw T#
2.3 1.9 1.8

Center Temp : +11.6C Cloud Region Temp : -8.5C

Scene Type : SHEAR (1.10^ TO DG
Member Since: Posts: Comments:
Quoting allancalderini:
Really??? I know this sounds awful but it should be fun fighting with other people like stay away from this when I watch an episode of the simpsons when Marge was fighting a women for a cake I was lol.
Yes.I wasn't going down without a fight.However there were other fights reported in the area including robberies.
Member Since: December 31, 1969 Posts: Comments:
Quoting wxmod:
Still a LOT of dust off Africa. MODIS


That is some psychedelic african dust man!
Member Since: Posts: Comments:
Quoting JLPR2:


You got two different runs there...
18z and 06z


Look closely at the dates, JL. One is for the 24th and the other is the 25th. It is from a loop run.
Member Since: December 31, 1969 Posts: Comments:
470. JLPR2
Plenty of moisture to work with.

Member Since: Posts: Comments:
Member Since: Posts: Comments:


Member Since: Posts: Comments:
Right... back from my weekly politics fix... lol

Not on this blog... lol

And I am sticking around until the 00Zs come out... want to see where the GFS ends up w/ 94L. I as skeptical as CyberTeddy about that massive swing in the GFS, and I want to see if it shows up for more than one run. Given the fact that we've had a couple of Caribbean runners already, I would not be surprised if we end up with such a track, but some consistency has to be shown.
Member Since: December 31, 1969 Posts: Comments:
Quoting Chicklit, Grothar:




You can see two distinct entities here. As Gro said, if the Eastern one gobbles up the Western one, the Fujuwharic effect will likely send the consolidated storm more North. If the Western one just slows down and absorbs the Eastern one and captures it, more likely to resume Westward movement after a hiccup or two.
Member Since: December 31, 1969 Posts: Comments:
Quoting sunlinepr:
Mona passage or E RD...


Check the wind-barbs there.
That's a really big system anticipated.
Member Since: December 31, 1969 Posts: Comments:
464. wxmod
Still a LOT of dust off Africa. MODIS

Member Since: Posts: Comments:
Quoting sunlinepr:
Mona passage or E RD...

VERY bad because i live in Aguadilla.
Member Since: Posts: Comments:
Quoting lovemamatus:
If you are right.....this could spell (dare I say it?) for N.O.

No...
Member Since: Posts: Comments:
Quoting washingtonian115:
All ways better to get ahead of the croweds :).I had to learn the hard way with Isabel.Fought people over canned food.
Really??? I know this sounds awful but it should be fun fighting with other people like stay away from this when I watch an episode of the simpsons when Marge was fighting a women for a cake I was lol.
Member Since: Posts: Comments:
Quoting Grothar:
GFS at 168 hours amd 180 hours







Grothar, 94L passes right thru the first Hebert Box. this may be bad for South Florida if it takes this route.Link
http://upload.wikimedia.org/wikipedia/commons/a/a 7/Hebert_boxes.jpg
Member Since: Posts: Comments:
459. JLPR2
Quoting pottery:

Ah !

Thanks....


You're welcome!
Member Since: Posts: Comments:
The bad part....Mona passage or E RD...

The good one.... 7 days left.... That forecast will change.... so for the moment... just watching...

Member Since: Posts: Comments:
Quoting CybrTeddy:


You'd have your kids college money in 6 hours.




if i had kids may be some day lol


but so ture
Member Since: Posts: Comments:
Quoting Relix:
No need to rush out and buy any stuff now. For all we know the storm may choke in dry air. I'll worry when its near the arc and in a threatening position. For now I am just watching it.
All ways better to get ahead of the croweds :).I had to learn the hard way with Isabel.Fought people over canned food.
Member Since: December 31, 1969 Posts: Comments:
Quoting JLPR2:


You got two different runs there...
18z and 06z

Ah !

Thanks....
Member Since: December 31, 1969 Posts: Comments:
452. JLPR2
Quoting Relix:
No need to rush out and buy any stuff now. For all we know the storm may choke in dry air. I'll worry when its near the arc and in a threatening position. For now I am just watching it.


Hmm... hopeful, but no...
Our best chance is it missing us.
Member Since: Posts: Comments:
Quoting Tazmanian:
i wish i had $5000 for evere time some one said fish storm on this blog


You'd have your kids college money in 6 hours.
Member Since: December 31, 1969 Posts: Comments:
450. JLPR2
Quoting Grothar:
GFS at 168 hours amd 180 hours








You got two different runs there...
18z and 06z
Member Since: Posts: Comments:
449. Relix
No need to rush out and buy any stuff now. For all we know the storm may choke in dry air. I'll worry when its near the arc and in a threatening position. For now I am just watching it.
Member Since: Posts: Comments:
94L/INV/XX/XX
MARK
10.10N/30.30W
Member Since: Posts: Comments:
Quoting zillaTX:


stop with your .



NO am not even doing any thing i Quote the worng bloger and i re move my commet ad re place it with a .




why not you this mine your own BESS WAXS
Member Since: Posts: Comments:
Quoting Grothar:
GFS at 168 hours amd 180 hours







What !
It goes through the Islands TWICE ???
Member Since: December 31, 1969 Posts: Comments:
Quoting JLPR2:


I'll wait for the watches.
People here believe we are now immune to hurricanes since we have not seen one since 1998, therefore even then very few will be buying stuff to prepare. The two days before the storm the stampede arrives at the stores. XD
Its like here just one day or two before the storm pass near or make landfall is when the people start to worry.
Member Since: Posts: Comments:
444. JLPR2
Quoting sunlinepr:


Southern forecasted paths are serious... historically they tend to shift to the North....

Even a huge hurricane leaving its Coc in the Caribbean is more dangerous than in the North...

Hope, all models keep adjusting and moving it to the north...

Anyhow, time will bring the truth.... Next Friday we will know with the real of what we are facing...

I just came from Costco, preparing...


If the 18z track does happen, around the 22-23th we should have a pretty good idea.
Member Since: Posts: Comments:

The first one described is 94L.
NHC from 8 p.m. Discussion:
...TROPICAL WAVES...

TROPICAL WAVE EXTENDS FROM 11N24W TO 17N21W MOVING W AT 15-20 KT. THE WAVE IS EMBEDDED WITHIN AN EASTERN ATLC MONSOON GYRE FOCUSED AROUND A 1009 MB LOW CENTERED NEAR 11N24W. TOTAL PRECIPITABLE WATER IMAGERY INDICATES DEEP LAYER MOISTURE IN THE VICINITY OF THE WAVE FROM 08N-15N BETWEEN 18W-24W WITH ISOLATED MODERATE CONVECTION OCCURRING WITHIN 180 NM EITHER SIDE OF THE
WAVE AXIS.

TROPICAL WAVE EXTENDS FROM 10N39W TO 18N38W MOVING W AT 15-20 KT. THE WAVE REMAINS EMBEDDED WITHIN A BROAD AREA OF ENHANCED DEEP LAYER MOISTURE AS NOTED ON THE TOTAL PRECIPITABLE WATER IMAGERY FROM 06N-16N BETWEEN 30W-41W. GLOBAL MODEL DATA SHOWS THAT THE WAVE COINCIDES WITH A 700 MB TROUGH AXIS ALONG 37W. DUE TO A LARGE DRY AIRMASS ASSOCIATED WITH A SAHARAN AIR LAYER...NO
DEEP CONVECTION IS CURRENTLY ASSOCIATED WITH THE WAVE.
Member Since: Posts: Comments:
GFS at 168 hours amd 180 hours one on the 24th and one on the 25th.






Member Since: December 31, 1969 Posts: Comments:
Quoting Tazmanian:
.


stop with your .
Member Since: Posts: Comments:
Quoting KoritheMan:


Either way, we would not be talking about a major hurricane if it decided to move this way, as the GFS suggests a little bit of westerly shear. Also, recall last year how Nate was supposed to impact the northern Gulf Coast from a similar location but failed to do so. And that was three weeks later.

yes your right. I just hope it stays close to the coast it will stay weak if it moves north. but I am thinking that if it continues to move north and closer to the Trough to the north it may get pulled to the NNE & then NE across the gulf. Temps in the gulf are 85F to 87F like Rocket Fuel for a Tropical Storm.
Member Since: Posts: Comments:
Quoting JLPR2:


I'll wait for the watches.
People here believe we are now immune to hurricanes since we have not seen one since 1998, therefore even then very few will be buying stuff to prepare. The two days before the storm the stampede arrives at the stores. XD
No buy it now so you won't be in a rush and all ready be prepared.
Member Since: December 31, 1969 Posts: Comments:
Quoting JLPR2:
Oh well, hoping for a track shift with the 00z GFS.
*fingers crossed*


Southern forecasted paths are serious... historically they tend to shift to the North....

Even a huge hurricane leaving its Coc in the Caribbean is more dangerous than in the North...

Hope, all models keep adjusting and moving it to the north...

Anyhow, time will bring the truth.... Next Friday we will know with the real of what we are facing...

I just came from Costco, preparing...
Member Since: Posts: Comments:
Member Since: Posts: Comments:
436. JLPR2
Quoting washingtonian115:
Very smart to go before the big crowds.Hope you also have your plans in place along with canned goods.


I'll wait for the watches.
People here believe we are now immune to hurricanes since we have not seen one since 1998, therefore even then very few will be buying stuff to prepare. The two days before the storm the stampede arrives at the stores. XD
Member Since: Posts: Comments:
Well, the models don't look very good for the caribbean Islands right now............
Looks like a large system is anticipated.
The wave heights within the storm look pretty awesome too, around the 23rd....

Will keep an eye on this one, whatever happens.
Member Since: December 31, 1969 Posts: Comments:
Center still over water.

Member Since: December 31, 1969 Posts: Comments:
Quoting washingtonian115:
Very smart to go before the big crowds.Hope you also have your plans in place along with canned goods.


Yes,also that as I always every start of the season in June,I buy the goods to have suficient supply.
Member Since: December 31, 1969 Posts: Comments:
Quoting brazocane:
My crude idea of where the center is:



Link Floater Page for Helen which is still ID'd as TD7

Lin Rainbow Loop 07k
Member Since: Posts: Comments:
.
Member Since: Posts: Comments:
Member Since: Posts: Comments:
My crude idea of where the center is:

Member Since: Posts: Comments:
Quoting Tropicsweatherpr:
wash115, I am already preparing for anything that whatever this system may bring to PR if it comes to the Eastern Caribbean. I went today to a hardware store and bought panels,flashlights,candles and a power plant. I am avoiding the big rush when a watch and warnings are issued.
Very smart to go before the big crowds.Hope you also have your plans in place along with canned goods.
Member Since: December 31, 1969 Posts: Comments:
Quoting popartpete:
I know it's going to be said sooner or later: Will 94L go through Herbert's Box?

There is no such thing as Herbert's Box.
And Hebert's boxes are imaginary.
goodnight! Sorry to call Helene poof but good grief.
She's barely hanging on.
Member Since: Posts: Comments:

Viewing: 476 - 426

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | 32 | 33 | 34 | 35 | 36Blog Index

Top of Page

Category 6™

About

Cat 6 lead authors: WU cofounder Dr. Jeff Masters (right), who flew w/NOAA Hurricane Hunters 1986-1990, & WU meteorologist Bob Henson, @bhensonweather