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: 776 - 726

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

The 00z Bams were updated a few minutes ago as they didn't do that earlier.

WHXX01 KWBC 180349
CHGHUR
TROPICAL CYCLONE GUIDANCE MESSAGE
NWS NATIONAL HURRICANE CENTER MIAMI FL
0349 UTC SAT AUG 18 2012

DISCLAIMER...NUMERICAL MODELS ARE SUBJECT TO LARGE ERRORS.
PLEASE REFER TO NHC OFFICIAL FORECASTS FOR TROPICAL CYCLONE
AND SUBTROPICAL CYCLONE INFORMATION.

ATLANTIC OBJECTIVE AIDS FOR

DISTURBANCE INVEST (AL942012) 20120818 0000 UTC

...00 HRS... ...12 HRS... ...24 HRS. .. ...36 HRS...
120818 0000 120818 1200 120819 0000 120819 1200

LAT LON LAT LON LAT LON LAT LON
BAMS 11.1N 25.5W 11.5N 27.5W 12.2N 29.2W 12.8N 31.5W
BAMD 11.1N 25.5W 11.4N 28.1W 11.9N 30.3W 12.4N 32.5W
BAMM 11.1N 25.5W 11.6N 28.3W 12.3N 30.6W 12.9N 33.0W
LBAR 11.1N 25.5W 11.4N 28.8W 11.9N 32.3W 12.3N 35.8W
SHIP 20KTS 25KTS 32KTS 43KTS
DSHP 20KTS 25KTS 32KTS 43KTS

...48 HRS... ...72 HRS... ...96 HRS. .. ..120 HRS...
120820 0000 120821 0000 120822 0000 120823 0000

LAT LON LAT LON LAT LON LAT LON
BAMS 13.4N 34.2W 14.7N 42.3W 15.1N 51.8W 13.4N 60.4W
BAMD 13.0N 34.7W 14.4N 39.8W 15.6N 45.2W 16.8N 49.6W
BAMM 13.5N 35.6W 14.7N 42.4W 15.2N 50.4W 14.7N 58.6W
LBAR 12.8N 39.3W 13.5N 46.3W 13.2N 51.3W .0N .0W
SHIP 51KTS 66KTS 82KTS 100KTS
DSHP 51KTS 66KTS 82KTS 100KTS

...INITIAL CONDITIONS...
LATCUR = 11.1N LONCUR = 25.5W DIRCUR = 270DEG SPDCUR = 17KT
LATM12 = 11.2N LONM12 = 22.0W DIRM12 = 270DEG SPDM12 = 17KT
LATM24 = 11.1N LONM24 = 17.3W
WNDCUR = 20KT RMAXWD = 50NM WNDM12 = 20KT
CENPRS = 1009MB OUTPRS = 1012MB OUTRAD = 150NM SDEPTH = S
RD34NE = 0NM RD34SE = 0NM RD34SW = 0NM RD34NW = 0NM
Member Since: Posts: Comments:
72 hours, and is seeming like 06z run

Member Since: December 31, 1969 Posts: Comments:
Member Since: Posts: Comments:
Quoting zillaTX:


eh?

cyclones
Member Since: Posts: Comments:
Keep the entertainment..err I mean models coming.
Member Since: December 31, 1969 Posts: Comments:
Quoting sunlinepr:


Dont panic!!! Is there a Home depot open?

I'm going to buy a lot of rope....



Can you buy enough to tie future Isaac and Joyce to Gordon before he exits stage right?

that way they follow him
Member Since: December 31, 1969 Posts: Comments:
770. JLPR2
Triplets? O.o

Member Since: December 31, 1969 Posts: Comments:
Quoting Hurricanes101:
meanwhile the low that is/was Helene is still in the same spot in 3 days lol

and still just off the coast too!
Member Since: Posts: Comments:
Quoting xtremeweathertracker:


Funny you should mention that Gro...i called my wife that just today!! LOL


That's terrible. :)
Member Since: December 31, 1969 Posts: Comments:
Quoting STXHurricanes2012:
Could be 3


Dont panic!!! Is there a Home depot open?

I need to buy some rope....

Member Since: December 31, 1969 Posts: Comments:
Quoting KEEPEROFTHEGATE:


maybe

i always like

lugensquash


With or without butter?
Member Since: December 31, 1969 Posts: Comments:
Quoting Grothar:


No, I think it is the Norwegian spelling. In German
Die Doofen means the stupids. I was just wondering if it is still in use.

Oh.
Member Since: Posts: Comments:
764. JLPR2
Quoting TropicalAnalystwx13:
Well, that's new.



Brother and sister moving along together. GFS better start turning them N soon. xD
Member Since: December 31, 1969 Posts: Comments:
Quoting STXHurricanes2012:
Could be 3


eh?
Member Since: Posts: Comments:
Still sending future Isaac west..Joyce appears to join the picture.
Member Since: December 31, 1969 Posts: Comments:
meanwhile the low that is/was Helene is still in the same spot in 3 days lol
Member Since: December 31, 1969 Posts: Comments:
Quoting bappit:
I hear the word "doofus" a lot. Is dufus French?


No, I think it is the Norwegian spelling. In German
Die Doofen means the stupids. I was just wondering if it is still in use.
Member Since: December 31, 1969 Posts: Comments:
Could be 3
Member Since: Posts: Comments:
Well, that's new.

Member Since: Posts: Comments:
54 hours, yes two cyclone
Member Since: December 31, 1969 Posts: Comments:
18z Wavewatch III:

Member Since: Posts: Comments:
Quoting scott39:
My wife calls me a few names and it aint Dufus!


Well i regretted it as soon as it left my mouth, for a high heel was the return present!!
Member Since: December 31, 1969 Posts: Comments:
Member Since: December 31, 1969 Posts: Comments:
What a dufus nightmare.... double strike...
could du-f-us

I mean....(freak us)

Member Since: December 31, 1969 Posts: Comments:
Quoting bappit:
I hear the word "doofus" a lot. Is dufus French?


no, its me...:)
Member Since: Posts: Comments:
I bet the forecasters at the NHC are gathered around their computers praying and chanting and anounting the screen hoping that the GFS will agree with them on this run for Helene!! LOL
Member Since: December 31, 1969 Posts: Comments:
We have 2 systems....

Member Since: December 31, 1969 Posts: Comments:
Quoting xtremeweathertracker:


Funny you should mention that Gro...i called my wife that just today!! LOL
My wife calls me a few names and it aint Dufus!
Member Since: Posts: Comments:
I hear the word "doofus" a lot. Is dufus French?
Member Since: Posts: Comments:
While everyone's waiting on the operational GFS, I just did a blog. Enjoy.
Member Since: Posts: Comments:
42 hours
Member Since: December 31, 1969 Posts: Comments:
Quoting Grothar:
This is not directed at anyone, but do they still use the word dufus?


doo·fus (dfs)
n. pl. doo·fus·es Slang
An incompetent, foolish, or stupid person.
Member Since: December 31, 1969 Posts: Comments:
Quoting Grothar:
This is not directed at anyone, but do they still use the word dufus?


Funny you should mention that Gro...i called my wife that just today!! LOL
Member Since: December 31, 1969 Posts: Comments:
Quoting Grothar:
This is not directed at anyone, but do they still use the word dufus?


LOL. Yes, but I'm pretty sure my 14 year old thinks I'm a dufus when I do!
Member Since: Posts: Comments:
Quoting Grothar:
This is not directed at anyone, but do they still use the word dufus?


maybe

i always like

lugensquash
Member Since: December 31, 1969 Posts: Comments:
Quoting Grothar:
This is not directed at anyone, but do they still use the word dufus?
Yes, its still works very well. Do you have someone in mind?
Member Since: Posts: Comments:
30 hours
Member Since: December 31, 1969 Posts: Comments:
This is not directed at anyone, but do they still use the word dufus?
Member Since: December 31, 1969 Posts: Comments:
Member Since: December 31, 1969 Posts: Comments:
Quoting TXCaneCrasher:


Please tell me the storms they were off by 50-100 miles before? I would really like to know.

I could tell you that, but I would just be making stuff up.

(I hope you are not referring to the ensemble model posts.)
Member Since: Posts: Comments:
Anyone who is taking those maps as a serious threat to where they live....need prozac. 94L hasnt even developed yet. Its all in fun right now..chill
Member Since: Posts: Comments:
Quoting RTSplayer:


I've seen them be off by 50 or even 100 miles before, and a few hours later issue a re-position, even though the official direction of movement was quite the different direction.

It has happened before a few times.


Please tell me the storms they were off by 50-100 miles before? I would really like to know.
Member Since: Posts: Comments:
Quoting GTcooliebai:
Post 700. Beautiful Storm, yet deadly and destructive.


That's how serious 94L forecast can turn...
Member Since: December 31, 1969 Posts: Comments:
Member Since: December 31, 1969 Posts: Comments:
Quoting washingtonian115:
Can you stop.It may get people mislead from the real model runs..
only the keeper allowed to post any kind of map for the next hour
Member Since: Posts: Comments:
Whats wrong with posting maps?
Member Since: Posts: Comments:
Can you stop.It may get people mislead from the real model runs..
Member Since: December 31, 1969 Posts: Comments:
Member Since: Posts: Comments:
Quoting TropicalAnalystwx13:

Trade winds across the Caribbean and stronger troughs are indicative of an atmospheric-based El Nino.

But nothing to do with the OTHER factors...
e.i. Wind shear(Upper level convective outflow, all over the caribbean) EDIT: (As in all the time). Divergent air aloft in the deep tropics, with all the main energy located in the Equatorial pacific...
Member Since: Posts: Comments:
Quoting Levi32:


I'm not sure how that's unusual for a TS when it's the weaker systems that have the least uniformity in wind field, which would make such distortion expected from a low-end TS. Mature hurricanes would be strong in all quadrants.


Levi, are you still confident in your forecast posted yesterday that Helene will eventually move into the northern GOM, possibly just offshore toward Tx/La??
Member Since: December 31, 1969 Posts: Comments:

Viewing: 776 - 726

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