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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1326. SLU
OF NOTE:

The formation of TS Helene yesterday marks the 3rd earliest date for the formation of the 8th named storm after only 2005 and 1936.

If Joyce forms before the 22nd of August, it will break the record set by TS Jerry in 1995 for the earliest formation of the 10th named storm in recorded history.

WHAT A BUST OF A SEASON!
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Quoting serialteg:
20kt shear on most of 94l's path...low wind shear on top rite now



Predicted to decrease per GFS.
Member Since: December 31, 1969 Posts: Comments:
Wow...

(Edit: This was actually the 00z run, I didn't see)

GFDL actually takes Gordon to 94kts on the 20th...

That seems unlikely given the water temperature, but that's amazing.

Not sure, but I think that would probably be some kind of record for a storm so far to the NE...
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Quoting washingtonian115:
If that verify we won't be seeing you or our other PR friends on here for a while.

Your avatar...lol
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Quoting washingtonian115:
If that verify we won't be seeing you or our other PR friends on here for a while.

If this were to verify you wouldn't see me for awhile!

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http://www.weather.unisys.com/satellite/sat_wv_east _loop-12.gif

At the end of this, last frame you make out the center based on the 5 convection blowups.
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Quoting WeatherNerdPR:
Bust season.
agreed.
Quoting mitthbevnuruodo:
Wow! Wasn't expecting a lovely looking hurricane Gordon when I woke up!

Why do I have to sleep and go to work?! I miss too much LOL
Agreed.

Am I agreeing w/ everybody because everybody's right, or just because I haven't gotten out of bed to make coffee yet?

lol
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Look how well defined this is!

Gordon Dvorak loop


Very rare to see something that symmetrical without a full anti-cyclone.
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Quoting WeatherNerdPR:

If that verify we won't be seeing you or our other PR friends on here for a while.
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20kt shear on most of 94l's path...low wind shear on top rite now

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Wow do I have good eye sight.Knew on Mexican radar where Helene's center was! Nice!
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Gordon tapping the trough for assisted outflow.

There's no real anti-cyclone at all. The southern side is actually blowing in the wrong direction in the upper levels, so it's actually being sheared on the south side, but still intensifying.

GFDL from 0600z wants to take it to 90mph...


I figure the water temps can maintain hurricane status for another 24 to 30 hours...

With the forward speed so high, it may even be able to coast into the 25C or 24C zones as a minimal hurricane...
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Quoting RTSplayer:


It kinda is a bust even though it's had so many storms already.

Debby was the only eventful system, and went the wrong way.

IF they had that much rain on the Texas/Oklahoma path the models thought it was taking, it probably would have busted the drought...


Beryl made landfall in N-Fl in May as nearly a Category 1.
Chris became the farthest north June hurricane.
Debby did as you said.
Ernesto caused a bad amount of damage in the Yucatan and was probably a moderate Category 2 at landfall.

This season isn't a bust. 8-3-0 is rather impressive for August 18th. What's more, it's an El Nino year to boot.
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Quoting RTSplayer:


It kinda is a bust even though it's had so many storms already.

Debby was the only eventful system, and went the wrong way.

IF they had that much rain on the Texas/Oklahoma path the models thought it was taking, it probably would have busted the drought...

Well, it's been more interesting than 2011 so far. And we're ahead in named storms as well.
Quoting floridaboy14:
i dont know but some people consider a bust season when a hurricane doesnt hit the US. for example of issac was a major that plowed the carribean and went out to sea, lots of people would consider it a bust. as for 94L, im not buying the recurvutre just yet..... thats over a week out. im focused on how strong it gets toward the islands

I was being sarcastic :P
I'm still unsure of where 94L will go. Probably near me, but I hope it just goes out to sea.
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1310. SLU
110kt wind barb at 850mb just as "Isaac" reaches the islands

Link
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I knew Gordon was going to do this!.I just knew it!.that's why I didn't give up on him.He looks really beautiful!!.
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Quoting WeatherNerdPR:
Bust season.
i dont know but some people consider a bust season when a hurricane doesnt hit the US. for example of issac was a major that plowed the carribean and went out to sea, lots of people would consider it a bust. as for 94L, im not buying the recurvutre just yet..... thats over a week out. im focused on how strong it gets toward the islands
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Quoting WeatherNerdPR:
Bust season.


It kinda is a bust even though it's had so many storms already.

Debby was the only eventful system, and went the wrong way.

IF they had that much rain on the Texas/Oklahoma path the models thought it was taking, it probably would have busted the drought...
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Quoting mitthbevnuruodo:
Wow! Wasn't expecting a lovely looking hurricane Gordon when I woke up!

Why do I have to sleep and go to work?! I miss too much LOL

It happened overnight. I was not expecting it either...
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Wow! Wasn't expecting a lovely looking hurricane Gordon when I woke up!

Why do I have to sleep and go to work?! I miss too much LOL
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Bust season.
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1303. SLU
Quoting BahaHurican:
Except for this...

... which later became Irene...


Great!. That 80% blob became TS Harvey. It took us 9 TS before we got a hurricane in 2011. This year we could have 4 hurricanes in 9 named storms. :)
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...GORDON A LITTLE STRONGER...
8:00 AM AST Sat Aug 18
Location: 33.9°N 39.6°W
Moving: E at 18 mph
Min pressure: 985 mb
Max sustained: 80 mph
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...GORDON A LITTLE STRONGER...
8:00 AM AST Sat Aug 18
Location: 33.9°N 39.6°W
Moving: E at 18 mph
Min pressure: 985 mb
Max sustained: 80 mph

...HELENE JUST NORTH OF CABO ROJO...
7:00 AM CDT Sat Aug 18
Location: 21.9°N 97.5°W
Moving: NW at 8 mph
Min pressure: 1007 mb
Max sustained: 40 mph
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Quoting WeatherNerdPR:

This is what you were trying to post, right?


I got it right now, I used the link of the page, instead of the direct image URL. Sometimes it works sometimes it doesn't. This time it didn't.
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SHOWER AND THUNDERSTORM ACTIVITY CONTINUES IN ASSOCIATION WITH A
TROPICAL WAVE LOCATED A COUPLE HUNDRED MILES SOUTHWEST OF THE CAPE
VERDE ISLANDS. CONDITIONS APPEAR CONDUCIVE FOR GRADUAL DEVELOPMENT
DURING THE NEXT FEW DAYS...AND THIS SYSTEM HAS A MEDIUM CHANCE...40
PERCENT...OF BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS
AS IT MOVES WESTWARD AT 15 TO 20 MPH.

40% want to see the 12z GFS run today. ensembles anywhere from the gulf to west of bermuda
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Quoting nrtiwlnvragn:


Hard to determine anything from it, at least for me



Mexican radars do ok with hurricanes... I've used them before.
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Quoting RTSplayer:
This track is definitely wrong.




Ivan exited the coast and went back over the Atlantic, and then crossed Florida back into the Gulf before heading west.

It did NOT make that ridiculous bee-line back to the SW in that fashion...


This is much more accurate.



Well, does it work?

This is what you were trying to post, right?
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Quoting RTSplayer:
This track is definitely wrong.




Ivan exited the coast and went back over the Atlantic, and then crossed Florida back into the Gulf before heading west.

It did NOT make that ridiculous bee-line back to the SW in that fashion...


This is much more accurate.


Probably because there's no data during while Ivan was a low.
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SHOWER AND THUNDERSTORM ACTIVITY CONTINUES IN ASSOCIATION WITH A
TROPICAL WAVE LOCATED A COUPLE HUNDRED MILES SOUTHWEST OF THE CAPE
VERDE ISLANDS. CONDITIONS APPEAR CONDUCIVE FOR GRADUAL DEVELOPMENT
DURING THE NEXT FEW DAYS...AND THIS SYSTEM HAS A MEDIUM CHANCE...40
PERCENT...
OF BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS
AS IT MOVES WESTWARD AT 15 TO 20 MPH.
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This track is definitely wrong.




Ivan exited the coast and went back over the Atlantic, and then crossed Florida back into the Gulf before heading west.

It did NOT make that ridiculous bee-line back to the SW in that fashion...


This is much more accurate.

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im really curious what the long range is for 94L for all we know some ensembles show it in the gulf. very uncertain. shows the leewards need to watch this one. if it gets into the carribean there are many scneaios but this one most likely will not be a fish storm
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Zoom in and click on the mid level wind overlay.





RGB Western Atlantic


Notice, the mid-level circulation is far, far inland, just as I said, though over night it too must have turned north.

At any rate, it's decoupled from the alleged LLC by at least a 100 miles or so...
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Quoting BahaHurican:
Beautiful little hurricane... wonder how much of that energy is going to remain even in transition to impact the eastern Azores....

It should start to get chilly maybe by end of day.

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Quoting BahaHurican:
Except for this...

... which later became Irene...


Irene was a nasty one, let's just hope that Isaac doesn't follow suit.
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Quoting WeatherNerdPR:

Do you have a link to that radar?


Hard to determine anything from it, at least for me



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Quoting WeatherNerdPR:

Do you have a link to that radar?

yes here you go...
Link
Just click the "Altamira" site
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Quoting SLU:
.... and I must agree with you Teddy. This season is far more interesting than last year at this same stage.
Except for this...

... which later became Irene...
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Quoting STXHurricanes2012:
She's still off the coast still about 20-30 mi.
According to Mexican Radar site.

Do you have a link to that radar?
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She's still off the coast still about 20-30 mi.
According to Mexican Radar site.
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Discussion of 94L by Crown Weather.

Link
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Still with that gross feature I see...I disagree lol!
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Quoting Thing342:
Gordon's eye is huge. Nearly a degree wide.
Beautiful little hurricane... wonder how much of that energy is going to remain even in transition to impact the eastern Azores....
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1278. SLU
The "I"s have it?





















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Good Morning...
Gordon is probably a Cat 2. That microwave pass showed a rather impressive eyewall.

Helene, on the other hand...

Gross.
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1276. trey33
Quoting LargoFl:
..if it makes it to This point..it could be dangerous for us, me i hope it recurves before that point but we'll see, half the models bring it here, half recurve..too early to tell just yet


Largo,
what is the timing if it does?
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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