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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1676. Skyepony (Mod)
Quoting Tazmanian:



is that a eye in 94L?


No..

ASCAT missed 94L
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1675. LargoFl
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Morning... the buzz seems to be about 94L. Washingtonian115 gotta give it to you... you've been talking about the "I" storm for some time now expressing your concern about this potential "bad boy."
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FWIW, Gordon has moved into second place on the 2012 ACE list. Meanwhile, Helene has a really good chance of staying in last place for the duration:

1: ERNESTO - 7.6625
2: GORDON - 3.1675
3: CHRIS - 2.7675
4: DEBBY - 2.4450
5: BERYL - 2.1600
6: FLORENCE - 1.4375
7: ALBERTO - 1.3750
8: HELENE - 0.4050

ACE

ACE
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Topped out about an hour or two ago..

Dry air penetrated the eye-wall on the latest frame.



It might survive and fix this, but that's going to take some wind out of it...pun intended.
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Quoting Skyepony:
94L looking like an S..


It's actually a 2. :D
I know my ABC's and 123's xD
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1670. ncstorm
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Now remember the storm that will become "I" killed 28 people from flooding.So you can say that 94L soon to be "I" came out of Africa bad and seems he wants to continue his rain of terror.
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1668. ncstorm
Here is the UKMET last run

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1667. air360
Quoting Skyepony:
94L looking like an S..



Or at least a backwards S....
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Quoting Skyepony:
94L looking like an S..




is that a eye in 94L?
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1665. LargoFl
geez we got a weather event going on right here..havent seen this much rain in a long time..flooding big time i bet in the low lying area's..and Still pouring.............
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Quoting washingtonian115:
Even the experts know their's something wrong with those "I" storms.


Well, it's not just superstition, it's statistics.


I guess it's about the timing in the season. For at least the past decade, maybe 2 decades, the "I" storms usually happen in a sweet spot for size and intensity in space and time.

You know what I'm saying...
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1663. Skyepony (Mod)
94L looking like an S..

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Quoting KeyWestwx:
yeah... it looks as the storm , if it heads that direction , will start to impact the lesser antillies by Friday and the boat should be on its way home by that time.I'm house and dog sitting for them this week. We all live in Key West.
Biggest problem would be if the storm moves faster than expected... but definitely the cruise line would indicate if there are changes to the itinerary.
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Quoting ncstorm:
Jim Cantore is talking about 94L..from twitter..

Jim Cantore ‏@JimCantore

The next potential "I" storm is that 1008mb Low near 12N30W: http://www.nhc.noaa.gov/tafb/ATSA_06Z.gif … It could impact the Antilles as early as Thursday.
Even the experts know their's something wrong with those "I" storms.
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1660. LargoFl
FLOOD ADVISORY
NATIONAL WEATHER SERVICE TAMPA BAY AREA - RUSKIN FL
1029 AM EDT SAT AUG 18 2012

FLC057-103-181530-
/O.NEW.KTBW.FA.Y.0071.120818T1429Z-120818T1530Z/
/00000.N.ER.000000T0000Z.000000T0000Z.000000T0000 Z.OO/
HILLSBOROUGH FL-PINELLAS FL-
1029 AM EDT SAT AUG 18 2012

THE NATIONAL WEATHER SERVICE IN RUSKIN HAS ISSUED AN

* URBAN AND SMALL STREAM FLOOD ADVISORY FOR...
NORTHWESTERN HILLSBOROUGH COUNTY IN FLORIDA.
THIS INCLUDES THE CITIES OF...LUTZ...TEMPLE TERRACE...TAMPA
INTERNATIONAL AIRPORT...TAMPA

CENTRAL PINELLAS COUNTY IN FLORIDA.
THIS INCLUDES THE CITIES OF...CLEARWATER...LARGO...PINELLAS PARK...
SEMINOLE


* UNTIL 1130 AM EDT

* AT 1029 AM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED
RAINFALL RATES OF TWO INCHES PER HOUR ASSOCIATED WITH THUNDERSTORMS
OVER THE ADVISED AREA...LOCALIZED FLOODING IS IMMINENT OR OCCURRING.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

KEEP CHILDREN FROM BEING SWEPT AWAY IN FLOODED DITCHES AND DRAINS.
FLOOD WATERS ARE USUALLY DEEPER THAN THEY APPEAR AND MAY STALL YOUR
VEHICLE. JUST ONE FOOT OF FLOWING WATER IS POWERFUL ENOUGH TO SWEEP
VEHICLES OFF THE ROAD. TURN AROUND...DONT DROWN.

&&

LAT...LON 2812 8261 2818 8238 2817 8210 2789 8253
2793 8254 2793 8257 2796 8256 2796 8266
2798 8262 2799 8267 2796 8267 2794 8271
2792 8263 2787 8258 2775 8276 2783 8284
2793 8285

$$
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1659. ncstorm
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this blog is about too be come vary busy
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I think it may be a little stronger but they are the experts.
HURRICANE CENTER LOCATED NEAR 34.1N 38.6W AT 18/1500Z
POSITION ACCURATE WITHIN 20 NM

PRESENT MOVEMENT TOWARD THE EAST OR 90 DEGREES AT 16 KT

ESTIMATED MINIMUM CENTRAL PRESSURE 983 MB
EYE DIAMETER 20 NM
MAX SUSTAINED WINDS 70 KT WITH GUSTS TO 85 KT.
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Quoting Patrap:
That feature shows up nicely below Cuba in the WV loop

GOM WV Loop

Yes it does, thx, it seems to be utilizing DMAX already for being 2 days old. Convection in the heat of the day should put some clothes back on him. If it survives and develops, it has no issues ahead of it.
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1655. Gorty
Quoting BahaHurican:
So this justifies what I've been thinking about both Helene and 94L...

Is it fair to minus a post because you don't like the message??? lol

Really? I know we had K on the 24th... We had I and J storms after the 18th???

Let's not even go there... or consider the fact that there's another convention in NC the following week...
Sheesh.



Aww man I miss counted :( It will tie 2005. 2005 got to L.

So it also had 5 storms in Aug.
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1654. ncstorm
Jim Cantore is talking about 94L..from twitter..

Jim Cantore ‏@JimCantore

The next potential "I" storm is that 1008mb Low near 12N30W: http://www.nhc.noaa.gov/tafb/ATSA_06Z.gif … It could impact the Antilles as early as Thursday.
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1653. LargoFl
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Quoting unknowncomic:
94L already looks like banding with center at 12.5/30.


Should be a TD/TS within 24 hours IMO.
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1651. Skyepony (Mod)
Hurricane Gordon~ Click pic for loop.
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Quoting RTSplayer:
Oh My God...

If the GFS is best on timing, and the Ships intensity is within 10kts of the correct value for 120 hours, then it's SW of PR and SE of Dominican republic at 168 hours...

However, the intensity is forecast as 105kts at the 120 hours mark, which the GFS says will still be 12 to 18 hours east of the Lesser Antilles.

If this was to verify, then it would pass the Lesser Antilles as a strong category 3 or weak category 4, and continue intensifying until near landfall (or if it makes the pass anyway).


So these scenarios from the most recent SHIPS and GFS are just terrible compared to earlier runs.
O.o...well, we've gotten away every for the most part since Louis but this looks like it coul be the one :/
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Quoting stormchaser19:
Good morning people,The EURO shows a weaker system,but looks the strong ridge, i´m starting doubting this storm will recurve


This run seems suspect as the Euro has been consistently showing a major hurricane on each run.
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Quoting BahaHurican:

Is it fair to minus a post because you don't like the message??? lol

No, lol.
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Quoting Tropicsweatherpr:
Tx13,you think Gordon weakens the Ridge or it has no effect at all?


well I'm not TA but from me I think it is having an effect on the ridge but I think it will not be enough to have an effect I think whatever effectes are happening the ridge will redevelop these are just my thought we will have to wait and see
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Quoting unknowncomic:
Still want to experience a hurricane? You can, would not advise it.
On a uncharted islands.Not with anyone else getting harm.
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Hurricane warning for the Azores. We don't see that much.
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Tropical Depression HELENE RSS Feed icon NESDIS Satellite | NDBC Obs | Storm Archive
...HELENE MOVES INLAND JUST SOUTH OF TAMPICO MEXICO...WEAKENS TO A TROPICAL DEPRESSION...
10:00 AM CDT Sat Aug 18
Location: 22.0°N 98.0°W
Moving: NW at 9 mph
Min pressure: 1008 mb
Max sustained: 35 mph
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Quoting sar2401:


No, just seabreeze type storms. The front that supposed to drag Helene along is still hung up in north Alabama and now looks like it wants to turn stationary. The high that's currently over the Indiana/Ohio area may push what's left of the front further south by Monday or Tuesday but it's not going to be a major player in anything that develops in GOM.
So this justifies what I've been thinking about both Helene and 94L...

Quoting TropicalAnalystwx13:
Tropical Storm Irene was designated in two days. It looks like Isaac will too.

They may take similar paths.
Is it fair to minus a post because you don't like the message??? lol

Quoting Gorty:
With Issac, 2012 will be more active then 2005 in August!
Really? I know we had K on the 24th... We had I and J storms after the 18th???

Quoting dearmas:


Guess what will be here in Tampa about that time frame....RNC. Guess we will seeif all the drills//training that has been going on for months will be needed
Let's not even go there... or consider the fact that there's another convention in NC the following week...
Sheesh.

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1642. Gorty
Off topic but with the 2011 October snowstorm, was this blog or another blog on this site active talking about it?

I sure missed it if it was this or another blog.
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Helene downgraded to a TD: Wind: 35 MPH — Location: 22.0N 98.0W — Movement: NW
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Gordon remains at 80 mph in this advisory. Forecast to intensify slightly before entering cooler waters and higher wind shear. Meanwhile, Helene has weakened to a TD.

BULLETIN
TROPICAL DEPRESSION HELENE ADVISORY NUMBER 12
NWS NATIONAL HURRICANE CENTER MIAMI FL AL072012
1000 AM CDT SAT AUG 18 2012

...HELENE MOVES INLAND JUST SOUTH OF TAMPICO MEXICO...WEAKENS TO A
TROPICAL DEPRESSION...


SUMMARY OF 1000 AM CDT...1500 UTC...INFORMATION
-----------------------------------------------
LOCATION...22.0N 98.0W
ABOUT 15 MI...25 KM SSW OF TAMPICO MEXICO
MAXIMUM SUSTAINED WINDS...35 MPH...55 KM/H
PRESENT MOVEMENT...NW OR 305 DEGREES AT 9 MPH...15 KM/H
MINIMUM CENTRAL PRESSURE...1008 MB...29.77 INCHES
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Quoting washingtonian115:
Lord here we go..
Still want to experience a hurricane? You can, would not advise it.
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1638. LargoFl
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1637. KEEPEROFTHEGATE (Mod)
Quoting hydrus:
Excellent post Pat, I was thrown off a tad with the misnomers.


yep right now its nothing but a dipiction on a model and as for a name well at the moment its 94L thats it
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Quoting GeorgiaStormz:
good morning guys....gordon going good today

Up to a hurricane, waiting on the next advisory which will be soon and we have the invest that could be a big problem for many people. Also dont forget Helene since she could try to strengthen later. Bust season, I dont think so.
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Quoting Tropicsweatherpr:
Tx13,you think Gordon weakens the Ridge or it has no effect at all?

Very little effect.
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Lord here we go..
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94L already looks like banding with center at 12.5/30.
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1632. ncstorm
Quoting RTSplayer:
Oh My God...

If the GFS is best on timing, and the Ships intensity is within 10kts of the correct value for 120 hours, then it's SW of PR and SE of Dominican republic at 168 hours...

However, the intensity is forecast as 105kts at the 120 hours mark, which the GFS says will still be 12 to 18 hours east of the Lesser Antilles.

If this was to verify, then it would pass the Lesser Antilles as a strong category 3 or weak category 4, and continue intensifying until near landfall (or if it makes the pass anyway).


So these scenarios from the most recent SHIPS and GFS are just terrible compared to earlier runs.


the people of the lesser antilles should start experiencing 94L conditions by early as wednesday with wave height and then wind and rain to follow
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Quoting stormchaser19:
Good morning people,The EURO shows a weaker system,but looks the strong ridge, i´m starting doubting this storm will recurve


I'm starting to think it could recurve in the GOM
hmm...

anyway Good Morning guys
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Tx13,you think Gordon weakens the Ridge or it has no effect at all?
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good morning guys....gordon going good today
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1628. LargoFl
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Looks to still be strengthening, eye is becoming more defined ans convection is increasing.
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Quoting Patrap:



Well, that's Kinda like rolling the dice here.

: )


yeah... it looks as the storm , if it heads that direction , will start to impact the lesser antillies by Friday and the boat should be on its way home by that time.I'm house and dog sitting for them this week. We all live in Key West.
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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