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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Exploding convection!!!

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Quoting tropicfreak:
Keep in mind guys that lots and lots can change with 94L's track. Once we have a better defined center and a designated tropical system the models are going to have a better idea as to what will happen. Don't put much stock into them right now. Just know that there's a disturbance out there that may develop soon, and will impact someone... just don't know who.


Lol. Prepare to be blasted.
Member Since: December 31, 1969 Posts: Comments:
Quoting ncstorm:


because Helene isnt a monster..



Lol...Wow. So now I'm a wishcaster and I'm jealous because I don't have something bearing down on me? You are ridiculous.
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.

Hurricane Charley was forecast to go into Tampa Bay but instead made a sharp right turn and hit Punta Gorda. A change in direction of a few degrees created a landfall forecast error (based on the infamous "center line") of about 60 mi. along the shoreline. It went ashore as a Cat 4...small but destructive. After that was when forecasters told people not to pay too much attention to the center line.
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Quoting Grothar:


That would be close. The last fix was 11.1 12.5 so it could have moved a little since then. Looks like it will be wrapping up pretty good.


That could be good. I would think that earlier development and initialization a little further notth would make future model runs trend a but further north I would think. But then again I'm not sure how the strength and location if the High will play into this.
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971. JLPR2
Quoting GTcooliebai:
This was the predicted forecast track for Hurricane Irene 300 hrs. out and we all know how that panned out.



I'm keeping a close eye on it, this was Irene 162hrs out.


So yeah... The GFS has its moments. Yet we still could see a shift on the track as the LLC hasn't really established itself yet.
Member Since: December 31, 1969 Posts: Comments:
Keep in mind guys that lots and lots can change with 94L's track. Once we have a better defined center and a designated tropical system the models are going to have a better idea as to what will happen. Don't put much stock into them right now. Just know that there's a disturbance out there that may develop soon, and will impact someone... just don't know who.
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Quoting JLPR2:


That was ridiculously excessive.


I agree, "you all" is a lot of people.
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Quoting washingtonian115:
He's mad.For what reason?.i have no idea.Well I'm off for tonight.Remember I won't say I told you so...


because Helene isnt a monster..
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Quoting Skyepony:
94L Having two centers should slow it's development a little..

OSCAT


That's not 94L, that's the wave ahead of it.
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Quoting Hurricanes101:


wow, that is a bit much dont you think?

I am watching the blog, and I see people being a bit over-dramatic about the model run, but I dont see anyone wishing the storm their way

well actually there is one, you


No drama???? I'm the dramatic one? Lol. You people are unreal.

Quoting CaribBoy:
I'm very anxious and excited lol my heart is beating a bit faster :) Yeah speculation is fun!!!

Quoting CaribBoy:
WORST CASE SCENARIO FOR THE WINDWARDS/LEEWARDS
Quoting Gearsts:
Omg im scared with this system and GFS showing consistancy per run and PR and DR been a target also the time of the month favors a hit for the islands.
Member Since: December 31, 1969 Posts: Comments:
Goodnight everyone..see yall later today!
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Quoting GTcooliebai:
372 hrs. out into fantasy land, but looks like the islands wouldn't be done yet.



GT, if you stop posting that I'll give you a cookie.
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Quoting caneswatch:


That wasn't Irene, Irene was in August not September.
It was, but somehow the dates got messed up I saved it and uploaded it to photobucket.
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Quoting JLPR2:


That was ridiculously excessive.
He's mad.For what reason?.i have no idea.Well I'm off for tonight.Remember I won't say I told you so...
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960. JLPR2
Quoting GTcooliebai:
372 hrs. out into fantasy land, but looks like the islands wouldn't be done yet.



That would be rather unpleasant.
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959. JLPR2
Quoting MississippiWx:
Well, I hope you all get your major hurricane that ruins your countries/islands. Better you than me, since you want it and all.


That was ridiculously excessive.
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Quoting Skyepony:
94L Having two centers should slow it's development a little..

OSCAT


Yes, my thoughts exactly.
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Trending East--keep the trend up.
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372 hrs. out into fantasy land, but looks like the islands wouldn't be done yet.

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Quoting allancalderini:
Maybe he will be retire.


The way he's being played up, maybe he should be retired right now.
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Quoting GTcooliebai:
This was the predicted forecast track for Hurricane Irene 300 hrs. out and we all know how that panned out.



That wasn't Irene, Irene was in August not September.
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Quoting MississippiWx:


Far from a guarantee. I think some of us are taking the GFS as gospel truth. A storm that strengthens quicker than anticipated goes north of the islands.


My concern is we are only talking a week out. The pattern this year is for storms to gradually strengthen as they traverse the ATL. I think the islands should watch this one carefully...just my opinion.
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Quoting 954FtLCane:


center seems to be up by 12.5 & 26


That would be close. The last fix was 11.1 12.5 so it could have moved a little since then. Looks like it will be wrapping up pretty good.
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Quoting GTcooliebai:
This was the predicted forecast track for Hurricane Irene 300 hrs. out and we all know how that panned out. If you want accuracy 3 days out is accurate, even 5 days forecasts can be wrong.



It was only 100 miles off 300 hours out and spot-on with intensity... Not bad if you ask me.
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949. Skyepony (Mod)
OSCAT
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Quoting MississippiWx:
Well, I hope you all get your major hurricane that ruins your countries/islands. Better you than me, since you want it and all.


wow, that is a bit much dont you think?

I am watching the blog, and I see people being a bit over-dramatic about the model run, but I dont see anyone wishing the storm their way

well actually there is one, you
Member Since: December 31, 1969 Posts: Comments:
Quoting MississippiWx:
Well, I hope you all get your major hurricane that ruins your countries/islands. Better you than me, since you want it and all.
Who said that we all want it? I dont want to be with no water and power for 1 month like georges and i dont want any loss of life. Go to bed
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Quoting washingtonian115:
U.S is spared from a hit.But not without feeling some rip currents and huge waves.
Just based on these 2 runs, but a lot can change, the troughs being depicted aren't really that strong as the one we are currently feeling.
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Quoting Grothar:
Beginning to round itself out.




center seems to be up by 12.5 & 26
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Quoting JLPR2:


Nah, I'll check out the models tomorrow, if by tomorrow we are still a target, then I will buy some stuff.


yeS,we need wait until the fromation of TD at least
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943. Skyepony (Mod)
I spotted a funnel cloud in North Melbourne today. Someone else with a better view reported it. Had to be somewhere & couldn't chase.

A woman got struck by lightning in Port St John yesterday.

Fresh ASCAT..it's the only thing it caught between MX & Africa.
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Quoting MississippiWx:


Far from a guarantee. I think some of us are taking the GFS as gospel truth. A storm that strengthens quicker than anticipated goes north of the islands.


126 hours from now with the islands is not that far away..(Wednesday)..and it wasnt just some tropical storm the GFS was showing either..its pretty clear with almost every major model showing this system that it will form..
Member Since: December 31, 1969 Posts: Comments:
I see the blog is in doom mode tonight.

No surprise considering this is the I storm. I heard the models got updated just to show doom when it comes to the I storm.
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Mainwhile..... 94L IS FIRING UP!!!

Link
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BASED ON THESE RUNS...NO US NE COAST THREAT NOW???
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As long as it stays away from Florida, I'll remain calm and be cautious with believing the GFS. Heck, even if it heads right over my house, I still won't really care. But if it heads towards FL, well, I'll be a little more concerned and unhappy.
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This was the predicted forecast track for Hurricane Irene 300 hrs. out and we all know how that panned out.

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


Far from a guarantee. I think some of us are taking the GFS as gospel truth. A storm that strengthens quicker than anticipated goes north of the islands.


00z GFS doesn't turn this stronger in a fast way if you look at the timeframes.
Member Since: December 31, 1969 Posts: Comments:
Hurricane Icarus 2018
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Quoting tropicfreak:


That would be a big ouchie for Bermuda if that were to verify!


Not to mention big surf for the eastern US.... if it doesn't directly impact.
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Quoting Tropicsweatherpr:


Or a Hugo track.


Darn, that doesn't look good at all for the home team!!
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Quoting GTcooliebai:
300 hrs. and look out for some sort of fujiwhara action since these 2 systems are close together. Could end up something like Dog and Easy.

U.S is spared from a hit.But not without feeling some rip currents and huge waves.
Member Since: December 31, 1969 Posts: Comments:
Member Since: December 31, 1969 Posts: Comments:
240 hours, so people of lesser antilles,Puerto Rico and Dominican Republic Needs to pay attention and i wanna to see the european now XD
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927. JLPR2
Quoting sunlinepr:


I did text messages already.... Remember that this local election thing will affect comerce on sunday... I don't think politics are going to announce this or if they are going to use it for their advantage... from them anything can be expected...

But batteries, canned food, Gasoline, water and other supplies should be acquired tomorrow... anyhow something we use everyday....


Nah, I'll check out the models tomorrow, if by tomorrow we are still a target, then I will buy some stuff.
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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