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: 1576 - 1526

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

From me
Member Since: Posts: Comments:
Quoting tatoprweather:
PR mets just watching this one for now but I'm just beginning to prepare. I have a second home in Rincon and the main one in Bayamon so I need to left both hurricane ready. What would be a better place as a shelter is this thing decides to make an unwelcome visit: Rincon which is located to the west of the island or Bayamon just SW of San Juan?
A lot depends on the track, yes? But I'd say Bayamon, thinking about how hilly Rincon is by comparison.

Quoting ProgressivePulse:


No dis-respect to persons in the Greater Antilles but, the good thing is that there are a lot of mountains along 94L's way to SFL.
Unless, of course, it follows the example of past doozies and hits PR then turns west over the Bahamas. There are all sorts of possibilities with this one, based on the models, so I'm not making too much of a commitment to any one scenario... lol...

I just hope Caribboy hasn't wished for more than he can handle...

Member Since: Posts: Comments:
Member Since: Posts: Comments:
1573. Gorty
Active August! We could very will have 5 storms! Maybe 6... Joyce? Or Joyce will start off September.
Member Since: Posts: Comments:
1572. dearmas
Quoting SFLWeatherman:
8Am not good for S FL!!


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

They may take the same paths.
Ohhh no they won't(according to my model).
Member Since: Posts: Comments:
1570. sar2401
Quoting mati:


When was the last Hurricane to hit Portugal?


Gordon 2006. Caused damage in Portugal and Spain.
Member Since: Posts: Comments:
Tropical Storm Irene was designated in two days. It looks like Isaac will too.

They may take similar paths.
Member Since: Posts: Comments:
1568. Patrap
Member Since: Posts: Comments:
1566. Patrap
Tossing Storm Names around TD's that arent a TS yet is awful confusing to Lurkers and others.

Please keep the designation given currently to avoid
Confusion,
Thats why we have names, to keep the Logic flowing.

Thanx
Member Since: Posts: Comments:
1565. LargoFl
Member Since: Posts: Comments:
1564. Gorty
Quoting RTSplayer:
Helene should have been down-graded to a remnant low about 18 hours ago...

It probably never should have been named.


Im gonna tell you what I tell other people: If the NHC believes something meets the criteria for a TS, then they name it. They believed Ex TD7 met all the requirements for a TS so they named it.

They know a lot more than us.
Member Since: Posts: Comments:
1563. sar2401
Quoting BahaHurican:
Is this from the front that's supposed to be pulling Helene???



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.
Member Since: Posts: Comments:
1562. SLU


26% chance of RI
Member Since: Posts: Comments:
Maybe topped out.

The upper level winds on the south side are too strong and in the wrong direction.



Fixed
Member Since: December 31, 1969 Posts: Comments:
1560. LargoFl
Member Since: Posts: Comments:
1559. SLU
12z 94L shear forecast

SHEAR (KT) 25 18 11 6 6 4 6 6 4 3 2 5 4

SHIPS takes it to 105kts and the LGEM to 103kts in 120hrs ..GULP.
Member Since: Posts: Comments:
Gordon is pushing Category 2 hurricane intensity according to some satellite-derived intensity estimates.

Member Since: Posts: Comments:
Quoting Patrap:
Helene Rainbow Loop



That dry belt of air N of Helene ain't helping much, but looks like it's about to get mixed out.
Member Since: December 31, 1969 Posts: Comments:
1556. gugi182
Looks like this will be the last year they used the name: ISSAC for a name, just the name sounds haunting. ISSAC
Member Since: Posts: Comments:
1555. LargoFl
Member Since: Posts: Comments:
1554. Patrap
Hunting Hugo
By Jeffrey Masters, Ph.D. — Director of Meteorology, Weather Underground, Inc.



In September of 1989, a NOAA hurricane hunter airplane intercepted Hurricane Hugo as it approached the Caribbean islands, just before Hugo's destructive rampage through the Caribbean and South Carolina. The crew of the airplane were the first people to encounter the mighty hurricane--and very nearly became its first victims. The mission remains the most harrowing flight ever conducted by the NOAA hurricane hunters. I served as flight meteorologist on that flight, and feel fortunate indeed to be able to tell the story.

— Dr. Jeff Masters (Chief Meteorologist, Weather Underground, Inc.)
Member Since: Posts: Comments:
Quoting Hurrihistory:
The video Micheal Laca sent, is that from his Hurricane Hugo Chase in 1989?
Yes.
Quoting Gorty:


Could Gordon and Issac moisten up the environment for Joyce?
Well Gordon is all the way up north in the Atlantic XD.But it's a good possibility that Isaac could moisten the environment to help Joyce survive.Especially since he is expected to be a huge storm.
Member Since: Posts: Comments:
Quoting washingtonian115:
You know GFS did a pretty good job in sniffing out the track of Ernesto and keeping it a weak system until it reached the N.W caribbean even before he develop..
And it has done well with Gordon with maybe the exception of it rolling off Africa as a storm, but it gets a pass from me.
Member Since: Posts: Comments:
1551. mati
The Southern Azores Islands need to keep an eye on this one.


When was the last Hurricane to hit Portugal?
Member Since: Posts: Comments:
1550. LargoFl
Member Since: Posts: Comments:
1549. Patrap
Helene Rainbow Loop


Member Since: Posts: Comments:
Quoting Hurrihistory:
The video Micheal Laca sent, is that from his Hurricane Hugo Chase in 1989?

This?

Member Since: Posts: Comments:
Quoting gugi182:
Ships models putting 94L at 120 hours at a Cateogry 3 Major Hurricane with 120 MPH winds.

The shear forecast on the latest SHIPS run is almost scary: No more than 6kts of shear after 18 hours.
Member Since: Posts: Comments:
1546. LargoFl
Quoting TampaBayStormChaser:
Very calm in northeast st. pete right now...but a lot of dark clouds and lightning to my NW over Largo.
yes really booming here..seems to be letting up just a little now..whew we needed that rain...............
Member Since: Posts: Comments:
1545. ncstorm
Good Morning Everyone..slept in late hanging with the night shift..so the Euro is going west into the GOM and the GFS is recurving..
Member Since: December 31, 1969 Posts: Comments:
Quoting ProgressivePulse:
But, I do agree with Levi's prior assessment on a re-curve between 65-80. Personally think it will be closer to the 75-80 mark.
Whether or not this passes through the CAR or not, I have a hard time seeing a recurve with this system before 70W. Quite a few pple kept drawing attention to the way Helene basically festered for five days in the western GOM on the forecast maps, rather than heading west [i.e. due to the high building back]. I can buy a weakness in the vicinity of the east coast later next week.

Member Since: Posts: Comments:
1543. Gorty
Quoting washingtonian115:
You know GFS did a pretty good job in sniffing out the track of Ernesto and keeping it a weak system until it reached the N.W caribbean even before he develop..


And I think it did a pretty good job with Gordon taking it a while before developing.
Member Since: Posts: Comments:
Look at Hurricane Gordon go...7/3/0



The Southern Azores Islands need to keep an eye on this one.



Member Since: Posts: Comments:
Helene should have been down-graded to a remnant low about 18 hours ago...

It probably never should have been named.
Member Since: December 31, 1969 Posts: Comments:
1539. gugi182
Ships models putting 94L at 120 hours at a Cateogry 3 Major Hurricane with 120 MPH winds.
Member Since: Posts: Comments:
You know GFS did a pretty good job in sniffing out the track of Ernesto and keeping it a weak system until it reached the N.W caribbean even before he develop..
Member Since: Posts: Comments:
1537. Gorty
Quoting washingtonian115:
I think that's the one the models develop into Joyce right in behind Isaac.


Could Gordon and Issac moisten up the environment for Joyce?
Member Since: Posts: Comments:
Quoting washingtonian115:
Pay attention to the animals as they could be the first one to tell you a storm is coming.Micheal Laca sent me a video of his chase in PR,and he showed how the hoarse's were running to higher ground to get to safety.
The video Micheal Laca sent, is that from his Hurricane Hugo Chase in 1989?
Member Since: Posts: Comments:
Quoting Thing342:
ATCF says Helene is now a TD.

Helene has been a TD or weaker for most of her life as she wandered about.
Member Since: December 31, 1969 Posts: Comments:
1534. LargoFl
wow this is a bad one..bet over 2 inches already and still going..going to be flooding in the low lying areas quick..................get ready Tampa..this is all coming to you..slow mover too.............
Member Since: Posts: Comments:
According to this Helene may not be toast.
Member Since: Posts: Comments:
Looking at the last several model runs especially the GFS, I think by late Sunday we should have a good handle on the approach to islands.

By mid week we should have a very good idea if it is gonna turn or maintain a wnw -nw heading.

What I do not like what I am seeing in the GFS runs is that once they lock on to a system it has been pretty much dead on.

It will be interesting to see how it handles a fully developed CV system versus the earlier shallow and sheared systems we have had so far.
Member Since: Posts: Comments:
Quoting BahaHurican:
It's possible. Currently some models are bringing it your way. I'd say this is a good time to give a little more attention to NHC website.

Which one of the Leewards are u in... [Antigua???]


Yes. Just wanted to know what I am (we are) are up against
Member Since: Posts: Comments:
Quoting Gorty:
Does any models develop the next wave ready to leave Africa?
I think that's the one the models develop into Joyce right in behind Isaac.
Member Since: Posts: Comments:
1529. Grothar
This is the actual GFS model run which I posted earlier this morning. Very close consensus with the
GFS models. However, other models want to move 94L more to the WNW and NW right before they enter the Antilles. However, since last night, the models are moving 94L on the curve a little later in each run.


Member Since: Posts: Comments:
Quoting washingtonian115:
Wouldn't be surprise to see Gordon become a 85-90mph storm.


Max intensity map suggests it could be high end of cat 2 based on pressure, or low end of cat 4 based on max winds.

However, that formula only works for ideal conditions.

Based on the map, it could be as low as 970mb at 35N 30W, which it's supposed to pass close to, but it would either be topped out at that intensity, or else already be weakening...


So I'd say the pressure could theoretically go 10 to 15mb lower at the most, since this is only mediocre conditions.

If it was to strengthen that much more, it would definitely need to accomplish it within the next 36 hours, else it will be over water not warm enough for further strengthening.

Member Since: December 31, 1969 Posts: Comments:
Quoting dartboardmodel:
Quick question for you guys… I have just recently moved to Charleston S.C. and I was wondering if I should be worried about 94L??? I have never lived by the ocean before and I obviously have never experienced a tropical storm or hurricane before. The funny thing is I always wanted to experience what one would be like but I don’t want to be blown away by a Cat. 3 or higher. I guess I have mixed feelings about it.
Good to see you in the blog... 94L is still so far out that anybody actively worrying about it is stressing a little too much. OTOH.... if you live in Charleston, it's always a good idea to keep track of what's going in on in the tropics, especially during August and September. Even a simple look at NHCs homepage will at least keep you abreast of concerns the tropical cyclone experts are tracking.

Of course, the more INTERESTING way of following what's going on is IMO by hanging out in the Doc's blog... lol

Member Since: Posts: Comments:
Quoting sar2401:


There's a chance 94L could affect the Lesser Antilles, Northern Antilles, PR, Cuba, Florida, Georgia, SC, NC, and on up the coast. There's also a chance it could recurve out to see and only threaten Bermuda. Regardless of all the models runs being thrown about here, 94L is still an invest, and models are notoriously bad about forecasting both track and intensity at this stage of the game. It's hurricane season. You should be prepared for any type of tropical storm, and now's the time to start, if you haven't already. 94L will develop into something and go somewhere, but it's far too early to give anything more than a chance guess. Keep an eye on the storm and models over the five days. We should have a much better idea of what's going to happen then. Until then, take any post in all caps and with lots of exclamation points with a grain of salt, especially if it includes WOW!. :)


One thing I look for in the models... Consistency. If a model is constantly showing development and strong development over many runs, watch for the other models coming into agreement.
Member Since: Posts: Comments:

Viewing: 1576 - 1526

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