Hawaii braces for Felicia; 99L near the Cape Verdes Islands may develop

By: Dr. Jeff Masters , 3:55 PM GMT on August 10, 2009

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A strong tropical wave (99L) is just south of the Cape Verdes Islands, 800 miles off the coast of Africa. This morning's QuikSCAT pass showed a nearly closed surface circulation, stretched out along one axis. The satellite saw winds of up to 45 mph in a band of heavy thunderstorms well south of the Cape Verdes Islands. The islands have seen winds of only 10 - 15 mph and some occasional rain showers thus far from the disturbance. Heavy thunderstorm activity associated with 99L died down this morning, but appears to be making a comeback late this morning. Wind shear is moderate, about 10 knots, and sea surface temperatures are moderately warm, about 27 - 28°C. There is a large area of dry air to 99L's north that is interfering with the storm's organization, though.


Figure 1. Current satellite image of disturbance 99L.

Wind shear is expected to be moderate, 5 - 15 knots, through Wednesday. SSTs will remain relatively constant at 27°C, but the dry, stable air of the Saharan AIr Layer (SAL) to 99L's north will be problem for it. NHC has given 99L a moderate (30 - 50% chance) of developing into a tropical depression by Wednesday morning, which is a reasonable forecast. Most of the models show some weak development, but none of them predict 99L will become a hurricane. It is too early to say if 99L will recurve north of the Lesser Antilles Islands or not, since it will be at least 5 days before the storm makes it that far. It is unusual, though, for storms forming this far north to make it all the way across the Atlantic to hit the Lesser Antilles Islands.

The GFS and ECMWF models are predicting the possible development of a new tropical wave coming off the coast of Africa late this week.

Felicia continues to weaken, but is a flash flooding threat to Hawaii
Tropical Storm Felicia has weakened steadily over the past 24 hours, thanks to cool sea surface temperatures and increasing shear. Recent satellite loops show that strong upper-level winds from the west have pushed the storm's heavy thunderstorm activity to the northeast side of the center, exposing the surface center as a swirl of low clouds. Felicia's relatively meager heavy thunderstorm activity is steadily moving away from the center of the storm.


Figure 2. History of hurricane activity over Hawaii since 1950. Hawaii islands have been hit by only 9 tropical cyclones of tropical depression or greater strength, with 4 others passing withing 75 miles of an island. Image credit: NOAA Coastal Services Center.

Sea surface temperatures (SSTs) under Felicia are 25°C, well below the 26°C threshold typically needed to sustain a hurricane. SSTs will slowly increase to 26°C by Tuesday. Wind shear has increased to a high 30 knots, and is expected to increase further to 40 knots by Tuesday. The high shear combined with the cool SSTs should continue to weaken Felicia today. I give a 30% chance that the shear will completely rip away Felicia's heavy thunderstorm activity by the time the storm reaches Hawaii, leaving only a swirl of low-level clouds that will not cause significant flooding problems. The wind speed probabilities forecast shows about a 25% chance Felicia will still be a weak tropical storm at 3 am Hawaiian time Tuesday morning, and a 15% chance the storm will have dissipated. If Felicia does hold together that long, it would be only the tenth tropical cyclone of tropical depression or higher strength to affect the islands since 1950 (Figure 2). Large swells from Felicia are already affecting the Big Island, and a high surf warning has been posted for east-facing shores of the Big Island and other Hawaiian islands. Felicia or its remnants may bring heavy rain, flash flooding, and mud slides to the islands beginning this afternoon, and a Flash Flood Watch has been posted for most of the islands.

Links to follow:
Long range radar from the Big Island
Wundermap for Hawaii

I'll have an update Tuesday morning.

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Quoting WeatherStudent:


I agree, Reed, but from your perspective, does this look more like a sea dweller or a land threater?


Too early to make that sort of prediction, probably will have an idea when it reaches the Islands.
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I dont know if this blog is turning into the Acholoic blog or if the blog is just turning us into acholoics lol
Member Since: August 29, 2006 Posts: 22 Comments: 1352
1485. Patrap
Quoting ALCoastGambler:
I sure hope it doesn't take as long to finish the West side as it did to do the East side




It sure beats that Ol Mobile Bay
I-10 thing ya'll forced to Drive ..LOL
Member Since: July 3, 2005 Posts: 428 Comments: 129844
drak if you are out there what is your take on 99L thus far
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Some convection forming. We might see a good DMAX that will push it over the edge.
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Quoting extreme236:


It hasn't dissipated lol
When I say that I mean the yellow goes poof
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Quoting WeatherStudent:
I see, thank you. but i was actually referrinbg to pre-90l


Tell me your kidding correct.....Lets wait for it to emerge off and holds together before we start looking at things like that.....CALM DOWN !
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1480. viman
000
FXCA62 TJSJ 101936
AFDSJU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
336 PM AST MON AUG 10 2009

.DISCUSSION...A TROPICAL WAVE LOCATED ALONG 59 WEST LATE THIS
AFTERNOON...AND ASSOCIATED SMALL AREA OF LOW PRESSURE WITH
BURST OF SHOWERS AND THUNDERSTORMS JUST EAST OF THE WINDWARD
ISLANDS...IS EXPECTED TO MOVE WEST TO WEST NORTHWEST TONIGHT
THROUGH EARLY TUESDAY AND THEN PASS ACROSS OR JUST SOUTH OF THE
LOCAL AREA LATE TUESDAY THROUGH EARLY WEDNESDAY. ALTHOUGH IT
APPEARS THAT BULK OF ASSOCIATED MOISTURE WILL PASS MAINLY SOUTH OF
THE FA...AT LEAST A BAND OF MOISTURE SHOULD AFFECT THE LOCAL AREA
LATE TUESDAY THROUGH EARLY WEDNESDAY AND INTERACT WITH TUTT TO OUR
NORTH AND LOCAL EFFECTS...TO PRODUCE AN INCREASE IN CLOUDINESS...
SHOWERS AND THUNDERSTORMS ACROSS THE LOCAL ISLANDS.

A BRIEF BREAK IS EXPECTED...THEN A SECOND AND STRONGER TROPICAL
WAVE (CURRENTLY NEAR 47.5 WEST) IS EXPECTED TO ENTER THE EASTERN
CARIBBEAN EARLY WEDNESDAY AND BEGIN TO AFFECT THE LOCAL AREA
WEDNESDAY NIGHT THROUGH THURSDAY OR EARLY THURSDAY NIGHT...
FOLLOWED BY SHARP DRYING LATE THURSDAY NIGHT OR FRIDAY. THIS
TROPICAL WAVE HAS THE POTENTIAL TO PRODUCE A SIGNIFICANT INCREASE
IN CLOUDINESS...SHOWERS...THUNDERSTORMS AND GUSTY WINDS ACROSS THE
LOCAL ISLANDS.

THEREAFTER...WE WILL CONTINUE TO WATCH THE TROPICAL WAVE NEAR THE
CAPE VERDE ISLANDS...AS WELL AS THE WAVE BEHIND IT...AS SEVERAL
GLOBAL MODELS CONTINUE TO INDICATE INTERESTING POTENTIAL
DEVELOPMENTS WITH THESE TWO FEATURES OVER THE NEXT SEVERAL DAYS.
STAY TUNED...ITS AUGUST IN THE TROPICS.
Member Since: August 12, 2007 Posts: 0 Comments: 382
45 Min till 8PM TWO
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Quoting wunderkidcayman:

so that is why convection diminish to get better looking at the surface it will increase tonight I would not be surprised if we have red at 8pm or 2am


We aren't going to have anything close to red at 8pm and most likely not at 2am. Its gonna be til tomorrow before we can judge what 99L is going to do.
Member Since: August 2, 2007 Posts: 19 Comments: 19234
Quoting antonio28:




I go with A since Dpass show a Close LLC with 99L. Just need to fired convection and that could happend in the DMax hours. GFS nows show a Major in the CATL in 5 Days, fingers crossed here in the NE Caribbean.
lets hope it stays away from everyone even more South Florida and new Orleans which took a beating in 2004,2005
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Quoting nrtiwlnvragn:
Best looking QuikScat on 99L so far.



so that is why convection diminish to get better looking at the surface it will increase tonight I would not be surprised if we have red at 8pm or 2am
Member Since: June 13, 2009 Posts: 2 Comments: 12716
Quoting Patrap:
The New TwinSpan I-10 is now open Eastbound Via 10.




Its Like 35 Ft Higher than the older one
I sure hope it doesn't take as long to finish the West side as it did to do the East side
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Quoting cyclonekid:

D) Barbados Blob dissipates and 99L drops to yellow.


It hasn't dissipated lol
Member Since: August 2, 2007 Posts: 19 Comments: 19234
Quoting Chucktown:
Link

18Z GFS at 312 continues the trend as well offshore


No trend at all here with the GFS in terms of track its all over the place which is what you'd expect at such a long-range.Any model that far out has very little skill level.Remember the usual term for the long wave to be in any one general position is 6-10 days.

Adrian
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i can see that happening to some people on this blog you should try a baliys shake there good a alittle vanila icecream and add a shot of baliys and blend its so good

i might just take you up on that
Member Since: August 29, 2006 Posts: 22 Comments: 1352
Quoting Acemmett90:

i can see that happening to some people on this blog you should try a baliys shake there good a alittle vanila icecream and add a shot of baliys and blend its so good
for those who are wondering, its an irish cream, sometimes goes by the name Baileys...if I am going to drink bailys, I'd prefer it straight up, maybe a little crushed ice to chill it, forget the ice cream.
Member Since: August 15, 2008 Posts: 0 Comments: 2515
Quoting Seflhurricane:
8Pm TWO will be out within the Hour lets do a poll

What will happen at 8PM

A) No Change
B) wave near the windward islands goes to orange
C) 99L Dissipates And drops to Yellow


Quoting Seflhurricane:
8Pm TWO will be out within the Hour lets do a poll

What will happen at 8PM

A) No Change
B) wave near the windward islands goes to orange
C) 99L Dissipates And drops to Yellow


I go with A since Dpass show a Close LLC with 99L. Just need to fired convection and that could happend in the DMax hours. GFS nows show a Major in the CATL in 5 Days, fingers crossed here in the NE Caribbean.
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1466. Patrap
Quoting ALCoastGambler:
Wrong bridge Patrap. They are talking about the toll bridge. North to South



Im well aware what Bridge is da Causeway AL...LOL

Member Since: July 3, 2005 Posts: 428 Comments: 129844
Quoting nrtiwlnvragn:
Best looking QuikScat on 99L so far.




Officially a Closed Circulation. All we need is a good DMAX.
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Quoting hunkerdown:
your poll is all over the place, two subjects within one questions...there could be more than one correct answer just with the three youve given...and I see the true student was the first to answer, well done :)
sorry C should be 99L drops to yellow NO way its going to dissipate
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Any IR loop of 99l?
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Quoting Seflhurricane:
8Pm TWO will be out within the Hour lets do a poll

What will happen at 8PM

A) No Change
B) wave near the windward islands goes to orange
C) 99L Dissipates And drops to Yellow

D) Barbados Blob dissipates and 99L drops to yellow.
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Quoting WeatherStudent:


why does it take it out to sea, tim? also, do you believe it?


Take what out to sea....you talking about 99L or the future one...99L i don't think goes out to sea...it is high in lat. and most storm don't make it across when that high but, it appears to me it gets trapped under the High and keeps moving West......if it does that it will develop.
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1459. Patrap
The New TwinSpan I-10 is now open Eastbound Via 10.




Its Like 35 Ft Higher than the older one
Member Since: July 3, 2005 Posts: 428 Comments: 129844
Quoting Patrap:
The Causeway is a Engineering MArvel..I remeber driving on it when it was just one span,..and that was spookie.

Katrina didnt Budge her,but the Twin Spans East of it took a beating
Wrong bridge Patrap. They are talking about the toll bridge. North to South
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1457. JLPR
nice



but the south side seems weaker right now
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Wow, amazing to see that good of a quickscat on something that ugly.
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alot of dry air in the central atlantic
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A
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Quoting Seflhurricane:
8Pm TWO will be out within the Hour lets do a poll

What will happen at 8PM

A) No Change
B) wave near the windward islands goes to orange
C) 99L Dissipates And drops to Yellow
your poll is all over the place, two subjects within one questions...there could be more than one correct answer just with the three youve given...and I see the true student was the first to answer, well done :)
Member Since: August 15, 2008 Posts: 0 Comments: 2515
1452. Patrap
The Causeway is a Engineering MArvel..I remeber driving on it when it was just one span,..and that was spookie.

Katrina didnt Budge her,but the Twin Spans East of it took a beating
Member Since: July 3, 2005 Posts: 428 Comments: 129844
yup...it just started
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I figured we'd see an "out to sea" solution on this run.. 18Z GFS normally has a long term storm go out to sea after a few runs. Part of the game if you ask me. Tonight will probably have the storm striking NYC again lol.. Though this whole back to back runs reminds me alot of pre-Dean (2007) ;)
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Quoting presslord:
Pat...coming up on Modern Marvels on History Channel: Lake P Causeway...
I hope not the rebuilding of the twinspan...lol
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They always say if the LLC is closed and still in tact then there is always a chance
Member Since: August 29, 2006 Posts: 22 Comments: 1352
1446. WxLogic
Quoting nrtiwlnvragn:
Best looking QuikScat on 99L so far.




Most definitely... and still have chance to at least develop into a TD.
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Quoting extreme236:


Which is why I believe it still has potential. It has the structure, and if it can rock a good dmax tonight it's good to go.


I agree i think 99L will still be a player to the WEST! The longer it can hold together and get away from the stuff just to the North and it really does have to go much further before conditions start to improve a great deal.
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1444. JLPR
Quoting Seflhurricane:
8Pm TWO will be out within the Hour lets do a poll

What will happen at 8PM

A) No Change
B) wave near the windward islands goes to orange
C) 99L Dissipates And drops to Yellow


I will go with A
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Quoting presslord:
Pat...coming up on Modern Marvels on History Channel: Lake P Causeway...


Oh I want to watch this. Is it coming on now?
Member Since: August 2, 2006 Posts: 0 Comments: 1240
Quoting WeatherStudent:


C.


Doubtful, it could drop to yellow but it hasn't dissipated.
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Quoting extreme236:


Which is why I believe it still has potential. It has the structure, and if it can rock a good dmax tonight it's good to go.


I agree. Im not giving up on 99L just yet.
Member Since: August 2, 2006 Posts: 0 Comments: 1240
Quoting nrtiwlnvragn:
Best looking QuikScat on 99L so far.


i agree closed LLC i see all we need is a healthy amount of convection and we could have ourselfs tropical depression
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Pat...coming up on Modern Marvels on History Channel: Lake P Causeway...
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Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.

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