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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Pat...coming up on Modern Marvels on History Channel: Lake P Causeway...
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Quoting hunkerdown:
shouldn't you two be on the same page ?


Gettin there..lol.
Member Since: August 2, 2006 Posts: 0 Comments: 1240
1436. Patrap
ReliefWEB
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Quoting nrtiwlnvragn:
Best looking QuikScat on 99L so far.




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.
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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
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Best looking QuikScat on 99L so far.


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Quoting TampaSpin:
I just seen the GFS model and how strong of storm its showing . Heck i had to go pee after seeing that! WeatherStudent you can plee or plead the fifth which ever way you like.....just tell our attorney to tell Ana or Billy Bob to stay away from here if he or she is going to take the fifth with you!


Im pretty dang sure we're going to see development out of that wave.. intensity will at least be a Strong TS or a minimal Hurricane if it does.
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shouldn't you two be on the same page ?

Women....lol
Member Since: August 29, 2006 Posts: 22 Comments: 1352
Death toll and those feared missing in Taiwan keeps on increasing...

'Hundreds lost in Taiwan typhoon'
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Quoting TampaSpin:
I just seen the GFS model and how strong of storm its showing . Heck i had to go pee after seeing that! WeatherStudent you can plee or plead the fifth which ever way you like.....just tell our attorney to tell Ana or Billy Bob to stay away from here if he or she is going to take the fifth with you!
HAHAHA
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GFS bent on this making this thing a hurricane.

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convection starting to refire in 99L but has alot of dry air to its north
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now youre talking

Yeah buddy i might need a few of those by the time this week is over so if my posts start getting a little topsy turvy take them with a grain of salt...one time i tried to look at a hurricane on the visible loop when i was tipsy and i spun right out my chair....bad idea lol
Member Since: August 29, 2006 Posts: 22 Comments: 1352
Quoting alaina1085:


Yuck..lol. Ill have a mudslide. I love chocolate.
shouldn't you two be on the same page ?
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I just seen the GFS model and how strong of storm its showing . Heck i had to go pee after seeing that! WeatherStudent you can plee or plead the fifth which ever way you like.....just tell our attorney to tell Ana or Billy Bob to stay away from here if he or she is going to take the fifth with you!
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1406 A commrade in arms. I love the Long Island Ice Tea. Usually start with 2 of those and then hit the Jack on the Rocks.

My opinion. The first one 99l fishing for the Oceanic White tip. and the second not sure. As far as Barbados will go poof. Nothing to back that up JMHO.
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Presslord if it is a act we should change his name from WS to Hollywood student. As far as B remember what Rumsfeld said there are unknown unknowns.
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1419. BA
wave watch 3 not seeing anything significant in the gulf up to 180 hours out
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good evening, i think 99L will be yellow and the Barbados AOI will stay yellow for the next TWO.
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Quoting louisianaboy444:
LOL... I could use a drink right about now too

Long island ice tea?
golfer's cocktail ain't too bad either...of a ice cold shot of Patron Silver
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1415. Patrap
NHC Tropical Model Overview


If ya gonna drive with the Models,ya might as well have the Keys,..but be back for dinner WS.
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just call him Mr. Adjective
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Quoting louisianaboy444:
LOL... I could use a drink right about now too

Long island ice tea?


Yuck..lol. Ill have a mudslide. I love chocolate.
Member Since: August 2, 2006 Posts: 0 Comments: 1240
Pressure Tendency (PTDY): -0.02 in ( Falling )

Someone posted earlier how the barbaos disturbance gained more divergence aloft than convergence so the pressure might start to fall a bit
Member Since: August 29, 2006 Posts: 22 Comments: 1352
Quoting Weather456:


I'll email you
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Quoting louisianaboy444:
LOL... I could use a drink right about now too

Long island ice tea?
now youre talking
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1408. Dakster
Quoting louisianaboy444:
LOL... I could use a drink right about now too

Long island ice tea?


Not really my drink - but if you're pouring.
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1407. KEEPEROFTHEGATE (Mod)
Quoting Weather456:
Still not a 100% convince about intensity but development of the wave seems likely.

Later
later 456
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LOL... I could use a drink right about now too

Long island ice tea?
Member Since: August 29, 2006 Posts: 22 Comments: 1352
Quoting Seflhurricane:
evening weather do you believe the NHC will change the probability of development for the cape verde tropical wave or the one near the windward islands your thought????


I'll email you
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1403. Dakster
Quoting presslord:
Pat...many times I have pleaded FOR a fifth....


LOL... I could use a drink right about now too..

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1402. KEEPEROFTHEGATE (Mod)
Quoting WeatherStudent:
interestings, it penetrated right through the through, it prob. did so cause of it's horrendous intensity. we'll see what the midnight run conveys.
you should take a nap so yer refreshed for the next run
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Quoting Weather456:
Still not a 100% convince about intensity but development of the wave seems likely.

Later
evening weather do you believe the NHC will change the probability of development for the cape verde tropical wave or the one near the windward islands your thought????
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Quoting Acemmett90:

in court or on this site
tell me, what is the court serving up these days, other than sentences
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Quoting WeatherStudent:
interestings, it penetrated right through the through, it prob. did so cause of it's horrendous intensity. we'll see what the midnight run conveys.


Did you get a Thesaurus? You are really tossing out the adjectives and adverbs out there today.
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Still not a 100% convince about intensity but development of the wave seems likely.

Later
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Quoting presslord:
Pat...many times I have pleaded FOR a fifth....
I usually just have to beg....LOL
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1396. N3EG
Quoting WeatherStudent:


Go over the Constituional bi-laws of this great nation of ours, aquack, then we'll talk, madame.


Kids...you cain't learn 'em nuthin no more...
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1395. aquak9
Quoting WeatherStudent:


Go over the Constituional bi-laws of this great nation of ours, aquack, then we'll talk, madame.


I'm fairly well-versed in that area, WS...sounds like you are, too. Congrats. :)

So many young folks use common phrases these days, and have no idea the true meaning behind them.
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Link

18Z GFS at 312 continues the trend as well offshore
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Central Pacific about to get their second named storm of the season lol
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Quoting WeatherStudent:


Go over the Constituional bi-laws of this great nation of ours, aquack, then we'll talk, madame.
that would be bylaws...just want to keep you on the right track
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Out to sea on the GFS with mid latitude trough amplification

Bill? i sure hope so bye bye Bill you won't be hurting anyone my friend i can have a shot to that pat
Member Since: August 29, 2006 Posts: 22 Comments: 1352

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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.