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

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

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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**tapping microphone*** Is this thing on?
Member Since: Posts: Comments:
Quoting Acemmett90:

i pulled my hair out yesterday with some of the comments and some left me shaking my head

really they were making me LMAO
people were being rude and the recipient was saying "Good evening sir." lol
i was rollin
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I do believe this:is an area to watch, just keep your eyes peeled!
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Hmmm... interesting...

The orange circle gives everyone a lot of lead time to get ready, the yellow one could surprise a lot of folks.

The SST's are very high in Caribbean and GOM, so there's lots of fuel for a fire. Time for the media to start paying attention....
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Ban people for making innocent comments?

I understand if someone gets abusive, but...
Member Since: August 13, 2007 Posts: 0 Comments: 489
Quoting kmanislander:
Well I see that the area near 59W has caught the attention of the NHC as I surmised earlier today that it would.

The convection and organization has been on a steady upward tick all day. I would not be surprised to see this area continue to improve. The real test will be to see how it fares during the afternoon heat.

Any prognosis for direction etc with specific regard to Cayman Islands? I know it is early days but in my mind, this poses more of an "immediate" (in terms of proximity) potential threat to Caribbean than 99L - will not hold u to anything u may say LOL
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What is forecast to happen with that massive high pressure over NC?
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Quoting louisianaboy444:
Poll how many hairs will i pull out tonight...

a) none
b) 10
c) 15
d)Rogane for men


LMAO... Better be none :P
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Quoting 69Viking:


A bunch of us mentioned this area today before the NHC made it yellow!


We can share LOL
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Surely the Barbados blog is much closer to all of the nice SST's and low dust that the Caribbean Sea has to offer..then the Gulf?

How is shear projected over the Caribbean Sea this week?
Member Since: August 13, 2007 Posts: 0 Comments: 489
You can spot a small low level circulation on RGB imagery
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Poll how many hairs will i pull out tonight...

a) none
b) 10
c) 15
d)Rogane for men
Member Since: August 29, 2006 Posts: 22 Comments: 1365
99L= fish storm
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Using a dellLaptop while my Home System is getting a Lobotomy and new upgrade,..
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Quoting Patrap:
Heya Kman...that Wave has potential as to track and Forming into a Quick threat for many


Hi Pat,

Indeed, that is why I was watching it so closely. That area has been known to spin systems up quickly and some have been very strong. There is high pressure expanding in the Caribbean and shear is very low there now.

This is the one to focus on now IMO
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Shear is low for #2 AOI
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Quoting Drakoen:
They might make the Barbados disturbance an invest if the trend continues. While conditions are fairly dry, upper level winds are favorable for development.


It has been raining cats and dogs all day.

Plenty of acoustics to go with it too!!
Member Since: August 13, 2007 Posts: 0 Comments: 489
Bet Florida panhandle folks think this disturbance is heading their way this weekend from Barbados, right?
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464. WAHA
Quoting hurricanehanna:
So the yellow AOI could get named before the orange one?

yes
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Quoting hurricanehanna:
So the yellow AOI could get named before the orange one?


I doubt it, because all it will take is a convection increase for 99L to develop. It already has a good structure. The AOI near the Antilles has to develop all of that.
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Quoting Acemmett90:

new poll
HOW many people will get banned tonight?
A 10
B 20
C Alot
i will Go with B i know a few on here now that need to be banned to keep the atmosphere quiet
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oh great, anotehr oen to track, where might this one ehad, guys?

here's a dart...throw it...lol who knows
Member Since: August 29, 2006 Posts: 22 Comments: 1365
Quoting futuremet:
Tampaspin

What is noticeable about the convergence and divergence of the Antilles is the fact that they are well stacked. If the divergence was elongated, this would indicate that the most of the convection was a result of upper level diffluence, which was the case over the past few days as a anticyclone was located over the region when the TUTT was lifting. Persistent low level convergence can also indicate the formation of some sort of surface low.


Its really wrapping very quickly considering what it looked like late last nite. Its actually better organized than 99L currently is in my honest opinion.
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Quoting tornadofan:
Kudos to Kman for mentioning the now yellow area.


A bunch of us mentioned this area today before the NHC made it yellow!
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d-max is in the AM and s-min is in the PM? I always get them confused.
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Quoting WeatherStudent:
oh great, anotehr oen to track, where might this one ehad, guys?

@ you, RUN!
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there have been slight pressue drops from this morning. a west wind at barbados and a wsw wind in st vincent. indications that a surface low is about forming
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So the yellow AOI could get named before the orange one?
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The center of the system just east of Barbados:
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449. 7544
Quoting cg2916:
They mentioned the Barbados area. I'm surpsrised.


might be 90l soon before the new wave off of africa would we all laugh if the 60 waves becomes anna first ahahahah
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Heya Kman...that Wave has potential as to track and Forming into a Quick threat for many
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Quoting futuremet:
Tampaspin

What is noticeable about the convergence and divergence of the Antilles is the fact that they are well stacked. If the divergence was elongated, this would indicate that the most of the convection was a result of upper level diffluence, which was the case over the past few days as a anticyclone was located over the region when the TUTT was lifting. Persistent low level convergence can also indicate the formation of some sort of surface low.


Those are some really nice observations. This disturbance will be very interesting to watch. Now that the NHC is monitoring the system, we could very well see Invest 90L.
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Kudos to Kman for mentioning the now yellow area.
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this blog is going to go bonkers before the 8Pm TWO i has been crazy today wait till tonight
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They might make the Barbados disturbance an invest if the trend continues. While conditions are fairly dry, upper level winds are favorable for development.
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Well I see that the area near 59W has caught the attention of the NHC as I surmised earlier today that it would.

The convection and organization has been on a steady upward tick all day. I would not be surprised to see this area continue to improve. The real test will be to see how it fares during the afternoon heat.
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Storm setups in the Gulf are always bad during EL-Nino years, in fact most hurricanes during El-Nino years are majors...look it up.
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Quoting bajelayman2:


Hi Futuremet, I am thinking, though many will think me crazy, that the Barbados blob (cool name), may just be Ana...


Perhaps...perhaps....

I thought this wave diminishing completely yesterday.
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Dr. Masters co-founded wunderground in 1995. He flew with the NOAA Hurricane Hunters 1986-1990. Co-blogging with him: Bob Henson, @bhensonweather

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