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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189. IKE
Quoting watchingnva:


you love feeding the hysteria don't you, your probably sitting back laughing...lol


good on ya...it is slightly amusing.


Sorry...I'm not laughing about any of this.
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Looks like 99L models are saying lets go west!

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187. IKE
Quoting Orcasystems:


This is hilarious... models at 5 days plus are at best questionable....

Models at 9 days out..and people think the sky is falling... I think there is a nursery rhyme about this?


Doesn't the NHC look at 1-2 week models for the MJO? I've read their discussions on that and it does go out for a 2-3 week period.
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Quoting IKE:


Probably won't curve north and out....

9 days out though.


Okay .. Ike... Please Tell Me theres a Trought to Pick it up?
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185. 7544
gfs away from fla now
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Quoting BurnedAfterPosting:


Off the top of my head; Charley made landfall in the afternoon, Dennis in 2005 did as well. So did Floyd in 1999


Gustav made landfall in the morning just last year, Katrina (2005) made landfall early morning also.
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I would consider Katrina a daytime landfall too.
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its blowing up
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Quoting IKE:


Probably won't curve north and out....

9 days out though.


There's a chance 99L will leave a weakness in the ridge that will allow it to recurve. However, that door will only be open for a short period as they pass the islands. If 99L gains to much latitude, the door will slam shut and the beast keeps moving west.
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According to Hurricanecity.com

"QUOTE"
Going back to 1900, 61.11% of Atlantic Hurricane seasons with 1st named storm starting after August 9th saw a major hurricane hit land. The majority of landfalls in those seasons were in South Florida with 5 majors.
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Quoting IKE:


Probably won't curve north and out....

9 days out though.


you love feeding the hysteria don't you, your probably sitting back laughing...lol


good on ya...it is slightly amusing.
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Quoting IKE:


Probably won't curve north and out....

9 days out though.


This is hilarious... models at 5 days plus are at best questionable....

Models at 9 days out..and people think the sky is falling... I think there is a nursery rhyme about this?
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Quoting IKE:
If the GFS is completely wrong about this system, I'll be shocked. The ECMWF shows it, but appears delayed compared to the GFS.


I will be shocked as well. GFS/ECMWF combo is the best there is when it comes to cyclogenesis and both model agree on a similar 500mb pattern coming up
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No reason for anyone to get excited or panic. Just watch it for the next several days and see what happens. The model support is concerning though.
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Quoting weatherneophyte:
Ok, I can in no way comment on any weather systems, but I do spend a lot of time lurking here and learning. I do have a question. I posed to my wife that it seems that hurricanes always make landfall at night in the US. She thought it was a ridiculous statement, but couldn't remember a hurricane making landfall in the daytime. Is there a scientific reason for this, or is it just a matter of blind luck?


Off the top of my head; Charley made landfall in the afternoon, Dennis in 2005 did as well. So did Floyd in 1999
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about the canes hitting only at night, they do have a tendency to do that... its interesting and worth exploring

also, people stop paying so much attention to long range models PLEASE. as i say they are for 'entertainment purposes only'. just track the storm and refrain from making fools out of yourselves :)
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Quoting IKE:


Probably won't curve north and out....

9 days out though.

THAT aint good!! actully thats BAD!!
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Well for now GFS has been consistent with "B"... we'll see how 12Z CMC/ECMWF/NOGAPS represent this feature along with "A".
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LOL, now you guys are making 10-day predictions of intensity for a storm that hasn't even formed yet...the models are even worse on intensity than they are on track...
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169. 7544
watch the gfs turn it ne next
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KYhomeboy and 69Viking

I mentioned the Sountern Caribbean earlier and no response. Glad some others are noticing.
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166. IKE
Quoting sammywammybamy:



Lol Ike..

Help Me Please?

Whats it Mean??


Probably won't curve north and out....

9 days out though.
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Quoting IKE:
Look at the steering in 9 days.....no troughs...



dammit ike, why?
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164. IKE
If the GFS is completely wrong about this system, I'll be shocked. The ECMWF shows it, but appears delayed compared to the GFS.
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Quoting 69Viking:


He made no mention of it I guess because none of the models are picking it up for development. Wind shear is pretty low in the area so I'm keeping an eye it since it's a lot closer to home than 99L!


Rain flowing freely here in Barbados, very little wind though.
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Quoting IKE:
Look at the steering in 9 days.....no troughs...




Lol Ike..

Help Me Please?

Whats it Mean??
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Quoting Drakoen:


The entire eastern seaboard


Lets hope this thing stays away.
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Quoting CaneWarning:


East coast including Florida, or are you thinking more of a threat to Carolina?


The entire eastern seaboard
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Quoting WeatherStudent:


oh my god, that image just left me breathless, fm, for the love of god, let's hope not.


cmon...its a model 7 days out on a system that hasn't even left the coast yet...relax...
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158. IKE
Look at the steering in 9 days.....no troughs...

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Quoting Funkadelic:


OMG I know right.. Thats strange to see all this model support this far out. Question Futuremet: Based on steering (and I know its a hell of a long time from land) What State'(s) should keep an eye on this thing?

Thanks in advance buddy.


SE states
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Quoting IKE:
9 days from now....



Ike... Does it go out Further...

I think i know were its going to go from there........

.....
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Quoting Drakoen:
Again the pattern over the next two weeks favors east coast hits. The Bermuda high ridge builds westward and a trough sets up over the eastern Plains region.
do u think what i wrote (post 112) is possible?
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154. JRRP
.
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Quoting Drakoen:
Again the pattern over the next two weeks favors east coast hits. The Bermuda high ridge builds westward and a trough sets up over the eastern Plains region.


East coast including Florida, or are you thinking more of a threat to Carolina?
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Quoting IKE:
9 days from now....



:(
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Quoting sammywammybamy:
Canesrule1


That Is Not Funny!!!!!!!!!

bro calm down!, lol, i'm giving u what models say and what the steering is, im not lying.
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Ok, I can in no way comment on any weather systems, but I do spend a lot of time lurking here and learning. I do have a question. I posed to my wife that it seems that hurricanes always make landfall at night in the US. She thought it was a ridiculous statement, but couldn't remember a hurricane making landfall in the daytime. Is there a scientific reason for this, or is it just a matter of blind luck?
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we should be getting a floater setup this afternoon as 99l approaches 30w...

barbados system is firing off some decent convection trying to wrap up around the coc/llc...i wanna see if it can continue to do this throughout the day and night...
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148. IKE
9 days from now....

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Quoting futuremet:


That has got to be a cat 4 or 5...



OMG I know right.. Thats strange to see all this model support this far out. Question Futuremet: Based on steering (and I know its a hell of a long time from land) What State'(s) should keep an eye on this thing?

Thanks in advance buddy.
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146. JRRP
oh God again to the carib
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Quoting extreme236:


Just because the GFS is spinning up its landfall theories again doesnt mean this is definitely going to one specific area, especially something hasnt formed yet.


Im Just Saying in the Next 100 years ...


Im not Saying that 99L or the Wave behind it will hit florida

the Odds are actually against it... i think
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i think that 99L will be classified as a TD before Wednesday.
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Again the pattern over the next two weeks favors east coast hits. The Bermuda high ridge builds westward and a trough sets up over the eastern Plains region.
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12Z GFS at 216 hours. Notice 99l/Ana? off the East Coast, may cause enough weakness in the ridge to recurve the "Beast", hopefully.
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Quoting CycloneOz:


WPB landfall would have me at 301 N. Olive Ave, West Palm Beach, FL in the Governmental Center parking structure.

yah sounds like fun until you have a palm tree up your butt
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Well as expected... as we move through the day(s) the models are starting to show a more real representation of the strength of the AB High(s).
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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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