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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789. 7544
anyone thinks the gfs is under est the high pressure and anna and bill could get further west and not turn that fast up the east coast
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How do I decide the posts I want to see?? Everytime I am on here it looks like the blog is filtering for me...It is really annoying!! Sorry if this is a simple fix but I am still learning to navigate on here. BTW is it worth the $10 to join? TIA
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Time to see how many people get baited by WS. LOL.

See what you started IKE. Its all your fault for posting models.
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Quoting IKE:


Is now....

Thought so but wasn't sure, thanks
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Quoting jasoniscoolman10:
u see 99L ON THIS MAP NOW.
not really just its "outer bands" wait till tomorrow
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The EURO is now the only model that develops the new AOL at the Lesser Antillies. It forms 99L and keeps it alive, then recurves it before heading to the USA but then allows a more westward track on the wave off Africa behind 99L. Might just get 90L and 91L by tomorrow.
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Quoting IKE:
12Z ECMWF....


Still shows 99L developing. I still think it has a chance but its obviously going to take some time.
Member Since: August 2, 2007 Posts: 19 Comments: 19234
778. IKE
Quoting ALCoastGambler:
Ike when is the H supposed to build over AL, FL, or is it already building?


Is now....

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Quoting IKE:
12Z ECMWF....


And so the train starts...
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interesting EURO.. shows the area in the lesser antillies, 99L, and pre-90L developing some.

Link
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Quoting canesrule1:
oh be quiet i bet u, u can't type any better


Maybe not, but I can proofread my post before I post.
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771. IKE
12Z ECMWF....
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Quoting TStormSC:


What do you know, we got a little yeller fella out there now. Maybe at least a little SE rainmaker if nothing else.
i believe it will die out by tonight and well if it does make it then it could become something when it reaches the gulf of mexico's 90+ degree water, wait and see...
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Quoting IKE:


I was just looking at that. Almost all state met offices are talking about it.
Ike when is the H supposed to build over AL, FL, or is it already building?
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Quoting Acemmett90:

i dont know weather to laugh or cry thats was so funny
LOL
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What do you know, we got a little yeller fella out there now. Maybe at least a little SE rainmaker if nothing else.
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Quoting BrandiQ:



You should proofread your post before you post....


He doesn't know how to type or proofread, all his posts are like that.
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760. IKE
Quoting WeatherStudent:
What does that all mean, Ike? Potentially speaking here, that is.


Increased rain chances.
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Quoting presslord:
"Woman" ?!?!?!?!?!?!?!?! whew...


ya like you in that dress..
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Quoting presslord:


unfortunately....that is the proof read version...


WOW... That's a shame...
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Quoting presslord:
"Woman" ?!?!?!?!?!?!?!?! whew...
LMAO
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"Woman" ?!?!?!?!?!?!?!?! whew...
Member Since: August 13, 2007 Posts: 0 Comments: 10513
751. IKE
Quoting sporteguy03:
Ike found this from Melbourne's Afternoon Discussion:

Wed-sun...mid-latitude shortwave forecast to drift south through
Tennessee Valley at midweek looks to stall north of the state and
eventually washes out north of the region through the end of the
workweek. Consequently the subtropical ridge will become the bigger
player for the peninsula during this time period while moving
back north of the area Thursday. The ridge axis will lie north of
central Florida through the remainder of the extended forecast
opening up the tropics as the upstream focus.
Low-level flow will
remain fairly light with a daily sea breeze moving inland and thus
higher chances of showers and storms favoring the central and west
Central Peninsula after midweek. Still cannot rule out a small
threat for overnight and early morning showers along the
coast...especially the Treasure Coast. Shower and storm chances
are forecast to increase back to climatology by Thursday as deeper layer
moisture advects into the region through the weekend. High
temperatures will remain near climatology with upper 80s to near 90
degrees along the coast and lower 90s across the interior.

Rare for Melbourne to update they usually have one complete update.


I was just looking at that. Almost all state met offices are talking about it.
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Quoting IKE:


C post 721.


I meant the East Coast monster that the GFS is predicting, but thanks anyways, will have to watch that particular wave when it enters the GOM.
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Ike found this from Melbourne's Afternoon Discussion:

Wed-sun...mid-latitude shortwave forecast to drift south through
Tennessee Valley at midweek looks to stall north of the state and
eventually washes out north of the region through the end of the
workweek. Consequently the subtropical ridge will become the bigger
player for the peninsula during this time period while moving
back north of the area Thursday. The ridge axis will lie north of
central Florida through the remainder of the extended forecast
opening up the tropics as the upstream focus.
Low-level flow will
remain fairly light with a daily sea breeze moving inland and thus
higher chances of showers and storms favoring the central and west
Central Peninsula after midweek. Still cannot rule out a small
threat for overnight and early morning showers along the
coast...especially the Treasure Coast. Shower and storm chances
are forecast to increase back to climatology by Thursday as deeper layer
moisture advects into the region through the weekend. High
temperatures will remain near climatology with upper 80s to near 90
degrees along the coast and lower 90s across the interior.

Rare for Melbourne to update they usually have one complete update.
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Quoting BrandiQ:



You should proofread your post before you post....


unfortunately....that is the proof read version...
Member Since: August 13, 2007 Posts: 0 Comments: 10513
Quoting Drakoen:


He's in his second year at college should be expected


Then next year he will know everything, and in his senior year realize he actually knows nothing. LOL Well, that's how it was for me anyway. :)
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Member Since: October 28, 2006 Posts: 57 Comments: 31667
Quoting IKE:


Also shows a low heading for SE Florida.


That's TW wave with attendant low currently @45W which NAM is hinting towards an organized disturb region heading WNW.
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Quoting reedzone:
Earlier, about a month ago I predicted the tropics to start getting active around now.. The pattern this year looks to be putting the East Coast at risk more then the Gulf Coast. I see soem East Coast misses of course, meaning fish storm lol. Though for this upcoming storm, it's soo far out, but I can see a "Floyd" like situation. Notice the GFS has the storm moving over Hispaniola, so it will weaken some if it does that, but all bets are off on the landfall until about probably 5 days. By then, we might get an idea of where the area will be, but not the exact state or county, just the regions like Gulf Coast, East Coast.


all storms that explode off the coast of africa with this pattern will be fish as they will ride the upper level currents right into the weakness, its the storms that start getting strong around puerto rico, then ride the weakness right into the east coast.
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Quoting keywestbrat:
mcmftlaud, that was brilliant and hilarious, thanks


Thanks KeyWestBrat
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Link
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Dr. Masters co-founded wunderground in 1995. He flew with the NOAA Hurricane Hunters from 1986-1990. Co-blogging with him: Bob Henson, @bhensonweather

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