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 WxLogic:
12Z CMC Showing both "A" and "B" on a more W track as expected (at least by me)... like I mentioned before... models are underestimating the AB High strength.


Yep
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Hurricane Preparation
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MARINE WEATHER DISCUSSION


A THIRD WAVE IS ALONG 26W WITH A SURFACE LOW ALREADY INDICATED
NEAR 14N25W AT 12Z THIS MORNING. PREVIOUS GUIDANCE APPEARS TO
HAVE MOVED IT WESTWARD TOO QUICKLY AND CURRENT NHC THINKING IS
MUCH SLOWER AND STILL JUST E OF THE TROPICAL ATLC ZONE EARLY
NEXT WEEK. MENTIONED IN THIS MORNING HIGH SEAS WITH LOW NEAR
16N35W AT SUNRISE WED AND AMENDED FORECAST TO MENTION POSSIBLE
TROPICAL CYCLONE PER NHC.
Member Since: September 23, 2005 Posts: 16 Comments: 11635
Quoting MahFL:
I remember reading about how the levee inspectors would meet up to check the levee, they'd do a quick look see, hang about a bit, then go to a nice resteraunt and all order steaks for lunch. Those people should have been shot with s#@!.

Report and ignore.
Member Since: December 21, 2007 Posts: 13 Comments: 3047
Quoting Patrap:
A Logical poll.

If you have a Hurricane Plan and Supplies,and a Place to evac to outside your State,.

Post .. 7


7


7
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Quoting BurnedAfterPosting:


To me that is one of the most inaccurate maps there is
Yea...its becoming less and less trustworthy.
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12Z CMC Showing both "A" and "B" on a more W track as expected (at least by me)... like I mentioned before... models are underestimating the AB High strength.
Member Since: August 14, 2008 Posts: 4 Comments: 5071
6.5 ?? Does that count?
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Quoting Patrap:
A Logical poll.

If you have a Hurricane Plan and Supplies,and a Place to evac to outside your State,.

Post .. 7


7


7
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Anyone lives in Barbados? The blob looks nice on radar
Member Since: July 19, 2008 Posts: 43 Comments: 4051
Gotta run out. Don't let WS hit this while I'm gone.




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325. IKE
Quoting cyclonekid:
What in the world?


Wave near 45W.
Member Since: June 9, 2005 Posts: 23 Comments: 37860
Quoting BurnedAfterPosting:


To me that is one of the most inaccurate maps there is
LMAO, i agree 100%
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Quoting Patrap:
A Logical poll.

If you have a Hurricane Plan and Supplies,and a Place to evac to outside your State,.

Post .. 7


7


7
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all 99l has to do is maintain some persistant convection i think it could do that within the next 12 to 24 hours when things can become more conducive....so we wait.....
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321. 7544
Quoting cchsweatherman:


Haven't had much time to do some good analysis, but in performing some quick analysis, it doesn't seem much has changed.

In looking at water vapor imagery, its clear that some dry air and possibly SAL to the north has affected the system preventing further organization and convective development. Also, like a few have mentioned, the system lacks a defined SE wind which is needed for this to complete a closed surface low. Over the past several hours, it appears that the invest has been moving slightly north of due west and should continue to do so for the next 48-72 hours.

Overall, Invest 99L still stands some more improvement both in organization and thunderstorm action before becoming a tropical cyclone.


yeap sah dust is effecting 99l right now i agree
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and the winner is B (orange) with 6 votes.
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Want to know how I quote an image?
Member Since: December 21, 2007 Posts: 13 Comments: 3047
Quoting cyclonekid:
What in the world?


To me that is one of the most inaccurate maps there is
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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?


Don't forget about Charley in 2004. He showed up a little early for happy hour.
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A Logical poll.

If you have a Hurricane Plan and Supplies,and a Place to evac to outside your State,.

Post .. 7


7
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Quoting eddye:
okay cchsweatherman what you think 0f 99l


Haven't had much time to do some good analysis, but in performing some quick analysis, it doesn't seem much has changed.

In looking at water vapor imagery, its clear that some dry air and possibly SAL to the north has affected the system preventing further organization and convective development. Also, like a few have mentioned, the system lacks a defined SE wind which is needed for this to complete a closed surface low. Over the past several hours, it appears that the invest has been moving slightly north of due west and should continue to do so for the next 48-72 hours.

Overall, Invest 99L still stands some more improvement both in organization and thunderstorm action before becoming a tropical cyclone.
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What in the world?
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312. 7544
orange and every time there is a strong over cat 1 hurricane the gfs has it going all over theplace so we cant judge by these early runs wait and watch is all we can do for now
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Quoting Orcasystems:

LOL
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In Barbados the wind is picking up a bit from the NW
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Quoting jasoniscoolman10:


I was able to quote an image!
Member Since: December 21, 2007 Posts: 13 Comments: 3047
TD - orange
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Quoting FloridaTigers:


Miami luckily has some of the best building codes in the country because of Andrew. You won't see the damage in Miami on the coastline from storm surge like MS or AL, because of the geography of the coastline. However, a category five winds would cause far more damage inland. If Andrew hit only 10 miles to the north, it would've been the example of a metropolitan area demolished by mother nature, ala how Katrina is NOLA today.


Absolutely Dade and Broward county have the best building codes when it comes to hurricane mitigation..... However, buildings built to code had failures of windows and shutters during baby Wilma......
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Just curious... have two hurricane ever hit a gulf coast state and an east coast state at the same time?
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Quoting PcolaDan:
My new tag line:
"Quietly sits here shaking his head."
:)



Here is mine :)

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12Z CMC
Member Since: July 19, 2008 Posts: 43 Comments: 4051
My new tag line:
"Quietly sits here shaking his head."
:)
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Quoting canesrule1:
the TWO will be out in about 30 minutes.
LETS DO A POLL!!!!

WHAT IS YOUR PREDICTION FOR THE 2 O'CLOCK TWO?

A.YELLOW

B.ORANGE

C.RED

D.TD

E.NOTHING

Maybe Yellow for Barbados Blob...I doubt it though. They want to see how it will sustain its convection.
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yah it looks poorly organised right now

Convection wise but structural wise not that bad its has an almost closed LLC and vorticity values are going up like StormW eluded to
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Quoting BenBIogger:


B


Orange
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Quoting WeatherStudent:



absolutely FM, i'm vers cared myself. adrian, also known as hurricane23, once said on this blog,a nd i will quote the following '' if the pattern sets up perfectly over the conus, with a major cane out in the atlantic, the us will experience a once in a lifetime hurricane hit'' unqquote. that indeeds appears to be shapping up for next time. i dont know about y'all, but this upcoming weekend, i'll be taking the tiem to go over my hurricane kit, just in case, :)


move to Alaska..
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Quoting FloridaTigers:


Miami luckily has some of the best building codes in the country because of Andrew. You won't see the damage in Miami on the coastline from storm surge like MS or AL, because of the geography of the coastline. However, a category five winds would cause far more damage inland. If Andrew hit only 10 miles to the north, it would've been the example of a metropolitan area demolished by mother nature, ala how Katrina is NOLA today.


You could make the argument that NOLA is an example of a metropolitan area being demolished by poor planning and engineering. The city survived the hurricane just fine. Poor levys destroyed the city.
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Quoting weathersp:
I just noticed that when the 12z GFS has hitting "Bill" near MD on the 24th. The 24th is also when I start school again!

Bwahahaha!

Senior! Wo0t!

*sorry had to get that out*
00z had it hitting Miami, 06z had it hitting New Orleans, and previous runs ranged from southern texas to a fish storm.
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Are we safe from this virus that hit the blog? Was it only on the last blog? From an image?
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Quoting Drakoen:


No. Development into a tropical storm.


Your right.. TS
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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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