Hawaii braces for Felicia; 99L near the Cape Verdes Islands may develop
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.
Reader Comments
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Well there goes the dream of a zero-zero-zero season I guess. Good morning everyone!
Neither do I for some reason.
Same here.
Not quite. Forecast is for a Storm, that can change. Still 0, 0, 0 with the only entity battling dry air
Dvorak intensity estimates were sufficient for classification and the QS pass showed a closed low. What more do you need?
neither do I somehow I think this is a caribbean system
I was thinking more Florida/GOM, but your guess is as good as mine.
if they wouldn't classified, then someone will say, oohh they are too conservative,sometimes i don't underatand how people react, by the way good morning everyone
Based on the images this morning from NHC as predicted..MOJO is rising..
Stay well, enjoy the day
unless they know something we don't know
I'm a little more concerned about what the gfs is doing with the wave behind it even though its still over Africa and is a long term MODEL forecast to show how much I'm currently worried about TD2 but it could become Ana hmm...
If those dots are indicating strength you are going to be WAY off. Where those red dots are on 'your' map is where shear and SAL will be the greatest.
While TD2 wanders and probably recurves out to sea, the high will build in enough to keep the second problem on a full westward track until reaching the Islands, then it could either go OTS, or head up the USA Coastline. Lots of time to watch this one.
Oh, I knew there would be a problem! I didn't check the windshear! Thanks for pointing that out.
110600Z POSIT NEAR 14.4N27.9W
MOVING 270 DEGREES TRUE AT 11 KNOTS
11/06Z WIND 25KTS GUSTS 35 KTS
11/18Z WIND 30 KTS GUSTS 40 KTS
12/06Z WIND 35 KTS GUSTS 45 KTS
12/18Z WIND 35 KTS GUSTS 45 KTS
14/06Z WIND 45 KTS GUSTS 55 KTS
15/06Z WIND 50 KTS GUSTS 60 KTS
...................................
Oh, heck no! In fact I think they DUCKED the gun!
they don't want to alarm people about something that hasn't even formed yet
Well the EURO now makes it a Hurricane if that's anything new, oh yea.. It also hits the northern Islands. My local news is talking about that particular wave which is coming off the African Coastline today.
Well, it probably won't be "Bill" if you ask me.
TS MAKA
Date : 11 AUG 2009 Time : 123000 UTC
Lat : 13:56:15 N Lon : 171:46:59 W
CI# /Pressure/ Vmax
2.9 /1001.0mb/ 43.0kt
Final T# Adj T# Raw T#
(3hr avg)
2.9 3.1 3.7
It appears that the 850mb vort max is moving off the coast now. We should see a slow to gradual organization trend for the next 48 hours as this generally moves WNW. Conditions appear excellent for organization due to all the moisture left behind from TD2. Shear is about 8 knots and should stay to 5-15 knots throughout the next 72 hours. We should see the NHC mention this by later today.
Thanks for the info.
99 is now Two, dude.
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