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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Yes I did. Obviously a hurricane.
or .. or ... or
I think the wait is going to be killing a few people on here.
GA? Nah, never happens. Not in a million years.
Well... thirty years at least.
Really?I live in SPBC too,in Boca Raton.You?And that would be disasterous if a storm like that came but I'd imagine it more deadly if it would kind of ride along the coast from south to north starting from Miami to West Palm, that way everyone experiences the worst of the eyewall.:o
Wouldn't want to say typically yes for Florida...IT all depends on the Bermuda/Azores high and how strong they are. Anything that is near the Caribbean or Bahamas is always a threat for someone.
i agree fully...patience is not something that alot of people on this site have much of...
Tammy hit Georgia
In size that is... Diameter, radius, area.. etc.
NexSat, NRL/AFRICA/Overview
I see the circulation and the fact that storms started firing near the circulation towards the end of the loop. This could be the sleeper that nobody is talking about because they're worried about 99L which is 6 days away from any land interaction!
That has got to be a cat 4 or 5...
Tammy made landfall near Jacksonville Beach, but I was referring to hurricanes, anyway.
my boogieboard awaits with expectation :D
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.
12Z GFS at 216 hours. Notice 99l/Ana? off the East Coast, may cause enough weakness in the ridge to recurve the "Beast", hopefully.
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...
Viewing: 101 - 151
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