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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Convection wise but structural wise not that bad its has an almost closed LLC and vorticity values are going up like StormW eluded to
Maybe Yellow for Barbados Blob...I doubt it though. They want to see how it will sustain its convection.
"Quietly sits here shaking his head."
:)
Here is mine :)
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......
I was able to quote an image!
LOL
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.
If you have a Hurricane Plan and Supplies,and a Place to evac to outside your State,.
Post .. 7
7
Don't forget about Charley in 2004. He showed up a little early for happy hour.
To me that is one of the most inaccurate maps there is
yeap sah dust is effecting 99l right now i agree
7
Wave near 45W.
7
7
Report and ignore.
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.
Yep
...then hosed down with tar and rolled in feathers.
Don't make me ignore you too (not trying to sound mean).
0.
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