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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This morning on the radio I heard the meteorologist: TD #02. Immediately hoped to WU. She said the 52W wave is looking dangerous. TD 02 will miss the island and she mentioned the mega ultra powerful future Bill which would pass south of PR. Of course... just models and this will all surely vary.
I believe that is the wave currently @50W being represented there.
I expect this from the CMC and occasionally the GFS but three trusted models? That system behind TD 2 is the one to watch.
That's what I was thinking....the wave near 50W makes it into the GOM. Not TD2(for now).
That GFDL map he posted was at 114 hours...4 1/2 days...seems about right for the wave near 50W.
Yes, it is. TD2 has a greater chance of going out to sea.
Agree.
Yea, I'm not so much ruling out 50W but still give it a low chance in the time being.
Looks like something associated with the wave in the C-ATL, the timing would agree anyway. It's hard to pick out the instigator on that run.
At this point it MAY make it to anywhere E of Brownsville...Long way to go and a lot of wait and see...
Do need to be careful on the GFDL run, the system near South Florida is at the very edge of the GFDL domain, and my past experience is the steering at the end of the model run may not be that accurate. Agree, that would be the system currently ~51W.
A million thanks, Oz!!! And a million thanks to everyone!! We're all part of something really good...
So am I but run a visible loop. There is no way you cant classify a spin like that.
I agree. Conditions will be pristine behind TD2, especially if it comes off lower.
Pretty much. VERY hot waters, low shear. We better hope that if the models are right and this thing hits Florida, it doesn't cross into the GOM.
That's a tough question.
It may not amount to anything with that wave but some rain, but, it could be more.
Yea....
Because Invest 99L became TD Two.
The WU maps havent updated. Give it time.
99L has been upgraded to TD2
"LONG TERM (THURSDAY NIGHT-MONDAY)...THE GFS AND ECMWF MODELS
REMAIN IN DECENT AGREEMENT DURING THE EXTENDED TIME PERIODS AND A
BLEND WAS UTILIZED IN THE EXTENDED PORTION OF THE FORECAST. THE
GENERAL WEATHER PATTERN DURING THIS TIME ALOFT WILL FEATURE A
MOVEMENT OF THE H5 SUBTROPICAL RIDGE. INITIALLY THIS RIDGE STARTS
OUT IN A POSITION WELL OFF SHORE ROUGHLY OVER BERMUDA. THE RIDGE
WILL THEN SLOWLY RETROGRADE WESTWARD TO A POSITION OFF THE
SOUTHEAST COAST BY SUNDAY MORNING AND THEN BEGIN TO STRENGTHEN BY
MONDAY. THIS WILL LEAVE FLORIDA IN A DEEP SOUTHEASTERLY FLOW AND
OPEN THE AREA TO FAIRLY SIGNIFICANT TROPICAL MOISTURE FEED OVER
THE WEEKEND. GFS PWAT VALUES RISE SHARPLY ON SATURDAY TO VALUES OF
AS HIGH AS 2.3 INCHES. THIS INCREASED TROPICAL MOISTURE AND THE
PRESENCE OF A FAIRLY WELL DEFINED VORT MAX ROTATING NORTHWESTWARD
ALONG THE PERIPHERY OF THE H5 RIDGE...HAS LEAD TO THE INCREASING
OF POPS ON SATURDAY TO THE LIKELY CATEGORY. PRESENCE OF ORGANIZED
LIFT AND GOOD MOISTURE SHOULD ALLOW FOR HIGHER COVERAGE OF STORMS
OVER THE WEEKEND. THIS INCREASE IN POPS WAS THE BIGGEST CHANGE. IT
ALSO LEAD TO AN INCREASED SKY COVER AND A SUBSEQUENT SLIGHT
LOWERING OF TEMPERATURES. NEWEST MEX GUIDANCE SUGGESTS UPPER 80S
TO LOW 90S ON SATURDAY AND SUNDAY AND THIS IS IN LINE WITH THE
THOUGHT PROCESS OF ENHANCED CONVECTIVE ACTIVITY."
invest 99 was upgraded to a tropical depression.. so there is no invest99 anymore
Invest-TD-TS-H-MH
Invest 99L was upgraded to TD 2 but some websites will be slow to update the information.
I can't see it with my glasses on either.
Looks like a significant cane.
Has a long way to go
Thanks
Yeah, with that many closed Isobars, who cares, just run, lol.
Dr. Masters will prolly update soon.
I see the tropics are waking up too (after many false starts).
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