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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WTNT42 KNHC 111010
TCDAT2
TROPICAL DEPRESSION TWO SPECIAL DISCUSSION NUMBER 1
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL022009
600 AM AST TUE AUG 11 2009
FIRST LIGHT VISIBLE SATELLITE IMAGES SHOW THAT THE BROAD LOW
PRESSURE AREA ASSOCIATED WITH A TROPICAL WAVE THAT WE HAVE BEEN
TRACKING OVER THE FAR EASTERN TROPICAL ATLANTIC HAS ACQUIRED
SUFFICENT ORGANIZED DEEP CONVECTION TO BE DESIGNATED AS A TROPICAL
DEPRESSION. THE TROPICAL CYCLONE IS SITUATED OVER MARGINALLY WARM
SEA SURFACE TEMPERATURES AND THE VERTICAL SHEAR IS CURRENTLY RATHER
WEAK. THE OFFICIAL FORECAST SHOWS GRADUAL STRENGHENING OVER THE
NEXT COUPLE OF DAYS AND IS A BLEND OF THE VARIOUS NUMERICAL
GUIDANCE TOOLS. AS USUAL THERE IS CONSIDERABLE UNCERTAINTY AS TO
THE STRENGTH OF THIS SYSTEM LATER IN THE FORECAST PERIOD. IF THE
CYCLONE MOVES FARTHER NORTH THAN ANTICIPATED BELOW IT WILL PROBABLY
ENCOUNTER STRONGER SHEAR AND NOT INTENSIFY AS MUCH AS FORECAST. ON
THE OTHER HAND IF THE SYSTEM MOVES FARTHER SOUTH THAN EXPECTED LATE
IN THE PERIOD...IT WILL PROBABLY BECOME STRONGER THAN ANTICIPATED
HERE.
INITIAL MOTION IS ABOUT 270/11. THIS TRACK IS LIKELY TO MORE OR
LESS CONTINUE FOR THE NEXT 2-3 DAYS DUE TO THE FLOW SOUTH OF A
FAIRLY WELL-ESTABLISHED MID-LEVEL SUBTROPICAL RIDGE. LATER IN THE
PERIOD...A SLIGHT WEAKNESS IN THE RIDGE IS LIKELY TO INDUCE A MORE
WEST-NORTHWESTWARD MOTION. THE OFFICIAL FORECAST IS A LITTLE
SLOWER THAN THE MODEL CONSENSUS AND WELL TO THE SOUTH AND WEST OF
THE BAM TRACKS. THIS IS ALSO SOUTH OF THE LATEST HWRF TRACK.
FORECAST POSITIONS AND MAX WINDS
INITIAL 11/1000Z 14.4N 28.6W 25 KT
12HR VT 11/1800Z 14.6N 30.1W 30 KT
24HR VT 12/0600Z 14.8N 32.3W 35 KT
36HR VT 12/1800Z 15.0N 34.6W 35 KT
48HR VT 13/0600Z 15.2N 36.8W 40 KT
72HR VT 14/0600Z 16.0N 41.2W 45 KT
96HR VT 15/0600Z 17.5N 45.5W 50 KT
120HR VT 16/0600Z 19.5N 49.5W 50 KT
$$
FORECASTER PASCH
ADVANCED DVORAK TECHNIQUE
ADT-Version 7.2.3
Tropical Cyclone Intensity Algorithm
----- Current Analysis -----
Date : 11 AUG 2009 Time : 093000 UTC
Lat : 13:49:05 N Lon : 171:16:59 W
CI# /Pressure/ Vmax
2.8 /1002.0mb/ 41.0kt
Final T# Adj T# Raw T#
(3hr avg)
2.8 2.9 3.5
Latitude bias adjustment to MSLP : +0.0mb
Center Temp : -42.0C Cloud Region Temp : -53.9C
Scene Type : CURVED BAND with 0.79 ARC in LT GRAY
Positioning Method : FORECAST INTERPOLATION
Ocean Basin : EAST PACIFIC
Dvorak CI > MSLP Conversion Used : ATLANTIC
Tno/CI Rules : Constraint Limits : 0.7T/6hr
Weakening Flag : OFF
Rapid Dissipation Flag : OFF
next report TS MAKA
Some models gives CAT3 for this TS!
Woo hoo, we finally got one!!
Better hope it quickly intensifies and pulls more poleward. I'm not at all liking that bolded excerpt above that I posted from the latest NHC discussion.
Yeah morning WeatherStudent,
So much work to do for NHC!
WOW WS, never thought you could wake up so early. I've been lurking for about an 1hr. We have tropical depression 2, and we will have 3 shortly thereafter.
I see. Happy birthday. Looks like you got a tropical surprise to go along with it. >_>
So that's a real possibility?
All I wish for is for no viruses.
Yeah... I hope Dr. Masters posts a new blog soon. A Category 5 blogcane will make landfall here soon ...
Models have been forecasting a weakness in the subtropical ridge to the north over the next 5-7 days. If the system is vertically coherent by that time, it may feel it enough to recurve.
If it remains weak, it will be steered westward with the low-level flow and then there could be trouble.
That is why the agressive system the models are developing will likely be TD 3 or TD 4.
The reason why I say TD 4 is becuz of the mid-Atlantic mid-low level swirl that could poetentially develop.
Yeah, for those of us on the Gulf Coast
A more westward track is worse not only for the Gulf Coast, but for the Caribbean as well. Also, historically, the strongest tropical cyclones in the Atlantic basin occur in the western or northwestern Caribbean Sea, where oceanic heat content is very high.
But this is all speculation at this point. Let's not get ahead of ourselves.
morning every1 (even though I have not slept yet, haha) ...but I digress.
With TD2 being called and it's forecast strengthening into Ana sometime over the next few days, it looks like our so far 0,0,0 season will be no more.
TD02 looks to be the beginning of an active Atlantic period it seems (based on the models, of course), so it looks like the '09 season has finally begun! :)
LMFAO!
Does the "prairie" in your name indicate that you live in Prairieville, LA? That's where I am. >_>
The one near 50W seems to have a dangerous future.
I remembered you said 11 August, correct?
Maka seems rather similar to Ioke, particularly in regards to track.
Sorry for the gripe but need to state my view since I am a paid member. :)
01C.NONAME
02C.NONAME - say what now? looks puzzled and confused
08C.FELICIA
>.<
This El Nino is going to be weak at best.
Link
Sorry for two posts. Blog would not allow image to be linked. Doesn't like (plus) sign in img html tag. Image is below.
LOL... thats a certainty. Good morning all. Just stopping in before I head to the Fire Station
Blame CPHC, when they created what is now 01C they first did it as 02C and had to renumber.
08/11/2009 01:00AM 1,458 invest_RENUMBER_cp022009_cp012009.ren
08/11/2009 12:44AM 1,293 invest_RENUMBER_cp922009_cp022009.ren
Ike, can you post a link to the site you got that from?
BTW...Convection firing off the coast of Africa where the Tropical Wave of Doom is forecast to organize.
GFS at 276 hrs.
This one looks like big trouble for a lot of folks.......
Maybe a 10-15 day event.
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