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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Yeah...
not likely.
I've seen many cases when the opposite occured. Example
Dannielle went out to sea, while France behind continued west.
Goerges went west, while Ivan and jeanne soon follow out to sea.
Houston,TX extended discussion....
"GENERAL HEIGHT WEAKNESS ALONG THE COAST FROM FRIDAY INTO THE
WEEKEND. ECMWF TRANSFORMS WEAK CLOSED-OFF COASTAL LOW INTO AN
INVERTED TROF SATURDAY WHILE THE LESS-AGGRESSIVE GFS SOLUTION
KEEPS TEXAS UNDER WEAK RIDGING...DEVELOPING AN INVERTED TROF ACROSS
SOUTHERN TEXAS A DAY LATER ON SUNDAY. ALL AND ALL...A MORE
SYNOPTICALLY WET PATTERN THROUGH DAYS 3-5 WITH THE BIG QUESTION
MARK BEING THE THE EXTENT OF LOWERED HEIGHTS. CURRENT SATELLITE
TRENDS ARE LEANING THIS WAY...WITH LARGE TROF MAKING ITS WAY INTO
THE PAC NW ALONG WITH THE ANCHORED ATLANTIC ST HIGH. CONFIDENCE IS
GROWING THAT ABOVE SCENARIO(S) WILL PLAY OUT...ESPECIALLY IF THERE
IS LITTLE MOVEMENT OF ST HIGH AND A MORE POSITIVELY-TILTED WESTERN
U.S TROF DOES AMPLE WORK ON THE DESERT SW RIDGE (OR TROUGH WINS OUT
AND KEEPS HIGHER HEIGHTS AT BAY OVER BAJA REGION). ATTM...HAVE
RESISTED THE URGE TO INCREASE POPS TO 40-50 ON THURSDAY...BUT THE
CONFIDENCE THAT SE TX WILL RECEIVE SOME DROUGHT-RELIEVING RAIN IS
ON THE UP AND UP."
I was NOT expecting this.
We are all playing the wait and see game again...Going to be an interesting few weeks at the very least.
"LONG TERM...
THE EXTENDED IS WHERE THINGS START TO GET TRICKY. THE TROPICAL
WAVES ALONG 61W AND 51W LOOK LIKE THEY EVENTUALLY PHASE OVER THE
CARRIBEAN. WE SHOULD SEE THESE FLARE UP WITH ACTIVITY THROUGH THE
NEXT 36 HOURS WHICH WILL HELP DEFINE THEM A LITTLE BETTER. BUT IT
IS THESE OR THE UNIFIED FEATURE OF THESE THAT MOVES INTO THE GULF.
THE WAVE WILL INTERACT WITH THE OLD FRONTAL BOUNDARY OVER THE
NORTHERN GULF AND WEAKENING SHEAR ALOFT BY SAT NIGHT INTO SUN.
THIS IS WHERE WE FIND WHICH MODEL SOLUTION IS INITIALIZING BETTER
IF AT ALL. ALL DID A FAIRLY GOOD JOB YESTERDAY WHILE THE ECMWF IS
DOING A BETTER JOB THIS MORNING. WITH REGARDS TO THE CURRENT
SYNOPTIC PATTERN ALOFT...THE GFS CREATES TWO CENTERS AND ELONGATES
THE THE UPPER HIGH ALONG THE SOUTHEAST COAST. 00Z SOUNDINGS SHOW A
DISTINCT CENTER JUST OFF THE COAST OF SOUTH CAROLINA. THE GFS ALSO
SHOWS UPPER WINDS OF 10KT WHILE ACTUAL SPEEDS ARE 20KT. THE ECMWF
DOES A VERY GOOD JOB AT REPRESENTING THIS UPPER HIGH. THIS HIGH
WILL EVENTUALLY BUILD WESTWARD BLOCKING ANY DISTURBANCE FROM
HEADING NORTH UNTIL IT FINDS ITS WAY INTO THE GULF. THE MID LEVEL
RIDGE CONTINUES TO BUILD INTO THE EAST COAST AND CENTRAL PART OF
THE COUNTRY...ACCORDING TO THE ECMWF...FORCING ANY FEATURE THAT
WOULD DEVELOP INTO THE NORTH CENTRAL THEN NW GULF BY THE START OF
NEXT WEEK. OBVIOUSLY WITH A WEAKER RIDGE PATTERN FROM THE
GFS...THE FEATURE WOULD MOVE INTO FLA. SO ALL IN ALL...IT IS
SIMPLY SOMETHING TO CONTINUE WATCHING. HAVE NOT INCREASED RAIN
CHANCES FOR THIS FEATURE ON THIS PACKAGE. TO BRING POP NUMBERS UP
MORE...I WOULD LIKE TO SEE MORE AGREEMENT WITH SUCCESSIVE MODEL SOLUTIONS."
Brings up goose bumps, no?
Never ready for the wait see game...It is a long, always changing, and frustrating deal. Patience has never been my strong suit...
But, if needs arise from a land falling system...yes, Portlight is ready. Although now is an excellent time to make a donation and help increase that financial reserve prior to the needs arising. Allows for better planning and deployment.
Will be interesting to see if you get a chance to run that webcam this year.
Then the Gulf and ....................
A comback story
I know what you mean, but not much consolation if that one is a cane itself, considering the SST's in the Gulf.
Miami...
"IN THE EXTENDED PERIOD, FRIDAY INTO EARLY NEXT WEEK, THE GFS HAS
BEEN CONSISTENT FOR SEVERAL RUNS NOW SHOWING THE NORTHERN FRINGES OF
A TROPICAL WAVE MOVING ACROSS THE REGION ON SATURDAY. THIS IS A WAVE
THAT IS CURRENTLY NEAR 50W AND EVEN PWAT IMAGERY SHOWS A BROAD
MOISTURE MAXIMUM AT OVER TWO INCHES. THE GFS FORECAST SOUNDING
DOES INDICATE THE MOISTURE SURGE ON SATURDAY ALONG WITH A AN
INCREASE IN THE EASTERLY FLOW. SO HAVE INCREASED THE POPS UP TO
HIGH END CHANCE TO ACCOUNT FOR THIS FEATURE. THEN SUNDAY INTO THE
FIRST OF NEXT WEEK SHOULD SEE MORE TYPICAL DIURNAL ACTIVITY ONCE
AGAIN.".....
Melbourne....
"SAT-MON...BOTH THE ECM AND GFS SHOW A WEAK T-WAVE AND ASCD MOISTURE
RIDING WWD UNDERNEATH THE WRN ATLC RIDGE SAT-EARLY SUN. THE NEW ECM
TAKES THE DISTURBANCE/MOISTURE FARTHER WWD TWD THE GOMEX WHILE THE
GFS TURNS IT NWD INTO FL...WHICH WOULD MAKE FOR A VERY WET WEEKEND
...ESPECIALLY SAT. HAVE GONE PRETTY CLOSE TO THE MEX NUMBERS (50)
WHICH SEEM LOWER THAN WHAT THE MODEL GUIDANCE WOULD SUGGEST FOR SAT
...FOLLOWED BY 40 SUN AND 3-/40 MONDAY AS LOW TO MID LEVEL EASTERLIES
ARE PROGGED TO REBUILD INTO ECFL FOR THE START OF NEXT WEEK."
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
800 AM EDT TUE AUG 11 2009
FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...
THE NATIONAL HURRICANE CENTER HAS INITIATED ADVISORIES ON TROPICAL
DEPRESSION ONE...LOCATED ABOUT 280 MILES WEST OF THE SOUTHERNMOST
CAPE VERDE ISLANDS.
A SMALL AREA OF LOW PRESSURE ASSOCIATED WITH A TROPICAL WAVE
CONTINUES TO PRODUCE DISORGANIZED SHOWERS AND THUNDERSTORMS NEAR
THE WINDWARD ISLANDS. DEVELOPMENT...IF ANY...IS EXPECTED TO BE
SLOW TO OCCUR AS IT MOVES GENERALLY WESTWARD AT 10 TO 15 MPH OVER
THE SOUTHEASTERN CARIBBEAN SEA DURING THE NEXT COUPLE OF DAYS.
THERE IS A LOW CHANCE...LESS THAN 30 PERCENT...OF THIS SYSTEM
BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS. LOCALLY
HEAVY RAIN AND GUSTY WINDS WILL CONTINUE TO AFFECT PORTIONS OF THE
WINDWARD ISLANDS THE REST OF TODAY.
SHOWER AND THUNDERSTORM ACTIVITY ASSOCIATED WITH A TROPICAL WAVE
LOCATED ABOUT 600 MILES EAST OF THE LESSER ANTILLES REMAINS
DISORGANIZED. DEVELOPMENT OF THIS SYSTEM IS LIKELY TO BE SLOW AS
IT MOVES WESTWARD AT 10 TO 15 MPH. THERE IS A LOW CHANCE...LESS
THAN 30 PERCENT...OF THIS SYSTEM BECOMING A TROPICAL CYCLONE DURING
THE NEXT 48 HOURS.
ELSEWHERE...TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE
NEXT 48 HOURS.
PUBLIC ADVISORIES ON TROPICAL DEPRESSION ONE ARE ISSUED UNDER WMO
HEADER WTNT32 KNHC AND UNDER AWIPS HEADER MIATCPAT2. FORECAST/
ADVISORIES ON TROPICAL DEPRESSION ONE ARE ISSUED UNDER WMO HEADER
WTNT22 KNHC AND UNDER AWIPS HEADER MIATCMAT2.
$$
FORECASTER BERG
i am surprised
TD1?????
Try TD2.
It's been so long since TD 1, I assure you they forgot.
lol lol
Guess a corrected one will be coming...TD02. They have 01
Agree...they'll correct.
hey. first time blogging last night and i got it right
But, due to the early stage of the season, relatively, I would expect most to be more Westerly moving.
Isn't that the trend this early in the season, usually?
This is what I remember from all previous years.
When very late in the season, I usually breathe a sigh of relief, as most are then going North of Barbados, albeit via the Northern islands.
Am I wrong?
I wouldnt call it banding, but the convection within the mid-level turning.
Click on image to view original size in a new window
There was a discussion posted yesterday in which models are reacting to the upward MJO motion by spinning up these systems and that it should last into the first week of Sept... I guess we'll see how it fluctuates in the ATL basin.
There could be a chance that the strength "B" is foretasted to be could be related to a stronger MJO pulse coming into the W ATL.
Interesting...maybe it does make it into the GOM.
very correct.. ususaly when september comes around the storms start to move a bit more to the north
I still see 99L on the Wunderground site.
Yeah, WU sometimes is slow on upgrades.
Look at this loop. it appears to be another system that is near FL, not so much Td 2.
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.
Viewing: 2951 - 3001
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