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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models keep shifting west
TROPICAL WAVE IS ALONG 58W S OF 18N MOVING W 10-15 KT. WAVE IS
LOCATED ALONG A MOISTURE MAXIMUM AS OBSERVED ON THE TOTAL
PRECIPITABLE WATER IMAGERY. A LOW LEVEL CYCLONIC CIRCULATION IN
THE LOW CLOUDS IS ALSO ALONG THE WAVE AXIS NEAR 13N. SCATTERED
MODERATE TO ISOLATED STRONG CONVECTION IS OVER THE WINDWARD
ISLANDS FROM 12N-15N BETWEEN 57W-62W.
Well then you would need the same amount if not more Divergence to cancel it out because if your convergence is too high or higher than your divergence then the pressure will just go up which would weaken the low...Most of the time when storms are weakening in the pressure goes up it is because they are losing the Divergence aloft
And will probably continue to do so.
Also shows a low heading for SE Florida.
You have got to be kidding me. You are the first person on my ignore list.
yeah Shutter up and evac to alaska
models are not nearly aggresive with this as they were.
I just saw that, interesting.. Whats your take on this mysterious future storm IKE?
Link?
That must be the area ~45W that GFS has heading into the Gulf.
"LONG TERM (THURSDAY THROUGH MONDAY)...
THE TROPICAL WAVE ALONG 58W SOUTH OF 18N SHOULD PASS WELL SOUTH OF
FLORIDA STRAITS AND HAVE LITTLE AFFECT ON THE LOCAL WEATHER. ON THE
OTHER HAND...THE TROPICAL WAVE ALONG 45W SOUTH OF 18N MAY CROSS THE
FLORIDA KEYS SOMETIME THIS WEEKEND. FOR NOW...POPS WILL BE RAISED BY
10 PERCENT FOR THE FRIDAY NIGHT THROUGH SATURDAY NIGHT TIME FRAME.
EXACT TIMING OF THIS TROPICAL WAVE WILL BE ABLE TO BE BETTER
DETERMINED IN THE NEXT FEW DAYS."
That can't be good.
I hope it rises to T2.0
Must say that I'm really impressed with your knowledge and observations this afternoon. You are correct in regards to a system needing more divergence than convergence. You can have all the convergence in the world, but without divergence to allow the storms to "breathe", storms will die out. Keep up the good work.
C post 721.
well the stronger it gets the more north it will go, since the models are now forecasting it to stay weak for a while, the lower level current keeps it more west, to WNW.
I'm guessing this was tongue-in-cheek humor. Very Funny.
You should proofread your post before you post....
".LONG TERM (WEDNESDAY NIGHT THROUGH MONDAY)...
MID/UPPER LEVEL TROUGH REMAINS OVER THE CENTRAL GULF COAST STATES TO
START OUT THE EXTENDED PERIOD (WED NIGHT) WITH FRONTAL BOUNDARY
DRAPED FROM THE MID ATLANTIC REGION DOWN TO THE GULF COAST. BOTH THE
GFS AND ECMWF ARE DIGGING THE UPPER TROUGH SLIGHTLY DEEPER WITH EACH
MODEL RUN...AND NOW INDICATE AN UPPER LOW BECOMING CUT-OFF OVER THE
TENNESSEE VALLEY ON THURSDAY. THE DEEPER THIS TROUGH...THE MORE IT
WILL HELP ENHANCE SHOWER/THUNDERSTORM ACTIVITY THURSDAY INTO FRIDAY.
THE UPPER RIDGE FINALLY BEGINS TO PUSH BACK INTO THE SOUTHEAST U.S.
THIS WEEKEND...AND KICKS THAT LOW BACK UP INTO THE NORTHEASTERN
STATES.
BIG QUESTION MARK IS TIMING/TRACK OF TROPICAL WAVE THAT IS FORECAST
TO MOVE TOWARDS THE FL PENINSULA THIS WEEKEND. GFS CONTINUES TO SHOW
A GOOD AREA OF MOISTURE ASSOCIATED WITH THIS FEATURE OVER THE AREA
AT LEAST SATURDAY...POSSIBLY INTO SUNDAY AS WELL...SO HAVE KEPT POPS
AT 50% FOR BOTH SAT AND SUN TO ACCOUNT FOR THIS SCENARIO. IF MODELS
CONTINUE TO SHOW CONSISTENCY WITH THIS FEATURE OVER THE NEXT FEW
RUNS...POPS WILL LIKELY NEED TO BE INCREASED FURTHER."
He's in his second year at college should be expected
I noticed that. The real keeperofthegate would not act so idiotic, and usually provides useful information.
Thanks KeyWestBrat
all storms that explode off the coast of africa with this pattern will be fish as they will ride the upper level currents right into the weakness, its the storms that start getting strong around puerto rico, then ride the weakness right into the east coast.
It's probably choking on dry air right now. But look! It might also be clearing a path for the "B" storm.
So, which will win? SAL or 99L? I thought the SAL was supposed to be weakening...
That's TW wave with attendant low currently @45W which NAM is hinting towards an organized disturb region heading WNW.
Then next year he will know everything, and in his senior year realize he actually knows nothing. LOL Well, that's how it was for me anyway. :)
unfortunately....that is the proof read version...
Wed-sun...mid-latitude shortwave forecast to drift south through
Tennessee Valley at midweek looks to stall north of the state and
eventually washes out north of the region through the end of the
workweek. Consequently the subtropical ridge will become the bigger
player for the peninsula during this time period while moving
back north of the area Thursday. The ridge axis will lie north of
central Florida through the remainder of the extended forecast
opening up the tropics as the upstream focus. Low-level flow will
remain fairly light with a daily sea breeze moving inland and thus
higher chances of showers and storms favoring the central and west
Central Peninsula after midweek. Still cannot rule out a small
threat for overnight and early morning showers along the
coast...especially the Treasure Coast. Shower and storm chances
are forecast to increase back to climatology by Thursday as deeper layer
moisture advects into the region through the weekend. High
temperatures will remain near climatology with upper 80s to near 90
degrees along the coast and lower 90s across the interior.
Rare for Melbourne to update they usually have one complete update.
I meant the East Coast monster that the GFS is predicting, but thanks anyways, will have to watch that particular wave when it enters the GOM.
I was just looking at that. Almost all state met offices are talking about it.
Viewing: 701 - 751
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