Hawaii braces for Felicia; 99L near the Cape Verdes Islands may develop

By: Dr. Jeff Masters , 3:55 PM GMT on August 10, 2009

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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.

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Quoting stormdude77:


if that convection continues, thats scary...as it is the llc is under the heaviest of it right now just to the ene of barbados...watch the up to date conditions on the island over the next 3 hours for a wind shift from nw/wnw/w to a se/ese direction...

pressure is dropping slowly...nothing dramatic...and winds are nothing terrible...just alot of rain.
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Quoting KEEPEROFTTHEGATE:


I ALSO SEE THIS ROTATION. I DISAGREE THAT IT WILL BECOME A NOREASTER THOUGH.

Please don't use caps.
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Quoting conchygirl:
Fortunately schools are starting back up so the kids will be returning to the classroom and the blog will return to some semblance of normal. :)


Yes thank god. If I have to read another of Weatherstudents posts I will hurt someone.
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Quoting SavannahStorm:
This reminds me of the time we had 10 or so different versions of STORMTOP running around.

STORMTOP
STORMT0P
STROMTOP
STORMCROW
STORMFLOP
Stormno

and a few others

Stormno is still very much annoyi... around...
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Quoting Patrap:
Using a Handle over 6 letters will always have the attention of the wayward souls.

They are harder to detect visually,and since Saturday,numerous attempts have be made to pass viruses and malware here.

I advise caution .


Thanks Pat.
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This reminds me of the time we had 10 or so different versions of STORMTOP running around.

STORMTOP
STORMT0P
STROMTOP
STORMCROW
STORMFLOP
Stormno

and a few others
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Quoting BurnedAfterPosting:


that isnt current either

I know that, but its a better shot imo.
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Quoting Acemmett90:

i don't know how to if i did i would have those two banned for life allready
me too.
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I'm having a brain fart. I thought when stacked there needs to be more convergence than divergence....am i thinking just the opposite....heck i no its been 12 months since last year......LOL

Think about it like this...Convergence is at the lower level and spins inward so the more convergence you have the more pressure thats why you need balancing divergence if not more divergence so the air can escape into the upper levels of the atmosphere..it allows the storm to breathe so to speak
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Using a Handle over 6 letters will always have the attention of the wayward souls.

They are harder to detect visually,and since Saturday,numerous attempts have be made to pass viruses and malware here.

I advise caution .
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Quoting Acemmett90:

so true it so sad that people have to go that far to get attention
btw u should put the Shaqcane handle pic back
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new poll:
who is sick of the polls?
a) i am!
b) not me!
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623. IKE
Quoting WeatherStudent:


afternoon ike, have you've noticed the latest addition to the 2pm NHC's TWO? if so, your thoughts on it? thanks ikster.


Stick with what the NHC says. I see a rotation in the clouds...convection has been increasing.
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Quoting Acemmett90:

yah my anti virus cought it and terminated it
can u please tell he how to write a letter to the admin? please.
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Fortunately schools are starting back up so the kids will be returning to the classroom and the blog will return to some semblance of normal. :)
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I'll be glad when the kids go back to school...
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I'm having a brain fart. I thought when stacked there needs to be more convergence than divergence....am i thinking just the opposite....heck i no its been 12 months since last year......LOL
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I remember one time we had so many imposters in here that nobody knew who was real anymore they had to shut down the blog
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The last QS pass was this morning and it missed the area by Barbados
Quoting BurnedAfterPosting:


yes it is, the time at the top is always the current time, the timestamp in purple at the bottom shows it was done at 10pm, we havent gotten to 10pm yet today for that area

that is the descending pass from last night


Correct
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610. 7544
ok can we get back to weather
Member Since: May 6, 2007 Posts: 0 Comments: 6874
I have to get to work. Please if there are ludacris posts from me report the imposter Thank you
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Quoting leftovers:
how many getting banned tonight ? more got viruses on their computers! regulars who you have not posted in awhile are more likely down with a broken computers i was protected with windows one nevertheless it still got through.


How did they get the virus? From a link?
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Quoting stormpetrol:


that isnt current either
I'm sure Pat has done a good job of posting reminders about checking supplies (he always had a good list), but I noticed my neighbor checking his generator yesterday. Not a bad idea while things are quiet. It's no fun rushing at the last. Some may have let their guard down a bit since it's been a quiet season.
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trolls are out in force today...
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Quoting KEEPEROFTTHEGATE:


I AGREE ITS PATHETIC WE NEED TO DEVELOP A SERIOUS GAMEPLAN TO HALT THE IMPOSTOR BEFORE HE STEALS MULTIPLE IDENTITIES LIKE LAST YEAR. HE EVEN STOLE MINE TWICE.
Ignore and reported and im writing a letter to the admin so u can be banned out of the site!!!!!!!
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Quoting boltdwright:


No, it is not, read the time on the image.


yes it is, the time at the top is always the current time, the timestamp in purple at the bottom shows it was done at 10pm, we havent gotten to 10pm yet today for that area

that is the descending pass from last night
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Quoting boltdwright:


No, it is not, read the time on the image.


Quikscat missed the area near 59W this morning. The time of a pass is the purple number at the bottom of the image, not the time at the top
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Quoting Skyepony:
That's up 2 mb since the last plane was out there.


Product: Air Force Vortex Message (URPN12 KNHC)
Transmitted: 10th day of the month at 17:48Z
Aircraft: Air Force Aircraft (Last 3 digits of the tail number are 309)
Storm Number & Year: 08E in 2009
Storm Name: Felicia (originating in the Northeast Pacific basin)
Mission Number: 8
Observation Number: 04
A. Time of Center Fix: 10th day of the month at 17:20:30Z
B. Center Fix Coordinates: 20°55'N 150°32'W (20.9167N 150.5333W) (View map)
B. Center Fix Location: 307 miles (494 km) to the ENE (74°) from Hilo, on the island of Hawaii, HI, USA.
C. Minimum Height at Standard Level: 1,479m (4,852ft) at 850mb
D. Estimated (by SFMR or visually) Maximum Surface Wind: 23kts (~ 26.5mph)
E. Location of the Estimated Maximum Surface Wind: 42 nautical miles (48 statute miles) to the SSW (206°) of center fix
F. Maximum Flight Level Wind Inbound: From 324° at 23kts (From the NW at ~ 26.5mph)
G. Location of Maximum Flight Level Wind Inbound: 67 nautical miles (77 statute miles) to the SW (214°) of center fix
H. Minimum Sea Level Pressure: 1007mb (29.74 inHg)
I. Maximum Flight Level Temp & Pressure Altitude Outside Eye: 17°C (63°F) at a pressure alt. of 1,677m (5,502ft)
J. Maximum Flight Level Temp & Pressure Altitude Inside Eye: 19°C (66°F) at a pressure alt. of 1,676m (5,499ft)
K. Dewpoint Temp (collected at same location as temp inside eye): 15°C (59°F)
K. Sea Surface Temp (collected at same location as temp inside eye): Not Available
L. Eye Character: Not Available
M. Eye Shape: Not Available
N. Fix Determined By: Penetration, Wind, Pressure and Temperature
N. Fix Level: 850mb
O. Navigation Fix Accuracy: 0.02 nautical miles
O. Meteorological Accuracy: 1.5 nautical miles
Remarks Section - Remarks That Were Decoded...
Maximum Flight Level Wind: 23kts (~ 26.5mph) in the southwest quadrant at 16:59:30Z
Maximum Flight Level Wind Outbound: 45kts (~ 51.8mph) in the northeast quadrant at 17:43:30Z
Remarks Section - Additional Remarks...
FLT LVL CTR ORIENTED N-S. SFC NOT VISIBLE DUE TO UNDERCAST

So Felicia is a TD.
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Quoting KEEPEROFTTHEGATE:


I AGREE ITS PATHETIC WE NEED TO DEVELOP A SERIOUS GAMEPLAN TO HALT THE IMPOSTOR BEFORE HE STEALS MULTIPLE IDENTITIES LIKE LAST YEAR. HE EVEN STOLE MINE TWICE.


Another imposter
594. IKE
Their both imposters. I have them both on ignore.
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Quoting hurricanehanna:


Nope - not me. And I hope it's wrong!


Oh sorry. I dont remember who that was...hmm.
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Link
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ghcc loop of Barbados AOI
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Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.

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