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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1689. hydrus
Quoting CycloneOz:


Do I win "unique sentence of the day?" Huh? Do I, do I?
Oh yeah,a good solar thrashing and then three large cat 4 hurricanes making landfall simultaneously on the U.S.coast.Hopefully that NEVER happens,solar blast or not.
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1688. Patrap
Isnt that the House built by the Guy from Gulf Breeze who took all those UFO pics in the 90's...?

Grin,snicker..snort..
Member Since: July 3, 2005 Posts: 430 Comments: 130818
Quoting robie1conobie:
What part of p'cola r u from dan? I am from gulf breeze.

Out near the airport.
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I believe the last hurricane to hit North Carolina was Isabel in 2003. I'd say we're over due. But like others have said, let's let it get into the Atlantic first!! 7 days out models can change tremendously.
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Quoting IceSlater:
What do you all think about the wave that is coming off Africa in the next 48 hours? GFS long range has a major storm in 10 days east of the Bahamas...


Its looking pretty likely that wave will develop. All the models develop it, some take it to Cane status.
Member Since: July 8, 2005 Posts: 259 Comments: 24625
1684. 7544
where is 99l here 12 or 15 n tia

Link
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Quoting IceSlater:
What do you all think about the wave that is coming off Africa in the next 48 hours? GFS long range has a major storm in 10 days east of the Bahamas...


I would assert that that wave is far more likely to become a significant threat down the road, even if 99L becomes Ana.
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Quoting PcolaDan:


The Dome of a Home.

What part of p'cola r u from dan? I am from gulf breeze.
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1681. IKE



Member Since: June 9, 2005 Posts: 23 Comments: 37860
Another question that I should know the answer to what does DMAX mean?
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What do you all think about the wave that is coming off Africa in the next 48 hours? GFS long range has a major storm in 10 days east of the Bahamas...
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Quoting sammywammybamy:



It has Already Started to Fire Convection


ok, has DMAX started at 99L now?
BTW i mentioned b4 we are ment to get a storm here today, well its ok its way.
Member Since: September 30, 2007 Posts: 9 Comments: 15991
Quoting RAM48:
Ladys & Gentlements I read that models take the next two waves coming out of Africa into a major cane and latter will hit the east coast, any idea what part of the east coast?


Way to early to tell. Its not even in the Atlantic
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Quoting robie1conobie:
TWC has a special about this hurricane proof dome home they built on p'cola beach. it made it through Ivan. Smartest people on the island, they had the gov't help fund the building for research purposes.


The Dome of a Home.

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Quoting Funkadelic:


So if the wave behind 99L develops it will likely go out to sea right? What other models besides the GFS, forcast that "Recurve" to occur?


Actually all bets are off. It could hit Mexico for all we know, or strike NYC, or hit Florida.. We should know when it gets near the Lesser Antillies 5-7 days.
Member Since: July 1, 2008 Posts: 13 Comments: 7437
TWC has a special about this hurricane proof dome home they built on p'cola beach. it made it through Ivan. Smartest people on the island, they had the gov't help fund the building for research purposes.
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1671. Patrap
NATIONAL WEATHER SERVICE NEW ORLEANS LA
407 PM CDT MON AUG 10 2009

.SHORT TERM...
WET TROPICAL AIRMASS WILL CONTINUE TO FUEL SCATTERED MOSTLY LATE
MORNING AND AFTERNOON SHOWERS AND THUNDERSTORMS THE NEXT COUPLE
DAYS WITH NOCTURNAL ACTIVITY MAINLY OVER WATER AND COASTAL
SECTIONS. THE MID/UPPER RIDGE IS CENTERED OVER THE MID/SOUTHERN
ATLANTIC COAST REGION WITH WATER VAPOR LOOPS SHOWING THE APEX OF
THE RIDGE ALONG THE NORTH GULF COAST. A SHORTWAVE TROUGH WILL
LOWER 500 MB HEIGHTS OVER THE OHIO VALLEY AND TENNESSEE VALLEY
AREAS LATE TUESDAY AND TUESDAY NIGHT WHICH WILL ALSO HELP PUSH A
FRONTAL BOUNDARY SOUTH THROUGH THE SAME REGION. THIS FRONT WILL
HAVE IMPACT ON OUR AREA IN THE LONG TERM.

.LONG TERM...
THE SHORTWAVE TROUGH OVER THE SOUTHEAST AND EAST WILL MOVE EAST
OFF THE ATLANTIC COAST LATE THURSDAY/THURSDAY NIGHT. THE FRONT
SHOULD GET A PUSH BY HIGH PRESSURE TO THE NORTH WITH THE WEAK
BOUNDARY EXPECTED TO APPROACH THE COAST WEDNESDAY NIGHT INTO
THURSDAY. DRIER AIR/LOWER PRECIPITABLE WATER WILL MOVE INTO THE
AREA...ESPECIALLY THE NORTHWEST HALF...WEDNESDAY NIGHT INTO
FRIDAY. HAVE ADJUSTED THE POPS DURING THE PERIOD TO DECREASE IN
SOME OF THE INLAND AREAS AND INCREASE IN COASTAL SECTIONS AND
COASTAL WATERS.

AS WE HAVE BEEN TRACKING IN THE MODELS AND ON SATELLITE...A
TROPICAL WAVE WITH WELL DEFINED LOW LEVEL CURVATURE LOCATED NEAR
46W WILL LIKELY TRACK WEST INTO THE EAST/SOUTHEAST GULF OF MEXICO
THIS WEEKEND WITH A NORTHERN EXTENSION MOVING ACROSS THE NORTH
CENTRAL GULF COAST AROUND SUNDAY NIGHT OR MONDAY. AFTER A
RELATIVELY DRIER PERIOD THURSDAY AND FRIDAY...RAIN CHANCES ARE
LIKELY TO INCREASE OVER THE WEEKEND WITH MORE WIDESPREAD HEAVY
RAIN POTENTIAL AFTER THE TROPICAL WAVE MOVES ACROSS THE FORECAST
AREA. WILL CONTINUE TO TRACK THIS FEATURE AND FINE TUNE THE POPS
AND TIMING OF HEAVY RAIN POTENTIAL.
22/TD
Member Since: July 3, 2005 Posts: 430 Comments: 130818
1668. RAM48
Ladys & Gentlements I read that models take the next two waves coming out of Africa into a major cane and latter will hit the east coast, any idea what part of the east coast?
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1666. Patrap
Im glad I didnt know what a Blog was in 05,..and 27 mths post Storm in A FEMA trailer will really make one appreciate a Goose Egg season so far.

Member Since: July 3, 2005 Posts: 430 Comments: 130818
Quoting WeatherStudent:


Good morning, Aussie. How are ya?

Its 10am and its only 11C, its a dark and its trying very hard to rain, ment to be a chance of a storm today. I think I'll go back to bed.
What happened to 99L while i was sleeping, looked like the local cat caught it and ripped it apart. DMAX later will help it get organized again.
Member Since: September 30, 2007 Posts: 9 Comments: 15991
1664. hydrus
Quoting Michfan:
This blog has less patience than my 5 yr old when it comes to Spongebob. Systems take time to develop folks. Too many of you are spoiled by 2005.
lol....
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wavewatch wave model is showing 8ft. surf off of fl. east coast on sunday. I dont care if it is a trop. wave, its finally bringing a real swell.
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1662. flsky
Patrap - I sent you an email.
Member Since: October 24, 2006 Posts: 0 Comments: 2134
1660. IKE
Accuweather's take....

"Last Update: 10-AUG-2009 5:04pm EDT

A tropical wave and associated area of low pressure located along 25 west, south of 21 north, continues to be monitored for possible tropical development. The wave is located just to the west-southwest of the Cape Verde Islands and is moving west at around 10 knots. Latest satellite imagery shows that the wave continues to lose much of its deep thunderstorm activity, and this trend is expected to continue. An elongated trough just to the west of the wave is helping to increase the upper-level wind shear over the eastern Atlantic. Satellite imagery depicts this well as cirrus clouds from the thunderstorm activity are being pulled northeastward away from the wave. Latest computer guidance suggests that shear may weaken as the wave moves westward the next day or two, and some development is possible if the wave can hold together.

A second tropical wave and associated area of low pressure located along 58 west, south of 18 north, is also being monitored for possible tropical development. Satellite images show an increase in shower and thunderstorm activity with this wave and a weak circulation center can be seen in visible images. This wave will be entering an area of higher wind shear over the eastern Caribbean as it moves to the west. As a result, development if any would be slow to occur.

We are also tracking tropical waves along 46 west, south of 18 north, along 71 west, south of 16 north, and along 91 west, south of 16 north. All three of these other waves are moving west at 10-15 knots and show little chance of development. Strong upper-level winds and dry air are preventing any of these waves from developing.

By AccuWeather.com Meteorologist Josh Newhard"
Member Since: June 9, 2005 Posts: 23 Comments: 37860
Quoting gwadaman:
Kman whats your take on the area of weather over barbados and southern islands. Do you think this will clear out by sun up? Have a boat in St. Vincent and want to punch and head for Barbados around 4.30am


Sorry, can't help you there. I stay away from forecasting, especially for anyone planning to take a boat out.


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Quoting hahaguy:


True , but that's all he ever says.
hes a man of few words but many truths
Member Since: August 15, 2008 Posts: 0 Comments: 2515
SPECIAL FEATURES...

TROPICAL WAVE IS ALONG 27W FROM 7N TO 21N WITH A 1009 MB LOW
ALONG THE WAVE NEAR 15N MOVING W NEAR 10 KT. SATELLITE IMAGERY
INDICATES THE LOW/MID LEVEL CYCLONIC CIRCULATION REMAINS...
HOWEVER UPPER LEVEL NORTHERLY WINDS ON THE ERN PERIPHERY OF AN
UPPER LEVEL ANTICYCLONE CENTERED NEAR 19N45W IS BRINGING DRY AIR
ALOFT TO THE WESTERN SIDE OF THE WAVE THUS INHIBITING ANY DEEP
LAYERED CONVECTION. AN AREA OF SCATTERED
MODERATE CONVECTION IS
FROM 9N-14N BETWEEN 23W-30W. CONDITIONS APPEAR FAVORABLE FOR
DEVELOPMENT OF THIS SYSTEM AND IT COULD BECOME A TROPICAL
DEPRESSION DURING THE NEXT DAY OR TWO. ASSOCIATED SHOWERS AND
THUNDERSTORMS WITH LOCALLY GUSTY WINDS COULD AFFECT PORTIONS OF
THE CAPE VERDE ISLANDS DURING THE NEXT 24 HOURS. SEE THE
TROPICAL WEATHER OUTLOOK UNDER AWIPS/WMO HEADERS MIATWOAT/ABNT20
KNHC FOR ADDITIONAL DETAILS.
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1654. IKE
Quoting hahaguy:


True , but that's all he ever says.


LOL...true.
Member Since: June 9, 2005 Posts: 23 Comments: 37860
TWD


TROPICAL WAVE IS ALONG 27W FROM 7N TO 21N WITH A 1009 MB LOW
ALONG THE WAVE NEAR 15N MOVING W NEAR 10 KT. SATELLITE IMAGERY
INDICATES THE LOW/MID LEVEL CYCLONIC CIRCULATION REMAINS...
HOWEVER UPPER LEVEL NORTHERLY WINDS ON THE ERN PERIPHERY OF AN
UPPER LEVEL ANTICYCLONE CENTERED NEAR 19N45W IS BRINGING DRY AIR
ALOFT TO THE WESTERN SIDE OF THE WAVE THUS INHIBITING ANY DEEP
LAYERED CONVECTION. AN AREA OF SCATTERED MODERATE CONVECTION IS
FROM 9N-14N BETWEEN 23W-30W. CONDITIONS APPEAR FAVORABLE FOR
DEVELOPMENT OF THIS SYSTEM AND IT COULD BECOME A TROPICAL
DEPRESSION DURING THE NEXT DAY OR TWO. ASSOCIATED SHOWERS AND
THUNDERSTORMS WITH LOCALLY GUSTY WINDS COULD AFFECT PORTIONS OF
THE CAPE VERDE ISLANDS DURING THE NEXT 24 HOURS.
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some convection, albeit small, is firing close to the center of 99L.

the quikscat shows the center just north of 14N and just east of 27W.
Member Since: August 6, 2007 Posts: 0 Comments: 693
1651. Patrap
12:04 AM GMT on August 11, 2009
Quoting flsky:
Is anyone on this board a disaster housing inspector?



What ya need to know...?
Member Since: July 3, 2005 Posts: 430 Comments: 130818
1649. reedzone
12:04 AM GMT on August 11, 2009
Quoting at5626:
http://wunder.com/modelmaps/maps.asp?model=NAM&domain=US

The GFS takes both of these systems into the east coast. I know it is a while from now, but still. Be ready for anything! I myself have not experienced a hurricane. Just Bertha's waves last year, which by the way, were AWESOME!


Actually the new GFS run takes the wave that just came off of Africa out to sea, west of Bermuda. West is the key, the high should build in enough for a recurvature to occur WEST of Bermuda.
Member Since: July 1, 2008 Posts: 13 Comments: 7437
1647. Patrap
12:03 AM GMT on August 11, 2009


What ya need to Know ..?
Member Since: July 3, 2005 Posts: 430 Comments: 130818
1646. hahaguy
12:03 AM GMT on August 11, 2009
Quoting IKE:


He wouldn't be lying.


True.
Member Since: August 12, 2007 Posts: 2 Comments: 2838
1645. AllyBama
12:02 AM GMT on August 11, 2009
it is really bad that this time of year, TWC can't alot more than 2-5 minutes for the Tropical Update..I think that they would be surprised to hear how many people are interested in what is going on, even if a system is over 2,000 miles away..they could even do it in two different segments - scheduling one just for a "broader" view of any questionable areas...

guess they don't care what us coastal people are interested in and that is why we have places like WU..
Member Since: August 3, 2006 Posts: 133 Comments: 20639
1644. IKE
12:02 AM GMT on August 11, 2009
Member Since: June 9, 2005 Posts: 23 Comments: 37860
1643. Michfan
12:02 AM GMT on August 11, 2009
This blog has less patience than my 5 yr old when it comes to Spongebob. Systems take time to develop folks. Too many of you are spoiled by 2005.
Member Since: September 7, 2007 Posts: 0 Comments: 1748
1642. flsky
12:02 AM GMT on August 11, 2009
Is anyone on this board a disaster housing inspector?
Member Since: October 24, 2006 Posts: 0 Comments: 2134
1641. at5626
12:02 AM GMT on August 11, 2009
http://wunder.com/modelmaps/maps.asp?model=NAM&domain=US

The GFS takes both of these systems into the east coast. I know it is a while from now, but still. Be ready for anything! I myself have not experienced a hurricane. Just Bertha's waves last year, which by the way, were AWESOME!
1639. IKE
12:01 AM GMT on August 11, 2009
Quoting hahaguy:


Probably said the Atlantic basin is quiet lol.


He wouldn't be lying.
Member Since: June 9, 2005 Posts: 23 Comments: 37860

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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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