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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1639. IKE
Quoting hahaguy:


Probably said the Atlantic basin is quiet lol.


He wouldn't be lying.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
1638. Patrap
The Atlantic Basin,

One Invest,..and One AOI.

That's about as Busy as Bourbon Street round noon on Ash Wednesday.
Member Since: July 3, 2005 Posts: 421 Comments: 127636
Quoting chevycanes:


latest quikscat


Hot damn! Thats a really well-defined CLOSED surface circulation right there. Let's just wait and see whether or not it can develop some convection to protect it.
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Quoting WPBHurricane05:


How ironic:

NHC Intellectual Property

LOL!!
and you wonder why he asks so many questions
Member Since: August 15, 2008 Posts: 0 Comments: 2515
1635. hahaguy
Quoting IKE:


What did he say, if anything, about the Atlantic.


Probably said the Atlantic basin is quiet lol.
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Now all that 99L needs is some more convection, here is my prediction:

50-70% chance of TD from 99L
40-60% chance of TS from 99L
0-20% chance of Hurricane from 99L
Member Since: Posts: Comments:


latest quikscat
Member Since: August 6, 2007 Posts: 0 Comments: 693
1632. IKE
Quoting jurakantaino:
Dr. Lyons does all he could to mention all whats going on in the tropics, but the little time they give to update the tropics is ridiculous, specially this time of the year.


What did he say, if anything, about the Atlantic.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
Quoting WeatherStudent:


absolutely kman, to add to that, the steering pattern when a storm is out there, can eitehr make us or break us. hopefullyw e'll ahve a through type of a pattern come next week, so taht african beast that many of teh models are predicting for that tiem, ehads out to sea.


I'm sorry but you sound like a high school kid trying to BS his way through a term paper. C'mon
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99L stays Orange.
Member Since: August 9, 2009 Posts: 10 Comments: 4903
Dr. Lyons does all he could to mention all whats going on in the tropics, but the little time they give him to update the tropics is ridiculous, specially this time of the year.
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Quoting CycloneOz:


Do I win "unique sentence of the day?" Huh? Do I, do I?


not even close, pal....WS has ya beat by miles...
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1626. snotly
Quoting IKE:
Looks like the NHC is hanging their hat on it possibly coming back.

71 days into the season....

0-0-0.


Don't rule it out just yet.

Didn't Katrina form from the leftovers of a tropical circulation wasn't it from TD 10?
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Quoting bajelayman2:


I agree, the Barbados blob is actually picking up a fine rotation, started this afternoon and now looks to be getting quite nice.

Either that or I am nuts.


Maybe I'm nuts, but I don't see any rotation...
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Quoting Vortex95:
Is it me or has the blog been stretched.


What does this mean?
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Good Morning/Evening all
Member Since: September 30, 2007 Posts: 9 Comments: 15932
Quoting CycloneOz:
I think the Earth needs a good solar spanking in order to give up her cyclonic booty!


Do I win "unique sentence of the day?" Huh? Do I, do I?
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Looks nicely developing to me?

http://www.ssd.noaa.gov/goes/east/catl/loop-wv.html
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With a close circulation it stands a chance of developing. Plus is moving W into marginal warmer waters, low shear, and SAL lifting away, is reasonable for it to be left in orange.
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I really believe our solar poster is dead-on right about why this season is inactive.

No sunspots means that the Earth isn't getting spanked every hour or so by intense solar activity.

I think the Earth needs a good solar spanking in order to give up her cyclonic booty!
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Quoting extreme236:


It hasn't dissipated lol


I agree, the Barbados blob is actually picking up a fine rotation, started this afternoon and now looks to be getting quite nice.

Either that or I am nuts.
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1616. IKE
Quoting CycloneOz:


TRIP ZEROES, BABY!

Sweet Dreams of Gooseeggs, all! :)


Yup....the blank continues.

When will it end? I don't see it for the next couple of days.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
1615. Patrap
2
Member Since: July 3, 2005 Posts: 421 Comments: 127636
Quoting Stormchaser2007:
The wave exiting Africa is the one the GFS develops in a monster. We'll see what that does.



It's not just the GFS on development, the GFDL, EURO, and CMC form a tropical cyclone out of that.
Member Since: July 1, 2008 Posts: 13 Comments: 7340
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
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Quoting IKE:
Looks like the NHC is hanging their hat on it possibly coming back.

71 days into the season....

0-0-0.


TRIP ZEROES, BABY!

Sweet Dreams of Gooseeggs, all! :)
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Quoting Stormchaser2007:
The wave exiting Africa is the one the GFS develops in a monster. We'll see what that does.



All the model's develop it too. If 99L doesn't become Ana Im betting that will.
Member Since: July 8, 2005 Posts: 259 Comments: 23618
A serial killer stalks the sea
To destroy each TC wannabee
The MO is to choke
Then it's all up in smoke
The killer is SAL! ...unfortunately.
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The wave exiting Africa is the one the GFS develops in a monster. We'll see what that does.

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000
ABNT20 KNHC 102342
TWOAT
TROPICAL WEATHER OUTLOOK
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
800 PM EDT MON AUG 10 2009

FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...

THE BROAD AREA OF LOW PRESSURE LOCATED JUST TO THE WEST-SOUTHWEST
OF THE SOUTHERN CAPE VERDE ISLANDS IS MOVING WESTWARD AT 10 TO 15
MPH. SHOWER AND THUNDERSTORM ACTIVITY REMAINS LIMITED THIS
EVENING. HOWEVER...THIS SYSTEM STILL HAS SOME POTENTIAL TO BECOME
A TROPICAL DEPRESSION DURING THE NEXT DAY OR SO. THERE IS A MEDIUM
CHANCE...30 TO 50 PERCENT...OF THIS SYSTEM BECOMING A TROPICAL
CYCLONE DURING THE NEXT 48 HOURS.

A SMALL AREA OF LOW PRESSURE ASSOCIATED WITH A TROPICAL WAVE IS
PRODUCING DISORGANIZED SHOWERS AND THUNDERSTORMS NEAR THE WINDWARD
ISLANDS. DEVELOPMENT OF THIS SYSTEM...IF ANY...IS EXPECTED TO BE
SLOW TO OCCUR AS IT MOVES WESTWARD AT 10 TO 15 MPH. LOCALLY HEAVY
RAIN AND GUSTY WINDS SHOULD CONTINUE TO SPREAD OVER PORTIONS OF THE
WINDWARD ISLANDS THROUGH TUESDAY MORNING. 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.

$$
FORECASTER ROBERTS/BROWN

Member Since: Posts: Comments:
THE BROAD AREA OF LOW PRESSURE LOCATED JUST TO THE WEST-SOUTHWEST
OF THE SOUTHERN CAPE VERDE ISLANDS IS MOVING WESTWARD AT 10 TO 15
MPH. SHOWER AND THUNDERSTORM ACTIVITY REMAINS LIMITED THIS
EVENING. HOWEVER...THIS SYSTEM STILL HAS SOME POTENTIAL TO BECOMEA TROPICAL DEPRESSION DURING THE NEXT DAY OR SO. THERE IS A MEDIUM
CHANCE...30 TO 50 PERCENT...OF THIS SYSTEM BECOMING A TROPICAL
CYCLONE DURING THE NEXT 48 HOURS.

I love the wording of NHC.
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Quoting Stormchaser2007:
Probably too far east to do any good.

That's very close to where the Quikscat located a closed low If I'm not mistaken
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1602. IKE
Looks like the NHC is hanging their hat on it possibly coming back.

71 days into the season....

0-0-0.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
I hate to say this but... I told ya so :P

Same as before, mainly because 99L is closed and well defined.
Member Since: July 1, 2008 Posts: 13 Comments: 7340
NHC now says some potential during the next day or so...probably recognize the good structure and know it just needs a convective increase to be classified.
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TWO out no change
Member Since: July 8, 2005 Posts: 259 Comments: 23618
Actually looking at the most current loop of 99L, it actually looks better now than it has all day.....Dmax may do wonders! No way it goes to yellow.
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Wow almost every post since i refreshed the page answered my question thanks everybody!
Member Since: July 28, 2009 Posts: 1 Comments: 64
Quoting plywoodsale:


I think Yellow most likely - convection has diminished and development if any will be slow to occur.


Nope its orange still.
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Ok I have a question

While the QS shows a closed low definitely with 99L, does the low seem broad to you guys?
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We'll see what happens this evening.
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TWOAT
TROPICAL WEATHER OUTLOOK
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
800 PM EDT MON AUG 10 2009

FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...

THE BROAD AREA OF LOW PRESSURE LOCATED JUST TO THE WEST-SOUTHWEST
OF THE SOUTHERN CAPE VERDE ISLANDS IS MOVING WESTWARD AT 10 TO 15
MPH. SHOWER AND THUNDERSTORM ACTIVITY REMAINS LIMITED THIS
EVENING. HOWEVER...THIS SYSTEM STILL HAS SOME POTENTIAL TO BECOME
A TROPICAL DEPRESSION DURING THE NEXT DAY OR SO. THERE IS A MEDIUM
CHANCE...30 TO 50 PERCENT...OF THIS SYSTEM BECOMING A TROPICAL
CYCLONE DURING THE NEXT 48 HOURS.

A SMALL AREA OF LOW PRESSURE ASSOCIATED WITH A TROPICAL WAVE IS
PRODUCING DISORGANIZED SHOWERS AND THUNDERSTORMS NEAR THE WINDWARD
ISLANDS. DEVELOPMENT OF THIS SYSTEM...IF ANY...IS EXPECTED TO BE
SLOW TO OCCUR AS IT MOVES WESTWARD AT 10 TO 15 MPH. LOCALLY HEAVY
RAIN AND GUSTY WINDS SHOULD CONTINUE TO SPREAD OVER PORTIONS OF THE
WINDWARD ISLANDS THROUGH TUESDAY MORNING. 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.

$$
FORECASTER ROBERTS/BROWN
Member Since: Posts: Comments:
New TWOAT has everything as is.
Member Since: Posts: Comments:

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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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