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

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

Share this Blog
4
+

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

Comments will take a few seconds to appear.

Post Your Comments

Please sign in to post comments.

or Join

Not only will you be able to leave comments on this blog, but you'll also have the ability to upload and share your photos in our Wunder Photos section.

Display: 0, 50, 100, 200 Sort: Newest First - Order Posted

Viewing: 1389 - 1339

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | 32 | 33 | 34 | 35 | 36 | 37 | 38 | 39 | 40 | 41 | 42 | 43 | 44 | 45 | 46 | 47 | 48 | 49 | 50 | 51 | 52 | 53 | 54 | 55 | 56 | 57 | 58 | 59 | 60 | 61 | 62 | 63 | 64 | 65 | 66Blog Index

Out to sea on the GFS with mid latitude trough amplification

Bill? i sure hope so bye bye Bill you won't be hurting anyone my friend i can have a shot to that pat
Member Since: August 29, 2006 Posts: 22 Comments: 1352
Pat...many times I have pleaded FOR a fifth....
Member Since: Posts: Comments:
18z intensity forecasts for 99L (full size):

Member Since: Posts: Comments:
7pm advisory-NHC Poll
a-Yellow circle and orange turns to yellow
b-Yellow circle and orange circle remains
c-Yellow circle turns orange and orange remains
d-Yellow circle turns ornage and orange circle turns yellow
E-Other
Member Since: Posts: Comments:
The wave the GFS and others are developing will emerge over the next 2 days.
Member Since: Posts: Comments:
1383. aquak9
hunkerdown, I often hafta go plee after a fifth, too...but I really want to see if WS understands the meaning of the statement.

And I'm not being mean...I think he might know the answer.
Member Since: Posts: Comments:
bi-laws??!
Member Since: Posts: Comments:
1381. Drakoen
Out to sea on the GFS with mid latitude trough amplification.
Member Since: Posts: Comments:
1380. Patrap
In Uptown NOLA,..if one Pleads the FiFth,..were usually getting another Shot of Jack Daniels from the Bartender..
Member Since: Posts: Comments:
Quoting Weather456:
Other than TCHP, not sure why the GFS has such a bomb. Conditions must be near perfect.


Or it's been hanging out with the CMC on Friday nights again.

Member Since: Posts: Comments:
1377. 7544
o6 gfs says ok lets go back to fla again ?

Link
Member Since: Posts: Comments:
Afternoon all


the models usually seem fairly decent on intensity


Not so much bajelay...Intensity is usually one of the hardest things to forecast....
Member Since: Posts: Comments:
Aqua...excellent exercise...
Member Since: Posts: Comments:
Quoting BA:


don't get me wrong, I really like OS X and as far as a laptop goes I think the new macbooks are simply the best...right tool for the right job otherwise, macs make terrible gaming machines ;)

and btw, windows 7 is very nice so if you are stuck on windows at least you won't be stuck on that vista garbage soon

if you can afford the apple tax and you are not a gamer macs are my choice


Thanks for the help. Im not a gamer, I just use alot of graphics and softwares for school.
Member Since: August 2, 2006 Posts: 0 Comments: 1240
Quoting aquak9:
WS- ok, so you're going to plee or plead the fifth.

I'm not being mean, I'm gonna teach ya something here. What does the word "fifth" mean in that statement??

Nobody else answer- I want to see if he knows what this statement really means.
doesn't matter since he will be pleeing, not to be confused with fleeing
Member Since: August 15, 2008 Posts: 0 Comments: 2515
Just for fun...GFS wind speed for 174 hours:

Member Since: Posts: Comments:
The thing is, the models usually seem fairly decent on intensity, but track can vary quite a bit, especially until the cane actually forms, thus Westward is still a strong possible.

Correct?

I seem to remember a cane last year or year before that did just that, defying the models and staying Westward. And that was after is was already developed, thus the models would have had a better handle on it.
Member Since: Posts: Comments:
Quoting caneluver:


Probably will not develope. GFS way to agressive


Its been showing this for days now and so have the other models. Certainly tons of support for development.
Member Since: August 2, 2007 Posts: 19 Comments: 19234
1364. 10Speed
Quoting mobilegirl81:
If you watch the GFS real close it shows a ghost storm entity coming out of the carribean, moving into the gulf, and going into the central gulf coast.


Yeah, I noted that yesterday evening and don't like the looks of it. That same model hints at some potential tag alongs too. Just what we do not need is a funnel of storms running up the GOM or Florida....again.
Member Since: Posts: Comments:
Other than TCHP, not sure why the GFS has such a bomb. Conditions must be near perfect.
Member Since: Posts: Comments:
Quoting TheCaneWhisperer:
Don't mention the "Boxes"



Do you mean Eeee-bare Boxes?
Member Since: Posts: Comments:
Nice Avatar. I love Duffy's. The original by the tracks was the best.
Quoting Acemmett90:
I hate vista also it sucks
Member Since: Posts: Comments:
1359. aquak9
WS- ok, so you're going to plee or plead the fifth.

I'm not being mean, I'm gonna teach ya something here. What does the word "fifth" mean in that statement??

Nobody else answer- I want to see if he knows what this statement really means.
Member Since: Posts: Comments:
1355. BA
Quoting alaina1085:


Well I just want a computer without vista! I hate vista...lol. But I also need something with a good graphic card. Im still shopping.


don't get me wrong, I really like OS X and as far as a laptop goes I think the new macbooks are simply the best...right tool for the right job otherwise, macs make terrible gaming machines ;)

and btw, windows 7 is very nice so if you are stuck on windows at least you won't be stuck on that vista garbage soon

if you can afford the apple tax and you are not a gamer macs are my choice
Member Since: Posts: Comments:
Quoting troy1993:
Hey weather 456 do you think the tropical wave that every computer model is developing will develop into a siginficant tropical cyclone?


I'm not sure at this point, but it looks so. I'm not too exited though, since 1), its still a bit far out and 2) likely affect someone.
Member Since: Posts: Comments:
Don't mention the "Boxes"
Member Since: Posts: Comments:
1351. JLPR
Quoting caneluver:


Probably will not develope. GFS way to agressive


I do hope your right
Member Since: Posts: Comments:
1350. DDR
Hey 456
We had some major flooding here today,local met says it an area of low pressure.
Member Since: Posts: Comments:
Quoting WeatherStudent:


I'll plee the fifth, PressLord, :)
gecko...you plead the fifth :)
Member Since: August 15, 2008 Posts: 0 Comments: 2515
Looks like it makes 20N60W on that run. EEEK!
Member Since: Posts: Comments:
So where is the wave the models say will become the big player in the ATL currently located?

He's in Africa packing for his long journey across the sea...his expedition starts tomorow
Member Since: August 29, 2006 Posts: 22 Comments: 1352
Quoting BA:


don't believe the hype, macs can get viruses just like windows machines can

the issue is macs currently have such a small market share they just haven't been a target

and before you even think I'm anti-mac... my main workstation is a mac pro, I also own a new macbook and an iphone...however, I refuse to be a mac "fanboy" and buy into the garbage the fanboys use to push the product

I prefer OS X (and it is my main OS) but I also use Windows and several other flavors of *nix.


Well I just want a computer without vista! I hate vista...lol. But I also need something with a good graphic card. Im still shopping.
Member Since: August 2, 2006 Posts: 0 Comments: 1240
1341. JLPR
Quoting Drakoen:
Wow


lol Drak we thought the same thing xD
Member Since: Posts: Comments:
So the GFS shows a major passing through the Northern Windwards August 18-20th, correct?
Member Since: Posts: Comments:
1339. JLPR
wow =P

Member Since: Posts: Comments:

Viewing: 1389 - 1339

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | 32 | 33 | 34 | 35 | 36 | 37 | 38 | 39 | 40 | 41 | 42 | 43 | 44 | 45 | 46 | 47 | 48 | 49 | 50 | 51 | 52 | 53 | 54 | 55 | 56 | 57 | 58 | 59 | 60 | 61 | 62 | 63 | 64 | 65 | 66Blog Index

Top of Page

About

Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.