Felicia not weakening; new African wave may develop

By: Dr. Jeff Masters , 3:12 PM GMT on August 08, 2009

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Hurricane Felicia has not weakened today, and continues to hold its own in spite of cool sea surface temperatures beneath it. Recent satellite imagery shows that the tops of thunderstorms surrounding the eye have cooled slightly, indicating that the updrafts sustaining the eyewall are maintaining their strength. The appearance of the hurricane has improved some today, with the storm assuming a more symmetric appearance.


Figure 1. Current satellite image of Hurricane Felicia.

Sea surface temperatures (SSTs) under Felicia have now fallen to 24.7°C, well below the 26°C threshold typically needed to sustain a hurricane. SSTs will slowly increase to 26°C by the time the storm reaches Hawaii, though. Wind shear is expected to remain low to moderate, 5 - 15 knots, through Monday morning. By Monday night, shear will rise to 20 knots, and remain above 20 knots thereafter. The higher shear combined with the relatively cool SSTs should mean that Felicia will be rapidly weakening in its final 24 hours before reaching Hawaii. Several of the computer models continue to show that this shear will be high enough to tear Felicia apart before it reaches Hawaii, though it appears to me that Felicia's current strength and annular structure will help it resist the shear enough to allow the storm to hit Hawaii as a tropical depression with 35 mph winds. Regardless, Felicia will bring heavy rain Hawaii beginning on Monday morning, and these rains will have the capability of causing flash floods and mudslides. The Hurricane Hunters are scheduled to make their first low-level investigation of Felicia this afternoon (around 10 am Hawaiian time). The NOAA jet also flies into Felicia today, and will drop a series of dropsondes that will be used to gather data that will be fed into today's 12Z and 00Z computer model runs.

Typhoon Morakot hits Taiwan
Typhoon Morakot hit Taiwan yesterday, battering the island with Category 1 winds and heavy rain. The Taipei airport recorded sustained winds of 56 mph, gusting to 76 mph, at the peak of the storm. Morakot killed 6 on Taiwan and 10 in the Philippines, and is headed towards a final landfall on mainland China as a tropical storm later today. Storm chaser James Reynolds intercepted the storm and posted videos on typhoonfury.com and Youtube. Morakot is still visible today on Taiwan radar.


Figure 2. Visible satellite image of a spinning tropical wave leaving the coast of Africa. The image was taken at 8am EDT 8/8/09.

African tropical wave may develop
A strong tropical wave with a moderate amount of spin is moving off the coast of Africa this morning. The wave is under about 10 - 20 knots of wind shear and has sea surface temperatures beneath it of 27°C. These conditions are probably too marginal to allow development over the next two days. As the wave moves westward away from Africa over the next few days, wind shear should slowly decrease and the SSTs will warm, potentially allowing for some slow development. The UKMET, GFS, and NOGAPS models all indicate the possibility that this will become a tropical depression 3 - 5 days from now. The ECMWF model forecasts that strong easterly winds over the wave will create too much shear to allow development. The wave is well south of the Saharan Air Layer, so dry air and African dust should not interfere over the next 3 - 5 days. I give the wave a medium (30 - 50% chance) of developing into a tropical depression in the next seven days.

I'll have an update on Sunday.

Jeff Masters

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1368. aquak9
Quoting SevereHurricane:


I have GRL2 and it was worth every penny, but to have GRL2 you need a subscription to Allisonhouse(Data).


AllisonHouse Data worth every penny- might be my imagination, but it seems to come in quicker and easier, lighter load, goes faster(?).

Not to be confused with AllisonKrause.
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1365. hahaguy
Quoting Drakoen:
I think we have a closed low at the surface. Or nearly closed. Sharp wind shifts are occurring.


Looks that way.
Member Since: August 12, 2007 Posts: 2 Comments: 2838
Quoting Drakoen:
I think we have a closed low at the surface. Or nearly closed. Sharp wind shifts are occurring.


Agreed Drakoen
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Quoting Drakoen:
I think we have a closed low at the surface. Or nearly closed. Sharp wind shifts are occurring.


Indeed.

It'll be interesting to see what the surface map shows.
Member Since: June 9, 2007 Posts: 4 Comments: 15790
1362. Drakoen
I think we have a closed low at the surface. Or nearly closed. Sharp wind shifts are occurring.
Member Since: October 28, 2006 Posts: 57 Comments: 29938
1361. HadesGodWyvern (Mod)
Japan Meteorological Agency

Tropical Disturbance Summary (0000z 09AUG)
=========================================

At 9:00 AM JST, Tropical Depression, Former Goni (994 hPa) located at 18.0N 108.0E has 10 minute sustained winds of 25 knots with gusts of 40 knots and is reported as moving south slowly

---
Goni weakening
Member Since: May 24, 2006 Posts: 50 Comments: 44881
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Getting a little too close for comfort.

Member Since: June 9, 2007 Posts: 4 Comments: 15790
Quoting Patrap:

GR Level X

View storm features in 3D with GR2Analyst's exclusive Volume Explorer



I have GRL2 and it was worth every penny, but to have GRL2 you need a subscription to Allisonhouse(Data).
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New surface maps should be out very soon
Member Since: May 16, 2009 Posts: 1 Comments: 1231
Quoting hurricane23:


Cant go wrong with GR products.

Yep

WELL worth the money.


Member Since: June 9, 2007 Posts: 4 Comments: 15790
1355. Drakoen
GFS and CMC have been persistent with dual cyclones forming we will have to see. One of things that I wanted to watch out for this season is whether we would get a start that would not stop.
Member Since: October 28, 2006 Posts: 57 Comments: 29938
1354. Patrap

GR Level X

View storm features in 3D with GR2Analyst's exclusive Volume Explorer

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Quoting Acemmett90:

truce
k
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1352. Drakoen
Quoting Relix:
GFS confirms what I suspected... it will likely go north and miss the islands. Risk to coast? Fish? Of course its too early... are there any ridges or steering currents the GFS is not taking into consideration?


Too early.
Member Since: October 28, 2006 Posts: 57 Comments: 29938
Quoting Stormchaser2007:


GRLevel2 Analyst.

$250


Cant go wrong with GR products.
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Quoting WeatherStudent:


This is not a sports blog; therefore, go advertise that else where.
k ill stop now back to the tropics! lol
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Quoting cyclonekid:
Is that a pic that comes from a website or a software that you have?


GRLevel2 Analyst.

$250
Member Since: June 9, 2007 Posts: 4 Comments: 15790
Quoting Acemmett90:

GO Gators by the way duffys is spocering the miami dolphins this year
GO CANES!!!!
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Image as of 10pm EDT
Member Since: June 9, 2007 Posts: 4 Comments: 15790
I dont think it's quite DMAX. http://www.die.net/earth/
Until you see daylight over the AOI we haven;t reached Dmax.
Member Since: August 27, 2008 Posts: 0 Comments: 1497
Quoting Drakoen:


You have bad taste...


Drak...did you really think I was being serious? It's hard to convey "tongue and cheek" in text.

Enjoy your post, the only one I would actually add to the original list would be StormW
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Quoting Stormchaser2007:
Minneapolis tornado warned storm:

Is that a pic that comes from a website or a software that you have?
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More symmetrical appearance...getting more organized.

Member Since: August 2, 2007 Posts: 19 Comments: 19234
Quoting weatherwatcher12:

It's around 1-2 am out there
its 2:30am now
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1333. Patrap
We alway's use the wunderground during the Atlantic Season
...


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Quoting louisianaboy444:
wait till 1 or 2 am then things will get very intreasting

You have to remember the time zones it is later near the wave than it is in the U.S so it may be entering DMAX right about now....

It's around 1-2 am out there
Member Since: May 16, 2009 Posts: 1 Comments: 1231
10:00 EDT
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Quoting Relix:
GFS confirms what I suspected... it will likely go north and miss the islands. Risk to coast? Fish? Of course its too early... are there any ridges or steering currents the GFS is not taking into consideration?

Is it correct to say that since this has not developed the GFS didn't get to initialize correctly or not.
Member Since: May 16, 2009 Posts: 1 Comments: 1231
NHC/NOAA and friends want to make sure this doesn't fizzle before making it an invest.
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wait till 1 or 2 am then things will get very intreasting

You have to remember the time zones it is later near the wave than it is in the U.S so it may be entering DMAX right about now....
Member Since: August 29, 2006 Posts: 22 Comments: 1342
Minneapolis tornado warned storm:

Member Since: June 9, 2007 Posts: 4 Comments: 15790
1323. Relix
GFS confirms what I suspected... it will likely go north and miss the islands. Risk to coast? Fish? Of course its too early... are there any ridges or steering currents the GFS is not taking into consideration?
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1322. aquak9
everyone's on board?

Ya'll are agreeing??

(reaches for valium)
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Quoting 7544:
hi all hard to belive this isnt even labled a invest by now


It should by tomorrow...
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The GFS is also developing the next Twave that will leave the coast on Tuesday/Wednesday....
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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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