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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1068. Skyepony (Mod)
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8:30 Eastern
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Quoting WeatherStudent:


I wish I knew; however, early tendencies would potential take it towards florida based on several bloggers in here and based on the longwave steering pattern.


Where did you get your skills? I am impressed. Is it gonna hit me? Should I shutter?
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It's a warm, sultry, mysterious Lowcountry saturday evening...
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Felicia dropsonde

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Nice open air...

Member Since: June 9, 2007 Posts: 4 Comments: 15923
See?? Burned makes a great point...it's a beautiful thing...
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Quoting presslord:



...so...ah...Drak...

What I hear you saying is ...the first wave is gonna obliteraate South Florida...and the second wave is gonna come along and blow all the rubble away...

Is that about it?


at least the city wouldnt have to pay for a cleanup crew lol
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Hm this isnt even DMAX...

Member Since: June 9, 2007 Posts: 4 Comments: 15923
Quoting Drakoen:


I think this one will be Ana... finally and then Bill might be behind her.



...so...ah...Drak...

What I hear you saying is ...the first wave is gonna obliteraate South Florida...and the second wave is gonna come along and blow all the rubble away...

Is that about it?
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Quoting caneluver:
Is that wave really going to turn into a hurricane and hit the east coast? I better go and get some supplies first thing tomorrow morning....
The line at home depot was horendous, people buying up lemons, cuz that is what this season is, and you are not going to make lemonade out of it no matter how much you try.
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1056. Drakoen
The convection is within a very low shear environment.
Member Since: October 28, 2006 Posts: 57 Comments: 30578
1055. Drakoen
Quoting AllStar17:


First time being impressed all season?


Nope but this one has the most model support thus far.
Member Since: October 28, 2006 Posts: 57 Comments: 30578
I wonder if there will be a special advisory on the new wave. lol
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Quoting Drakoen:
Very impressive:


First time being impressed all season?
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1051. Dakster
To everyone in Hurricane alley... I would be disappointed to learn that any of you are not prepared WELL in advance. Every year I make sure I replace supplies... Lived down here too long to not be prepared. I only have sympathy for someone who has recently moved into Hurricane Alley.


I have a plan and know exactly what I will do and where we will go. No pressure, No Unnecessary stress.
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I made a mistake, it was not the the 55W wave the ECMWF was latching on. Rather, the mid level trough with slight surface cyclonic signature. The vorticity maxima of this wave is primary focused at 500mb and will take a bit of time for it to initialize at the surface adequately. The ECMWF is actually in consensus with the GFS, because it dissipates the wave near 55W, and develops the wave behind it. Due to the favorable upper atmospheric conditions, the CMC and NOGAPS are still latching and expects some sort cyclogenesis to occur. Thus there are two major possibilities:both of them coalesce into a tropical cyclones, or the wave 50W wave deteriorates and the rear wave develops. There is a possibility for both of them to develop, but given the favorable upper-air conditions, that does not seem probable.

ECMWF

GFS
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1046. Drakoen
The EUMETSAT loop shows the circulation on the southeastern portion of the convection.
Member Since: October 28, 2006 Posts: 57 Comments: 30578
1044. Drakoen
Quoting StSimonsIslandGAGuy:
I was wondering if they would find Felicia to be stronger than expected. But since she is not, it seems unlikely to be a threat besides heavy rain.

At the rate this season is going, I'll have my first frost before a named storm *grumbles* And so will Drakoen.


I think this one will be Ana... finally and then Bill might be behind her.
Member Since: October 28, 2006 Posts: 57 Comments: 30578
Dr. Masters:
"I give the wave a medium (30 - 50% chance) of developing into a tropical depression in the next seven days."

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Pat....Stuff like dat is why you are da man!!!!!!!!!!!!!!!!!!
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8:15 Eastern, 7:15 Central
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1039. azimut
Convection building on the CV wave nicely
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1037. Drakoen
Very impressive:
Member Since: October 28, 2006 Posts: 57 Comments: 30578
Quoting StSimonsIslandGAGuy:
skyepony that's not very impressive for a hurricane, 982 mb and 68kt winds. Solidly in Cat 1, but in the weak half of Cat 1.


L. Eye Character: Not Available
M. Eye Shape: Not Available
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The new wave looks to be organizing nicely. Although it seems to have lifted north a bit.
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1030. Skyepony (Mod)
StSimon~ It's held pretty steady since the 1st penetration, a little after 18Z.
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1029. Patrap
If you want to Donate,Donate to Portlight.org ,a Dr. Masters and wunderground sponsored Non-Profit that serves the un-served,under-served and disabled in Post disaster events.



portlight.org

Member Since: July 3, 2005 Posts: 426 Comments: 128875
1028. Dakster
Quoting FloridaTigers:
How did you get a picture of my pole? >:(


You should see the others I have... :-)

AT least I got you all to laugh a little...
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Quoting iceman55:
donate 30$
$85.00
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1023. Patrap


Bourbon St. and St Peters St.

Live webcam
Member Since: July 3, 2005 Posts: 426 Comments: 128875
Quoting presslord:
jeffs....all that is fine and dandy....but...

WHERE'S IT GONNA HIT?!?!?!

OMG ITS COMING RIGHT FOR US! RUN FOR THE HILLS!!!!!!11!!!!
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Quoting presslord:
jeffs....all that is fine and dandy....but...

WHERE'S IT GONNA HIT?!?!?!
S-FLA (i hope)
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QuikSCAT revealed a circulation over the edge of Africa

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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.