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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2519. Drakoen
The GFS is the only model that recurves this out to sea for now.
Member Since: October 28, 2006 Posts: 57 Comments: 30615
Oh my gosh, could this be it?!Ana is waking up now.
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2517. Relix
Poll: D

I need to say... this is in a higher lat that the islands so they will probably be safe (reminder: too early, too early, too early!) but coast interests should keep an eye on it. I don't trust the models with their latest run.
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i know that it's always hot in the gulf at this time of year - some of the hottest waters on earth - i wasn't sure if it was any hotter than USUAL for this time of the year.
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Quoting jasoniscoolman10:
here is the tropical wave..lots of t.stormon the top of this wave but no in the middle of the wave yet..its going to need some t/storm in the middle soon.


You're way off again...
Member Since: July 19, 2008 Posts: 43 Comments: 4051
2513. Dakster
At the 2 TWO

A. Gone
B. Yellow
C. Orange
D. Red
E. TD
F. Red Alert

Based on what you all are saying I'll go with D. Red...
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2512. Drakoen
Member Since: October 28, 2006 Posts: 57 Comments: 30615
Quoting jasoniscoolman10:
here is the tropical wave..lots of t.stormon the top of this wave but no in the middle of the wave yet..its going to need some t/storm in the middle soon.


That's not where the COC is located
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Ike is a good example. It had a rather high latitude and didn't recurve. It ended up in the gulf in fact.
Member Since: August 2, 2007 Posts: 19 Comments: 19234
Models will continuously show this pattern of recurvature. Not going to happen.
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G'morning all. I see one of our wave actually got a number. Nice to know it is still way out.
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Quoting sammywammybamy:


Rapid Intesification????

It Seems..


No. Just good organization.
Member Since: August 2, 2007 Posts: 19 Comments: 19234
Quoting WeatherStudent:
for the love of god, one can clearly see that some of those models are already begining to turn it northwest, incrediably surreal.
No, it is not surreal. Go to the NHC's model page for a description of the BAMs and LBAR.
Member Since: August 15, 2008 Posts: 0 Comments: 2515
Now I think 99L may become a code red at 2pm or 8pm and a Td by 5pm or 11pm.
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Quoting mobilegirl81:
The models have done this to previous systems(Frances, Jean, Ivan);Driving them out to sea.


The models had Ivan going out to sea with that monster high to it's north?
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Quoting CybrTeddy:
99L is becoming better organized by the minute. They might have to go with Red alert at 2 PM. Closed low, organized convection, persistence, model support. TD 2 is possible by 5 PM.

Someone do a TCFA survey.
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2501. Drakoen
Quoting mobilegirl81:
The models have done this to previous systems(Frances, Jean, Ivan);Driving them out to sea.


Dean, Ike. Bertha was suppose to recurve out to sea before even getting to 40W. It is simply too early to make that assumption.
Member Since: October 28, 2006 Posts: 57 Comments: 30615
Quoting CybrTeddy:
99L is becoming better organized by the minute. They might have to go with Red alert at 2 PM. Closed low, organized convection, persistence, model support. TD 2 is possible by 5 PM.


I might actually agree with this. I do believe red at 2pm and a TD today is a good possibility.
Member Since: August 2, 2007 Posts: 19 Comments: 19234
Quoting nrtiwlnvragn:
Latest surface map indicates westward movement.



Also notice how the TPC is forecasting the high off the US East Coast to build into the Western Atlantic replacing the troughing occurring due to the passing cold front in the North-Central Atlantic.
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Quoting hurricane23:
Lol just ran the 12z NAM and its a weak low pressure are near the northern islands.Most likely 99L.


No, it is not, it is one the waves between 55-40W
Member Since: July 19, 2008 Posts: 43 Comments: 4051
2495. Drakoen
Quoting hurricane23:
Lol just ran the 12z NAM and its a weak low pressure are near the northern islands.Most likely 99L.


That's not possible. It is not 99L
Member Since: October 28, 2006 Posts: 57 Comments: 30615
99L is becoming better organized by the minute. They might have to go with Red alert at 2 PM. Closed low, organized convection, persistence, model support. TD 2 is possible by 5 PM.
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Just ran the 12z NAM and it has a weak low pressure area near the northern islands.Most likely a different system though.
Member Since: May 14, 2006 Posts: 8 Comments: 13839
The models have done this to previous systems(Frances, Jean, Ivan);Driving them out to sea.
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Quoting truecajun:
the SSTs in the gulf aren't any hotter than usual for this time of the year are they?


They're much above normal. Some of the hottest SST's on Earth are in the GOMEX. They're hotter than in 2005.
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As for guidance on the latitude of 99L, if anything has a decent handle on an invest area, it is usually the BAM suite. (especially BAMS and BAMM)
http://euler.atmos.colostate.edu/~vigh/guidance/northatlantic/track_early1.png
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2488. Drakoen
Quoting extreme236:
Special SAB classification indicates 99L very close to TD status:

09/1330 UTC 14.2N 21.8W T1.5/1.5 99L -- Atlantic


That is close...
Member Since: October 28, 2006 Posts: 57 Comments: 30615
Special SAB classification indicates 99L very close to TD status:

09/1330 UTC 14.2N 21.8W T1.5/1.5 99L -- Atlantic
Member Since: August 2, 2007 Posts: 19 Comments: 19234
Quoting PcolaDan:
For those of you that use Google Earth and don't know about these, guiWeather has some good KML's.
(Orca, the buoy and ship data is pretty kool.)


The link you gave is just a small sample of all of the different .kml files that are available for GE. I must have 50 or more different ones.. including almost every different weather one you can find.

They also have a really good one on the Rigs in the gulf..and their weather station data.
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Yeah moving West clear, maybe next models will changes track map.
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Quoting AussieStorm:

SST's below the 26°C threshold typically needed to sustain a hurricane
That is sustain, once prominently developed. SSTs below 28 would not lend well for developemnt.
Member Since: August 15, 2008 Posts: 0 Comments: 2515
2483. Drakoen
I should have looked at the hi-res quickscat. It does have a closed low located near 13N-13.5N.
Member Since: October 28, 2006 Posts: 57 Comments: 30615
Latest sfc map shows a closed low with 99L. Things becoming more interesting fast.
Member Since: August 2, 2007 Posts: 19 Comments: 19234
2479. Drakoen
.
Member Since: October 28, 2006 Posts: 57 Comments: 30615
Latest surface map indicates westward movement.

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this is for whomever it applies...

To whatever extent I've learned anything here over the last four years, it's come from reading others and thinking about what they say...not arguing...never learned a damned thing when I was running my mouth...
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Quoting truecajun:
the SSTs in the gulf aren't any hotter than usual for this time of the year are they?

0 to 1 C above someone's definition of "normal". Sure, it is warm, but not 4 C warm.

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2475. Relix
90L should be moving WNW, NW... all I see is W. I am going to have breakfast haha. G'morning WG
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Quoting sammywammybamy:


Your Saying youll think itll be a fish ..

But the steering patterns show that it will move WNW then W then WNW again


Yes iam saying this storm will eventually feel the tug of mid latitude trough forecast to come down during the next few days.The lower pressure area i see is nearly around 14.2 or something like that.Per this QUIKSCAT i think its safe bet it has a closed llc.
Member Since: May 14, 2006 Posts: 8 Comments: 13839
For those of you that use Google Earth and don't know about these, guiWeather has some good KML's.
(Orca, the buoy and ship data is pretty kool.)
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Currently in Praia CV at 14:00 UTC

81ºF/27ºC
wind W 2mph
Preassure 21.91 in.
DP 77ºF/25ºC
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gulf SSTs are above normal,yes
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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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