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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Quoting stormsurge39:
The area in the gulf is not too close to land to form into a possible TD or even ANA. This is where ANA should have been named back in MAY, maybe it will get its chance this time. The waters are hot and the wind is right. This is something for the northern gulf coast to keep its aye on for heavy downpours and some wind.


Your kidding right?
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Quoting Stormchaser2007:


Well the Bertha wave was highly anticipated by all of the models for a long time and it was also very easy to track the wave all throughout its journey across Africa.


They mentioned this tropical wave very quickly. I wasn't expecting it to show up on the surface analysis this quick usually they wait for more data.
Member Since: October 28, 2006 Posts: 57 Comments: 30827
116. IKE
? GFS 12Z @ 96 hours....

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Quoting IKE:


You know what, WS....I thought you had grown up a little?


lol I was actually beginning to think so too aside from plethora of questions I have been asked.
Member Since: October 28, 2006 Posts: 57 Comments: 30827
Quoting Stormchaser2007:
Wow...

Probably the clearest ive seen the EATL in a while.

All those waves over the past 2 weeks have really cleared out the air.
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Quoting Tropicsweatherpr:


I ask because I remember that they mentioned the wave that gave birth to Bertha when it was still inside the West Africa area.


Well the Bertha wave was highly anticipated by all of the models for a long time and it was also very easy to track the wave all throughout its journey across Africa.
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The area in the gulf is not too close to land to form into a possible TD or even ANA. This is where ANA should have been named back in MAY, maybe it will get its chance this time. The waters are hot and the wind is right. This is something for the northern gulf coast to keep its aye on for heavy downpours and some wind.
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Quoting jpritch:
Drak, what does BenBlogger's graphic mean as far as weather in the arctic goes over the coming week? I wish I knew enough to figure it out!


High pressure, less storminess, Tighter circumpolar low.
Member Since: October 28, 2006 Posts: 57 Comments: 30827
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Quoting KYhomeboy:
Morning all!

Nice looking wave exiting the African coast I see. Conditions seems to be marginal to favorable across the atlantic right now and for the upcoming days. If this does develop, any idea on a general track. I understand that it might be a bit premature to ask, but what it the set up like in terms of the high and steering flow?
For the time being it will move due west. I also imagine this one will be going north of the islands. Can't tell after that though.
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107. IKE
Quoting WeatherStudent:
i betcha ike is still holding on to the hope that it wont develop because of what his precious ecmwf model is showing, pleae.


You know what, WS....I thought you had grown up a little?
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Quoting Stormchaser2007:


Probably by tomorrow afternoon. When/IF they start mentioning it, they'll likely declare it an invest shortly after.


I asked because I remember that they mentioned the wave that gave birth to Bertha when it was still inside the West Africa area.
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Quoting extreme236:


True, but it only took Fay 5-6 days to form...its taken Ana 2 months lol


True..lol
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GFS 12z @ 78 hours:

Member Since: August 2, 2007 Posts: 19 Comments: 19234
Drak, what does BenBlogger's graphic mean as far as weather in the arctic goes over the coming week? I wish I knew enough to figure it out!
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Quoting Drakoen:
The ECMWF shows a pattern more favorable for ridging, the GFS pattern favors a strong Azores high and a cut-off high off the eastern seaboard with a flat trough between the two features.


Thanks for taking the time to share your knowledge Drakoen. It's very helpful to those of us in what seems like a perpetual learning mode.
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Quoting Stormchaser2007:


Second to Fay.


True, but it only took Fay 5-6 days to form...its taken Ana 2 months lol
Member Since: August 2, 2007 Posts: 19 Comments: 19234
Quoting extreme236:
Could this finally be the most anticipated named storm ever...the ANA???


Second to Fay.
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Quoting WeatherStudent:


which one should be believed more, drakoen?


The ECMWF does better in the long-range. I would lean more towards it's forecast than the inconsistent GFS. At least for the time being.
Member Since: October 28, 2006 Posts: 57 Comments: 30827
Quoting Stormchaser2007:

McAfee just came up with 10 warnings. It may just be me though. I have 7 other tabs open.
I believe its this site...I only had this site open
Member Since: August 15, 2008 Posts: 0 Comments: 2515
Could this finally be the most anticipated named storm ever...the ANA???
Member Since: August 2, 2007 Posts: 19 Comments: 19234
Good Morning Ya'll!

Anyone have a comment about that flare up of thunderstorms in the Gulf? Is that just typical daytime heating flareup?
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Quoting Drakoen:
The ECMWF shows a pattern more favorable for ridging, the GFS pattern favors a strong Azores high and a cut-off high off the eastern seaboard with a flat trough between the two features.


The GFS has been too inconsistent with its forecast regarding the NAO. The ECMWF's NAO forecast fluctuates less. So, I am leaning more towards the ECMWF's outcome.
Member Since: July 19, 2008 Posts: 43 Comments: 4051
Quoting Tropicsweatherpr:
Will NHC start to mention it at the 2 PM TWO or is early for them to do that?


They will probably wait till it clears the coast completely first.
Member Since: August 2, 2007 Posts: 19 Comments: 19234
Wow...

Probably the clearest ive seen the EATL in a while.

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Member Since: October 28, 2006 Posts: 57 Comments: 30827
Quoting Tropicsweatherpr:
Will NHC start to mention it at the 2 PM TWO or is early for them to do that?


Probably by tomorrow afternoon. When/IF they start mentioning it, they'll likely declare it an invest shortly after.
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Will NHC start to mention it at the 2 PM TWO or is early for them to do that?
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The ECMWF shows a pattern more favorable for ridging, the GFS pattern favors a strong Azores high and a cut-off high off the eastern seaboard with a flat trough between the two features.
Member Since: October 28, 2006 Posts: 57 Comments: 30827
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Quoting Drakoen:


I didn't put the app there lol. That person is on my ignore list.


They must be on mine too :)
RU notifying admin? 10Q
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Well about to pack for my trip to the NE tommorow morning....I'll try to check in if I can next week; if not, happy hunting Folks and I'll see everyone around the 18th.....WW
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Finally, something in the Atlantic worth mentioning.
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Quoting futuremet:


I don't use McAfee, it takes too much ram. Avira only uses 1MB of ram. It is very efficient too.

My backup AV is malwarebytes.
I'm on a linux box so I'm always browsing safe and secure. Makes for an ultra stable platform without ANY resource dependent security layer needed.
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Morning all!

Nice looking wave exiting the African coast I see. Conditions seems to be marginal to favorable across the atlantic right now and for the upcoming days. If this does develop, any idea on a general track. I understand that it might be a bit premature to ask, but what it the set up like in terms of the high and steering flow?
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Quoting hurricane23:


Not only that but based on some of the long-range models i looked at late last night things should really start to pick up across the atlantic sometime next week.NAO will be going positive.


Perhaps

GFS 06Z



ECMWF 00Z



Member Since: July 19, 2008 Posts: 43 Comments: 4051
Quoting WeatherStudent:


adrian, what about steering pattern wise for this little critters of nature?


Anyones guess...It all just basically comes down to luck and chance at where the long wave pattern just happens to be when a hurricane just happens to come along.August is more likely to have ridging in the W. Atlantic than Sept or Oct, that's for sure (BUT) i have no faith in any forecast over 84 hrs. And the usual term for the long wave to be in any one general position is 6-10 days.

Adrian
Member Since: May 14, 2006 Posts: 8 Comments: 13841
Quoting Drakoen:


The 12z DAM forecast for cyclogenesis off the African coast south of the CV islands. A synoptic scale upper level anticyclone and forecast low SAL should allow this wave to develop. The DAM sides with the GFS, CMC, UKMET, and NOGAPS forecast. The DAM views the ECMWF as incorrectly handling the upper level easterlies.


Sounds like an interesting run...looks like a decent chance at some development over the next few days.
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If the CV train is starting in earnest, we will start to see waves emerge off the coast every 3-4 days but not everyone will develop...Model consensus will be key and to see how they look after clearing the CV islands.
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The graphic that BenIBlogger posted is another thing I wanted to mention. Increased 500hpa geopotential heights over the northeast and Canadian Meritimes. This favors a flatter trough and the amplification of the ridge. Storms coming from the Tropical Atlantic need to be watched.
Member Since: October 28, 2006 Posts: 57 Comments: 30827

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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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