Category 4 Hurricane Felicia peaks in intensity

By: Dr. Jeff Masters , 2:51 PM GMT on August 06, 2009

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Category 4 Hurricane Felicia put on a very impressive burst of intensification yesterday, peaking out with 140 mph winds. Recent infrared satellite loops show that Felicia is maintaining its Category 4 intensity, as the cloud tops surrounding the eye have stayed relatively constant in temperature.


Figure 1. Current satellite image of Hurricane Felicia.

While Felicia is an impressive hurricane now, its days are numbered. Sea surface temperatures (SSTs) under Felicia have already declined 1.5°C from yesterday, and are now 27°C--about 1°C above the 26°C threshold needed to sustain a hurricane. Felicia's west-northwest track will continue to take the storm into a region of cooler waters, which should induce a slow but steady weakening trend, beginning later today. Felicia has a very thick ring of intense thunderstorms surrounding the eye, which is characteristic of a class of hurricanes called "annular" hurricanes. Due to their structure, annular hurricane tend to resist weakening, and Felicia will probably weaken only very slowly at first. By Friday morning, SSTs should fall to 26°C, and decline to 24.5°C by Saturday. Wind shear is expected to remain in the low to moderate range over the next three days, 5 - 15 knots. On Sunday, Felicia will be encountering very strong westerly winds aloft, which should create 30 - 40 knots of wind shear. By Monday night, when most of the models predict Felicia will be nearing the Hawaiian Islands, the high shear may be able to tear the storm apart. Only the GFDL model holds on to Felicia that long, predicting that the storm will be a tropical depression with 35 mph winds when it blows through the Hawaiian Islands. The rest of the models dissipate Felicia by Monday. While the current forecast calls for Felicia to have a minor impact on Hawaii, NHC is taking this storm seriously and has scheduled a flight of the NOAA jet into Felicia on Friday. The jet will drop a series of dropsondes that will be used to gather data that will be fed into tomorrow night's 00Z computer model runs. Regular low-level flights by the Hurricane Hunters are scheduled to begin Saturday afternoon.


Figure 2. The eye of Hurricane Felicia as seen by NASA's MODIS instrument on the Terra spacecraft yesterday. The image was taken at 19 UTC 8/5/09 while Felicia was rapidly intensifying. At the time, Felica was a Category 3 hurricane with 115 mph winds. Felicia peaked in intensity as a Category 4 hurricane with 140 mph winds 9 hours after this photo was taken. Image credit: NASA.

Typhoon Morakot takes aim at Taiwan
Category 1 Typhoon Morakot is headed towards Taiwan, and is expected to make landfall tonight. Satellite loops show that the clouds surrounding the eye are developing very cold tops as they push high into the troposphere, a sign the storm is intensifying. Morakot is expected to intensify into a Category 2 typhoon before making landfall. Storm chaser James Reynolds is intercepting the storm and will be posting live updates on his typhoonfury.com web site and twitter for those who want to follow the storm. The large eye of Morakot is now visible on Taiwan radar.

The Atlantic is quiet
There are no areas of disturbed weather in the Atlantic worth mentioning today, and no computer models forecast tropical storm development over the next seven days.

I'll have an update on Friday.

Jeff Masters

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873. TheCaneWhisperer
2:41 PM GMT on August 07, 2009
Quoting IKE:
Found this from the Birmingham,AL. morning discussion...looks like a trough returns mid to late next week....

".DISCUSSION...

QUIET WEATHER CONDITIONS EXPECTED TODAY AND TOMORROW...FOR MOST OF
THE AREA...AS UPPER LEVEL RIDGING CROSSES THE SOUTHEASTERN CONUS AND
SETS UP TO OUR EAST BY SUNDAY. WILL MAINTAIN HIGHS A COUPLE DEGREES
ABOVE CLIMO FOR TODAY AND SATURDAY...LOW TO MID 90S. DRIER AIR WILL
CONTINUE TO SLOWLY MOVE INTO THE AREA THROUGH TONIGHT. WITH CLEAR
SKIES...A FEW SPOTS IN THE NORTHEAST COULD SEE LOWS IN THE LOWER
60S. ELSEWHERE...MID 60S TO LOWER 70S EXPECTED.

AS THE RIDGE SHIFTS EASTWARD...A MID LEVEL VORT MAX WILL MOVE AROUND
THE SOUTHERN AND WESTERN EDGES OF THE RIDGE....ALONG THE NORTHERN
GULF COAST AND IN TO LOUISIANA SATURDAY. GOOD AGREEMENT FROM THE
NAM...GFS...AND LOCAL WRF IN TAKING FEATURE INTO ARKANSAS SUNDAY AND
MAKING A TURN TO THE EAST TOWARD THE TENNESSEE VALLEY BY MONDAY. AS
THIS SYSTEM PROGRESSES...SOUTHERLY FLOW AND MOISTURE WILL RETURN TO
CENTRAL ALABAMA...WITH ISOLATED SH/TS ACTIVITY AS EARLY AS SATURDAY
AFTN ACROSS THE SOUTHERN PORTION OF THE FORECAST AREA. INCREASED
COVERAGE...PARTICULARLY DURING MAX DAYTIME HEATING...IS EXPECTED ON
SUNDAY AND MONDAY. HIGH TEMPS IN THE LOWER 90S EXPECTED EACH
AFTERNOON WITH LOWS IN THE LOWER 70S.

RIDGE WEAKENS ACROSS THE AREA BY MID WEEK AS TROUGHING ATTEMPTS TO
RE-ESTABLISH ITSELF ACROSS THE EASTERN CONUS...RETURNING CENTRAL
ALABAMA TO AN UNCERTAIN AND OFTEN PESKY NORTHWESTERLY FLOW PATTERN.
WILL MAINTAIN POPS AND TEMPS CLOSE TO GUIDANCE...AND CLIMO...FOR
EACH PERIOD NEXT WEEK."



By By to August if that happens
872. CycloneOz
2:22 PM GMT on August 07, 2009
Quoting Patrap:


.."Cry Havoc and Let Slip, the Tropics of 09"..





The GoM is open?

Who approved that?
Member Since: August 26, 2006 Posts: 10 Comments: 3753
871. IKE
2:20 PM GMT on August 07, 2009
NEW BLOG!
Member Since: June 9, 2005 Posts: 23 Comments: 37858
869. IKE
2:17 PM GMT on August 07, 2009
Member Since: June 9, 2005 Posts: 23 Comments: 37858
868. bajelayman2
2:16 PM GMT on August 07, 2009
Morning Sir & Sirs. Back for a bit, then out again.
Member Since: August 13, 2007 Posts: 0 Comments: 488
867. HIEXPRESS
2:15 PM GMT on August 07, 2009
Quoting Patrap:


.."Cry Havoc and Let Slip, the Tropics of 09"..




"Cry Havoc and Let Slip, the Tropics of 09"
Member Since: October 13, 2005 Posts: 4 Comments: 2156
866. bajelayman2
2:14 PM GMT on August 07, 2009
Quoting Stormchaser2007:
New wave just emerged off of Africa...looks decent.



I think the wave exiting today, is the wave that GFS predicted about a week ago, would develop (exiting around 8th).

Have not checked on the current GFS however.

Member Since: August 13, 2007 Posts: 0 Comments: 488
864. jeffs713
2:10 PM GMT on August 07, 2009
Quoting IKE:
Found this from accuweather on the Atlantic....

"A change in the upper air pattern through the weekend could increase potential for tropical development in the Gulf of Mexico. A persistent upper ridge of high pressure over the southwestern U.S. and compensating upper trough over the eastern U.S. and the northern development over the western Atlantic basin much of the summer. This pattern will change over the weekend as the upper ridge shifts eastward and takes up camp over the southeastern U.S. This will open the door for tropical moisture or even a disturbance over the northwestern Caribbean or the southern Gulf to track northward and northwestward. There are no trackable features at this time, but it is worth keeping eye on."

I don't like that. A ridge setting up in the SE is the absolute last thing Florida or the western GOM want. That would tend to favor one of 3 possibilities for a storm, especially a CVH... 1. Recurve w/o hitting the east coast. 2. direct FL strike (east coast more likely), and 3. western GOM strike.

Lets hope the high either stays very weak, or builds in so strongly to keep storms well south.
Member Since: August 3, 2008 Posts: 16 Comments: 5885
863. largeeyes
2:08 PM GMT on August 07, 2009
Quoting Skyepony:
We haven't seen shades of green like this in the ATL since last year..



1 in 20! Things are lookin up.
Member Since: August 22, 2006 Posts: 0 Comments: 1455
862. jeffs713
2:08 PM GMT on August 07, 2009
Quoting Skyepony:
We haven't seen shades of green like this in the ATL since last year..


That image is almost amusing. It looks like someone was trying to color in the entire MDR, GOM, and off the east coast.
Member Since: August 3, 2008 Posts: 16 Comments: 5885
861. Patrap
2:08 PM GMT on August 07, 2009
Quoting IKE:
Found this from accuweather on the Atlantic....

"A change in the upper air pattern through the weekend could increase potential for tropical development in the Gulf of Mexico. A persistent upper ridge of high pressure over the southwestern U.S. and compensating upper trough over the eastern U.S. and the northern development over the western Atlantic basin much of the summer. This pattern will change over the weekend as the upper ridge shifts eastward and takes up camp over the southeastern U.S. This will open the door for tropical moisture or even a disturbance over the northwestern Caribbean or the southern Gulf to track northward and northwestward. There are no trackable features at this time, but it is worth keeping eye on."


.."Cry Havoc and Let Slip, the Tropics of 09"..



Member Since: July 3, 2005 Posts: 426 Comments: 128668
860. IKE
2:06 PM GMT on August 07, 2009
Found this from the Birmingham,AL. morning discussion...looks like a trough returns mid to late next week....

".DISCUSSION...

QUIET WEATHER CONDITIONS EXPECTED TODAY AND TOMORROW...FOR MOST OF
THE AREA...AS UPPER LEVEL RIDGING CROSSES THE SOUTHEASTERN CONUS AND
SETS UP TO OUR EAST BY SUNDAY. WILL MAINTAIN HIGHS A COUPLE DEGREES
ABOVE CLIMO FOR TODAY AND SATURDAY...LOW TO MID 90S. DRIER AIR WILL
CONTINUE TO SLOWLY MOVE INTO THE AREA THROUGH TONIGHT. WITH CLEAR
SKIES...A FEW SPOTS IN THE NORTHEAST COULD SEE LOWS IN THE LOWER
60S. ELSEWHERE...MID 60S TO LOWER 70S EXPECTED.

AS THE RIDGE SHIFTS EASTWARD...A MID LEVEL VORT MAX WILL MOVE AROUND
THE SOUTHERN AND WESTERN EDGES OF THE RIDGE....ALONG THE NORTHERN
GULF COAST AND IN TO LOUISIANA SATURDAY. GOOD AGREEMENT FROM THE
NAM...GFS...AND LOCAL WRF IN TAKING FEATURE INTO ARKANSAS SUNDAY AND
MAKING A TURN TO THE EAST TOWARD THE TENNESSEE VALLEY BY MONDAY. AS
THIS SYSTEM PROGRESSES...SOUTHERLY FLOW AND MOISTURE WILL RETURN TO
CENTRAL ALABAMA...WITH ISOLATED SH/TS ACTIVITY AS EARLY AS SATURDAY
AFTN ACROSS THE SOUTHERN PORTION OF THE FORECAST AREA. INCREASED
COVERAGE...PARTICULARLY DURING MAX DAYTIME HEATING...IS EXPECTED ON
SUNDAY AND MONDAY. HIGH TEMPS IN THE LOWER 90S EXPECTED EACH
AFTERNOON WITH LOWS IN THE LOWER 70S.

RIDGE WEAKENS ACROSS THE AREA BY MID WEEK AS TROUGHING ATTEMPTS TO
RE-ESTABLISH ITSELF ACROSS THE EASTERN CONUS...RETURNING CENTRAL
ALABAMA TO AN UNCERTAIN AND OFTEN PESKY NORTHWESTERLY FLOW PATTERN.
WILL MAINTAIN POPS AND TEMPS CLOSE TO GUIDANCE...AND CLIMO...FOR
EACH PERIOD NEXT WEEK."
Member Since: June 9, 2005 Posts: 23 Comments: 37858
859. Skyepony (Mod)
2:04 PM GMT on August 07, 2009
We haven't seen shades of green like this in the ATL since last year..

Member Since: August 10, 2005 Posts: 174 Comments: 38198
858. IKE
2:02 PM GMT on August 07, 2009
Found this from accuweather on the Atlantic....

"A change in the upper air pattern through the weekend could increase potential for tropical development in the Gulf of Mexico. A persistent upper ridge of high pressure over the southwestern U.S. and compensating upper trough over the eastern U.S. and the northern development over the western Atlantic basin much of the summer. This pattern will change over the weekend as the upper ridge shifts eastward and takes up camp over the southeastern U.S. This will open the door for tropical moisture or even a disturbance over the northwestern Caribbean or the southern Gulf to track northward and northwestward. There are no trackable features at this time, but it is worth keeping eye on."
Member Since: June 9, 2005 Posts: 23 Comments: 37858
857. NEwxguy
2:01 PM GMT on August 07, 2009
Everyone's right,some of our biggest storms started out poorly,but there isn't a lot of friendly areas for it to take off,I'd be more worried about the waves off Africa,assuming the favorable MJO sticks around for the next couple of weeks.
Member Since: September 6, 2007 Posts: 881 Comments: 15840
856. Skyepony (Mod)
2:00 PM GMT on August 07, 2009
This will be your last annular report out of me about Felicia...

## ANNULAR HURRICANE INDEX (AHI) EP082009 FELICIA 08/07/09 12 UTC ##
## STORM NOT ANNULAR, SCREENING STEP FAILED, NPASS=5 NFAIL=2 ##
## AHI= 0 (AHI OF 100 IS BEST FIT TO ANN. STRUC., 1 IS MARGINAL, 0 IS NOT ANNULAR) ##
## ANNULAR INDEX RAN NORMALLY
Member Since: August 10, 2005 Posts: 174 Comments: 38198
855. IKE
1:56 PM GMT on August 07, 2009
Member Since: June 9, 2005 Posts: 23 Comments: 37858
854. HIEXPRESS
1:46 PM GMT on August 07, 2009
Quoting jeffs713:

IF everything else lines up. Shear is just one part of the equation, but it is one of the primary killers of waves this year along with dust and MJO.


You are right, or course. I said "it" implying only the shear, when I meant conditions in general.
Member Since: October 13, 2005 Posts: 4 Comments: 2156
853. Chicklit
1:44 PM GMT on August 07, 2009
Hi! Atlantic active again with the whatchmablobbits east of the Antilles and the new one just advected from Africa.

Looks like shear is a little suppressed in the Caribb. as well. Yellow coming soon?

Being cautious this time as I still have aftertaste of crow.ShearMap Blobs
Member Since: July 11, 2006 Posts: 14 Comments: 11353
852. Relix
1:39 PM GMT on August 07, 2009
The wave will surely pass south of the bigger antilles and could pretty well get into the Caribbean where it could pose problems. At least there's something to track...

Oh and Felicia is the perfect storm. Blossoms... travels... then dies and just leaves some water and wind. Perfect.
Member Since: August 3, 2006 Posts: 0 Comments: 2725
851. Orcasystems
1:31 PM GMT on August 07, 2009
Blog Update
Reflector site for those at work, which includes Weather456, daily update.


AOI

AOI
Member Since: October 1, 2007 Posts: 81 Comments: 26511
850. jeffs713
1:31 PM GMT on August 07, 2009
Quoting HIEXPRESS:
There is a lot more to "shear" than just a wind speed and direction. Even this is oversimplified. There could be wind from 5 different directions at 5 different altitudes, each with a different temperature and moisture content (and/or dust), and a computer algorithm might calculate and present a graphic as "low shear" or favorable. We will know when it becomes favorable, as a TC will form.

IF everything else lines up. Shear is just one part of the equation, but it is one of the primary killers of waves this year along with dust and MJO.
Member Since: August 3, 2008 Posts: 16 Comments: 5885
849. HIEXPRESS
1:27 PM GMT on August 07, 2009
There is a lot more to "shear" than just a wind speed and direction. Even this is oversimplified. There could be wind from 5 different directions at 5 different altitudes, each with a different temperature and moisture content (and/or dust), and a computer algorithm might calculate and present a graphic as "low shear" or favorable. We will know when it becomes favorable, as a TC will form.

Doc M:"...For example, it is common to find a strong jet of wind at about 600 mb blowing along the edge of the Saharan Air Layer (SAL)--that area of dry, dusty air that frequently lies to the north of developing tropical cyclones in the mid-Atlantic. This jet will create significant wind shear that will not show up on the standard 200-850 mb wind shear plots. Since upper-air measurements are very sparse over the open ocean, wind shear that is invisible on 200-850 mb wind shear analysis charts will often unexpectedly kill or weaken a developing tropical cyclone..."
Member Since: October 13, 2005 Posts: 4 Comments: 2156
848. potteryX
1:22 PM GMT on August 07, 2009
Good conflicting veiws here LOL.
We wait, we watch.....
Out for now.
847. jeffs713
1:21 PM GMT on August 07, 2009
Quoting NEwxguy:
GM looking at that mess approaching the lower islands,doesn't look very impressive,would really be surprised if anything came out of it.

The wave that spawned Katrina didn't look all that hot in the CATL, either.
Member Since: August 3, 2008 Posts: 16 Comments: 5885
845. Stormchaser2007
1:17 PM GMT on August 07, 2009
Quoting StormJunkie:
Very nice 850mb vort.

Huh? Not very symmetrical at all, and fairly weak.

Just not very impressed with that line of storms in the CATL. Given some time, maybe something happens...But I just can't find much interesting about it right now other then there is nothing else in the Atl.


Im talking about the area off of Africa. Although I see what your saying about the CATL wave.
Member Since: June 9, 2007 Posts: 4 Comments: 15921
844. jeffs713
1:17 PM GMT on August 07, 2009
Quoting Stormchaser2007:
New wave just emerged off of Africa...looks decent.


Waves almost always look decent when they first pull off Africa, since they are usually just maintaining continental convection. The issues come when the wave has to switch from the continental diurnal cycle, to the maritime diurnal cycle. If it survives that, it has a better chance. Lets look again in 24-36hr.
Member Since: August 3, 2008 Posts: 16 Comments: 5885
843. HIEXPRESS
1:17 PM GMT on August 07, 2009
GM
TRMM Africa
TRMM Americas
Member Since: October 13, 2005 Posts: 4 Comments: 2156
842. largeeyes
1:13 PM GMT on August 07, 2009
Quoting cyclonekid:
They really think something will form.


4-5% chance is "they really think something will form"? That is the first yellow in a long time, though.
Member Since: August 22, 2006 Posts: 0 Comments: 1455
841. StormJunkie
1:11 PM GMT on August 07, 2009
Very nice 850mb vort.

Huh? Not very symmetrical at all, and fairly weak.

Just not very impressed with that line of storms in the CATL. Given some time, maybe something happens...But I just can't find much interesting about it right now other then there is nothing else in the Atl.
Member Since: August 17, 2005 Posts: 26 Comments: 16872
840. Orcasystems
1:11 PM GMT on August 07, 2009
Quoting NEwxguy:
GM looking at that mess approaching the lower islands,doesn't look very impressive,would really be surprised if anything came out of it.


Looks better then it did yesterday

Member Since: October 1, 2007 Posts: 81 Comments: 26511
839. NEwxguy
1:10 PM GMT on August 07, 2009
GM looking at that mess approaching the lower islands,doesn't look very impressive,would really be surprised if anything came out of it.
Member Since: September 6, 2007 Posts: 881 Comments: 15840
837. IKE
12:53 PM GMT on August 07, 2009
Quoting potteryX:
Ike, 827.
About 3 to 6 MPH. Low.


Okay. It is low. I was just looking into the Caribbean.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
836. potteryX
12:51 PM GMT on August 07, 2009
OK. So low shear, lots of convection, a low, and Vorticity too.
But a jetsream just west of the Islands, and dry air to the north and west.
It has been persistant so far. Will be fun to see what happens next.......
835. Stormchaser2007
12:49 PM GMT on August 07, 2009
Very nice 850mb vort.

Member Since: June 9, 2007 Posts: 4 Comments: 15921
834. potteryX
12:48 PM GMT on August 07, 2009
Ike, 827.
About 3 to 6 MPH. Low.
833. Stormchaser2007
12:46 PM GMT on August 07, 2009
New wave just emerged off of Africa...looks decent.

Member Since: June 9, 2007 Posts: 4 Comments: 15921
832. cyclonekid
12:44 PM GMT on August 07, 2009
Shear currently low over the wave.
Member Since: July 14, 2009 Posts: 51 Comments: 1731
831. TayTay
12:44 PM GMT on August 07, 2009
Central Atlantic.
830. Stormchaser2007
12:44 PM GMT on August 07, 2009
Quoting TayTay:
I think this wave will struggle with the dust very soon. It's leaving the itcg and will lose a large amount of convection. The dry air and dust will hurt it and probably kill it.


More than likely the stable air.

Member Since: June 9, 2007 Posts: 4 Comments: 15921
829. Stormchaser2007
12:43 PM GMT on August 07, 2009
Quoting IKE:


Problem is...that's 4 days away. If that was there now. Looks to me like it's headed into increasing shear by tonight, unless that southern Caribbean shear lets up.

Right now it looks to be in Easterly shear. That should change by tonight but, shears decreasing out ahead of it.

Member Since: June 9, 2007 Posts: 4 Comments: 15921
828. potteryX
12:42 PM GMT on August 07, 2009
TayTay. Which wave are you talking about?
827. IKE
12:42 PM GMT on August 07, 2009
Quoting potteryX:
Shear is 4 to 8 meters per second in front of it Ike.


? I have no idea what that is...lol...
Member Since: June 9, 2005 Posts: 23 Comments: 37858
826. TayTay
12:41 PM GMT on August 07, 2009
I think this wave will struggle with the dust very soon. It's leaving the itcg and will lose a large amount of convection. The dry air and dust will hurt it and probably kill it.
825. IKE
12:41 PM GMT on August 07, 2009
Quoting cyclonekid:
I don't know...I just know that something is looking like it will form (its yellow for the one nearest Africa)


That system south of the Cape Verdes may have a better chance of making it through the Caribbean.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
824. potteryX
12:41 PM GMT on August 07, 2009
Shear is 4 to 8 meters per second in front of it Ike. Through next week Thursday looks like.
823. IKE
12:39 PM GMT on August 07, 2009
Quoting Stormchaser2007:
IF this can make it into the Eastern Caribbean than it should have favorable shear conditions.


Tuesday

Wednesday

Thursday


Problem is...that's 4 days away. If that was there now. Looks to me like it's headed into increasing shear by tonight, unless that southern Caribbean shear lets up.
Member Since: June 9, 2005 Posts: 23 Comments: 37858

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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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