Category 4 Hurricane Felicia peaks in intensity
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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Reflector site for those at work, which includes Weather456, daily update.
AOI
AOI
Oh and Felicia is the perfect storm. Blossoms... travels... then dies and just leaves some water and wind. Perfect.
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
You are right, or course. I said "it" implying only the shear, when I meant conditions in general.
## 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
"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."
".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."
.."Cry Havoc and Let Slip, the Tropics of 09"..
That image is almost amusing. It looks like someone was trying to color in the entire MDR, GOM, and off the east coast.
1 in 20! Things are lookin up.
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.
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.
"Cry Havoc and Let Slip, the Tropics of 09"
By By to August if that happens
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