[Tropical] Tropical Cyclone Discussion

[Nashville EMWIN]

WTNT41 KNHC 302024
TCDAT1
HURRICANE FRANCES DISCUSSION NUMBER  24
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
5 PM EDT MON AUG 30 2004

REPORTS FROM A NOAA P-3 HURRICANE HUNTER PLANE INDICATE THAT THE
CENTRAL PRESSURE HAS DROPPED TO 948 MB AND THERE WAS A FLIGHT
LEVEL...700 MB...WIND OF 122 KT JUST EAST-SOUTHEAST OF THE CENTER.
BASED ON THESE DATA THE CURRENT INTENSITY IS INCREASED TO 110 KT.
THERE IS STRONG UPPER-LEVEL OUTFLOW AND VERTICAL SHEAR IS EXPECTED
TO REMAIN LOW.  THERE WILL PROBABLY BE SOME FLUCTUATIONS IN
INTENSITY DUE TO INNER CORE PROCESSES...SUCH AS THE CONCENTRIC
EYEWALLS THAT WERE OBSERVED BY THE HURRICANE HUNTERS AND ALSO SEEN
IN TRMM AND SSM/I DATA.  HOWEVER...ADDITIONAL STRENGTHENING IS
CERTAINLY POSSIBLE AND THE OFFICIAL WIND SPEED FORECAST IS PROBABLY
CONSERVATIVE.

THE WIND RADII HAVE BEEN ADJUSTED A LITTLE BASED ON OBSERVATIONS
FROM THE STEPPED-FREQUENCY MICROWAVE RADIOMETER...SFMR...ON BOARD
THE NOAA AIRCRAFT.

THE HURRICANE REMAINS ON TRACK...275/12.  A DEEP-LAYER SUBTROPICAL
RIDGE IS LIKELY TO PREVAIL TO THE NORTH OF FRANCES OVER THE NEXT
SEVERAL DAYS.  BEYOND 72 HOURS...SOME WEAKENING OF THIS RIDGE IS
INDICATED BY THE GLOBAL MODELS.  THE BAD NEWS FOR THE BAHAMAS AND
FLORIDA PENINSULA IS THAT THERE IS NO SIGNIFICANT MID-LATITUDE
TROUGH IN THE CURRENT MODEL FORECASTS THROUGH 5 DAYS THAT COULD
SUBSTANTIALLY WEAKEN THIS RIDGE.  THE OFFICIAL FORECAST SHOWS SOME
SLOWING AND A SLIGHT BENDING OF THE TRACK TOWARD THE NORTHWEST
BEYOND 72 HOURS...BUT THIS FORECAST HAS BEEN SHIFTED A LITTLE LEFT
IN COMPARISON TO THE PREVIOUS ONE.  THIS IS IN GOOD AGREEMENT WITH
THE CONSENSUS OF THE DYNAMICAL MODELS.

ONCE AGAIN...IT IS EXTREMELY IMPORTANT NOT TO FOCUS ON THE EXACT
TRACK...ESPECIALLY AT 96 AND 120 HOURS...BECAUSE THE HURRICANE IS
NOT A POINT...ESPECIALLY A HURRICANE AS LARGE AS FRANCES...AND
FORECASTS AT THESE EXTENDED TIME RANGES CAN EASILY HAVE ERRORS OF
SEVERAL HUNDRED MILES.

FORECASTER PASCH

FORECAST POSITIONS AND MAX WINDS

INITIAL      30/2100Z 19.5N  60.0W   110 KT
 12HR VT     31/0600Z 19.7N  62.1W   115 KT
 24HR VT     31/1800Z 20.2N  64.8W   115 KT
 36HR VT     01/0600Z 21.0N  67.4W   115 KT
 48HR VT     01/1800Z 22.0N  70.0W   115 KT
 72HR VT     02/1800Z 24.0N  74.0W   120 KT
 96HR VT     03/1800Z 25.5N  77.0W   120 KT
120HR VT     04/1800Z 27.5N  80.0W   120 KT

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