[Tropical] Tropical Cyclone Discussion

EMWIN Server emwin at nashvilleweather.net
Tue Jul 26 15:33:43 CDT 2005


WTNT41 KNHC 262032
TCDAT1
TROPICAL STORM FRANKLIN DISCUSSION NUMBER  22
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
5 PM EDT TUE JUL 26 2005

A BAND OF DEEP CONVECTION...WITH CLOUD TOPS OF -70C TO -80-C...HAS
REDEVELOPED EAST THROUGH SOUTH OF THE STILL EXPOSED LOW-LEVEL
CENTER. GIVEN THAT THIS CYCLONE HAS HAD A RECON HISTORY OF STRONGER
THAN AVERAGE WINDS AT HIGHER LEVELS...I HAVE OPTED TO KEEP FRANKLIN
AS A 35-KT TROPICAL STORM FOR THIS ADVISORY. THIS IS SUPPORTED BY
AN 18Z REPORT OF 31 KT FROM SHIP PIBO LOCATED ABOUT 220 NMI
SOUTHEAST OF THE CENTER...OR ABOUT 70 NMI SOUTH-SOUTHEAST OF
BERMUDA...AND BY A TAFB DVORAK SATELLITE CURRENT INTENSITY ESTIMATE
OF 35 KT. OUTFLOW REMAINS RESTRICTED NORTHWEST-NORTHEAST.

THE MOTION OVER THE PAST 18 HOURS HAS BEEN A RATHER WOBBLY 020/04.
FRANKLIN IS CURRENTLY COMPLETING A 30 NMI WIDE COUNTER-CLOCKWISE
LOOP...BUT THE NET OVERALL MOTION HAS BEEN NORTHEASTWARD. FRANKLIN
MAY WOBBLE LIKE A CHILD'S TOP TO THE NORTH OR NORTH-NORTHEAST FOR
THE NEXT 24 HOURS OR SO BEFORE STEERING CURRENTS BECOME BETTER
DEFINED. A STRONG SHORTWAVE TROUGH IS FORECAST TO ERODE THE
MID-LEVEL RIDGE TO THE NORTH...WHICH HAS BEEN IMPEDING ANY
SIGNIFICANT POLEWARD MOTION...AND GRADUALLY LIFT OUT THE CYCLONE TO
THE NORTHEAST. THE OFFICIAL FORECAST TRACK IS SIMILAR TO THE
PREVIOUS ADVISORY AND IS A LITTLE EAST OF THE NHC MODEL CONSENSUS.

UNFAVORABLE UPPER-LEVEL SHEAR IS EXPECTED TO PERSIST FOR ANOTHER
18-24 HOURS...SO SOME FLUCTUATIONS IN STRENGTH ARE POSSIBLE DURING
THAT TIME. BY 30-48 HOURS...THE UPPER-LEVEL SHEAR IS FORECAST TO
WEAKEN TO LESS THAN 10 KT AND BECOME SOUTHEASTERLY...WHICH MAY
ALLOW FOR SOME MODEST INTENSIFICATION TO OCCUR BEFORE THE
UPPER-LEVEL WINDS BECOME STRONG SOUTHWESTERLY AHEAD OF AN
APPROACHING FRONTAL SYSTEM. BY 60 HOURS...FRANKLIN WILL ALSO BE
MOVING OVER SUB-24C SSTS...WHICH SHOULD BRING ABOUT RAPID WEAKENING
UNLESS THE CYCLONE GETS ABSORBED BY THE FRONTAL SYSTEM FIRST. THIS
FORECAST SCENARIO IS CONSISTENT WITH THE SHIPS INTENSITY MODEL.

THE 12 FT SEA HEIGHT RADIUS WAS INCREASED IN THE SOUTHEAST QUADRANT
BASED ON THE 19-FT SEA HEIGHT REPORT FROM SHIP PIBO.

FORECASTER STEWART

FORECAST POSITIONS AND MAX WINDS

INITIAL      26/2100Z 32.3N  68.2W    35 KT
 12HR VT     27/0600Z 33.4N  67.8W    35 KT
 24HR VT     27/1800Z 34.6N  67.5W    35 KT
 36HR VT     28/0600Z 36.2N  67.1W    40 KT
 48HR VT     28/1800Z 37.9N  66.2W    40 KT...BECOMING EXTRATROPICAL
 72HR VT     29/1800Z 40.5N  62.5W    30 KT...EXTRATROPICAL
 96HR VT     30/1800Z...ABSORBED BY FRONTAL SYSTEM

$$WWWW
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