TROPICAL STORM BERTHA DISCUSSION NUMBER 2

WTNT42 KNHC 031458
TCDAT2
TROPICAL STORM BERTHA DISCUSSION NUMBER 2
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL022008
1100 AM EDT THU JUL 03 2008

THIS MORNINGS VISIBLE SATELLITE IMAGERY SHOW THAT THE CLOUD PATTERN
HAS BECOME BETTER ORGANIZED WITH TWO DISTINCT SPIRALING BANDS
OF DEEP CONVECTION. DVORAK INTENSITY ESTIMATES FROM TAFB AND SAB
ARE 35 KT....THEREFORE THE SYSTEM HAS BEEN UPGRADED TO A TROPICAL
STORM...THE SECOND OF THE 2008 ATLANTIC SEASON.

RECENT MICROWAVE AND VISIBLE SATELLITE IMAGERY SUGGEST THAT THE
CENTER IS A LITTLE FARTHER NORTH AND WEST OF THE PREVIOUS
ESTIMATES. BECAUSE OF THE RELOCATION OF THE CENTER...THE INITIAL
MOTION IS A SOMEWHAT UNCERTAIN 285/12...A LITTLE FASTER THAN
BEFORE. BERTHA IS LOCATED TO THE SOUTH OF A MID-LEVEL RIDGE OVER
THE EASTERN ATLANTIC AND MODEL GUIDANCE IS IN FAIRLY GOOD AGREEMENT
ON A CONTINUED WEST-NORTHWESTWARD TRACK DURING THE NEXT 2-3 DAYS.
THEREAFTER...THE MODELS SUGGEST THAT BERTHA WILL APPROACH A
WEAKNESS IN THE SUBTROPICAL RIDGE OVER THE CENTRAL ATLANTIC. THE
GFS...HWRF...AND GFDL MODELS THEREFORE SHOW A NORTHWESTWARD TURN
LATE IN THE FORECAST PERIOD. THE NEW OFFICIAL FORECAST IS A LITTLE
FASTER AND NORTH OF THE PREVIOUS TRACK AND IS CLOSE TO A CONSENSUS
OF THE GFDL...GFS...HWRF...AND ECMWF MODELS.

VERTICAL WIND SHEAR IS FORECAST TO REMAIN LIGHT DURING THE NEXT FEW
DAYS...HOWEVER...COOLER WATERS ALONG THE FORECAST TRACK SHOULD
LIMIT INTENSIFICATION. SSTS ALONG THE TRACK ARE EXPECTED TO
INCREASE AFTER 48 HOURS WHICH WOULD FAVOR SOME STRENGTHENING.
HOWEVER...LATE IN THE FORECAST PERIOD SOUTHWESTERLY SHEAR IS
EXPECTED TO INCREASE WHICH AGAIN SHOULD HALT STRENGTHENING. THE
SHIPS AND LGEM MODELS PREDICT BERTHA TO BECOME A HURRICANE IN 72 TO
96 HOURS. HOWEVER...THE NEW INTENSITY FORECAST WILL REMAIN A
LITTLE MORE CONSERVATIVE WHICH IS CLOSER TO THE GFDL AND HWRF
SOLUTIONS.

OUTER RAINBANDS ASSOCIATED WITH BERTHA ARE EXPECTED TO BRING GUSTY
WINDS AND LOCALLY HEAVY RAINFALL TO PORTIONS OF THE SOUTHERN CAPE
VERDE ISLANDS DURING THE NEXT 24 HOURS.

FORECAST POSITIONS AND MAX WINDS

INITIAL 03/1500Z 13.3N 24.7W 35 KT
12HR VT 04/0000Z 13.8N 26.7W 40 KT
24HR VT 04/1200Z 14.7N 29.4W 45 KT
36HR VT 05/0000Z 15.6N 32.5W 45 KT
48HR VT 05/1200Z 16.6N 35.8W 50 KT
72HR VT 06/1200Z 18.5N 42.5W 55 KT
96HR VT 07/1200Z 21.5N 48.5W 55 KT
120HR VT 08/1200Z 25.0N 52.0W 55 KT


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