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TROPICAL STORM BARBARA DISCUSSION NUMBER 4
NATIONAL WEATHER SERVICE MIAMI FL
2 PM PDT WED JUN 20 2001
DVORAK INTENSITY ESTIMATES ARE 35 KT FROM BOTH TAFB AND SAB. A
QUIKSCAT PASS NEAR 15Z SHOWED UNCONTAMINATED VECTORS OF 30 KT.
PRESUMABLY THE WINDS IN THE CONVECTION WERE A LITTLE HIGHER AND SO
THE DEPRESSION IS UPGRADED TO TROPICAL STORM STATUS. BARBARA IS
STILL UNIMPRESSIVE IN THE IR IMAGERY...HOWEVER...WITH ILL-DEFINED
BANDS AND RELATIVELY WARM CLOUD TOPS. WHILE THE OUTFLOW PATTERN IS
STILL OK...WATER TEMPERATURES ARE ALREADY DECREASING...SO THERE
WOULD SEEM TO BE LITTLE ROOM FOR MUCH ADDITIONAL STRENGTHENING. THE
OFFICIAL FORECAST IS CLOSE TO THE SHIPS GUIDANCE.
VISIBLE IMAGERY SHOWS THAT THE CYCLONE HAS BEEN TRACKING MORE TO THE
WEST-NORTHWEST THAN INFERRED EARLIER FROM IR IMAGERY OR EVEN THE
QUIKSCAT PASS THIS MORNING. THE INITIAL MOTION ESTIMATE IS 295/13.
THE DEPRESSION IS CURRENTLY SOUTH OF A MID-TROPOSPHERIC RIDGE...BUT
WILL SOON...OR MAY ALREADY...BE FEELING THE EFFECTS OF A LARGE UPPER
COLD LOW NORTHWEST OF THE CYCLONE CENTERED NEAR 24N/147W. THUS THE
FORECAST TRACK HAS BEEN ADJUSTED NORTHWARD FROM THE PREVIOUS
ADVISORY. THE OFFICIAL FORECAST IS CLOSE TO THE AVIATION MODEL
GUIDANCE.
THE COOLER WATERS...AS WELL AS THE SHEAR ASSOCIATED WITH THE UPPER
COLD LOW...SHOULD PREVENT THIS SYSTEM FROM BEING A SIGNIFICANT
THREAT TO THE HAWAIIAN ISLANDS.
FORECASTER FRANKLIN
FORECAST POSITIONS AND MAX WINDS
INITIAL 20/2100Z 13.2N 131.0W 35 KTS
12HR VT 21/0600Z 14.1N 132.8W 40 KTS
24HR VT 21/1800Z 15.4N 135.0W 45 KTS
36HR VT 22/0600Z 16.6N 137.4W 40 KTS
48HR VT 22/1800Z 18.0N 140.0W 35 KTS
72HR VT 23/1800Z 19.5N 145.0W 30 KTS
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