540
WTNT45 KNHC 120831
TCDAT5
TROPICAL DEPRESSION FIFTEEN DISCUSSION NUMBER 3
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL152007
500 AM EDT FRI OCT 12 2007
SATELLITE IMAGERY THIS MORNING INDICATES THAT TROPICAL DEPRESSION
FIFTEEN HAS CHANGED LITTLE IN ORGANIZATION...WITH THE CENTER A
LITTLE LESS INVOLVED WITH THE CONVECTION THAN 6 HR AGO. SATELLITE
INTENSITY ESTIMATES ARE 30 KT FROM TAFB AND 25 KT FROM SAB...SO THE
INITIAL INTENSITY REMAINS 30 KT. THE CIRRUS OUTFLOW IS FAIR TO THE
EAST AND ALMOST NON-EXISTENT ELSEWHERE.
THE INITIAL MOTION IS A SOMEWHAT UNCERTAIN 090/3. THE DEPRESSION IS
EMBEDDED IN THE LOW/MID-LEVEL SUBTROPICAL RIDGE...A CONDITION THAT
IS FORECAST TO CAUSE 24 HR OR SO OF SLOW MOTION. AFTER THAT...A
LOW/MID-LEVEL TROUGH OR FRONTAL SYSTEM APPROACHING FROM THE WEST
WILL WEAKEN THE RIDGE AND STEER THE CYCLONE...OR ITS REMAINS...
NORTHWARD OR NORTH-NORTHEASTWARD. THE NEW FORECAST TRACK IS AGAIN
SHIFTED TO THE WEST OF THE PREVIOUS TRACK BASED ON THE INITIAL
POSITION AND MOTION...AND IT LIES NEAR THE RIGHT EDGE OF THE
GUIDANCE ENVELOPS
THE DEPRESSION IS CURRENTLY UNDER THE AXIS OF AN UPPER-LEVEL
TROUGH...WHICH HAS REDUCED THE VERTICAL WIND SHEAR FOR THE MOMENT.
HOWEVER...ALL DYNAMICAL GUIDANCE FORECASTS THE CYCLONE TO BE
BLASTED BY 40-50 KT OF UPPER-LEVEL NORTHERLY FLOW WITHIN 12-24 HR.
THIS SHOULD CAUSE THE DEPRESSION TO WEAKEN TO A REMNANT LOW IN
24-36 HR...AND THIS COULD OCCUR EARLIER. SOME OF THE DYNAMICAL
MODELS FORECAST A REMNANT CIRCULATION TO SURVIVE 48 HR...SO THE
OFFICIAL FORECAST CONTINUES TO INDICATE A REMNANT LOW TO THAT TIME.
FORECAST POSITIONS AND MAX WINDS
INITIAL 12/0900Z 30.0N 49.4W 30 KT
12HR VT 12/1800Z 30.1N 49.1W 30 KT
24HR VT 13/0600Z 30.4N 48.9W 25 KT
36HR VT 13/1800Z 30.9N 48.9W 25 KT...REMNANT LOW
48HR VT 14/0600Z 32.3N 48.6W 25 KT...REMNANT LOW
72HR VT 15/0600Z...DISSIPATED
FORECASTER BEVEN
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