Tropical Storm DOUGLAS

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TROPICAL STORM DOUGLAS DISCUSSION NUMBER   5
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP042008
800 PM PDT WED JUL 02 2008
 
DOUGLAS HAS LOST SOME ORGANIZATION THIS EVENING...WITH THE BROAD
LOW-LEVEL CIRCULATION CENTERED NEAR THE NORTH EDGE OF THE NOT VERY
IMPRESSIVE CONVECTION.  SATELLITE INTENSITY ESTIMATES ARE 35 KT
FROM TAFB AND 30 KT FROM SAB.  ADDITIONALLY...A SHIP WELL NORTHEAST
OF THE CENTER REPORTED 33 KT AT 00Z.  THE INITIAL INTENSITY REMAINS
35 KT...BUT THIS COULD BE A LITTLE GENEROUS.  WATER VAPOR IMAGERY
AND ANALYSES FROM CIMSS AT THE UNIVERSITY OF WISCONSIN SHOW 20 KT
OF NORTHEASTERLY VERTICAL WIND SHEAR ACROSS THE CENTER AT THIS
TIME.

THE INITIAL MOTION IS 315/8.  DOUGLAS IS ON THE SOUTHWESTERN SIDE OF
A MID-LEVEL RIDGE...WHICH THE LARGE-SCALE MODELS FORECAST TO BECOME
ORIENTED EAST-WEST NORTH OF DOUGLAS DURING THE NEXT 72-96 HR.  THIS
EVOLUTION WOULD ALLOW THE CURRENT MOTION TOWARD THE NORTHWEST TO
BECOME A WESTERLY MOTION BEFORE DOUGLAS DISSIPATES.  THE NEW
FORECAST TRACK FOLLOWS THIS SCENARIO...AND IS BASICALLY AN UPDATE
OF THE PREVIOUS TRACK IN BEST AGREEMENT WITH THE UKMET.  IT SHOULD
BE NOTED THAT THE ECMWF AND CANADIAN MODELS CALL FOR DOUGLAS OR ITS
REMAINS TO TURN TOWARD THE EAST AFTER 72 HR DUE TO INTERACTION WITH
A DEVELOPING DISTURBANCE CURRENTLY SOUTH OF THE GULF OF
TEHUANTEPEC.

DOUGLAS SHOULD CROSS THE 26C ISOTHERM IN ABOUT 12 HR AND MOVE OVER
COOLER WATER THEREAFTER.  THE LATEST INTENSITY GUIDANCE CALLS FOR
THE SYSTEM TO STEADILY WEAKEN FROM THIS POINT ON.  SINCE DOUGLAS
HAS ONE MORE DIURNAL CONVECTIVE MAXIMUM BEFORE CROSSING THE 26C
ISOTHERM...THE INTENSITY FORECAST SHOWS A SLIGHT STRENGTHENING
DURING THE FIRST 12 HR FOLLOWED BY WEAKENING UNTIL DISSIPATION IN
96 HR.  AN ALTERNATIVE SCENARIO IS THAT THE NORTHEASTERLY SHEAR
PREVENTS ANY STRENGTHENING TONIGHT AND DOUGLAS DISSIPATES FASTER
THAN CURRENTLY FORECAST.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      03/0300Z 18.8N 109.1W    35 KT
 12HR VT     03/1200Z 19.4N 109.8W    40 KT
 24HR VT     04/0000Z 20.0N 110.9W    40 KT
 36HR VT     04/1200Z 20.4N 111.8W    30 KT
 48HR VT     05/0000Z 20.7N 112.8W    25 KT
 72HR VT     06/0000Z 21.0N 114.5W    25 KT...REMNANT LOW
 96HR VT     07/0000Z...DISSIPATED
 
$$
FORECASTER BEVEN
 
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