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HURRICANE DOUGLAS DISCUSSION NUMBER 7
NATIONAL WEATHER SERVICE MIAMI FL
8 PM PDT SUN JUL 21 2002
DOUGLAS HAS CONTINUED TO RAPIDLY INTENSIFY AND IS NOW A HURRICANE
BASED ON CONSENSUS 65 KT...T4.0...DVORAK SATELLITE INTENSITY
ESTIMATES FROM ALL THREE SATELLITE AGENCIES. UPPER-LEVEL OUTFLOW IS
IMPRESSIVE AND REMAINS UNRESTRICTED IN ALL QUADRANTS.
THE INITIAL MOTION ESTIMATE IS 300/08. DOUGLAS REMAINS ON TRACK AND
THE OFFICIAL FORECAST IS JUST AN UPDATE OF THE PREVIOUS TRACK...
ALBEIT A LITTLE FASTER AFTER 36 HOURS. ALL AVAILABLE NHC FORECAST
GUIDANCE AGREES ON A MORE WESTWARD TRACK BY 24 TO 36 HOURS AND THEN
DUE WEST OR SLIGHTLY SOUTH OF WEST AFTER THAT WHEN THE CYCLONE
RAPIDLY WEAKENS OVER COOLER WATER AND IS STEERED MORE BY THE
LOW-LEVEL EASTERLY FLOW. THE AVN...UKMET...AND NOGAPS MODELS HAVE
BEEN GRADUALLY SHIFTING NORTHWARD...WHILE THE GFDL MODEL HAS BEEN
SLOWLY SHIFTING SOUTHWARD. THE OFFICIAL TRACK IS A CONSENSUS OF THE
GFDL...AVN...UKMET...AND NOGAPS MODELS FOR TRACK AND CLOSELY FOLLOWS
THE AVN AND MEDIUM BAM MODELS FOR THE SPEED.
DOUGLAS HAS BEEN RAPIDLY INTENSIFYING FOR THE PAST 24 HOURS AND THIS
USUALLY LASTS ABOUT 36 TO 42 HOURS. AS SUCH THE OFFICIAL FORECAST
CALLS FOR CONTINUED RAPID INTENSIFICATION THROUGH THE NEXT 12 HOURS
WITH A SLOWER INTENSIFICATION RATE AFTER THAT THROUGH 24 HOURS...
WHICH SEEMS REASONABLE GIVEN THE SMALL 10 TO 15 NM DIAMETER EYE SEEN
IN THE LOW-...MID-...AND UPPER-LEVELS ON A 21/1951Z TRMM OVERPASS.
BY 36 HOURS...DOUGLAS SHOULD BEGIN TO MOVE OVER COOLER WATER AND
START TO WEAKEN. BETWEEN 48 TO 72 HOURS...THE CYCLONE SHOULD BE
PASSING OVER SUB-24C SSTS AND BEGIN TO RAPIDLY WEAKEN. HOWEVER...IF
DOUGLAS SLOWS OR TURNS MORE WESTWARD SOONER THAN THE OFFICIAL
FORECAST IS INDICATING...THEN THE SYSTEM COULD BECOME A MAJOR
HURRICANE IN 24 TO 36 HOURS. THE OFFICIAL FORECAST IS CLOSE TO THE
SHIPS INTENSITY MODEL WHICH BRINGS DOUGLAS TO 84 KT AND 87 KT IN 24
AND 36 HOURS...RESPECTIVELY. THIS IS ALSO CONSISTENT WITH THE GFDL
MODEL DURING LOW- OR NO-SHEAR CONDITIONS LIKE DOUGLAS IS EXPECTED TO
REMAIN EMBEDDED IN THROUGHOUT THE FORECAST PERIOD.
WIND SPEED RADII AND 12 FT SEAS RADII WERE INCREASED BASED ON
SURROUNDING SHIP OBSERVATIONS AT 21Z AND 00Z.
FORECASTER STEWART
FORECAST POSITIONS AND MAX WINDS
INITIAL 22/0300Z 17.1N 110.7W 65 KTS
12HR VT 22/1200Z 17.5N 111.9W 80 KTS
24HR VT 23/0000Z 17.8N 113.6W 90 KTS
36HR VT 23/1200Z 18.1N 115.4W 85 KTS
48HR VT 24/0000Z 18.7N 117.7W 65 KTS
72HR VT 25/0000Z 19.5N 122.5W 55 KTS
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