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TROPICAL STORM DALILA DISCUSSION NUMBER   9
NATIONAL WEATHER SERVICE MIAMI FL
8 PM PDT SUN JUL 22 2001
 
CONVECTIVE BANDING HAS DECREASED AND TYHE CENTRAL DEEP CONVECTION 
HAS BECOME ELONGATED NORTHEAST-SOUTHWEST DUE TO UPPER-LEVEL 
NORTHEASTERLY SHEAR. OUTFLOW IS FAIR TO GOOD IN THE WESTERN 
SEMICIRCLE AND RESTRICTED TO THE EAST.  THE INITIAL INTENSITY WAS 
HELD AT 60 KT BASED ON DVORAK SATELLITE INTENSITY ESTIMATES OF 55 
KT...T3.5...FROM TAFB AND SAB.

INITIAL MOTION ESTIMATE IS 300/14.  THE PREVIOUS FORECAST HAD A GOOD 
HANDLE ON THE FORECAST TRACK OF DALILA BY DISCOUNTING THE GFDL MODEL 
AND ITS NORTHWARD TRACK INTO THE GULF OF CALIFORNIA. THE LATEST GFDL 
RUN IS NO LONGER AN OUTLIER AND IS IN THE MIDDLE OF THE REMAINING 
MODEL SUITE.  ALL OF THE MODEL GUIDANCE GENERALLY AGREE ON A 
WEST-NORTHWEST TO WESTWARD TRACK THROUGH THE PERIOD AS THE SYSTEM 
MOVES ALONG THE SOUTHERN PERIPHERY OF THE SUBTROPICAL RIDGE TO THE 
NORTH.  THE OFFICIAL FORECAST IS CLOSE TO THE PREVIOUS TRACK AND THE 
UKMET MODEL.

THE INTENSITY FORECAST IS NOT AS STRAIGHT-FORWARD AS THE TRACK 
FORECAST.  NORTHEASTERLY SHEAR IS DISRUPTING THE CENTRAL DEEP 
CONVECTION AND DALILA MAY NOT BE AS STRONG AS INDICATED.  THE SHIPS 
AND AVN MODELS ARE FORECASTING THE SHEAR TO GRADUALLY DECREASE AND 
BRING DALILA TO HURRICANE STRENGTH IN 12 HOURS. THE PREVIOUS 
FORECAST TREND WAS MAINTAINED IN CASE A BURST OF DEEP CONVECTION 
FIRES OFF LATER TONIGHT.
 
FORECASTER STEWART
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     23/0300Z 16.5N 103.7W    60 KTS
12HR VT     23/1200Z 17.3N 105.4W    65 KTS
24HR VT     24/0000Z 17.9N 107.1W    70 KTS
36HR VT     24/1200Z 18.5N 108.6W    80 KTS
48HR VT     25/0000Z 18.9N 110.1W    80 KTS
72HR VT     26/0000Z 20.0N 113.0W    75 KTS
 
 
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