WDPN32 PGTW 110300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 25W (VAMCO) WARNING NR 
008//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TYPHOON (TY) 25W (VAMCO), LOCATED APPROXIMATELY 203 NM
EAST OF MANILA, PHILIPPINES, HAS TRACKED WEST-NORTHWESTWARD AT 14 
KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE 
IMAGERY (MSI) SHOWS THE SYSTEM HAS INTENSIFIED WITH CURVED RAIN 
BANDS CONTINUING TO WRAP TIGHTER INTO LOW LEVEL CIRCULATION CENTER 
(LLCC). FURTHERMORE, AN EYE FEATURE HAS BEGUN TO APPEAR OVER THE 
PAST 6 HOURS. THE INITIAL POSITION IS PLACED WITH FAIR CONFIDENCE 
BASED UPON THE BANDING FEATURES IN THE MSI LOOP AS WELL AS IN THE 
MICROWAVE EYE FEATURE IN A 102203Z SSMIS 91GHZ IMAGE. MULTIPLE 
AGENCIES REPORT DVORAK CURRENT INTENSITY ESTIMATES OF T4.0/65KTS 
FROM PGTW, KNES, AND RJTD. THE INITIAL INTENSITY OF 75 KTS IS 
HEDGED SLIGHTLY HIGHER THAN THESE AGENCY INTENSITY ESTIMATES 
BASED ON A 102145Z CIMSS SATELLITE CONSENSUS INTENSITY ESTIMATE 
OF 67KTS AND AN INCREASING TREND NOTED IN ADJUSTED INTENSITY 
ESTIMATES FROM OBJECTIVE DVORAK METHODS. UPPER LEVEL ANALYSIS 
INDICATES THE SYSTEM REMAINS IN A FAVORABLE AREA WITH LOW 
(05-10KT) VERTICAL WIND SHEAR (VWS) AND STRONG RADIAL OUTFLOW 
ASSOCIATED WITH A POINT SOURCE DIRECTLY OVERHEAD. ADDITIONALLY, 
SEA SURFACE TEMPERATURES (SST) IN THE PHILIPPINE SEA REMAIN 
WARM AND FAVORABLE AT 29-30C. THE CYCLONE IS TRACKING ALONG THE 
SOUTHWESTERN PERIPHERY OF A SUBTROPICAL RIDGE (STR) TO THE 
NORTHEAST.  
3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS 
PROGNOSTIC REASONING MESSAGE.
   B. AS THE STR BUILDS IN THE NEAR TERM, TY 25W WILL CONTINUE 
TO TRACK ON A WESTWARD TRAJECTORY TOWARD THE PHILIPPINES THROUGH 
TAU 12. THE ENVIRONMENT WILL REMAIN HIGHLY FAVORABLE DURING THIS 
TIME. ADDITIONALLY, ANALYSIS OF MICROWAVE IMAGERY SUGGESTS THAT 
RAPID INTENSIFICATION IS LIKELY TO TAKE PLACE BEFORE LANDFALL. 
SHORTLY AFTER TAU 12 THE SYSTEM WILL MAKE LANDFALL OVER THE 
PROVINCE OF BULACAN ALONG THE EASTERN COAST OF LUZON. AFTERWARD, 
LAND INTERACTION WILL ERODE THE SYSTEM DOWN TO 65KTS BY TAU 24. 
AS TY VAMCO EXITS INTO THE WARM SCS IT WILL THEN RE-CONSOLIDATE 
AND STRENGTHEN TO 75KTS THROUGH TAU 72 DUE TO GENERALLY 
FAVORABLE VWS AND SST. NUMERICAL MODELS ARE IN TIGHT AGREEMENT 
DURING THIS INITIAL PERIOD OF THE FORECAST AND THUS LEND HIGH 
CONFIDENCE IN THE JTWC FORECAST TRACK WHICH IS LAID NEAR THE 
MULTI-MODEL CONSENSUS.
   C. AFTER TAU 72, TY VAMCO WILL TRACK WEST-NORTHWESTWARD AS THE 
STR IS WEAKENED BY AN APPROACHING MIDLATITUDE TROUGH. DURING THIS 
TIME, THE SYSTEM IS FORECAST TO WEAKEN STEADILY DUE TO INCREASING 
VWS AND COOLING SST TO 55 KTS BY TAU 96. THEREAFTER, THE SYSTEM 
WILL MAKE LANDFALL ALONG THE COAST OF CENTRAL VIETNAM WHEREUPON 
THE RUGGED TERRAIN WILL RAPIDLY ERODE THE SYSTEM DOWN TO 30KTS BY 
TAU 120. NUMERICAL MODELS SPREAD INCREASES FROM 345NM SPREAD AT 
TAU 96 TO OVER 580NM AT TAU 120. THIS INCREASING SPREAD IN 
NUMERICAL MODEL SOLUTIONS LENDS OVERALL POOR CONFIDENCE IN THIS 
FINAL PORTION OF THE JTWC FORECAST TRACK WITH IS PLACED NEAR THE 
MULTI-MODEL CONSENSUS.//
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