WDPN31 PGTW 300900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 04W (FOUR) WARNING 
NR 003//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL DEPRESSION 04W (FOUR), LOCATED APPROXIMATELY 89 NM NORTH-
NORTHEAST OF SONSOROL, HAS TRACKED WESTWARD AT 11 KNOTS OVER THE 
PAST SIX HOURS. ANIMATED ENHANCED MULTISPECTRAL SATELLITE IMAGERY 
(MSI) SHOWS DEEP CONSOLIDATING CENTRAL CONVECTION WRAPPING AROUND A 
TIGHT LOW LEVEL CIRCULATION (LLC). THE INITIAL POSITION IS PLACED 
WITH FAIR CONFIDENCE BASED ON LOW CLOUD TRACING IN THE MSI LOOP AND 
USING EXTRAPOLATION WITH 300411Z AMSR2 89GHZ, AND 300504Z ATMS 
88.2GHZ MICROWAVE SATELLITE PASSES. THE INITIAL INTENSITY OF 30KTS 
IS SET WITH FAIR CONFIDENCE BASED ON AN OVERALL ASSESSMENT OF 
MULTIPLE AGENCY DVORAK ESTIMATES OF T2.0/30KTS (PGTW), T3.0/45KTS 
(KNES), T1.5/25KTS (RJTD), T2.3/33KTS (ADT), AND SATELLITE CONSENSUS 
(SATCON) 33KTS. TD 04W REMAINS IN A FAVORABLE ENVIRONMENT WITH GOOD 
WESTWARD AND EQUATORWARD OUTFLOW, LOW (5-10KTS) VERTICAL WIND SHEAR 
(VWS) ALOFT, AND VERY WARM (30-31C) SEA SURFACE TEMPERATURES (SST) 
IN THE PHILIPPINE SEA. THE CYCLONE IS TRACKING ALONG THE SOUTHWEST 
PERIPHERY OF THE SUBTROPICAL RIDGE (STR) TO THE EAST-NORTHEAST. 
3. FORECAST REASONING.
   A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE 
PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. TD 04W WILL TRACK MORE NORTHWESTWARD OVER THE NEXT 72 HOURS 
UNDER THE STEERING INFLUENCE OF THE STR. THE SYSTEM WILL STEADILY 
INTENSIFY UNDER THE AFOREMENTIONED FAVORABLE CONDITIONS, AND BY TAU 
72, WILL REACH TYPHOON STRENGTH OF 65KTS. THE FORECAST TRACK IS LAID 
SLIGHTLY TO THE LEFT AND AHEAD OF MODEL CONSENSUS DURING THE FIRST 
36 HOURS TO OFFSET GFS AND JGSM TRACKERS THAT ARE RIGHT OF THE MODEL 
ENVELOPE. AFTER TAU 36, THE FORECAST TRACK IS MORE TO THE RIGHT OF 
FORECAST CONSENSUS, OFFSETTING THE SOLE EXTREME LEFT OUTLIER OF 
NVGM, WHICH REMAINS ON A WEST-NORTHWESTWARD TRACK TOWARD THE 
NORTHEAST PORTION OF THE PHILIPPINE ISLANDS.
   C. AFTER TAU 72, TD 04W WILL CONTINUE ON ITS NORTHWESTWARD TRACK 
UNDER THE SAME STR; HOWEVER, BY TAU 96, THE SYSTEM WILL BEGIN TO 
ROUND THE RIDGE AXIS THEN ACCELERATE NORTHEASTWARD. THE FAVORABLE 
CONDITIONS WILL PERSIST AND INTENSIFY THE CYCLONE TO A PEAK OF 70KTS 
BY TAU 96. AFTERWARD, AS IT BECOMES EXPOSED TO INCREASED POLEWARD 
OUTFLOW ASSOCIATED WITH THE PREVAILING WESTERLIES UNDER THE POLAR 
FRONT JET AND BEGINS RAPIDLY DECAYING DUE TO INCREASING VWS TO 45KTS 
BY TAU 120. NUMERICAL MODELS REMAIN IN FAIR AGREEMENT, LENDING 
OVERALL FAIR CONFIDENCE IN THE EXTENDED PORTION OF THE JTWC FORECAST 
TRACK.//
NNNN