WDPN31 PGTW 021500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 22W (GONI) 
WARNING NR 023//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL DEPRESSION (TD) 22W (GONI), LOCATED APPROXIMATELY
494 NM EAST OF DA NANG, VIETNAM, HAS TRACKED WESTWARD AT 11 KNOTS
OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED (EIR) 
SATELLITE IMAGERY SHOWS A WEAK SYSTEM WITH FLARING DEEP CONVECTION THAT 
IS SHEARED WESTWARD FROM A PARTIALLY EXPOSED AND RAGGED LOW LEVEL 
CIRCULATION (LLC). THE INITIAL POSITION IS PLACED WITH FAIR CONFIDENCE 
BASED ON THE LLC FEATURE IN THE EIR LOOP. THE INITIAL INTENSITY OF 
30KTS IS BASED ON THE DVORAK ESTIMATES OF T2.0/30KTS FROM PGTW AND 
KNES. UPPER LEVEL ANALYSIS INDICATES A MARGINAL ENVIRONMENT WITH HIGH 
(30 KTS+) VERTICAL WIND SHEAR (VWS) OFFSET BY STRONG WESTWARD OUTFLOW. 
THE CYCLONE IS TRACKING IN THE SOUTH CHINA SEA OVER WARM (29C) SEA 
SURFACE TEMPERATURES, STEERED BY A DEEP-LAYERED SUBTROPICAL RIDGE (STR)
TO THE NORTHWEST.
3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS 
PROGNOSTIC REASONING MESSAGE.
   B. TD 22W WILL TRACK WESTWARD UP TO TAU 12, THEN WEST-SOUTHWESTWARD 
AS THE STR BUILDS, AND BY TAU 72, WILL BE APPROXIMATELY 40NM OFF THE 
COAST OF SOUTHERN VIETNAM. THE ENVIRONMENT WILL IMPROVE SLIGHTLY AS 
ROBUST UPPER LEVEL OUTFLOW OVERCOMES THE STRONG VWS AND WILL LEAD TO A 
MODEST PEAK INTENSIFICATION TO 40KTS AT TAUS 36-48. AFTERWARD, VWS AND 
COOLING SST WILL OFFSET THE STRONG OUTFLOW AND WEAKEN THE SYSTEM DOWN 
TO 25KTS BY TAU 72. NUMERICAL MODELS ARE IN GOOD AGREEMENT WITH A 
GRADUAL AND EVEN SPREAD TO 220NM BY TAU 72, LENDING FAIR CONFIDENCE TO 
THIS PORTION OF THE JTWC FORECAST TRACK. 
   C. BEYOND TAU 72, TD GONI WILL MAKE LANDFALL NEAR QUI NHON BY TAU 78 
AND TRACK INLAND. INTERACTION WITH THE RUGGED TERRAIN, IN ADDITION TO 
THE  UNFAVORABLE ENVIRONMENT WILL RAPIDLY ERODE THE SYSTEM LEADING TO 
DISSIPATION BY TAU 96 AFTER IT CROSSES INTO CAMBODIA. NUMERICAL MODELS 
SPREAD OUT SIGNIFICANTLY, LENDING LOW CONFIDENCE TO THIS FINAL PORTION 
OF THE JTWC FORECAST TRACK. THERE IS A DISTINCT POSSIBILITY THAT TD 22W 
WILL DISSIPATE OVER WATER PRIOR TO LANDFALL DUE TO HIGH VWS AND COOLING 
SST OVERCOMING THE ROBUST OUTFLOW.//
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