WDPN31 PGTW 042100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 22W (GONI) WARNING NR 
032//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM 22W (GONI), LOCATED APPROXIMATELY 266 NM
EAST-SOUTHEAST OF DA NANG, VIETNAM, HAS TRACKED WESTWARD AT 05
KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED (EIR)
SATELLITE IMAGERY DEPICTS A FULLY EXPOSED LOW LEVEL CIRCULATION
CENTER (LLCC) WITH ASSOCIATED CONVECTION SHEARED 60 NM TO THE 
NORTHWEST. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE
BASED ON THE FULLY EXPOSED LLCC IN THE EIR LOOP AS WELL AS 
THE LOW LEVEL BANDING EVIDENT IN A 041615Z GMI 37 GHZ IMAGE. 
THE INITIAL INTENSITY OF 40 KTS IS PLACED WITH FAIR
CONFIDENCE BETWEEN MULTI-AGENCY DVORAK CURRENT INTENSITY 
ESTIMATES OF T3.0 (45 KTS, PGTW) AND T2.5(40 KTS, RJTD). THE
SYSTEM HAS CONTINUED TO TRACK WESTWARD ALONG THE SOUTHERN
PERIPHERY OF A DEEP-LAYER SUBTROPICAL RIDGE (STR) POSITIONED TO
THE NORTH AND THROUGH A MARGINAL ENVIRONMENT WITH MODERATE 
(15-20 KTS) VERTICAL WIND SHEAR (VWS) OFFSET SLIGHTLY BY THE
DIVERGENT WESTWARD OUTFLOW ALOFT AND WARM (26-27 CELSIUS) SEA
SURFACE TEMPERATURES. 
3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS 
PROGNOSTIC REASONING MESSAGE.
   B. THERE IS NO SIGNIFICANT CHANGE EXPECTED IN THE OVERALL 
FORECAST, AS THE SYSTEM WILL CONTINUE TO TRACK GENERALLY 
WESTWARD ALONG THE SOUTHERN PERIPHERY OF THE STR THROUGH THE 
ENTIRE FORECAST PERIOD WITH A SLIGHT WEST-SOUTHWESTWARD TRACK
CHANGE AFTER TAU 24. DUE TO THE MODERATE VERTICAL WIND SHEAR 
OVER THE NEXT 48 HOURS, TS GONI WILL CONTINUE TO WEAKEN TO 40 
KTS BY TAU 24 AFTER WHICH TIME IT WILL MAKE LANDFALL ALONG THE 
SOUTH CENTRAL COAST OF VIETNAM. THE SYSTEM WILL THEN BEGIN THE
AFOREMENTIONED WEST-SOUTHWESTWARD TRACK TOWARDS CAMBODIA. INTERACTION
WITH THE UNDERLYING TERRAIN WILL LEAD TO FURTHER WEAKENING TO
30 KTS BY TAU 36 AND LEAD TO FULL DISSIPATION OVER LAND BY TAU
72. DYNAMIC MODEL GUIDANCE IS IN FAIR AGREEMENT WITH A SPREAD
IN SOLUTIONS OF 120 NM AT LANDFALL WHICH INCREASES TO 150 NM BY
TAU 72. THIS FAIR AGREEMENT IN THE NUMERICAL MODEL TRACK
GUIDANCE LENDS OVERALL FAIR CONFIDENCE IN THE JTWC FORECAST 
TRACK WHICH LIES JUST SOUTH OF THE MULTI-MODEL CONSENSUS.//
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