WDPN31 PGTW 051500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 22W (GONI) WARNING 
NR 035//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL DEPRESSION (TD) 22W (GONI), LOCATED APPROXIMATELY 207 NM 
SOUTHEAST OF DA NANG, VIETNAM, HAS TRACKED WESTWARD AT 02 KNOTS 
(KTS) OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED (EIR) 
SATELLITE IMAGERY REVEALS A BROAD, FULLY-EXPOSED LOW LEVEL 
CIRCULATION CENTER (LLCC) WITH THE ASSOCIATED CONVECTION SHEARED TO 
THE NORTHWEST. THE INITIAL POSITION IS SET WITH HIGH CONFIDENCE 
BASED ON THE FULLY-EXPOSED NATURE OF THE SYSTEM AND AN EXTRAPOLATION 
FROM A 051035Z 91 GHZ COLOR COMPOSITE MICROWAVE IMAGE WHICH DEPICTS 
FORMATIVE BANDING WRAPPING INTO A BROAD LLCC. THE INITIAL INTENSITY 
IS ASSESSED AT 30 KTS AND IS SUPPORTED BY MULTI-AGENCY DVORAK 
CURRENT INTENSITY ESTIMATES OF T1.5-2.0 (25-30 KTS). TD 22W IS 
LOCATED IN A REGION OF MODERATE (10-20 KTS) VERTICAL WIND SHEAR 
(VWS) BEING OFFSET BY WARM (26-27 CELSIUS) SEA SURFACE TEMPERATURES 
(SST) AND DIVERGENCE ALOFT. THESE FACTORS CONTRIBUTE TO AN OVERALL 
MARGINAL ENVIRONMENT. ANIMATED EIR IMAGERY REVEALED THAT THE SYSTEM 
REMAINED QUASI-STATIONARY FOR THE MAJORITY OF THE PAST SIX HOURS. 
HOWEVER, TD 22W BEGAN TO TRACK SLOWLY WESTWARD ALONG THE SOUTHERN 
PERIPHERY OF A SUBTROPICAL RIDGE (STR) JUST PRIOR TO SYNOPTIC TIME.
3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS 
PROGNOSTIC REASONING MESSAGE.
   B. TD 22W WILL CONTINUE TO TRACK GENERALLY WESTWARD FOR THE 
DURATION OF THE FORECAST PERIOD UNDER THE INFLUENCE OF THE 
AFOREMENTIONED STR. DUE TO PERSISTENT MODERATE VWS AND COOLING SST, 
THE SYSTEM SHOULD STEADILY WEAKEN AS IT APPROACHES THE COAST, MAKING 
LANDFALL IN CENTRAL VIETNAM SHORTLY AFTER TAU 12. AS THE SYSTEM 
TRACKS INLAND, INTERACTION WITH THE UNDERLYING TERRAIN WILL CONTINUE 
TO WEAKEN THE SYSTEM, LEADING TO DISSIPATION OVER LAND BY TAU 36, IF 
NOT SOONER. NUMERICAL MODEL GUIDANCE IS IN FAIR AGREEMENT SHOWING A 
66 NM SPREAD IN THE SOLUTIONS AT LANDFALL WHICH INCREASES TO 143 NM 
BY TAU 36. THIS INCREASING SPREAD LENDS ONLY FAIR CONFIDENCE IN THE 
JTWC FORECAST TRACK WHICH IS POSITIONED NEAR THE MULTI-MODEL 
CONSENSUS.//
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