WDPN31 PGTW 181500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 24W (SARIKA) WARNING NR
25//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 24W (SARIKA), LOCATED APPROXIMATELY 189 NM
EAST-SOUTHEAST OF HANOI, VIETNAM, HAS TRACKED NORTHWESTWARD AT 10
KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE
IMAGERY DEPICTS A RAPIDLY WEAKENING LOW-LEVEL CIRCULATION CENTER
(LLCC) DISORGANIZED DEEP CONVECTION. A 181058Z SSMIS 91GHZ IMAGE
SHOWS TIGHTLY-CURVED SHALLOW BANDING, HOWEVER, DEEP CONVECTIVE
STRUCTURE HAS DETERIORATED AND THE CENTER IS OBSCURED. OVERALL,
THERE IS FAIR CONFIDENCE IN THE CURRENT POSITION BASED ON THE
AVAILABLE IMAGERY. THE INITIAL INTENSITY IS ASSESSED AT 55 KNOTS
BASED ON DVORAK ESTIMATES RANGING FROM 45 TO 65 KNOTS. UPPER-LEVEL
ANALYSIS SHOWS GOOD RADIAL OUTFLOW AHEAD OF AN APPROACHING SHORTWAVE
TROUGH TO THE NORTHWEST, WITH LOW (10 KNOTS) VERTICAL WIND SHEAR
(VWS). CURRENTLY TS SARIKA IS TRACKING ALONG THE SOUTHWESTERN
PERIPHERY OF A DEEP-LAYERED SUBTROPICAL RIDGE (STR) TO THE NORTHEAST.
3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING BULLETIN.
   B. TS SARIKA WILL CONTINUE TO TRACK GENERALLY NORTHWESTWARD ALONG
THE STR OVER THE NEXT 12 HOURS, PRIOR TO FINAL LANDFALL. VWS WILL
INCREASE AS THE SHORTWAVE TROUGH PASSES, HOWEVER THE WEAKENING TREND
WILL BE PARTIALLY OFFSET BY GOOD OUTFLOW AND THE WARM 28 DEGREE
CELSIUS WATERS OF THE GULF OF TONKIN. AFTER LANDFALL, THE SYSTEM
WILL DISSIPATE DUE TO LAND EFFECTS AS SARIKA ROUNDS THE STR AND
TURNS TO THE NORTH-NORTHEAST. AVAILABLE MODEL GUIDANCE IS IN GOOD
AGREEMENT, LENDING HIGH CONFIDENCE TO THE JTWC FORECAST TRACK.//