WDPN31 PGTW 290300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 21W (SINLAKU) WARNING 
NR 12//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 21W (SINLAKU), LOCATED APPROXIMATELY 275 NM 
SOUTHEAST OF DA NANG, VIETNAM, HAS TRACKED WESTWARD AT 10 KNOTS OVER 
THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED (EIR) SATELLITE 
IMAGERY SHOWS GOOD CONSOLIDATION WITH SPIRAL BANDING WRAPPING INTO 
THE LOW-LEVEL CIRCULATION CENTER. THE CURRENT POSITION IS BASED ON 
THE EIR ANIMATION WITH GOOD CONFIDENCE. THE INTENSITY IS BASED ON 
DVORAK INTENSITY ESTIMATES FROM ALL AGENCIES AND AN EARLIER. UPPER-
LEVEL ANALYSIS INDICATES TS SINLAKU REMAINS IN A HIGHLY FAVORABLE 
ENVIRONMENT WITH LOW (10 TO 15 KNOT) VERTICAL WIND SHEAR AND 
EXCELLENT POLEWARD AND EQUATORWARD OUTFLOW. TS SINLAKU IS TRACKING 
ALONG THE SOUTHWESTERN PERIPHERY OF A SUBTROPICAL RIDGE (STR).
3. FORECAST REASONING.
   A. NO CHANGE TO FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC 
REASONING MESSAGE.
   B. TS SINLAKU WILL CONTINUE TRACKING WEST UNDER THE STEERING 
INFLUENCE OF THE ELONGATED STR THROUGH THE REMAINDER OF THE 
FORECAST. FAVORABLE UPPER-LEVEL CONDITIONS ARE EXPECTED TO PERSIST 
ALLOWING THE SYSTEM TO FURTHER INTENSIFY. HOWEVER, BEYOND TAU 12, 
THE SYSTEM WILL MAKE LANDFALL NEAR QUI NHON, VIETNAM THEN RAPIDLY 
DISSIPATE AS IT TRACKS OVER THE ANNAMESE MOUNTAINS. ALL MODELS ARE 
IN GOOD AGREEMENT, GIVING A HIGH CONFIDENCE IN THE JTWC FORECAST 
TRACK, POSITIONED CLOSE TO THE MULTI-MODEL CONSENSUS.//
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