WDPN32 PGTW 031500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 10W (MAYSAK) WARNING NR 
008//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 18.5N 109.5E
   INITIAL INTENSITY: 40 KTS
   GEOGRAPHIC REFERENCE: 165 NM NORTH-NORTHEAST OF DA NANG, VIETNAM
   MOVEMENT PAST 6 HOURS: NORTHWARD AT 09 KTS
   SIGNIFICANT WAVE HEIGHT: 12 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A
COMPACT VORTEX WITH DEEP CONVECTION OVER THE LOW-LEVEL CIRCULATION
CENTER AND IN THE SOUTHWEST QUADRANT. MODERATE NORTHEASTERLY
VERTICAL WIND SHEAR (VWS) HAS CONTINUED TO PREVENT CONSOLIDATION OF
THE DEEP CONVECTION AROUND THE CORE OVER THE PAST 6 HOURS. ANIMATED
RADAR IMAGERY SHOWED THE CENTER OF ROTATION AS TS 10W MADE LANDFALL
OVER SOUTHERN HAINAN ISLAND. THE INITIAL POSITION IS PLACED WITH
MEDIUM CONFIDENCE BASED ON THE CENTER OF ROTATION IN ANIMATED RADAR
IMAGERY. THE INITIAL INTENSITY OF 40 KTS IS ASSESSED WITH MEDIUM
CONFIDENCE BASED ON A BLEND OF THE AGENCY DVORAK FIXES AND CIMSS
OBJECTIVE INTENSITY ESTIMATES. THE ENVIRONMENT IS CHARACTERIZED AS
MARGINAL WITH WARM SEA SURFACE TEMPERATURES AND MODERATE
EQUATORWARD OUTFLOW OFFSET BY THE SYSTEM'S TRACK OVER HAINAN ISLAND
AND MODERATE (15-20 KTS) VWS.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: SOUTHWESTERN PERIPHERY OF A DEEP-LAYER
SUBTROPICAL RIDGE (STR) CENTERED SOUTH OF KYUSHU

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.5 - 35 KTS
   RJTD: T2.5 - 35 KTS
   RCTP: T2.5 - 35 KTS
   KNES: T3.0 - 45 KTS
   CIMSS ADT: 53 KTS AT 031200Z
   CIMSS AIDT: 46 KTS AT 031200Z
   CIMSS D-MINT: 41 KTS AT 031026Z
   CIMSS D-PRINT: 46 KTS AT 031200Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL
   VWS: 15-20 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: MODERATE EQUATORWARD
   OTHER FACTORS: LAND INTERACTION OVER HAINAN ISLAND

ANALYSIS CONFIDENCE:
   INITIAL POSITION: MEDIUM
   INITIAL INTENSITY: HIGH
   INITIAL WIND RADII: LOW

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO
THE FORECAST FROM THE PREVIOUS WARNING.

FORECAST DISCUSSION: TROPICAL STORM (TS) 10W (MAYSAK) HAS SLOWLY
MADE ITS WAY ONSHORE OF HAINAN ISLAND OVER THE PAST 3 HOURS ON A
NORTH-NORTHWESTWARD TRACK. THE WEAKENING OF THE SOUTHWESTERN
EXTENSION OF THE PRIMARY STEERING RIDGE CENTERED TO THE NORTHEAST
IS EXPECTED TO FACILITATE THE NORTH-NORTHWESTWARD TRAJECTORY FOR
THE NEXT 24 HOURS, TURNING NORTH THEN NORTHEASTWARD THROUGH THE
REMAINDER OF THE FORECAST PERIOD. THE SYSTEM IS EXPECTED TO
REEMERGE OVER THE GULF OF TONKIN WITHIN THE NEXT 10 HOURS ALONG
THIS TRACK, THEN MAKE A SECOND LANDFALL ALONG THE SINO-VIETNAMESE
BORDER REGION JUST AFTER TAU 24. A BRIEF PERIOD OF INTENSIFICATION
UP TO A PEAK OF 45 KTS IS EXPECTED AS 10W TRANSITS OVER THE GULF OF
TONKIN, FOLLOWED BY RAPID DISSIPATION UPON LANDFALL OVER SOUTHEAST
CHINA.

MODEL DISCUSSION: MODEL TRACK GUIDANCE IS IN GOOD AGREEMENT ABOUT
THE TRAJECTORY OF TS 10W THROUGHOUT THE FORECAST PERIOD, WITH
MINIMAL ACROSS- AND ALONG-TRACK SPREAD. THE JTWC TRACK IS PLACED
CLOSE TO THE MULTI-MODEL CONSENSUS WITH HIGH CONFIDENCE THROUGHOUT
THE FORECAST PERIOD. INTENSITY GUIDANCE IS IN GOOD AGREEMENT ABOUT
THE PERIOD OF INTENSIFICATION OVER THE GULF OF TONKIN, REMAINING
WITHIN A 5 KT ENVELOPE UNTIL RAPID DISSIPATION OCCURS OVER LAND.
THE JTWC INTENSITY FORECAST IS PLACED CLOSE TO THE CONSENSUS WITH
HIGH CONFIDENCE.

FORECAST CONFIDENCE:
   TRACK 00-72 HR: HIGH
   INTENSITY 00-72 HR: HIGH//
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