WDPN32 PGTW 040900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 10W (MAYSAK) WARNING NR 
011//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 20.6N 107.8E
   INITIAL INTENSITY: 45 KTS
   GEOGRAPHIC REFERENCE: 109 NM EAST-SOUTHEAST OF HANOI, VIETNAM
   MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 07 KTS
   SIGNIFICANT WAVE HEIGHT: 16 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A PARTIALLY
EXPOSED LOWER-LEVEL CIRCULATION CENTER (LLCC) WITH DEEP CONVECTION
WRAPPING INTO THE SOUTHERN AND EASTERN PERIPHERY OF THE VORTEX. THE
VENTILATION ALOFT HAS IMPROVED IN THE PRESENCE OF LOW TO MODERATE
NORTHEASTERLY SHEAR. THE ENVIRONMENT IS GENERALLY FAVORABLE FOR
INTENSIFICATION, CHARACTERIZED BY WARM SEA SURFACE TEMPERATURE
(SST), VERY PLENTIFUL DEEP-LAYER MOISTURE, AND LOW TO MODERATE
VERTICAL WIND SHEAR (VWS). DATA FROM A 040453Z OSCAT-3 PASS REVEALS
THAT THE HIGHEST WINDS ARE CONFINED TO THE EASTERN SIDE OF THE
LLCC, AND THE VORTEX HAS TIGHTENED UP. THE INITIAL POSITION IS
ASSESSED WITH MEDIUM CONFIDENCE BASED ON THE CURVATURE OF THE RAIN
BANDS. THE INITIAL POSITION REMAINS AT 45 KTS WITH MEDIUM
CONFIDENCE BASED ON THE T3.0 DVORAK ESTIMATES FROM PGTW AND RJTD
AND THE AFOREMENTIONED OSCAT-3 PASS.

INITIAL WIND RADII BASIS: SCATTEROMETER DATA 

CURRENT STEERING MECHANISM: WESTERN PERIPHERY OF A MID-LEVEL
SUBTROPICAL RIDGE (STR) CENTERED NEAR THE RYUKYU ISLANDS

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.0 - 45 KTS
   RJTD: T3.0 - 45 KTS
   RCTP: T2.5 - 35 KTS
   KNES: T3.5 - 55 KTS
   CIMSS SATCON: 53 KTS AT 040600Z
   CIMSS ADT: 57 KTS AT 040600Z
   CIMSS AIDT: 53 KTS AT 040600Z
   CIMSS D-MINT: 50 KTS AT 040541Z
   CIMSS D-PRINT: 36 KTS AT 040600Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 10-15 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: MODERATE EQUATORWARD
   OTHER FACTORS: LAND INTERACTION

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: THE CIRCULATION IS BEING DRIVEN POLEWARD BY A
MID-LEVEL STR TO THE WEST. TROPICAL STORM 10W WILL TURN TOWARDS THE
NORTHEAST AS IT CROSSES THE RIDGE AXIS. LOW TO MODERATE VWS, WARM
SST, AND ABUNDANT DEEP-LAYER MOISTURE POINT TO AN ENVIRONMENT
FAVORABLE FOR DEVELOPMENT. MAYSAK STILL HAS APPROXIMATELY 6 HOURS
REMAINING OVER WATER TO INTENSIFY, SO A PEAK OF 50 KT IS POSSIBLE
PRIOR TO LANDFALL BETWEEN TAU 0 AND TAU 12. ONCE LANDFALL OCCURS,
THE CIRCULATION WILL TRAVERSE OVER RUGGED TERRAIN AND QUICKLY
WEAKEN. THE FORECAST CALLS FOR DISSIPATION TO OCCUR BY TAU 36.

MODEL DISCUSSION: THE AVAILABLE MODEL GUIDANCE AGREES ON A POLEWARD
TRACK UNTIL DISSIPATION. ECMWF AND NAVGEM LIE ON THE WESTERN SIDE
OF THE GUIDANCE ENVELOPE WITH HAFS-A ON THE OTHER END. THE JTWC
FORECAST TRACK IS PLACED NEAR THE CONSENSUS WITH HIGH CONFIDENCE.
THE RELIABLE INTENSITY AIDS ALL DEPICT STEADY TO RAPID WEAKENING
AFTER TAU 12 DUE TO THE FRICTIONAL AND DRYING EFFECTS OF LAND. THE
JTWC FORECAST CALLS FOR STEADY WEAKENING WITH HIGH CONFIDENCE AS
THE TROPICAL STORM INTERACTS WITH LAND.

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