WDPN31 PGTW 200300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 10W (JONGDARI) WARNING 
NR 005//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 31.2N 125.5E
   INITIAL INTENSITY: 35 KTS
   GEOGRAPHIC REFERENCE: 287 NM SOUTH OF KUNSAN AB
   MOVEMENT PAST 6 HOURS: NORTHWARD AT 20 KTS
   SIGNIFICANT WAVE HEIGHT: 15 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A SHALLOW
LOW-LEVEL CIRCULATION CENTER (LLCC) PARTIALLY OBSCURED BY CIRRUS
PLUME AS 10W PERSISTS DESPITE MODERATE VERTICAL WIND SHEAR INDUCED
BY THE NEARBY UPPER-LEVEL JET TO THE NORTH. EARLIER 202143Z RCM-2
SYNTHETIC APERTURE RADAR (SAR) WIND SPEED DATA DISPLAYS A BROAD
CIRCULATION WITH A SWATH OF 30-40KT WINDS IN THE NORTHEASTERN
QUADRANT OF THE CIRCULATION. THE INITIAL POSITION IS PLACED WITH
MEDIUM CONFIDENCE BASED ON THE AFOREMENTIONED ANIMATED MSI DUE TO
THE OBSCURATION OF THE UPPER-LEVEL CLOUDS. THE INITIAL INTENSITY OF
35 KTS IS ASSESSED WITH HIGH CONFIDENCE BASED ON THE AFOREMENTONED
SAR IMAGERY ALONGSIDE THE AGENCY AND OBJECTIVE FIXES LISTED BELOW.

INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK 

CURRENT STEERING MECHANISM: THE WESTERN PERIPHERY OF A SUBTROPICAL
RIDGE (STR) TO THE EAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.5 - 35 KTS
   RJTD: T2.0 - 30 KTS
   RCTP: T2.0 - 30 KTS
   KNES: T3.0 - 45 KTS
   CIMSS ADT: 32 KTS AT 192340Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY
UNFAVORABLE
   VWS: 10-15 KTS
   SST: 30-31 CELSIUS
   OUTFLOW: MODERATE RADIAL

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TROPICAL STORM (TS) 10W IS FORECAST TO TRACK
NORTHWARD ON WHILE UNDER THE INFLUENCE OF THE STR TO THE EAST.
AFTER 12 HOURS, THE TRACK WILL BECOME NORTHEASTWARD AS THE TS
ROUNDS THE RIDGE, MAKING LANDFALL BETWEEN 24-36 HOURS. THE SYSTEM
WILL GRADUALLY WEAKEN WHILE INUNDATED BY MODERATE VERTICAL WIND
SHEAR THAT INCREASES AS THE SYSTEM APPROACHES THE UPPER-LEVEL JET
TO THE NORTH. FAVORABLE SEA SURFACE TEMPERATURES, MODERATE VERTICAL
WIND SHEAR, AND MARGINAL UPPER-LEVEL DIVERGENCE WILL CAUSE THE
SYSTEM TO STAGNATE PRIOR TO LANDFALL. BASED ON THE MOUNTAINOUS
TOPOGRAPHY OF THE KOREAN PENINSULA, THE CIRCULATION IS EXPECTED TO
WEAKEN DRASTICALLY AS THE VORTEX BECOMES SHALLOW. 

MODEL DISCUSSION: DETERMINISTIC MODEL GUIDANCE IS IN GOOD AGREEMENT
THAT THE CIRCULATION WILL TRACK OVERALL NORTHEASTWARD OVER THE NEXT
36 HOURS. AS THE SYSTEM SHALLOWS OVER LAND, THE TRACK MAY VARY. THE
JTWC MULTI MODEL CONSENSUS GUIDANCE IS ALSO IN GOOD AGREEMENT OVER
THE NEXT TWELVE HOURS THAT IT WILL STAGNATE OR INTENSIFY
MARGINALLY, PRIOR TO CONSISTENT WEAKENING AFTER LANDFALL IS MADE.
IF THE CIRCULATION WOULD SURVIVE AFTER PASSING OVER THE KOREAN
PENINSULA, IT WILL BE EMBEDDED WITHIN THE BAROCLINIC ZONE AND
COOLER WATERS AND IS NOT EXPECTED TO BE TROPICAL. 

FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: HIGH
   INTENSITY 0 - 72 HR: MEDIUM//
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