WDPN32 PGTW 200900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 15W (PULASAN) 
WARNING NR 015//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 32.5N 120.4E
   INITIAL INTENSITY: 30 KTS
   GEOGRAPHIC REFERENCE: 437 NM WEST-SOUTHWEST OF CHINHAE, SOUTH
                         KOREA
   MOVEMENT PAST 6 HOURS: NORTHWARD AT 05 KTS
   SIGNIFICANT WAVE HEIGHT: OVER LAND

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
SPIRAL BANDS OF WEAK CONVECTIVE CLOUD LINES CAN BE SEEN WRAPPING
INTO THE LOW LEVEL CIRCULATION CENTER (LLCC) ON ANIMATED ENHANCED
INFRARED (EIR) SATELLITE IMAGERY AS WELL AS ANIMATED RADAR SCANS.
THE LLCC IS CURRENTLY POSITIONED OVER LAND AND OBSCURED BY DEEPER
CONVECTION BUBBLING UP OVER THE CENTER IN SCATTERED PLUMES. THE
OUTFLOW IS WEAKLY SHEARED TO THE EAST AS IT BEGINS TO FEEL THE
EFFECTS OF MID-LATITUDE WESTERLIES. THE INITIAL POSITION IS PLACED
WITH MEDIUM CONFIDENCE BASED ON ANIMATED RADAR SCANS AND SUBJECTIVE
AGENCY FIXES. THE INITIAL INTENSITY OF 30 KTS IS ASSESSED WITH
MEDIUM CONFIDENCE BASED ON PARTIAL SCATTEROMETRY DATA FROM 200821Z
AND SUPPORTED BY A DMINT ESTIMATE OF 31 KTS.

INITIAL WIND RADII BASIS: NOT APPLICABLE (THERE ARE NO INITIAL WIND
RADII).

CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE TO THE EAST.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: NO CURRENT ESTIMATE
   RJTD: T1.5 - 25 KTS
    
FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY
                                              UNFAVORABLE
   VWS: 5-10 KTS
   SST: OVER LAND
   OUTFLOW: WEAK EASTWARD
   OTHER FACTORS: LAND AND BAROCLINIC ZONE INTERACTION.

ANALYSIS CONFIDENCE:
   INITIAL POSITION: MEDIUM
   INITIAL INTENSITY: MEDIUM
   INITIAL WIND RADII: NOT APPLICABLE

3. FORECAST REASONING.

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

FORECAST DISCUSSION: THE SYSTEM WILL BEGIN TRACKING EASTWARD IN
ACCELERATING FLOW ALONG THE POLAR FRONT. THE ENHANCED THERMAL
GRADIENT IMMEDIATELY TO THE NORTH WILL CAUSE THE SYSTEM TO INITIATE 
THE TRANSITION PROCESS TO AN EXTRATROPICAL CYCLONE WITHIN THE NEXT
TWELVE HOURS, EVEN THOUGH IT WILL EMERGE OVER WATER AND INTENSIFY
MODESTLY. THE PRIMARY FACTOR CAUSING THE INTENSIFICATION IS THE
TIGHTENING PRESSURE GRADIENT AND FORWARD MOTION OF THE SYSTEM, IN 
ADDITION TO FAVORABLY WARM SEA SURFACE TEMPERATURES (27-29 C) 
BENEATH. AS THE SYSTEM MORPHS INTO AN EXTRATROPICAL LOW DUE TO 
INCREASING BAROCLINICITY AND UNDERGOES FRONTOGENESIS, IT WILL BECOME 
INCREASINGLY ASYMMETRIC, MAKING LANDFALL IN THE SOUTHERN REPUBLIC OF 
KOREA NEAR TAU 24. THE LAND INTERACTION AND 170-KNOT COMBINED JET MAX 
OVERHEAD WILL CONTINUE TO DEGRADE THE TROPICAL CHARACTERISTICS OF THE 
SYSTEM, RESULTING IN A FULLY EXTRATROPICAL CYCLONE BY TAU 36.

MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE IS IN TIGHT AGREEMENT
CONCERNING THE TRACK FORECAST BUT VARIES IN THE SPEED AT WHICH THE
SYSTEM WILL MOVE EASTWARD. THE MODELS ALSO VARY IN THE OVERALL
INTENSITY OF THE SYSTEM, WITH SOME DROPPING THE INTENSITY AS THE
TROPICAL NATURE OF THE STORM WINDS DOWN AND OTHERS STRENGTHENING
THE WINDS AS THE SYNOPTIC PATTERN BECOMES MORE ZONAL, INCREASING THE 
FORWARD SPEED OF THE SYSTEM. CONSIDERING THE CONSISTENCY OF HOW WELL 
THE GLOBAL MODELS HANDLE THE SYSTEM, THE JTWC FORECAST IS PREDICTED 
WITH MEDIUM CONFIDENCE THROUGH TAU 36.

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