WDPN32 PGTW 210900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 15W (PULASAN) 
WARNING NR 019//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 34.3N 125.4E
   INITIAL INTENSITY: 30 KTS
   GEOGRAPHIC REFERENCE: 113 NM SOUTH-SOUTHWEST OF KUNSAN AB
   MOVEMENT PAST 6 HOURS: EAST-NORTHEASTWARD AT 17 KTS
   SIGNIFICANT WAVE HEIGHT: 12 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS STRONG
CONVECTION LOCATED OVER THE LOW-LEVEL CIRCULATION CENTER (LLCC)
WITH FRONTOGENESIS IDENTIFIABLE TO THE SOUTH AND EAST. HIGH 25-30KT
VERTICAL WIND SHEAR FROM THE SOUTHWEST INTRODUCES DRY AIR TO THE
WESTERN PERIMETER OF THE SYSTEM. UPPER-LEVEL OUTFLOW IS POLEWARD
AND EQUATORWARD. THE INITIAL POSITION IS PLACED WITH HIGH
CONFIDENCE BASED ON THE AFOREMENTIONED CIRCULATION AND CONVECTION
ON ANIMATED MSI. A 210454Z GCOM W1 AMSR2 IMAGE SUPPORTS THE HIGH
CONFIDENCE ASSESSMENT OF 30KTS WITH WIND SPEED DATA OF 25-30KTS
SURROUNDING THE LOW-LEVEL CIRCULATION.

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

CURRENT STEERING MECHANISM: A SUBTROPICAL RIDGE (STR) SOUTHEAST OF
JAPAN

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.0 - 30 KTS
   RJTD: T2.0 - 30 KTS
   RCTP: T2.0 - 30 KTS
   CIMSS ADT: 34 KTS AT 210530Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: UNFAVORABLE
   VWS: 25-30 KTS
   SST: 27-28 CELSIUS
   OUTFLOW: STRONG POLEWARD AND EQUATORWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   INITIAL INTENSITY: HIGH
   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: TROPICAL STORM (TS) 15W WILL CONTINUE TO TRACK
EAST-NORTHEASTWARD AND BECOME EMBEDDED WITHIN THE POLAR FRONT JET
TO THE NORTH, PASSING OVER SOUTHERN SOUTH KOREA BETWEEN TAU 0-12
AND NORTHERN JAPAN BETWEEN TAU 24-36. BAROCLINIC FORCING WILL ALLOW
FOR INTENSIFICATION TO 35KTS DURING THE FIRST 12 HOURS OF THE
FORECAST PERIOD AS THE SYSTEM CONTINUES TO UNDERGO EXTRATROPICAL
TRANSITION. LAND INTERACTION AROUND TAU 24 WILL CAUSE WEAKENING
BELOW THE GALE THRESHOLD BY TAU 36. 

MODEL DISCUSSION: DETERMINISTIC MODEL GUIDANCE IS IN STRONG
AGREEMENT THAT THE SYSTEM WILL TRACK EAST-NORTHEASTWARD UNDER THE
STEERING INFLUENCE OF THE STR AND BECOME EXECUTE EXTRATROPICAL
TRANSITION AS TS 15W MOVES FARTHER NORTH. THE INTENSITY GUIDANCE
ALSO IS IN AGREEMENT THAT SLIGHT INTENSIFICATION CAN BE EXPECTED
DUE TO BAROCLINIC FORCING THAT WILL OCCUR AS THE SYSTEM BECOMES
FURTHER EMBEDDED IN THE POLAR FRONT JET.

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