WDPN32 PGTW 050900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 13W (BAILU) WARNING 
NR 014//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 38.4N 158.7E
   INITIAL INTENSITY: 30 KTS
   GEOGRAPHIC REFERENCE: 819 NM EAST OF MISAWA, JAPAN
   MOVEMENT PAST 6 HOURS: EAST-NORTHEASTWARD AT 13 KTS
   SIGNIFICANT WAVE HEIGHT: 15 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A PARTIALLY
OBSCURED LOW-LEVEL CIRCULATION WITH DEEP CONVECTION DRIFTING
EASTWARD WITH A FIELD OF STRATOCUMULUS (SC) CLOUDS WRAPPING AROUND
THE NORTHERN AND WESTERN PERIPHERY OF TROPICAL DEPRESSION (TD) 13W.
THE PRESENCE OF SC IS AN INDICATOR THAT EXTRATROPICAL TRANSITION IS
NEAR WHILE IN AN ENVIRONMENT OF HIGH VERTICAL WIND SHEAR (VWS) AND
LOW SEA SURFACE TEMPERATURES. CURRENTLY, THE TD IS UNDER AN
UPPER-LEVEL RIDGE AND LIES SOUTH OF THE BAROCLINIC ZONE. THE
INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE
AFOREMENTIONED MSI AND A 050537Z DMSP F-18 SSMIS 37GHZ PARTIAL
IMAGE CAPTURING THE WESTERN AND SOUTHERN PERIPHERY OF TD 13W. THE
89GHZ IMAGE FROM THE SAME SATELLITE PASS REVEALS THE WEAK DEEP
CONVECTION SHEARED TO THE EAST OF CENTER. THE INITIAL INTENSITY OF
30 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON THE AGENCY AND
OBJECTIVE FIXES LISTED BELOW.

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

CURRENT STEERING MECHANISM: A SUBTROPICAL RIDGE TO THE SOUTHEAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.0 - 30 KTS
   RJTD: T2.0 - 30 KTS
   KNES: T2.0 - 30 KTS
   CIMSS ADT: 33 KTS AT 050710Z
   CIMSS AIDT: 42 KTS AT 050710Z
   CIMSS D-PRINT: 30 KTS AT 050710Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: UNFAVORABLE
   VWS: 15-20 KTS
   SST: 21-22 CELSIUS
   OUTFLOW: WEAK EASTWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   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: TD 13W WILL CONTINUE TO TRACK NORTHEASTWARD
WHILE STEERED ON THE LOW-LEVEL FLOW BY A SUBTROPICAL RIDGE TO THE
SOUTHEAST. THE SYSTEM WILL MAINTAIN WARM-CORE TROPICAL
CHARACTERISTICS FOR THE NEXT TWELVE HOURS BEFORE STARTING
EXTRATROPICAL TRANSITION BETWEEN TAU 12-24. THE UPPER-LEVEL RIDGE
THAT TD 13W IS CURRENTLY UNDER WILL MOVE EASTWARD AND AN
UPPER-LEVEL TROUGH ASSOCIATED WITH THE JET WILL APPROACH, FORCING
FRONTOGENESIS AND A VERTICALLY TILTED CYCLONE ALOFT. 
TD 13W WILL WEAKEN WHILE UNDER THE RIDGE DUE TO THE HIGH
VERTICAL WIND SHEAR AND LACK OF THERMAL SUPPORT, RESULTING IN 
WEAKENING
TO 25KTS BY TAU 24. THE END-STATE WILL BE A 25KT EXTRATROPICAL
CYCLONE BY TAU 36.

MODEL DISCUSSION: DETERMINISTIC MODEL GUIDANCE IS IN STRONG
AGREEMENT THAT TD 13W WILL TRACK NORTHEASTWARD FOR THE REMAINDER OF
THE FORECAST PERIOD. THE CROSS-TRACK SPREAD AT TAU 36 IS
APPROXIMATELY 70NM. THE INTENSITY GUIDANCE IS SPREAD SIGNIFICANTLY,
WITH GFS AND HAFS-A FORECASTING INTENSIFICATION FOR THE FIRST 24
HOURS OF THE FORECAST TO APPROXIMATELY 35KTS, WHILE COAMPS-TC (GFS)
AND COAMPS-TC (NAVGEM) BOTH FORECAST RAPID WEAKENING. BEYOND THE
FORECAST PERIOD, IT IS POSSIBLE THAT THE SYSTEM MAY RE-INTENSIFY
DUE TO BAROCLINIC FORCING. THE TIMING OF EXTRATROPICAL TRANSITION
MAY VARY, AND THE FSU CYCLONE PHASE GUIDANCE INDICATES A TRANSITION
EARLIER THAN IN PREVIOUS MODEL RUNS.

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