Advisories

WDPN32 PGTW 121500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 13W (PEILOU) WARNING 
NR 023//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 30.3N 163.5E
   INITIAL INTENSITY: 30 KTS
   GEOGRAPHIC REFERENCE: 625 NM NORTHEAST OF MINAMI TORI SHIMA
   MOVEMENT PAST 6 HOURS: EAST-NORTHEASTWARD AT 07 KTS
   SIGNIFICANT WAVE HEIGHT: 14 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS TROPICAL
DEPRESSION (TD) 13W (PEILOU) AS A HIGHLY SHEARED AND FULLY EXPOSED
LOW LEVEL CIRCULATION CENTER (LLCC) COMPLETELY DEVOID OF
CONVECTION. THE COPIOUS AMOUNT OF DRY AIR ENVELOPING THE SYSTEM IS
ALSO IDENTIFYABLE IN ANIMATED SATELLITE IMAGERY. ENVIRONMENTAL
ANALYSIS REVEALS AN UNFAVORABLE ENVIRONMENT, CHARACTERIZED BY
MODERATRE TO HIGH (20-25 KTS) VERTICAL WIND SHEAR (VWS), MARGINAL
(26-27 C) SEA SURFACE TEMPERATURES (SST), POOR OUTFLOW, AND DRY AIR
ENTRAINMENT. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE
BASED ON THE FULLY EXPOSED LLCC. THE INITIAL INTENSITY OF 30 KTS IS
ASSESSED WITH MEDIUM CONFIDENCE BASED ON THE AGENCY DVORAK FIXES
AND CIMSS AUTOMATED INTENSITY ESTIMATES LISTED BELOW.

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

CURRENT STEERING MECHANISM: MONSOONAL SOUTHWESTERLY FLOW ALONG THE
NORTHWESTERN PERIPHERY OF A SUBTROPICAL RIDGE (STR) CENTERED TO THE
SOUTHEAST


AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.0 - 30 KTS
   RJTD: T2.0 - 30 KTS
   RCTP: T2.5 - 35 KTS
   KNES: T2.0 - 30 KTS
   PHFO: T2.5 - 35 KTS
   CIMSS ADT: 32 KTS AT 121330Z
   CIMSS AIDT: 33 KTS AT 121330Z
   CIMSS D-MINT: 40 KTS AT 121230Z
   CIMSS D-PRINT: 31 KTS AT 121200Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: UNFAVORABLE
   VWS: 20-25 KTS
   SST: 26-27 CELSIUS
   OUTFLOW: WEAK EQUATORWARD
   OTHER FACTORS: PERSISTENT DEEP-LAYER DRY AIR ENTRAINMENT

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 (PEILOU) IS FORECAST TO CONTINUE
TRACKING NORTHEASTWARD WHILE IT REMAINS EMBEDDED WITHIN THE STRONG
SOUTHWESTERLY MONSOONAL FLOW DIRECTED AROUND THE STR CENTERED TO
THE SOUTHEAST. BETWEEN TAU 0-12, PEILOU IS FORECAST TO CROSS THE
26C ISOTHERM AND ENCOUNTER 30-35 KTS OF VWS THAT WILL INDUCE
DRAMATIC DRY AIR ENTRAINMENT INTO THE CORE. AS A RESULT, 13W IS
FORECAST TO WEAKEN THROUGHOUT THE FORECAST PERIOD. 13W IS EXPECTED
TO ULTIMATELY BE ABSORBED BY THE TROUGH TO ITS NORTH AND ASSOCIATED
BAROCLINIC LOW TO ITS NORTHEAST BY TAU 36.

MODEL DISCUSSION: DETERMINISTIC MODEL TRACK GUIDANCE IS IN STRONG
AGREEMENT THROUGHOUT THE FORECAST PERIOD, SUPPORTING THE JTWC TRACK
FORECAST WITH HIGH CONFIDENCE. THE JTWC INTENSITY FORECAST RUNS
BELOW THE MODEL CONSENSUS DUE TO ITS MEMBERS ERRONEOUSLY
INCORPORATING THE BROADER WIND FIELD OF THE NEARBY BAROCLINIC LOW.
REGARDLESS, THE JTWC INTENSITY FORECAST IS PLACED WITH HIGH
CONFIDENCE. 

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