Advisories

WDPN32 PGTW 120900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 13W (PEILOU) WARNING 
NR 022//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 30.1N 162.7E
   INITIAL INTENSITY: 30 KTS
   GEOGRAPHIC REFERENCE: 584 NM NORTHEAST OF MINAMI TORI SHIMA
   MOVEMENT PAST 6 HOURS: NORTHEASTWARD AT 09 KTS
   SIGNIFICANT WAVE HEIGHT: 14 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS TROPICAL
DEPRESSION (TD) 13W AS A PARTIALLY EXPOSED LOW-LEVEL CIRCULATION
CENTER (LLCC) WITH A SMALL BALL OF CONVECTION SHEARED TO THE
SOUTHEAST. 13W HAS BEGUN INTERACTING WITH A WEAK TROUGH TO ITS
NORTH, WHICH CONTAINS SEVERAL CYCLONIC SPINNERS AND IS INDUCING A
WEAKNESS IN THE LOW-LEVEL FLOW ON THE NORTHERN PERIPHERY OF 13W.
ENVIRONMENTAL ANALYSIS REVEALS A MARGINAL ENVIRONMENT,
CHARACTERIZED BY BORDERLINE (26-27 C) SEA SURFACE TEMPERATURES (SST),
POOR OUTFLOW, AND PERSISTENT DEEP LAYER DRY AIR ENTRAINMENT, OFFSET
BY LOW TO MODERATE (15-20 KTS) VERTICAL WIND SHEAR (VWS). THE
INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE
PARTIALLY EXPOSED LLCC. THE INITIAL INTENSITY OF 30 KTS IS ASSESSED
WITH MEDIUM CONFIDENCE BASED ON THE AGENCY DVORAK FIXES AND THE
CIMSS AUTOMATED INTENSITY ESTIMATES LISTED BELOW, SUPPLEMENTED BY
THE 120651Z WSFM WIND SPEED PRODUCT THAT REVEALS A LARGE SWATH OF
CALM WINDS ALONG THE TROUGH AXIS AND 15-20 KT WINDS IN THE STORM'S
EXPOSED SEMICIRCLE. THE ELEVATED TD-STRENGTH WINDS ARE CONFINED TO
UNDER THE CONVECTIVE BALL IN THE SOUTHEASTERN QUADRANT.

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

CURRENT STEERING MECHANISM: MONSOONAL SOUTHWESTERLY FLOW ALONG THE
NORTHWESTERN PERIPHERY OF A MID-LEVEL RIDGE TO THE SOUTHEAST.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.5 - 35 KTS
   RJTD: T2.0 - 30 KTS
   RCTP: T2.5 - 35 KTS
   KNES: T2.5 - 35 KTS
   CIMSS SATCON: 43 KTS AT 120530Z
   CIMSS ADT: 34 KTS AT 120630Z
   CIMSS AIDT: 44 KTS AT 120630Z
   CIMSS D-MINT: 36 KTS AT 120244Z
   CIMSS D-PRINT: 39 KTS AT 120530Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL
   VWS: 15-20 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. 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 JUST AFTER TAU 24.

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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