Advisories

WDPN32 PGTW 111500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 13W (PEILOU) WARNING 
NR 019//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 26.1N 159.5E
   INITIAL INTENSITY: 30 KTS
   GEOGRAPHIC REFERENCE: 320 NM EAST-NORTHEAST OF MINAMI TORI SHIMA
   MOVEMENT PAST 6 HOURS: EAST-NORTHEASTWARD AT 15 KTS
   SIGNIFICANT WAVE HEIGHT: 15 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS TROPICAL
DEPRESSION 13W (PEILOU) WITH COLLAPSING DEEP CENTRAL CONVECTION
OBSCURING THE LOW-LEVEL CIRCULATION CENTER (LLCC) AND WEAK LOWER
LEVEL CLOUD BANDING. ADDITIONALLY, THE REMNANTS OF TROPICAL
DEPRESSION 15W ARE DRIFTING WESTWARD WITHIN PEILOU'S NORTHERN
PERIPHERY, DISRUPTING THE LOW LEVEL INFLOW INTO 13W. ENVIRONMENTAL
ANALYSIS REVEALS A HIGHLY UNFAVORABLE ENVIRONMENT, CHARACTERIZED BY
DEEP-LAYER DRY AIR ENTRAINMENT AND POOR DIVERGENCE ALOFT,
INSIGNIFICANTLY OFFSET BY THE LOW TO MODERATE (15-20 KTS) VERTICAL
WIND SHEAR (VWS) AND WARM (28-29 C) SEA SURFACE TEMPERATURES. THE
INITIAL POSITION IS PLACED WITH LOW CONFIDENCE BASED ON LOW-LEVEL
CLOUD BANDING IN ANIMATED EIR AND THE AGENCY POSITION FIXES. THE
INITIAL INTENSITY OF 30 KTS IS ASSESSED WITH LOW CONFIDENCE BASED
ON EXTRAPOLATION FROM A 111115Z METOPC-C ASCAT THAT DEPICTED 20 KTS
ALONG THE WESTERN FLANK. THE DVORAK FIXES AND AUTOMATED CIMSS
ESTIMATES ARE ASSESSED TO BE TOO HIGH.

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

CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE (STR) CENTERED TO THE
SOUTHEAST, ENHANCED BY THE MONSOONAL FLOW ASSOCIATED WITH THE LARGE
GYRE CENTERED TO THE WEST.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.0 - 45 KTS
   RJTD: T2.5 - 35 KTS
   RCTP: T3.0 - 45 KTS
   KNES: T3.0 - 45 KTS
   CIMSS ADT: 53 KTS AT 111330Z
   CIMSS AIDT: 41 KTS AT 111330Z
   CIMSS D-PRINT: 36 KTS AT 111330Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: HIGHLY UNFAVORABLE
   VWS: 15-20 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: WEAK EQUATORWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: LOW
   INITIAL INTENSITY: LOW
   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 IS FORECAST TO CONTINUE TRACKING
GENERALLY NORTHEASTWARD FOR THE DURATION OF THE FORECAST PERIOD
WHILE IT REMAINS STEERED BY THE NORTHWESTERN PERIPHERY OF THE STR
TO THE SOUTHEAST, WITH THE STEERING GRADIENT ENHANCED BY THE
MONSOONAL FLOW SURROUNDING THE LARGE LOW-LEVEL GYRE CENTERED TO THE
WEST, PROPELLING PEILOU NORTHEASTWARD. REGARDING INTENSITY, 13W IS
FORECAST TO GRADUALLY WEAKEN DUE TO THE INCREASING VWS, THE
DECREASING SSTS, AND THE COPIOUS AMOUNTS OF DRY AIR ENTRAINING INTO
THE CORE. TD 13W IS EXPECTED TO OPEN INTO A TROUGH AND DISSIPATE AS
A TROPICAL CYCLONE NO LATER THAN TAU 24.

MODEL DISCUSSION: DETERMINISTIC MODEL TRACK GUIDANCE IS IN STRONG
AGREEMENT THROUGHOUT THE FORECAST PERIOD, SUPPORTING THE JTWC TRACK
FORECAST WITH HIGH CONFIDENCE. LIKEWISE, THE RELIABLE INTENSITY
AIDS ARE IN STRONG AGREEMENT IN STEADY WEAKENING THROUGH
DISSIPATION AT TAU 24. AS A RESULT, THE JTWC INTENSITY FORECAST IS
ASSESSED WITH HIGH CONFIDENCE.

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