WDPN31 PGTW 061500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 15W (FIFTEEN) 
WARNING NR 003//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 29.6N 157.2E
   INITIAL INTENSITY: 25 KTS
   GEOGRAPHIC REFERENCE: 366 NM NORTH-NORTHEAST OF MINAMI TORI
SHIMA
   MOVEMENT PAST 6 HOURS: NORTHWARD AT 12 KTS
   SIGNIFICANT WAVE HEIGHT: 12 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A FULLY
EXPOSED LOW-LEVEL CIRCULATION CENTER (LLCC) WITH DEEP CONVECTION
SHEARED TO THE SOUTH-SOUTHWEST. THE INITIAL POSITION IS PLACED WITH
HIGH CONFIDENCE BASED ON THE AFOREMENTIONED ANIMATED EIR AND A
061213Z GPM GMI 89GHZ IMAGE REVEALING THE SHALLOW AND SHEARED
STRUCTURE OF TROPICAL DEPRESSION (TD) 15W. THE LLCC IS ELONGATED
ALONG A NORTH-SOUTH AXIS. DRY AIR BOUNDS THE NORTHERN PERIPHERY OF
TD 15W. THE INITIAL INTENSITY IS ASSESSED WITH HIGH CONFIDENCE
BASED ON A 060943Z METOP-B ASCAT IMAGE REVEALING 25KT WINDS TO THE
EAST AND SOUTHEAST OF THE LLCC.

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

CURRENT STEERING MECHANISM: A SUBTROPICAL RIDGE TO THE EAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T1.5 - 25 KTS
   CIMSS ADT: 27 KTS AT 061130Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY
UNFAVORABLE
   VWS: 20-25 KTS
   SST: 27-28 CELSIUS
   OUTFLOW: WEAK 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: TD 15W WILL TRACK NORTHWARD ON THE WESTERN
PERIPHERY OF A SUBTROPICAL RIDGE TO THE EAST, CURVING SLIGHTLY TO
THE NORTH-NORTHEAST BY THE END OF THE FORECAST PERIOD. OVER THE
NEXT 12 HOURS, TD 15W WILL SLIGHTLY INTENSIFY TO A PEAK OF 30KTS AT
TAU 12 WHILE THE CORE REMAINS MOIST. HIGH VERTICAL WIND SHEAR WILL
INHIBIT FURTHER INTENSIFICATION BEYOND 30KTS. THE CURRENT
UNFAVORABLE DRY AIR THREATENING THE LLCC WILL OVERTAKE THE SYSTEM
BY TAU 24, RESULTING IN GRADUAL WEAKENING. ULTIMATELY, THE
UNFAVORABLE FEATURES WILL LEAD TO DISSIPATION WITHIN THE NEXT 48
HOURS AS THE SYSTEM WEAKENS INTO THE LARGER FLOW.

MODEL DISCUSSION: DETERMINISTIC MODEL GUIDANCE IS IN GOOD AGREEMENT
THAT TD 15W WILL TRACK NORTHWARD FOR THE REMAINDER OF THE FORECAST
PERIOD. THE INTENSITY GUIDANCE HAS A LARGER SPREAD, WITH COAMPS-TC
AND HAFS-A INDICATING WEAKENING WHILE GFS AND THE JTWC SHIPS
GUIDANCE DEPICTS INTENSIFICATION. THERE IS MODERATE UNCERTAINTY IN
THE INTENSITY FORECAST DUE TO VARYING IMPACTS OF THE DRY AIR AND
VERTICAL WIND SHEAR ON TD 15W.

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