WDPN31 PGTW 060900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 15W (FIFTEEN) 
WARNING NR 002//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 28.4N 157.1E
   INITIAL INTENSITY: 25 KTS
   GEOGRAPHIC REFERENCE: 302 NM NORTH-NORTHEAST OF MINAMI TORI
SHIMA
   MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 06 KTS
   SIGNIFICANT WAVE HEIGHT: 12 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS DEEP
CONVECTION BUILDING OVER THE VORTICITY MAXIMUM OF TROPICAL
DEPRESSION (TD) 15W. THE ELONGATED TURNING IS ORIENTED ON A
NORTH-SOUTH AXIS WITH STRONG SOUTHERLY WIND TO THE EAST AND WEAK
EASTERLIES CLOSING THE LLCC. THE INITIAL POSITION IS PLACED WITH
HIGH CONFIDENCE BASED ON A 060520Z DMSP F-18 SSMIS IMAGE REVEALING
THE SHALLOW NATURE OF THE LLCC ALONG THE NORTHERN HALF, AND THE
DEEP CONVECTION SHEARED TO THE SOUTH OF THE CENTER. THE INITIAL
INTENSITY OF 25 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 (STR) TO THE EAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T1.0 - 25 KTS
   KNES: T2.0 - 30 KTS
   CIMSS ADT: 26 KTS AT 060540Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL
   VWS: 20-25 KTS
   SST: 27-28 CELSIUS
   OUTFLOW: WEAK EQUATORWARD

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 15W WILL REMAIN ON A NORTHWARD TRACK FOR
THE NEXT 24 HOURS WHILE UNDER THE WEAK STEERING INFLUENCE OF THE
SUBTROPICAL RIDGE TO THE EAST. AFTER TAU 24, THE SYSTEM WILL BEGIN
TO ROUND THE NORTHWESTERN PERIPHERY OF THE RIDGE, DRIVING
NORTH-NORTHEASTWARD FOR THE REMAINDER OF THE FORECAST PERIOD. THE
CURRENT ENVIRONMENT IS MARGINAL FOR DEVELOPMENT AS DRY AIR
IMPINGES INTO THE SYSTEM FROM THE NORTH AND WEST. UNDER STRONG
EASTERLY FLOW, HIGH VERTICAL WIND SHEAR OF 20-25KTS FROM THE
NORTHEAST WILL CONTINUE TO ERODE THE VERTICAL STRUCTURE OF THE
CIRCULATION. DESPITE THE PRESENCE OF THE DRY AIR AND SHEAR, TD 15W
IS FORECAST TO SLIGHTLY INTENSIFY TO 35KTS AT TAU 24 BEFORE
WEAKENING DUE TO A LACK OF THERMAL SUPPORT AFTER PASSING INTO COOL
SEA SURFACE TEMPERATURES, AN UNFAVORABLE UPPER-LEVEL ENVIRONMENT,
AND CONTINUED STRONG SHEAR WILL RESULT IN A PERIOD OF DISSIPATION
STARTING AT TAU 36 AND ENDING AT TAU 72.

MODEL DISCUSSION: DETERMINISTIC MODEL GUIDANCE IS IN GOOD AGREEMENT
THAT TD 15W WILL TRACK NORTHWARD FOR THE REMAINDER OF THE FORECAST
PERIOD WHILE UNDER THE STEERING INFLUENCE OF THE SUBTROPICAL RIDGE.
THE CYCLONE TO THE WEST MAY RESULT IN FASTER TRACK SPEED, WHICH MAY
RESULT IN VARIATIONS OF TRACK SPEED THROUGH THE END OF THE FORECAST
PERIOD. THE INTENSITY GUIDANCE IS SLIGHTLY SPLIT, WITH THE JTWC
SHIPS GUIDANCE INDICATING INTENSIFICATION WITHIN THE NEAR-TERM,
BUT HAFS-A AND GFS INDICATING CONTINUOUS WEAKENING BELOW WARNING
THRESHOLD FOR THE NEXT 72 HOURS.

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