WDPN31 PGTW 201500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 22W (TWENTYTWO) 
WARNING NR 001//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 14.9N 136.0E
   INITIAL INTENSITY: 25 KTS
   GEOGRAPHIC REFERENCE: 347 NM NORTH-NORTHWEST OF YAP
   MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 11 KTS
   SIGNIFICANT WAVE HEIGHT: 15 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS AN
ELONGATED BUT CLOSED LOW-LEVEL CIRCULATION CENTER (LLCC) WITH
CONVECTIVE BANDING WRAPPING INTO THE CENTER. A 201151Z 37GHZ
MICROWAVE IMAGE HIGHLIGHTS THE LOW-LEVEL BANDING WRAPPING INTO THE
CIRCULATION CENTER WITH A TIGHTLY CURVED CONVECTIVE BAND WRAPPING
ALONG THE EASTERN PERIMETER OF THE CIRCULATION. WATER VAPOR IMAGERY
HIGHLIGHTS THE STRONGLY ENHANCED OUTFLOW INTO AN UPPER-LEVEL
CYCLONE LOCATED TO THE NORTHEAST. TO THE SOUTH, UPPER-LEVEL FLOW IS
ENCOURAGED BY DIFFLUENCE EQUATORWARD. THE INITIAL POSITION IS
PLACED WITH HIGH CONFIDENCE BASED ON THE AFOREMENTIONED ANIMATED
EIR AND MICROWAVE IMAGERY. THE INITIAL INTENSITY OF 25 KTS IS
ASSESSED WITH MEDIUM CONFIDENCE BASED ON A PARTIAL 201130Z METOP-B
ASCAT IMAGE REVEALING 25KT WINDS WRAPPING INTO THE SYSTEM FROM THE
EAST SUPPLEMENTED BY THE AGENCY AND OBJECTIVE FIXES BELOW.

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

CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE (STR) TO THE NORTH

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T1.0 - 25 KTS
   RJTD: T1.0 - 25 KTS

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 5-10 KTS
   SST: 30-31 CELSIUS
   OUTFLOW: STRONG POLEWARD AND EQUATORWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   INITIAL INTENSITY: MEDIUM
   INITIAL WIND RADII: NOT APPLICABLE

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THIS INITIAL PROGNOSTIC REASONING
MESSAGE ESTABLISHES THE FORECAST PHILOSOPHY.

FORECAST DISCUSSION: TROPICAL DEPRESSION (TD) 22W WILL BE DRIVEN
WESTWARD FOR THE FIRST 36 HOURS OF THE FORECAST PERIOD BY A
SUBTROPICAL RIDGE (STR) TO THE NORTH. AFTER TAU 36, THE SYSTEM WILL
TRACK WEST-NORTHWESTWARD AS IT BEGINS TO ROUND THE RIDGE FOR THE
REMAINDER OF THE FORECAST PERIOD. IN THE EARLY FORECAST, THE SYSTEM
WILL GRADUALLY INTENSIFY TO A PEAK OF 60KTS BY TAU 72. THE
INTENSIFICATION WILL BE DRIVEN BY WARM SEA SURFACE TEMPERATURES,
HIGH OCEAN HEAT CONTENT, AND STRONG UPPER-LEVEL OUTFLOW. THE
MITIGATING FACTOR FOR INTENSIFICATION IS MODERATE TO HIGH VERTICAL
WIND SHEAR THAT IS INTRODUCED BETWEEN TAU 48-72. THE INTENSITY WILL
PLATEAU UNTIL TAU 96 WHILE STRIKING A BALANCE BETWEEN FAVORABLE
ENVIRONMENTAL FEATURES AND INCREASINGLY UNFAVORABLE VERTICAL WIND
SHEAR. WEAKENING WILL COMMENCE AT TAU 120, WHEN THE HIGH SHEAR
OVERWHELMS THE SYSTEM AND THE INTENSITY DECLINES TO 50KTS.

MODEL DISCUSSION: DETERMINISTIC MODEL GUIDANCE IS IN GOOD AGREEMENT
IN THE NEAR-TERM, WITH A CROSS-TRACK SPREAD OF 138NM BY TAU 72, BUT
OPENS TO 329NM BY TAU 120. THE OPENING IS LIKELY RELATED TO
DIFFERENT INTERPRETATIONS BETWEEN MODEL SOLUTIONS OF HOW SHARPLY
THE SYSTEM MOVES AROUND THE SOUTHWESTERN PERIPHERY OF THE NORTHERN
STR. GFS AND THE GFS ENSEMBLE TRACK THE SYSTEM NEARLY DUE WEST OVER
NORTHERN LUZON AT THE END OF THE FORECAST PERIOD WHILE ECMWF TRACKS
THE SYSTEM NORTHWESTWARD. THE INTENSITY GUIDANCE IS SPREAD BETWEEN
HAFS-A WITH A PEAK OF 60KTS AT TAU 96 AND HWRF WHICH INTENSIFIES TO
80KTS BY TAU 96.

FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: MEDIUM
   TRACK 72-120 HR: MEDIUM
   INTENSITY 0 - 72 HR: MEDIUM
   INTENSITY 72-120 HR: MEDIUM//
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