WDPN31 PGTW 221500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 02W (TWO) WARNING 
NR 001//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 23.2N 145.9E
   INITIAL INTENSITY: 30 KTS
   GEOGRAPHIC REFERENCE: 270 NM EAST-SOUTHEAST OF IWO TO
   MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 05 KTS
   SIGNIFICANT WAVE HEIGHT: 12 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS TROPICAL
DEPRESSION (TD) 02W WITH AN EXPOSED LOW-LEVEL CIRCULATION CENTER
(LLCC) AND FLARING CONVECTION ALONG THE EASTERN SEMICIRCLE. A
221103Z METOP-C ASCAT IMAGE REVEALED 25-30 KTS WITHIN THE
NORTHEASTERN QUADRANT OF THE SYSTEM. ADDITIONALLY, THE ASCAT SHOWED
HOW ASYEMETRIC THE WIND FIELD CURRENTLY IS, WITH THE ENTIRETY OF
THE WESTERN PORTION OF THE SYSTEM CONSIDERABLY WEAKER (10-15 KTS).
ENVIRONMENTAL ANALYSIS INDICATES THAT 02W IS IN A MARGINALLY
FAVORABLE ENVIRONMENT CHARACTERIZED BY MODERATE POLEWARD OUTFLOW
ALOFT, LOW TO MODERATE (15-20 KTS) SOUTHWESTERLY VERTICAL WIND
SHEAR, AND WARM (28-29 C) SEA SURFACE TEMPERATURES. THE PRESENCE
OF A TROPICAL UPPER TROPOSPHERIC TROUGH (TUTT) CELL POSITIONED TO
THE WEST OF THE SYSTEM IS CAUSING THE ELEVATED SHEAR AND OUTFLOW TO
BE RESTRICTED. IT IS ALSO LIKELY THE CAUSE FOR THE LACK OF CENTRAL
CONVECTION. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE
BASED ON THE MENTIONED ASCAT IMAGE AND THE EXPOSED LLCC. THE
INITIAL INTENSITY OF 30 KTS IS ALSO ASSESSED WITH HIGH CONFIDENCE
BASED ON THE COMBINATION OF THE ASCAT, AGENCY DVORAK, AND OBJECTIVE
INTENSITY ESTIMATES.

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

CURRENT STEERING MECHANISM: SOUTHWESTERN PERIPHERY OF A DEEP-LAYER
SUBTROPICAL RIDGE (STR) CENTERED TO THE NORTH-NORTHEAST.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.0 - 30 KTS
   RJTD: T1.0 - 25 KTS
   KNES: T1.5 - 25 KTS
   CIMSS DPRINT: 20 KTS AT 221200Z
   CIMSS DMINT: 27 KTS AT 220859Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 15-20 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: MODERATE POLEWARD
   OTHER FACTORS: PRESSURE FROM THE TUTT CELL TO THE WEST

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: TD 02W IS FORECAST TO TRACK NORTHWESTWARD,
ALONG THE SOUTHWESTERN PERIPHERY OF THE SUBTROPICAL RIDGE THROUGH
TAU 48. NEAR TAU 72, THE SYSTEM WILL BEGIN TO ROUND THE RIDGE AXIS
AND TURN NORTHEASTWARD AS IT SKIRTS THE EASTERN COAST OF CENTRAL
HONSHU. 02W WILL THEN ACCELERATE OFF TO THE NORTHEAST THROUGH THE
REMINDER OF THE FORECAST PERIOD. REGARDING INTENSITY, 02W IS
FORECAST TO MARGINALLY INTENSIFY THROUGH TAU 24 AS THE VORTEX
TRACKS AWAY FROM THE TUTT CELL AND SHEAR DECREASES. THE POLEWARD
OUTFLOW CHANNEL WILL BEGIN TO WANE SIMULTANEOUSLY THOUGH, PUTTING A
CAP ON THE INTENSIFICATION TREND. NEAR TAU 48, SEA SURFACE
TEMPERATURES WILL BEGIN TO DROP AS THE SYSTEM GAINS LATITUDE. SEA
TEMPERATURES ARE EXPECTED TO BE AROUND 25 C AT TAU 72 AND THEN 22 C
AT TAU 96, CAUSING THE SYSTEM TO WEAKEN AND DROP BELOW TROPICAL
STORM STRENGTH AS IT APPROACHES HONSHU. DISSIPATION IS FORECAST TO
OCCUR NEAR TAU 96 DUE TO COMBINATION OF COOL WATERS AND RAPIDLY
INCREASING SHEAR.

MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE AGREES ON A
NORTHWESTWARD TRACK WITH A RECURVE SCENARIO. NAVGEM IS THE PRIMARY
OUTLIER, AS IT HAS THE SYSTEM MOVE MORE QUICKLY AND RECURVE SOONER
THAN THE REMAINDER OF GUIDANCE SUGGESTS. THE JTWC TRACK FORECAST IS
PLACED CLOSER TO THE MAIN GROUPING OF TRACKERS WITH MEDIUM
CONFIDENCE THROUGH TAU 72 AND THEN LOW CONFIDENCE THEREAFTER. THE
LOWER CONFIDENCE AFTER TAU 72 IS ATTRIBUTED TO THE INCREASE IN
ALONG-TRACK SPREAD AS THE SHALLOW VORTEX RACES OFF TO THE
NORTHEAST. INTENSITY GUIDANCE IS IN MODERATE AGREEMENT WITH
CONSENSUS MEMBERS RANGING FROM 30-45 KTS THROUGH TAU 48 AND THEN
WEAKENING THROUGH TAU 96. HWRF AND COAMPS-TC (GFS BASED) ARE THE
TWO SLIGHTLY MORE AGGRESSIVE MODELS OF THE BUNCH. OVERALL, THE JTWC
INTENSITY FORECAST IS PLACED WITH MEDIUM CONFIDENCE THROUGHOUT THE
FORECAST PERIOD.

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