WDPN31 PGTW 070900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 02W (TWO) WARNING NR 
002//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 4.0N 147.6E
   INITIAL INTENSITY: 30 KTS
   GEOGRAPHIC REFERENCE: 582 NM SOUTH-SOUTHEAST OF HAGATNA, GUAM
   MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 09 KTS
   SIGNIFICANT WAVE HEIGHT: 11 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A
SLOWLY-CONSOLIDATING, SYMMETRIC LOW-LEVEL CIRCULATION CENTER (LLCC)
WITH FORMATIVE CONVECTIVE BANDING OVER THE NORTHERN AND WESTERN
SEMICIRCLES. A 070559Z GMI 89GHZ COLOR COMPOSITE MICROWAVE IMAGE
REVEALS IMPROVED ORGANIZATION WITH SHALLOW BANDING WRAPPING INTO A
RAGGED LLCC AND FRAGMENTED DEEP CONVECTIVE BANDING PRIMARILY OVER
THE NORTHERN SEMICIRCLE. THE INITIAL POSITION IS PLACED WITH MEDIUM
CONFIDENCE BASED ON THE MSI AND GMI IMAGE. ENVIRONMENTAL
CONDITIONS REMAIN FAVORABLE WITH MODERATE WESTWARD OUTFLOW AND LOW
VERTICAL WIND SHEAR (VWS) AS WELL AS WARM SST VALUES AND HIGH OCEAN
HEAT CONTENT. INITIAL INTENSITY OF 30 KTS IS ASSESSED WITH MEDIUM
CONFIDENCE AND IS HEDGED ABOVE THE DVORAK ESTIMATES BASED ON THE
CIMSS ADT ESTIMATE AND IMPROVED CONVECTIVE STRUCTURE. THE 070000Z
SOUNDINGS FROM BOTH CHUUK AND GUAM INTERNATIONAL AIRPORT INDICATE
DEEP EASTERLY FLOW REFLECTING THE STRONG EAST-WEST ORIENTED
SUBTROPICAL RIDGE POSITIONED TO THE NORTH.

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

CURRENT STEERING MECHANISM: SOUTHERN PERIPHERY OF A DEEP-LAYERED
SUBTROPICAL RIDGE (STR) ENTRENCHED TO THE NORTH.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T1.5 - 25 KTS
   RJTD: T1.5 - 25 KTS
   KNES: T1.5 - 25 KTS
   CIMSS ADT: 29 KTS AT 070540Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 10-15 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: MODERATE WESTWARD

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

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THE JTWC FORECAST TRACK HAS SHIFTED
SIGNIFICANTLY WEST OF THE PREVIOUS FORECAST, ESPECIALLY IN THE
EXTENDED FORECAST PERIOD.

FORECAST DISCUSSION: TD 02W IS FORECAST TO TRACK WEST-NORTHWESTWARD
THEN NORTHWESTWARD ALONG THE SOUTHERN AND SOUTHWESTERN PERIPHERIES
OF THE STR THROUGH THE FORECAST PERIOD. AS MENTIONED PREVIOUSLY,
THE LOW- TO MID-LEVEL STR IS CURRENTLY STRONG AND IS ORIENTED
EAST-WEST SUPPORTING THE WEST-NORTHWESTWARD TRACK IN THE EARLY PART
OF THE FORECAST. TD 02W WILL INTENSIFY SLOWLY THROUGH TAU 36 AS IT
CONSOLIDATES UNDER GENERALLY FAVORABLE CONDITIONS BUT IS FORECAST
TO INTENSIFY AT A STEEPER RATE AFTER TAU 36 AS POLEWARD OUTFLOW
IMPROVES. THE PEAK INTENSITY OF 90 KNOTS IS EXPECTED NEAR TAU 120. 

MODEL DISCUSSION: WITH THE EXCEPTION OF GFS, THE BULK OF NUMERICAL
MODEL GUIDANCE SUPPORTS THE JTWC FORECAST TRACK AND SHIFT WEST FROM
THE PREVIOUS JTWC TRACK FORECAST. THE 070000Z ECMWF ENSEMBLE STRIKE
PROBABILITY PRODUCT INDICATES A NARROW CONE OF 60-70 PERCENT STRIKE
PROBABILITY WEST OF 140E THROUGH TAU 96, WHICH SUPPORTS THE JTWC
FORECAST TRACK. THE COAMPS-TC ENSEMBLE AND UK MET ENSEMBLE
(MOGREPS) ALSO SHOW A SIMILAR GROUPING OF SOLUTIONS WEST OF 140E.
GLOBAL MODELS INDICATE A BROAD MIDLATITUDE RIDGE PERSISTING SOUTH
OF JAPAN, WHICH WILL STRENGTHEN THE EXISTING STR. ADDITIONALLY,
THERE ARE NO DYNAMIC SHORTWAVE TROUGHS SUFFICIENT TO WEAKEN THE STR
THROUGH THE FIRST THREE DAYS; IN FACT, THERE IS ONLY ONE SIGNICANT
SHORTWAVE TROUGH PASSING WELL TO THE NORTH OVER JAPAN WITHIN THE
NEXT 24 HOURS. GFS IS THE SOLE OUTLIER AND IS ON THE EASTERN EDGE
OF THE AIDS ENVELOPE. GFS APPEARS TO BE STRUGGLING WITH THE
FORMATION OF THIS SYSTEM IN THE EARLY TAUS AND SHOWS A NORTHWARD TURN 
INTO THE EAST-WEST ORIENTED STR FROM TAU 24 TO TAU 48. AFTER TAU 48, 
GFS ALSO RAPIDLY DEVELOPS ANOTHER SYSTEM EAST OF THE PHILIPPINES (ABOUT 
900 NM WEST), WHICH INTERACTS WITH AND SLINGS 02W DIRECTLY INTO AND 
THROUGH THE STR WITH NO EVIDENCE OF ANY DYNAMIC SHORTWAVE TROUGHS THAT 
COULD POSSIBLY WEAKEN THE STR. ADDITIONALLY, THE NORTHWARD TRACK IS 
LESS PROLONGED IN THE 070000Z RUN VERSUS THE 061800Z RUN AND THE 
TRACKER SHIFTED FURTHER WEST AWAY FROM GUAM. BOTTOMLINE: THERE ARE 
CONCERNING ISSUES WITH GFS WITHIN THE SYNOPTIC STEERING ENVIRONMENT 
THAT ARE ODD AND UNLIKELY, THEREFORE, THE JTWC FORECAST TRACK IS 
SHIFTED CLOSER TO THE JTWC MULTI-MODEL CONSENSUS WITH THE BULK OF THE
DETERMINISTIC AND PROBABILISTIC GUIDANCE.            

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