WDPN34 PGTW 130300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 09W (NINE)    
WARNING NR 001//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 26.9N 150.2E
   INITIAL INTENSITY: 25 KTS
   GEOGRAPHIC REFERENCE: 737 NM SOUTHEAST OF YOKOSUKA, JAPAN
   MOVEMENT PAST 6 HOURS: NORTHEASTWARD AT 06 KTS
   SIGNIFICANT WAVE HEIGHT: 10 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY DEPICTS TIGHTLY-CURVED LOW-
LEVEL CLOUD LINES WRAPPING INTO A PARTIALLY EXPOSED CENTER, WITH A 
SYMMETRIC REGION OF INTENSE CONVECTION PERSISTING OVER THE SOUTHERN 
SEMICIRCLE. A 122058Z SSMIS 91GHZ MICROWAVE IMAGE REVEALS DEEP 
CONVECTIVE BANDING CONFINED TO THE SOUTHERN QUADRANT, WITH A BROAD 
EXPOSED LOW-LEVEL CIRCULATION CENTER. A 130012Z ASCAT-B IMAGE
SUPPORTS THE INITIAL POSITION WITH HIGH CONFIDENCE AND SHOWS A
DEFINED CIRCULATION WITH AN EXTENSIVE SWATH OF 20-25 KNOT WINDS
OVER THE SOUTHERN SEMICIRCLE AND ISOLATED 30 KNOT WINDS UNDER THE
DEEP CONVECTION TO THE SOUTH. UPPER-LEVEL CONDITIONS ARE MARGINALLY
FAVORABLE DUE TO THE PRESENCE OF AN UPPER-LOW TO THE NORTH, WHICH
IS HINDERING POLEWARD OUTFLOW, OFFSET BY MODERATE EQUATORWARD
OUTFLOW. THE INITIAL INTENSITY OF 25 KTS IS ASSESSED WITH MEDIUM
CONFIDENCE BASED ON THE PGTW DVORAK ESTIMATE, CONSISTENT WITH THE
RECENT ASCAT DATA.

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

CURRENT STEERING MECHANISM: LOW- TO MID-LEVEL SUBTROPICAL RIDGE
(STR) ENTRENCHED TO THE SOUTHEAST AND EAST.

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

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 10-15 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: MODERATE EQUATORWARD
   OTHER FACTORS: DRY AIR ENTRAINMENT

ANALYSIS CONFIDENCE:
   INITIAL POSITION: MEDIUM
   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) 09W IS EXPECTED TO
TRACK POLEWARD ALONG THE WESTERN PERIPHERY OF THE NORTH-SOUTH
ORIENTED STR POSITIONED TO THE EAST THROUGH TAU 48. AFTER TAU 48,
THE SYSTEM WILL ROUND THE NORTHWESTERN PERIPHERY OF THE STR,
TRACKING NORTHEASTWARD. DUE TO A BRIEF PERIOD OF ENHANCED POLEWARD
OUTFLOW, THE SYSTEM WILL LIKELY INTENSIFY TO 35 KNOTS BY TAU 24. 
HOWEVER, THE PRESENCE OF DRY AIR WILL LIMIT INTENSIFICATION
THROUGHOUT THE FORECAST PERIOD. AFTER TAU 48, THE SYSTEM IS
FORECAST TO TRACK OVER COOLER SST (24-26C), WITH COLD SST VALUES
(22-24C) EXPECTED BY TAU 72. THEREFORE, THE SYSTEM IS FORECAST TO
DISSIPATE BY TAU 72.

MODEL DISCUSSION: DETERMINISTIC AND PROBABILISTIC MODEL GUIDANCE ARE 
IN GOOD AGREEMENT THROUGH THE FORECAST PERIOD LENDING HIGH CONFIDENCE 
TO THE JTWC FORECAST TRACK. RELIABLE INTENSITY GUIDANCE SUPPORTS THE 
JTWC INTENSITY FORECAST WITH MEDIUM CONFIDENCE.

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