WDPN33 PGTW 090900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 26W (TORAJI) 
WARNING NR 001//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 14.5N 131.6E
   INITIAL INTENSITY: 30 KTS
   GEOGRAPHIC REFERENCE: 616 NM EAST OF MANILA, PHILIPPINES
   MOVEMENT PAST 6 HOURS: WESTWARD AT 16 KTS
   SIGNIFICANT WAVE HEIGHT: 10 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A RAPIDLY 
CONSOLIDATING SYSTEM, WITH A SYMMETRIC CENTRAL DENSE OVERCAST 
OBSCURING THE LOW-LEVEL CIRCULATION CENTER (LLCC). A 090709Z SSMIS 
91GHZ COLOR COMPOSITE MICROWAVE IMAGE SUPPORTS THE INITIAL POSITION 
WITH MEDIUM CONFIDENCE AND SHOWS A COMPACT SYSTEM WITH CONVECTIVE 
BANDING WRAPPING TIGHTLY INTO A DEFINED LLCC, WHICH IS POSITIONED 
DIRECTLY UNDER THE CORE CONVECTION. ENVIRONMENTAL CONDITIONS ARE 
HIGHLY FAVORABLE WITH RADIAL OUTFLOW AND LOW VERTICAL WIND SHEAR. THE 
INITIAL INTENSITY OF 30 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED 
ON THE HIGH END OF THE AGENCY DVORAK ESTIMATES, CONSISTENT WITH THE 
IMPRESSIVE CONVECTIVE APPEARANCE. 

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

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

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T1.5 - 25 KTS
   RJTD: T2.0 - 30 KTS
   CIMSS D-PRINT: 49 KTS AT 090800Z

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

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) 26W IS FORECAST TO
TRACK WESTWARD TO WEST-NORTHWESTWARD THROUGH TAU 48, WITH LANDFALL
ANTICIPATED NEAR TAU 48. DUE TO THE FAVORABLE ENVIRONMENT AND
RAPIDLY IMPROVING CONVECTIVE ORGANIZATION, THE SYSTEM WILL LIKELY
REACH TROPICAL STORM STRENGTH QUICKLY AND CONTINUE TO INTENSIFY AT A 
FASTER-THAN-CLIMATOLOGICAL RATE, REACHING A PEAK OF 60 KNOTS BY TAU
36. HOWEVER, THERE IS MODERATE POTENTIAL FOR RAPID INTENSIFICATION
(RI), WHICH COULD ALLOW THE SYSTEM TO REACH MINIMAL TYPHOON
STRENGTH PRIOR TO LANDFALL. UNFORTUNATELY, RI GUIDANCE IS VERY
LIMITED AT THIS TIME. AFTER CROSSING LUZON AND WEAKENING, THE
SYSTEM SHOULD TRACK WEST-NORTHWESTWARD TO NORTHWESTWARD ALONG THE
SOUTHWEST PERIPHERY OF THE STR, WITH STEADY WEAKENING DUE TO
INCREASING VWS AND DRY AIR ENTRAINMENT.     

MODEL DISCUSSION: THE 090000Z ECMWF ENSEMBLE (EPS) INDICATES A
FAIRLY TIGHT CLUSTER OF SOLUTIONS THROUGH TAU 48, WITH LANDFALL
LIKELY OVER THE CENTRAL TO NORTHEAST COAST OF LUZON. AFTER TAU 48,
THE ECMWF ENSEMBLE DIVERGES WITH INCREASING UNCERTAINTY AFTER TAU
72. THE 090000Z GFS ENSEMBLE (GEFS) SHOWS A SIMILAR PLUME OF
SOLUTIONS. THE PRIMARY SOURCE OF THE LARGE SPREAD AND INCREASING
UNCERTAINTY AFTER TAU 72 IS DUE TO UNCERTAINTY IN THE SYSTEM'S
INTENSITY AND UNCERTAINTY IN THE DEGREE OF WEAKENING OF THE STR
OVER SOUTHEAST CHINA. IF THE SYSTEM IS STRONGER THAN EXPECTED, IT
MAY TRACK MORE NORTHWESTWARD TOWARD THE HONG KONG REGION AND IF IT
WEAKENS SIGNIFICANTLY, IT MAY STALL AND TURN EQUATORWARD UNDER THE
LOW-LEVEL STEERING FLOW.     

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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