WDPN33 PGTW 282100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 11W (CO-MAY) WARNING NR 
024//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 27.0N 125.0E
   INITIAL INTENSITY: 35 KTS
   GEOGRAPHIC REFERENCE: 153 NM WEST-NORTHWEST OF KADENA AB
   MOVEMENT PAST 6 HOURS: WESTWARD AT 14 KTS
   SIGNIFICANT WAVE HEIGHT: 16 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS TROPICAL
STORM (TS) 11W (CO-MAY) WITH A COMPLETELY EXPOSED LOW-LEVEL
CIRCULATION CENTER (LLCC) AS MUCH OF THE ASSOCIATED CONVECTION
REMAINS DISLOCATED TO THE WESTERN FLANK AND INTO THE NORTHERN
SEMICIRCLE. OVER THE LAST FEW HOURS, THE LOW- TO MID-LEVEL
CIRCULATION HAS BECOME RAGGED AND ELONGATED IN A SOUTHWEST TO
NORTHEAST ORIENTATION. ALOFT, WEAK EQUATORWARD OUTFLOW HAS BEEN
OBSERVED ON ANIMATED WATER VAPOR IMAGERY, WHICH HAS ASSISTED IN
MAINTAINING STEADY INTENSITIES AT THE SURFACE. THE INITIAL POSITION
IS PLACED WITH HIGH CONFIDENCE BASED ON THE FULLY EXPOSED LLCC ON
ANIMATED EIR. THE INITIAL INTENSITY IS ASSESSED WITH HIGH
CONFIDENCE BASED ON AN EARLIER 281247Z METOP-B ASCAT IMAGE AND
SUBJECTIVE DVORAK ESTIMATES LISTED BELOW.

INITIAL WIND RADII BASIS: SCATTEROMETER DATA 

CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE DIRECTLY TO THE
NORTH-NORTHEAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T1.5 - 25 KTS
   RJTD: T1.5 - 25 KTS
   CIMSS SATCON: 42 KTS AT 281230Z
   CIMSS ADT: 32 KTS AT 281840Z
   CIMSS AIDT: 36 KTS AT 281840Z
   CIMSS D-MINT: 34 KTS AT 281653Z
   CIMSS D-PRINT: 28 KTS AT 281840Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL
   VWS: 10-15 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: WEAK EQUATORWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   INITIAL INTENSITY: HIGH
   INITIAL WIND RADII: HIGH

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO
THE FORECAST FROM THE PREVIOUS WARNING.

FORECAST DISCUSSION: TS 11W IS FORECASTED TO TRACK TO THE
WEST-NORTHWEST OVER THE NEXT FEW HOURS AND THEN BEGIN TRACKING
GENERALLY TO THE NORTHWEST THROUGHOUT THE REMAINDER OF THE 96 HOUR
FORECAST PERIOD ALONG THE SOUTHWEST PERIPHERY OF A SUBTROPICAL
RIDGE PLACED DIRECTLY TO THE NORTHEAST OVER CENTRAL JAPAN. TS 11W
IS EXPECTED TO REMAIN IN A MARGINAL ENVIRONMENT OVER THE NEXT 24 TO
36 HOURS AS SEA SURFACE TEMPERATURES REMAIN WARM (28-29 C) AND
VERTICAL WIND SHEAR (VWS) REMAINS LESS THAN 20 KTS BEFORE MAKING
LANDFALL SOUTH OF SHANGHAI. BETWEEN TAU 30 AND TAU 36, TS 11W IS
FORECASTED TO MAKE LANDFALL AND BEGIN ITS DISSIPATION PHASE DUE TO
TOPOGRAPHIC INTERACTION UNTIL TAU 96. WITH REGARD TO INTENSITY, TS
CO-MAY IS EXPECTED TO MAINTAIN 35 KTS THROUGH THE AFOREMENTIONED
MARGINAL ENVIRONMENT UNTIL LAND INTERACTION BEGINS WEAKENING THE
SYSTEM TO 30 KTS BY TAU 48, AND COMPLETE DISSIPATION TO 20 KTS BY
TAU 96. 

MODEL DISCUSSION: NUMERICAL WEATHER PREDICTION (NWP) GUIDANCE IS IN
GOOD AGREEMENT THROUGHOUT THE INITIAL 30 HOURS OF THE FORECAST
PERIOD, WITH JUST A 39 NM CROSS-TRACK RIGHT BEFORE LANDFALL NEAR
TAU 30. AFTER THE SYSTEM MAKES LANDFALL, TRACK SOLUTIONS WITHIN THE
CONSENSUS BEGIN TO DIVERGE JUST AFTER TAU 48, WITH THE GFS TRACK
SOLUTION ILLUSTRATING A WESTWARD TRACK, WHILE THE MAJORITY OF THE
JTWC CONSENSUS MEMBERS SHOW A NORTHEAST RE-CURVATURE TOWARD THE
YELLOW SEA. THE JTWC TRACK FORECAST IS PLACED WITH MEDIUM
CONFIDENCE AND ALIGNED CLOSELY TO THE JTWC CONSENSUS. WITH REGARD
TO INTENSITY, MOST INTENSITY CONSENSUS MEMBERS ARE IN AGREEMENT
THAT INTENSITIES WILL CONTINUE NEAR 35 KTS WITH AN EXPECTED
WEAKENING PHASE AT LANDFALL (TAU 30). THE ONLY EXCEPTION IS
COAMPS-TC, SHOWING A GRADUAL INTENSIFICATION PHASE TO 45 KTS BEFORE
LANDFALL, AND A WEAKENING TREND THEREAFTER.

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