WDPN33 PGTW 290300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 11W (CO-MAY) WARNING NR 
025//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 27.5N 124.6E
   INITIAL INTENSITY: 35 KTS
   GEOGRAPHIC REFERENCE: 181 NM WEST-NORTHWEST OF KADENA AB
   MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 06 KTS
   SIGNIFICANT WAVE HEIGHT: 16 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS TROPICAL
STORM (TS) 11W (CO-MAY) WITH AN EXPOSED LOW-LEVEL CIRCULATION
CENTER (LLCC). THE ASSOCIATED CONVECTION REMAINS RESTRICTED TO THE
CENTERS WESTERN FLANK AND LOOSELY WRAPS INTO THE NORTHERN
SEMICIRCLE. THROUGH ANIMATED VISIBLE IMAGERY, FRAGMENTED LOW-LEVEL
CONVECTIVE CLOUD LINES HAVE BEEN OBSERVED WRAPPING INTO AN
ELONGATED CENTER. ON ANIMATED WATER VAPOR IMAGERY, A WEAK
EQUATORWARD OUTFLOW CHANNEL HAS BEEN OBSERVED, WHICH HAS CONTINUED
SUPPORTING SUSTAINED SURFACE INTENSITIES AT 35 KTS. THE INITIAL
POSITION HAS BEEN PLACED WITH HIGH CONFIDENCE BASED ON THE EXPOSED
LLCC ON ANIMATED VISIBLE SATELLITE IMAGERY. THE INITIAL INTENSITY
HAS BEEN ASSESSED WITH MEDIUM CONFIDENCE BASED ON CIMSS OBJECTIVE
INTENSITY ESTIMATES RANGING BETWEEN 32-43 KTS, AND SUBJECTIVE
AGENCY DVORAK ESTIMATES LISTED BELOW.

INITIAL WIND RADII BASIS: PERSISTENCE 

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

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.0 - 30 KTS
   RJTD: T2.0 - 30 KTS
   RCTP: T2.0 - 30 KTS
   CIMSS ADT: 32 KTS AT 280030Z
   CIMSS AIDT: 39 KTS AT 280030Z
   CIMSS D-MINT: 40 KTS AT 282139Z
   CIMSS D-PRINT: 43 KTS AT 290030Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL
   VWS: 5-10 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: WEAK EQUATORWARD

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

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 CONTINUE TRACKING TO
THE NORTHWEST THROUGHOUT THE REMAINDER OF THE 72 HOUR FORECAST
PERIOD AROUND THE SOUTHWESTERN PERIPHERY OF THE SUBTROPICAL RIDGE
LOCATED DIRECTLY TO THE NORTHEAST. WITH REGARD TO THE NEAR-TERM
FORECAST, TS 11W IS EXPECTED TO REMAIN IN A MARGINAL ENVIRONMENT AS
THE SYSTEM APPROACHES THE COAST OF EASTERN CHINA INTO TAU 30, WHILE
VERTICAL WIND SHEAR (VWS) REMAINS LOW TO MODERATE, SEA SURFACE
TEMPERATURES REMAIN WARM (28-29 C) AND THE SYSTEM RETAINS ITS MOIST
CORE. NEAR TAU 36, TS 11W IS EXPECTED TO MAKE LANDFALL
SOUTH-SOUTHEAST OF SHANGHAI AND BEGIN ITS INITIAL WEAKENING PHASE.
BETWEEN TAU 36 AND TAU 72, TS CO-MAY IS FORECASTED TO CONTINUE ITS
DISSIPATION PHASE DUE TO LAND INTERACTION UNTIL TAU 72. WITH REGARD
TO INTENSITY, TS 11W IS FORECASTED TO SUSTAIN 35 KTS TO 40 KTS 
THROUGH THE INITIAL 30 HOURS OF THE FORECAST PERIOD UNTIL TOPOGRAPHIC
INTERACTION BEGINS WEAKENING THE CYCLONE TO 30 KTS BY TAU 48, AND
COMPLETE DISSIPATION BY TAU 72.

MODEL DISCUSSION: NUMERICAL WEATHER PREDICTION (NWP) GUIDANCE IS IN
GOOD AGREEMENT THROUGH THE INITIAL APPROACH OVER WATER AS THE
SYSTEM NEARS COASTAL AREAS WITH A CROSS-TRACK SPREAD OF 54 NM.
HOWEVER, AFTER THE SYSTEM MAKES LANDFALL, THE CROSS-TRACK SPREAD
INCREASES TO 92 NM NEAR FINAL DISSIPATION. THEREFORE, THE JTWC
TRACK FORECAST WAS PLACED IN CLOSE PROXIMITY TO THE JTWC CONSENSUS
WITH MEDIUM CONFIDENCE THROUGHOUT THE 72 HOUR FORECAST PERIOD. THE
INTENSITY GUIDANCE WAS ALSO ASSESSED WITH MEDIUM CONFIDENCE THROUGH
TAU 72 DUE TO UNCERTAINTIES WITH LAND INTERACTION BETWEEN TAU 30
AND TAU 72. THE ONLY OUTLIER IS COAMPS TC, WHICH ILLUSTRATES AN
INTENSIFICATION PHASE TO 45 KTS BY TAU 36, AND A WEAKENING PHASE
THEREAFTER.

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