WDPN33 PGTW 290900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 11W (CO-MAY) WARNING NR 
026//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 28.1N 124.1E
   INITIAL INTENSITY: 35 KTS
   GEOGRAPHIC REFERENCE: 219 NM WEST-NORTHWEST OF KADENA AB
   MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 09 KTS
   SIGNIFICANT WAVE HEIGHT: 16 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A
WELL-DEFINED, YET SOMEWHAT DISORGANIZED, LOW LEVEL CIRCULATION CENTER 
(LLCC), WHICH IS BEGINNING TO ELONGATE AS IT TRACKS TOWARDS SHANGHAI. 
THE ANIMATED MSI, WHEN COMPARED TO ANIMATED WATER VAPOR IMAGERY AND A
290246Z GMI COLOR-ENHANCED 91GHZ MICROWAVE IMAGE, CLEARLY SHOW A
DECOUPLING OF THE VORTEX, WITH THE MID- TO UPPER-LEVEL VORTEX
POSITIONED NORTHWEST OF THE LLCC DUE TO PERSISTENT SOUTHEASTERLY
SHEAR. THE MSI SHOWS THE LOWER-LEVEL CLOUD LINES TO THE SOUTH OF AN
AREA OF FLARING CONVECTION, AND TRACING OF THESE CLOUD LINES, ALONG
WITH RADAR DATA, PROVIDES HIGH CONFIDENCE TO THE INITIAL POSITION.
THE INITIAL INTENSITY IS ASSESSED WITH MEDIUM CONFIDENCE, PLACED
ROUGHLY AT THE AVERAGE OF THE AVAILABLE OBJECTIVE AND SUBJECTIVE
INTENSITY ESTIMATES NOTED BELOW. EARLIER ASCAT DATA INDICATED
ISOLATED POCKETS OF 35 KNOT WINDS, MOSTLY CONSTRAINED TO THE
NORTHERN HEMISPHERE OF THE SYSTEM. ENVIRONMENTAL CONDITIONS ARE
MARGINAL, WITH RELATIVELY LOW DEEP-LAYER SOUTHERLY SHEAR (HIGHER
MID-LEVEL SHEAR), WARM SSTS EXCEEDING 28C AND  WEAK POLEWARD
OUTFLOW PROVIDED BY AN UPPER-LEVEL TROF OR WEAK LOW OVER EASTERN
CHINA.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: SOUTHWESTERN PERIPHERY OF A DEEP-LAYER
SUBTROPICAL RIDGE (STR) OVER CENTRAL JAPAN. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.0 - 30 KTS
   RJTD: T2.0 - 30 KTS
   RCTP: T2.0 - 30 KTS
   CIMSS SATCON: 37 KTS AT 290516Z
   CIMSS ADT: 35 KTS AT 290540Z
   CIMSS AIDT: 40 KTS AT 290540Z
   CIMSS D-PRINT: 31 KTS AT 290610Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL
   VWS: 10-15 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: WEAK POLEWARD
   OTHER FACTORS: DRY MID-LEVEL AIR TO THE SOUTH. VORTEX
DECOUPLING. 

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: TROPICAL STORM (TS) 11W IS FORECAST TO
CONTINUE TRACKING NORTHWESTWARD ALONG THE SOUTHWESTERN SIDE OF THE
DEEP STR SITUATED OVER THE NORTHERN COAST OF CENTRAL JAPAN THROUGH
THE FORECAST PERIOD. LANDFALL IN THE VICINITY OF SHANGHAI IS
ANTICIPATED SHORTLY AFTER TAU 24, AND THEREAFTER THE RAPIDLY
WEAKENING REMNANTS OF TS 11W WILL CONTINUE TRACKING NORTHWESTWARD
SLOWLY, ULTIMATELY COMING TO REST NEAR TAIHU LAKE BY THE END OF THE
FORECAST PERIOD. IN TERMS OF INTENSITY, WHILE CONDITIONS ARE NOT
FAVORABLE SIGNIFICANT INTENSIFICATION, SOME LEVEL OF MINOR
INTENSIFICATION IS LIKELY AS THE SYSTEM APPROACHES THE COASTLINE,
WITH A PEAK INTENSITY OF 40 KNOTS ANTICIPATED AT LANDFALL. ONCE THE
SYSTEM IS ASHORE, IT WILL WEAKEN RELATIVELY QUICKLY OVER LAND,
DISSIPATING AS A TROPICAL CYCLONE NEAR TAIHU LAKE BY TAU 72. THE
REMNANT VORTEX ASSOCIATED WITH THE REMNANTS OF TS 11W MAY MOVE BACK
OVER THE YELLOW SEA AFTER TAU 96 BUT AT THIS TIME, ARE NOT EXPECTED
TO REDEVELOP. 

MODEL DISCUSSION: DETERMINISTIC TRACK GUIDANCE IS IN GOOD AGREEMENT
ON THE OVERALL TRACK THROUGH TAU 48, WITH MINIMAL ALONG- OR
CROSS-TRACK UNCERTAINTY. AFTER TAU 48, AS MODELS BEGIN TO LOSE THE
VORTEX, TRACK SPREAD STARTS TO INCREASE SHARPLY, THOUGH THE BULK OF
THE GUIDANCE SUPPORTS A SLOWING OF TRACK SPEED AND A SLOW TURN TO
THE NORTHEAST. THE JTWC FORECAST IS POSITIONED NEAR THE MULTI-MODEL
CONSENSUS MEAN THROUGH THE FORECAST PERIOD WITH HIGH CONFIDENCE.
INTENSITY GUIDANCE IS ALSO IN GOOD AGREEMENT, SUPPORTING A SLIGHT
INTENSIFICATION PRIOR TO LANDFALL, FOLLOWED BY RAPID WEAKENING TO
DISSIPATION BY TAU 72. 

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