WDPN33 PGTW 300900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 11W (CO-MAY) WARNING NR 
030//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 30.7N 121.8E
   INITIAL INTENSITY: 40 KTS
   GEOGRAPHIC REFERENCE: 34 NM SOUTH-SOUTHEAST OF SHANGHAI, CHINA
   MOVEMENT PAST 6 HOURS: NORTH-NORTHWESTWARD AT 08 KTS
   SIGNIFICANT WAVE HEIGHT: 20 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS RAGGED CLOUD
BANDING WRAPPING TIGHTLY INTO THE PARTIALLY EXPOSED LOW-LEVEL
CIRCULATION CENTER (LLCC). WARMING CLOUD TOPS ON ANIMATED ENHANCED
INFRARED IMAGERY REINFORCES THE WEAKENING STRUCTURE AS THE SYSTEM
APPROACHES THE COAST OF CHINA. THE INITIAL POSITION IS PLACED WITH
HIGH CONFIDENCE BASED ON THE AFOREMENTIONED ANIMATED MSI A 300700Z
F-18 DMSP SSMIS 37GHZ MICROWAVE IMAGE REVEALS THE BROADENING
LOW-LEVEL STRUCTURE. THE 91GHZ VERSION OF THE SSMIS IMAGE DEPICTS
WEAK AND BROAD UPPER-LEVEL BANDING. THE INITIAL INTENSITY OF 40 KTS
IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON THE AGENCY AND
OBJECTIVE FIXES LISTED BELOW.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: A SUBTROPICAL RIDGE OVER JAPAN

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.5 - 35 KTS
   RJTD: T2.0 - 30 KTS
   RCTP: T2.0 - 30 KTS
   KNES: T2.5 - 35 KTS
   CIMSS SATCON: 48 KTS AT 300524Z
   CIMSS ADT: 39 KTS AT 300530Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: UNFAVORABLE
   VWS: 15-20 KTS
   SST: 27-28 CELSIUS
   OUTFLOW: WEAK POLEWARD

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TROPICAL STORM (TS) 11W WILL TRACK
NORTHWESTWARD ON THE SOUTHEASTERN PERIPHERY OF THE SUBTROPICAL
RIDGE OVER JAPAN. THE SYSTEM IS ANTICIPATED TO MAKE LANDFALL WITHIN
THE NEXT 12 HOURS. WEAKENING WILL OCCUR AFTER LANDFALL DUE TO
TOPOGRAPHIC INTERACTION AND AN INCREASE OF VERTICAL WIND SHEAR
ASSOCIATED WITH A TROUGH TO THE NORTH. AFTER THE SYSTEM DISSIPATES
AT TAU 36 THE TRACK IS UNCERTAIN, BUT IT IS POSSIBLE THAT THE
REMNANTS MAY PASS INTO THE YELLOW SEA, BUT THE CONDITIONS WILL NOT
BE FAVORABLE FOR REDEVELOPMENT. 

MODEL DISCUSSION: DETERMINISTIC MODEL GUIDANCE IS IN GOOD AGREEMENT
THROUGH THE NEXT 36 HOURS WITH A CROSS-TRACK SPREAD OF 70NM. AFTER
TAU 36, THE VORTEX TRACKERS STRUGGLE TO TRACK THE SHALLOWING SYSTEM
AND THE JTWC GUIDANCE BIFURCATES, LEADING TO LOW CONFIDENCE IN THE
TRACK BEYOND THE FORECAST PERIOD. THE INTENSITY GUIDANCE IS
CONFIDENT THAT SIGNIFICANT WEAKENING WILL LEAD TO DISSIPATION BY
TAU 36.

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