WDPN33 PGTW 040900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 10W (HAIKUI) WARNING NR 
028//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 23.2N 119.3E
   INITIAL INTENSITY: 60 KTS
   GEOGRAPHIC REFERENCE: 166 NM SOUTHWEST OF TAIPEI, TAIWAN
   MOVEMENT PAST 6 HOURS: WESTWARD AT 05 KTS
   SIGNIFICANT WAVE HEIGHT: 21 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) AND RADAR DATA SHOWS
THAT OVER THE PAST 12 HOURS, TROPICAL STORM (TS) 10W (HAIKUI) HAS
TRACED AN IRREGULAR TRACK, FIRST DIPPING SOUTHWEST OF KAOHSIUNG,
THEN TURNING SHARPLY NORTH PARALLEL TO THE SOUTHWEST COAST OF
TAIWAN, BEFORE FINALLY TURNING WEST TOWARDS PENGHU COUNTY. THE
ANIMATED MSI, RADAR AND DATA AND A 040537Z AMSR2 MICROWAVE SERIES
INDICATED THE LOW LEVEL CIRCULATION CENTER (LLCC) WAS LOCATED IN
THE VICINITY OF QIMEI ISLAND, MOVING SLOWLY TOWARDS THE WEST. THE
RADAR AND MICROWAVE IMAGERY SHOW A FAIRLY ROBUST CONVECTION ACROSS
THE SOUTHERN PERIPHERY, AN EYEWALL-LIKE FEATURE IN THE RADAR
IMAGERY, WITH THE REMAINDER OF THE CIRCULATION BEING DEVOID OF
SIGNIFICANT CONVECTIVE ACTIVITY. THE MOST RECENT MSI SHOWS A BURST
OF DEEP CONVECTION PUSHING TO THE EAST SIDE OF THE LLCC, AND MORE
DEEP CONVECTION FIRING OFF TO THE NORTH AND NORTHEAST. NOW THAT THE
SYSTEM HAS MOVED INTO MORE OPEN WATERS, THE FRICTIONAL EFFECTS AND
LAND AND THE INGESTION OF DOWNSLOPE FLOW ARE EASING, ALLOWING FOR A
BURST IN CONVECTION AND ORGANIZATION. THE INITIAL INTENSITY IS
ASSESSED WITH MEDIUM CONFIDENCE, SLIGHTLY LOWER THAN THE AGENCY
DVORAK CURRENT INTENSITY ESTIMATES IN LIGHT OF THE LOWER DATA-T
VALUES AND SIGNIFICANTLY LOWER OBJECTIVE ESTIMATES. ENVIRONMENTAL
CONDITIONS ARE GENERALLY FAVORABLE, WITH WARM SSTS, MODEST RADIAL
OUTFLOW AND LOW TO MODERATE EASTERLY SHEAR. THE SYSTEM IS NOW
TRACKING TO THE WEST-NORTHWEST ALONG THE SOUTHWESTERN PERIPHERY OF
A SUBTROPICAL RIDGE (STR) CENTERED SOUTH OF CHEJU DO.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: SOUTHWEST PERIPHERY OF A DEEP-LAYER STR
TO THE NORTHEAST. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.0 - 65 KTS
   RJTD: T4.0 - 65 KTS
   RCTP: T3.5 - 55 KTS
   KNES: T4.0 - 65 KTS
   CIMSS SATCON: 51 KTS AT 040524Z
   CIMSS ADT: 53 KTS AT 040530Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 10-15 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: MODERATE RADIAL
   OTHER FACTORS: PROXIMITY TO LAND. 

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: TS 10W IS FORECAST TO CONTINUE TRACKING
TOWARDS THE WEST-NORTHWEST ALONG THE SOUTHWESTERN SIDE OF THE
STEERING RIDGE, FOR THE NEXT 24 HOURS. LANDFALL IS EXPECTED AROUND
TAU 18 ALONG THE SOUTHEASTERN COAST OF CHINA, IN FAR SOUTHERN
FUJIAN PROVINCE. AFTER THE SYSTEM MOVES INLAND, THE STEERING
INFLUENCE SHIFTS TO A STRONG STR WHICH IS EXPECTED TO DEVELOP OVER
CENTRAL CHINA, WHICH WILL FORCE TS 10W ONTO A MORE
WEST-SOUTHWESTWARD TRACK AFTER TAU 24. IN TERMS OF INTENSITY, THE
SYSTEM IS FORECAST TO CONTINUE TO SLOWLY WEAKEN THROUGH LANDFALL,
THOUGH IF THE RECENT BURST OF CONVECTION CAN SURROUND THE INNER
CORE, IT IS POSSIBLE THE SYSTEM COULD BRIEFLY REINTENSIFY, OR AT
LEAST MAINTAIN ITS CURRENT INTENSITY. REGARDLESS, ONCE ASHORE THE
SYSTEM WILL RAPIDLY WEAKEN AND IS EXPECTED TO DISSIPATE NORTH OF
GUANGZHOU BY TAU 72. 

MODEL DISCUSSION: AVAILABLE TRACK GUIDANCE IS IN GOOD AGREEMENT ON
THE WEST-NORTHWEST TRACK THROUGH LANDFALL FOLLOWED BY A GRADUAL
TURN TO A WEST-SOUTHWEST TRACK AFTER TAU 24. GFS AND THE GEFS
ENSEMBLE REMAIN THE SOUTHERN OUTLIER, POSITIONING THE CENTER NEAR
HONG KONG BY THE END OF THE FORECAST. THE JTWC FORECAST REMAINS
CONSISTENT WITH THE LAST SEVERAL FORECASTS, WITH HIGH CONFIDENCE.
INTENSITY GUIDANCE IS ALSO IN GOOD AGREEMENT THAT THE SYSTEM WILL
WEAKEN SLIGHTLY PRIOR TO LANDFALL, THEN RAPIDLY WEAKEN OVER LAND
THROUGH THE REMAINDER OF THE FORECAST PERIOD. 

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