WDPN33 PGTW 032100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 10W (HAIKUI) WARNING NR 026//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 22.7N 120.0E
   INITIAL INTENSITY: 75 KTS
   GEOGRAPHIC REFERENCE: 166 NM SOUTH-SOUTHWEST OF TAIPEI, TAIWAN
   MOVEMENT PAST 6 HOURS: WEST-SOUTHWESTWARD AT 02 KTS
   SIGNIFICANT WAVE HEIGHT: 29 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A FULLY
EXPOSED LLCC, LOITERING JUST OFF THE SOUTHWESTERN COAST OF TAIWAN.
A 031751Z ATMS 165GHZ MICROWAVE IMAGE INDICATES A LARGELY UNRAVELED
CONVECTIVE BAND, LOOSELY WRAPPING AROUND THE NORTHERN AND WESTERN
PERIPHERY OF THE LLCC. ANIMATED RADAR IMAGERY FURTHER INDICATES A
WELL DEFINED LOW-MID LEVEL CIRCULATION THAT HAS HAD ITS UPPER
CONVECTION RIPPED OFF AND CARRIED WESTWARD. THE INITIAL POSITION IS
PLACED WITH HIGH CONFIDENCE BASED ON EIR AND ANIMATED RADAR
IMAGERY. THE INITIAL INTENSITY OF 75 KTS IS BASED ON A BULK OF BOTH
DVORAK AND AUTOMATED INTENSITY ESTIMATES INDICATING A RANGE OF
62-77KTS. BOTH THE MAGNITUDE OF THIS RANGE AND THE FACT THAT JTWC
IS TOWARDS THE UPPER ENVELOPE ARE THE REASONS FOR THE INTENSITY
BEING ASSESSED WITH MEDIUM CONFIDENCE.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: SOUTHERN PERIPHERY OF A DEEP-LAYER
SUBTROPICAL RIDGE (STR) TO THE NORTH.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.5 - 77 KTS
   RJTD: T5.0 - 90 KTS
   RCTP: T4.0 - 65 KTS
   KNES: T5.0 - 90 KTS
   CIMSS SATCON: 74 KTS AT 031254Z
   CIMSS ADT: 79 KTS AT 031730Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY
UNFAVORABLE
   VWS: 5-10 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: MODERATE RADIAL
   OTHER FACTORS: CONVECTIVE DECAPITATION FROM PASSING OVER THE
TAIWANESE MOUNTAIN RANGE.

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: TY 10W (HAIKUI) IS FORECAST TO SLOWLY REGAIN
WESTWARD TRACK MOTION OVER THE COMING HOURS AS THE SYSTEM ATTEMPTS
TO REGAIN CONVECTIVE COVER AFTER HAVING BEEN DECAPITATED AS IT
TRANSITED OVER TAIWAN. THROUGH TAU 24, THE SYSTEM IS FORECAST TO
WEAKEN TO AROUND 60KTS, AS THE CURRENTLY EXPOSED CIRCULATION TRACKS
OVER INCREASING COOLER WATERS AND INTO REDUCED OUTFLOW ALOFT. JUST
AFTER TAU 36, 10W WILL MAKE ITS SECOND AND FINAL LANDFALL ALONG THE
COAST OF FAR SOUTHERN FUJIAN PROVINCE, CHINA. THE SYSTEM WILL THEN
TRACK GENERALLY WESTWARD, CONTINUING TO WEAKEN THROUGH TAU 72 AND
EVENTUALLY DISSIPATING BY TAU 96.

MODEL DISCUSSION: NUMERICAL MODELS ARE IN FAIR AGREEMENT WITH A
BULK OF THE GUIDANCE GENERALLY FOLLOWING THE JTWC FORECAST TRACK
THROUGH TAU 48, AFTER WHICH CROSS TRACK SPREADING QUICKLY
ESCALATES. GFS AND UK-MET ENSEMBLE REMAIN DEFIANT, INDICATING A
SHARP EQUATORWARD TRACK SHIFT NEAR TAU 36, UNTIL DISSIPATION BY TAU
120 IN THE SOUTH CHINA SEA. FOR THESE REASONS, THE JTWC TRACK
FORECAST IS PLACED INITIALLY WITH MEDIUM CONFIDENCE AND WITH LOW
CONFIDENCE THERE AFTER. RELIABLE MODEL INTENSITY GUIDANCE IS IN
GOOD AGREEMENT WITH ALL MEMBERS INDICATING A SHARP WEAKENING TREND
THROUGH TAU 48, AFTER WHICH A MORE GRADUAL DECLINE THROUGH
DISSIPATION. FOR THIS REASON, THE JTWC INTENSITY FORECAST IS PLACED
WITH OVERALL MEDIUM CONFIDENCE.

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