WDPN33 PGTW 031500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 10W (HAIKUI) WARNING NR 025//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 22.8N 120.2E
   INITIAL INTENSITY: 80 KTS
   GEOGRAPHIC REFERENCE: 155 NM SOUTH-SOUTHWEST OF TAIPEI, TAIWAN
   MOVEMENT PAST 6 HOURS: WESTWARD AT 12 KTS
   SIGNIFICANT WAVE HEIGHT: 34 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
TYPHOON (TY) 10W (HAIKUI) HAS TRAVERSED THE RUGGED CENTRAL MOUNTAIN
RANGE OF TAIWAN, AND ALREADY MOVED BACK OUT OVER WATER ROUGHLY
BETWEEN TAINAN AND KAOHSIUNG BY THE 1200Z HOUR. WHILE THE SYSTEM
HAS BEEN DEGRADED TO SIGNIFICANT DEGREE, THE LOW-LEVEL EYE IS STILL
RELATIVELY INTACT ACCORDING TO RADAR IMAGERY. ANIMATED ENHANCED
INFRARED (EIR) AND SHORTWAVE INFRARED (SWIR) SATELLITE IMAGERY
ALONG WITH A 031201Z GPM SERIES OF MICROWAVE IMAGERY HOWEVER SHOW
THE VORTEX IS TILTED TO THE WEST WITH HEIGHT, WITH AN EIR EYE QUITE
A BIT FURTHER WEST THAN WHERE THE RADAR AND MICROWAVE DATA SHOW IT
TO BE. THIS IS NOT SURPRISING GIVEN THE FACT THAT THE VORTEX WOULD
HAVE BEEN TORN APART WHEN PASSING OVER THE HIGH TERRAIN AS WELL AS
BY THE PRESENCE OF MODERATE EASTERLY SHEAR. THE INITIAL POSITION IS
ASSESSED WITH HIGH CONFIDENCE BASED ON BOTH THE RADAR AND MICROWAVE
EYE FEATURES. THE INITIAL INTENSITY IS SET WITH MEDIUM CONFIDENCE,
BELOW THE OBJECTIVE AND SUBJECTIVE INTENSITY ESTIMATES WHICH RANGE
FROM 85 TO 102 KNOTS, MORE IN LINE WITH THE AGENCY DATA-T NUMBERS
OF T4.5 (77 KNOTS) AND THE RAW ADT OF T4.8. THE ENVIRONMENT REMAINS
OVERALL MARGINALLY FAVORABLE, WITH MODERATE EASTERLY SHEAR AND LAND
INTERACTION TEMPERING THE WARM SSTS AND DECENT RADIAL OUTFLOW.

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: NO CURRENT ESTIMATE
   RJTD: T5.5 - 102 KTS
   RCTP: T5.5 - 102 KTS
   KNES: T5.5 - 102 KTS
   CIMSS SATCON: 98 KTS AT 031201Z
   CIMSS ADT: 92 KTS AT 031200Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 15-20 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: MODERATE RADIAL
   OTHER FACTORS: VORTEX TILT

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: WHILE TY 10W HAS NOW MOVED BACK OVER WATER AND
BEGINS TO TRANSIT AWAY FROM THE COAST OF TAIWAN, IT WILL
STEADY UP ON A MORE WEST-NORTHWEST TRACK UNDER THE STEERING
INFLUENCE OF THE STR TO THE NORTH. A SECOND LANDFALL IS FORECAST
BETWEEN TAU 24 AND TAU 36 ALONG THE COAST OF FAR SOUTHERN FUJIAN
PROVINCE, CHINA. WHILE OVERALL CONDITIONS REMAIN FAVORABLE,
MULTIPLE FACTORS WILL PRECLUDE THE SYSTEM FROM INTENSIFYING; FIRST,
AN INFLUX OF DOWNSLOPE WIND WILL FLOW WEST OFF THE COAST OF TAIWAN
AND INJECT INTO THE NORTHERN PORTION OF THE CIRCULATION THROUGH THE
NEXT FEW HOURS. SECOND, SSTS WHILE WARM, ARE NOT AS WARM AS THOSE
EAST OF TAIWAN AND GET COOLER CLOSER TO THE CHINESE COAST. THIS
REDUCTION IS SST WILL ROB THE SYSTEM OF THE FUEL NEEDED TO
INTENSIFY. LASTLY, THE SYSTEM WILL MOVE INTO AN AREA OF VERY WEAK
UPPER-LEVEL OUTFLOW. THE COMBINATION OF THESE FACTORS WILL
GRADUALLY WEAKEN THE SYSTEM FOR THE DURATION OF ITS REMAINING TIME
OVER WATER WITH LANDFALL EXPECTED AS A MINIMAL TYPHOON. AFTER
LANDFALL, THE SYSTEM SLOWLY TURNS WESTWARD, THEN SOUTHWESTWARD
ALONG THE SOUTHERN SIDE OF A DEVELOPING ANTICYLCONE OVER CENTRAL
CHINA WHILE STEADILY WEAKENING. DISSIPATION OVER LAND TO THE
NORTHWEST OF HONG KONG IS EXPECTED BY TAU 96. 

MODEL DISCUSSION: DETERMINISTIC TRACK GUIDANCE IS IN GOOD
AGREEMENT THROUGH TAU 48, WITH ALL MEMBERS OF THE CONSENSUS
SUPPORTING THE JTWC TRACK WITH A SPREAD OF 65NM AT LANDFALL. AFTER
TAU 48, THE GFS, GEFS ENSEMBLE MEAN AND HAFS-A BREAK OFF THE REST
OF THE PACK AND DRIVE THE SYSTEM SHARPLY SOUTHWESTWARD OR SOUTH. BY
TAU 72, THE GFS TRACKER LIES NEAR HONG KONG, WHILE THE HAFS-A AND
GEFS HAVE STARTED TO TURN THE SYSTEM BACK TOWARDS TAIWAN. THIS
TREND CONTINUES THROUGH TAU 120, WITH THE GFS AND UKMET ENSEMBLE
MOVING THE SYSTEM TO THE EAST OF HAINAN WHILE THE GEFS AND HAFS-A
HAVE MOVED THE SYSTEM FURTHER EAST TOWARDS THE WEST COAST OF
TAIWAN. THE JTWC TRACK LIES CLOSE TO THE CONSENSUS MEAN BUT
DISSIPATES THE SYSTEM OVER LAND PRIOR TO IT REACHING THE COAST.
INTENSITY GUIDANCE IS IN FAIRLY GOOD AGREEMENT, WITH ALL MODELS
SHOWING A GRADUAL DECREASE IN INTENSITY THROUGH LANDFALL, FOLLOWED
BY RAPID WEAKENING AND DISSIPATION THEREAFTER. 

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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