WDPN33 PGTW 030900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 10W (HAIKUI) WARNING NR 024//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 22.9N 121.5E
   INITIAL INTENSITY: 105 KTS
   GEOGRAPHIC REFERENCE: 132 NM SOUTH OF TAIPEI, TAIWAN
   MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 10 KTS
   SIGNIFICANT WAVE HEIGHT: 42 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI), ANIMATED RADAR DATA
AND SURFACE OBSERVATIONS INDICATE THAT TYPHOON (TY) 10W (HAIKUI) IS
IN THE PROCESS OF MAKING LANDFALL ALONG THE EAST COAST OF TAIWAN,
IN THE VICINITY OF CHENGGONG, AS OF THE 1800Z HOUR. THE INITIAL
POSITION WAS SET WITH HIGH CONFIDENCE BASED ON THE 15NM EYE FEATURE
IN THE RADAR DATA, AS WELL AS AN EXTRAPOLATION OF A MICROWAVE EYE
EVIDENT IN THE 030454Z AMSR2 37GHZ IMAGE. THE RADAR DATA AND
MICROWAVE IMAGE SHOW THAT THE STRONGEST CONVECTION AND WINDS ARE IN
THE SOUTHERN PORTION OF THE EYEWALL, WHILE THE NORTHWESTERN EYEWALL
REMAINS PERSISTENTLY WEAKER. THE INITIAL INTENSITY OF 105 KNOTS WAS
ASSESSED WITH HIGH CONFIDENCE BASED ON THE AVERAGE OF THE AGENCY
DVORAK INTENSITY ESTIMATES AND SURFACE OBSERVATIONS FROM LUDAO
ISLAND AS THE SOUTHERN EYEWALL PASSED OVER THE STATION. THE OVERALL
STEERING PATTERN REMAINS FIRMLY IN PLACE, MOVING THE SYSTEM
WESTWARD ALONG THE SOUTHERN SIDE OF A DEEP-LAYER SUBTROPICAL RIDGE
(STR) TO THE NORTH. HOWEVER, LOCALIZED TERRAIN EFFECTS WILL PLAY A
LARGER ROLE IN THE STEERING FOR THE NEXT 12 TO 18 HOURS. IN THE
AGGREGATE, THE ENVIRONMENT REMAINS FAVORABLE, WITH EXPANDING RADIAL
OUTFLOW AND LOW VERTICAL WIND SHEAR THOUGH IT IS STRONGLY MITIGATED
BY THE MALIGN IMPACTS OF THE TERRAIN, LEADING TO A MARGINALLY
UNFAVORABLE ASSESSMENT OVERALL.

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: T6.0 - 115 KTS
   RJTD: T5.5 - 102 KTS
   RCTP: T6.0 - 115 KTS
   KNES: T5.5 - 102 KTS
   CIMSS SATCON: 103 KTS AT 030432Z
   CIMSS ADT: 97 KTS AT 030530Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY
UNFAVORABLE
   VWS: 5-10 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: STRONG RADIAL
   OTHER FACTORS: TERRAIN IMPACTS 

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: THE LATEST RADAR DATA SUGGESTS THAT AS THE
WESTERN PORTION OF THE EYE HAS MOVED ASHORE AND SLAMMED INTO THE
HIGH ELEVATION MOUNTAINS, IT HAS COME TO A STOP AND HAS AS OF THE
1900Z HOUR FAILED TO FULLY CROSS THE COASTLINE. THE SYSTEM WILL
LIKELY STAGNATE FOR A BIT NEAR ITS PRESENT LOCATION, BEFORE TURNING
SOUTHWESTWARD ALONG THE AXIS OF THE TERRAIN. BY TAU 12 IT SHOULD
ROUND THE SOUTHERN PORTION OF THE MOUNTAINS AND EMERGE INTO THE
TAIWAN STRAIT IN THE VICINITY OF KAOHSIUNG. ONCE BACK OVER WATER,
THE STEERING INFLUENCE DEEP STR TO THE NORTH WILL PUSH THE SYSTEM
BACK ONTO A WEST-NORTHWESTWARD TRACK. A SECOND LANDFALL ALONG THE
COAST OF FUJIAN PROVINCE, CHINA, IS EXPECTED AROUND TAU 36. AROUND
TAU 72, AN IMPRESSIVE, DEEP-LAYER RIDGE IS FORECAST TO DEVELOP TO
THE NORTH AND WEST OF TY 10W, WHICH WILL PUSH THE WEAKENING SYSTEM
ONTO A WEST, THEN SOUTHWEST TRACK AFTER TAU 72. IN TERMS OF
INTENSITY, THE HIGH AND RUGGED TERRAIN OF TAIWAN WILL SHRED THE
SYSTEM APART OVER THE NEXT 12 HOURS, AND AT BEST, THE SYSTEM WILL
EMERGE INTO THE TAIWAN STRAIT AS A MINIMAL TYPHOON. ONCE BACK OVER
WATER, CONDITIONS ARE GENERALLY FAVORABLE, BUT THE MINIMAL TIME
OVER THE STRAIT WILL HINDER ANY SIGNIFICANT INTENSIFICATION.
LANDFALL AS A STRONG TROPICAL STORM, OR POTENTIALLY A WEAK TYPHOON,
IS ANTICIPATED NEAR TAU 36. AFTER THE SECOND LANDFALL, THE SYSTEM
WILL RAPIDLY WEAKEN AND ULTIMATELY DISSIPATE OVER SOUTHEASTERN
CHINA NO LATER THAN TAU 120. 

MODEL DISCUSSION: DETERMINISTIC TRACK GUIDANCE IS IN GOOD
AGREEMENT, AT LEAST THROUGH TAU 72, WITH A TRACK INTO THE SOUTHERN
TAIWAN STRAIT BY TAU 12, AND A TRACK INTO SOUTHEASTERN CHINA
THEREAFTER, WITH AN 85NM SPREAD AT LANDFALL. AFTER TAU 72, SEVERAL
MODELS BEGIN TO SPLIT OFF FROM THE PACK INCLUDING THE GFS, GEFS
ENSEMBLE AND THE HAFS-A. THE HAFS-A TURNS THE SYSTEM SHARPLY BACK
TO THE EAST AT TAU 72, THEN SHARPLY NORTHEAST PARALLEL THE WEST
COAST OF TAIWAN THROUGH TAU 120. THE GFS MEANWHILE TAKES THE SYSTEM
BACK OVER THE SOUTH CHINA SEA TO THE SOUTH OF HONG KONG BY THE SAME
TIME AND THE GEFS ENSEMBLE MOVES INTO THE EASTERN PORTION OF THE
SOUTH CHINA SEA. THE REMAINDER OF THE GUIDANCE CONTINUES THE TRACK
INTO SOUTHERN CHINA TO THE NORTH OF HONG KONG. THE JTWC FORECAST
HEDGES TOWARDS THE CONSENSUS MEAN AND THE GFS SOLUTION AFTER TAU
96, WITH MEDIUM CONFIDENCE IN THE LATER TAUS. INTENSITY GUIDANCE IS
IN GOOD AGREEMENT THAT THE SYSTEM WILL RAPIDLY WEAKEN THROUGH TAU
12, THEN MORE SLOWLY WEAKEN THROUGH THE SECOND LANDFALL, FOLLOWED
BY A SLOW WEAKENING TO DISSIPATION BY TAU 120. 

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