WDPN33 PGTW 041500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 10W (HAIKUI) WARNING NR
029//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 23.6N 118.5E
   INITIAL INTENSITY: 50 KTS
   GEOGRAPHIC REFERENCE: 187 NM WEST-SOUTHWEST OF TAIPEI, TAIWAN
   MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 08 KTS
   SIGNIFICANT WAVE HEIGHT: 18 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A SYSTEM
THAT IS STRUGGLING TO SURVIVE. AFTER MOVING AWAY FROM THE COAST OF
TAIWAN AND INTO THE RELATIVELY OPEN WATERS OF THE TAIWAN STRAIT,
THE STRUCTURE OF TROPICAL STORM (TS) 10W (HAIKUI) HAS BECOME
INCREASINGLY DISORGANIZED. ANIMATED RADAR IMAGERY SHOWED A CLEAR
CUT CENTER SIX HOURS AGO, BUT THAT HAS NOW ERODED TO THE POINT
WHERE IT IS DIFFICULT TO LOCATE. LIKEWISE IN THE BEST AVAILABLE
PROXY VISIBLE SATELLITE IMAGERY. HINTS OF A POSSIBLE LOW LEVEL
CIRCULATION CENTER (LLCC) ARE PEAKING OUT FROM UNDER CONVECTIVE
DEBRIS IN THE PROXY VISIBLE IMAGERY BUT DO NOT PROVIDE ENOUGH
EVIDENCE FOR A HIGH CONFIDENCE POSITION ASSESSMENT. THE MOST RECENT
MICROWAVE IMAGE WAS FROM 040937Z AND SHOWED A SHARPLY TILTED VORTEX
WITH THE LOW-LEVEL ROTATION HANGING BACK WHILE THE UPPER-LEVELS
MOVED QUICKLY OFF TO THE WEST. THUS, THE INITIAL POSITION IS
ASSESSED WITH LOW CONFIDENCE. LIKEWISE, THE INITIAL INTENSITY, WHICH
IS SET LOWER THAN THE AGENCY CURRENT INTENSITY ESTIMATES, MORE IN
LINE WITH THE 47 KNOT ADT VALUE. AGENCY DATA-T VALUES HAVE DROPPED
TO T2.5. THE ENVIRONMENT REMAINS FAVORABLE OVERALL, BUT THE SYSTEM
DOES NOT HAVE ENOUGH TIME REMAINING OVER WATER TO RECOVER FROM THE
TERRAIN INDUCED DISRUPTIONS FROM TAIWAN AND WILL IN ANY COURSE
BEGIN TO BE DISRUPTED BY TERRAIN INFLUENCES FROM THE CHINESE COAST
IN SHORT ORDER.

INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK

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

AGENCY DVORAK AND AUTOMATED FIXES:
   PGTW: T3.5 - 55 KTS
   RJTD: T3.5 - 55 KTS
   RCTP: T3.0 - 45 KTS
   KNES: T3.5 - 55 KTS
   CIMSS ADT: 47 KTS AT 041130Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 5-10 KTS
   SST: 27-28 CELSIUS
   OUTFLOW: MODERATE WESTWARD
   OTHER FACTORS: FRICTIONAL EFFECTS FROM TERRAIN TO THE WEST.

ANALYSIS CONFIDENCE:
   INITIAL POSITION: LOW
   INITIAL INTENSITY: LOW
   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 SLOWLY
TO THE WEST-NORTHWEST ALONG THE SOUTHWEST SIDE OF THE STEERING
RIDGE FOR THE NEXT 12 TO 18 HOURS. UNCERTAINTY IN THE INITIAL
POSITION AND THUS TRACK SPEED, LEADS TO RELATIVELY LOW CONFIDENCE
IN THE TIMING OF THE EXPECTED LANDFALL ALONG THE CHINESE COAST,
THOUGHT STILL EXPECTED WITHIN THE NEXT 12 HOURS. THE SYSTEM IS NOT
LIKELY TO BE ABLE TO INTENSIFY IN THE TIGHT CONFINES OF THE TAIWAN
STRAIT, FOR WHILE ENVIRONMENTAL CONDITIONS REMAIN CONDUCIVE,
DISRUPTION OF THE LOW-LEVEL INFLOW AND VORTEX TILT WILL INHIBIT
CONSOLIDATION OF THE INNER CORE AND CONVECTIVE ORGANIZATION. THE
SYSTEM WILL MAKE LANDFALL AS A WEAK TROPICAL STORM, BETWEEN 40-45
KNOTS. AFTER LANDFALL, THE SYSTEM WILL TURN TOWARDS THE WEST AS A
STRONG, DEEP-LAYER ANTICYCLONE DEVELOPS OVER CENTRAL CHINA AND
ASSUMES THE STEERING ROLE. FRICTIONAL EFFECTS WILL STEADILY WEAKEN
THE REMNANTS OF TS 10W THROUGH THE FORECAST, WITH DISSIPATION
EXPECTED NO LATER THAN TAU 48 TO THE NORTH OF GUANGZHOU.

MODEL DISCUSSION: DETERMINISTIC TRACK GUIDANCE IS IN GOOD
AGREEMENT, WITH THE RELIABLE GUIDANCE CONFINED TO A 80NM TRACK
ENVELOPE AT TAU 48, LENDING HIGH CONFIDENCE TO THE JTWC FORECAST.
INTENSITY GUIDANCE IS ALSO IN GOOD AGREEMENT THAT THE SYSTEM WILL
RAPIDLY WEAKEN AFTER LANDFALL AND DISSIPATE BY TAU 48.

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