WDPN33 PGTW 301500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 10W (HAIKUI) WARNING NR 
009//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 21.0N 135.1E
   INITIAL INTENSITY: 50 KTS
   GEOGRAPHIC REFERENCE: 519 NM SOUTHEAST OF KADENA AB
   MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 08 KTS
   SIGNIFICANT WAVE HEIGHT: 21 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY SHOWS THAT
TROPICAL STORM (TS) 10W (HAIKUI) CONTINUES TO SLOWLY BUT STEADILY
IMPROVE STRUCTURALLY. VORTICAL HOT TOWERS OF DEEP CONVECTION HAVE
PERSISTED OVER THE PAST SIX HOURS, BUT CONTINUE TO STRUGGLE TO WRAP
UPSHEAR. CONVECTIVE CIRRUS DEBRIS SHROUDS THE LOW LEVEL CIRCULATION
CENTER (LLCC), BUT A 300857Z RCM-3 SAR PASS AND A 301146Z ASCAT-B
PASS DEPICTED A RATHER DISORGANIZED LLCC LOCATED ON THE NORTHERN
EDGE OF THE DEEP CONVECTION. THE INITIAL INTENSITY OF 50 KNOTS IS
ASSESSED WITH HIGH CONFIDENCE, BASED PRIMARILY ON ANALYSIS OF THE
SAR DATA WHICH SHOWED A BROAD REGION OF GALES IN THE NORTHEAST
QUADRANT OF THE CIRCULATION, WITH A COUPLE OF EMBEDDED 50 KNOT
READINGS. AGENCY DVORAK CURRENT INTENSITY ESTIMATES ARE JUST A
SHADE LOWER AT T3.0, WHILE THE ADT, AIDT AND SATCON AGREE ON A 50
KNOT INTENSITY AT ANALYSIS TIME. THE SYSTEM CONTINUES TO TRACK
TOWARDS THE NORTHWEST ALONG THE SOUTHWESTERN PERIPHERY OF A
DEEP-LAYER SUBTROPICAL RIDGE (STR) CENTERED TO THE NORTHEAST.
CONDITIONS REMAIN GENERALLY FAVORABLE NOW THAT THE NORTHERLY SHEAR
HAS BEGUN TO RELAX A BIT. SSTS ARE VERY WARM BUT OUTFLOW REMAINS
WEAK AND RELATIVELY CONSTRAINED TO THE EQUATORWARD DIRECTION.

INITIAL WIND RADII BASIS: SAR AND SCATTEROMETER DATA 

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

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.0 - 45 KTS
   RJTD: T3.5 - 55 KTS
   RCTP: T3.0 - 45 KTS
   KNES: T3.0 - 45 KTS
   CIMSS SATCON: 49 KTS AT 301043Z
   CIMSS ADT: 51 KTS AT 301140Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 5-10 KTS
   SST: 30-31 CELSIUS
   OUTFLOW: WEAK EQUATORWARD

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

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 NORTHWEST ALONG THE SOUTHWEST SIDE OF THE STRONG STR
THROUGH TAU 72. THE SYSTEM IS EXPECTED TO PASS SOUTH OF OKINAWA BY
TAU 48, THEN ENTER THE EAST CHINA SEA AS THE STR BUILDS TOWARDS THE
SOUTHWEST AND LINKS UP WITH A TRANSIENT ANTICYCLONE MOVING EAST
BEHIND A MID-LATITUDE TROUGH. BY TAU 72, ANOTHER, MORE VIGOROUS
TROUGH QUICKLY MOVES IN FROM THE WEST, WILL ERODE THE STEERING
RIDGE AND GENERATE A WEAKNESS IN THE RIDGE PATTERN WHICH WILL
INDUCE TS 10W TO TURN POLEWARD. LANDFALL ALONG THE COAST OF EASTERN
CHINA SOUTH OF SHANGHAI IS EXPECTED NEAR TAU 96, WITH THE SYSTEM
CONTINUING INLAND TO THE WEST OF SHANGHAI THROUGH THE REMAINDER OF
THE FORECAST. IN TERMS OF INTENSITY, WHILE THE SYSTEM HAS REMAINED
TUCKED UNDER THE CONVECTION FOR THE PAST FEW HOURS, THE RECENT
MICROWAVE IMAGERY SUGGESTS AND VERY TILTED AND DISORGANIZED VORTEX
STRUCTURE, WHICH CONTINUES TO INHIBIT SIGNIFICANT INTENSIFICATION.
THE LATEST HAFS-A AND VORTEX-SCALE GFS SHOW THAT THE VORTEX REMAINS
MISALIGNED FOR ANOTHER 36 HOURS BEFORE FINALLY ACHIEVING
SYMMETRIZATION. THUS, THE SYSTEM WILL INTENSIFY AT A VERY SLOW RATE
FOR THE NEXT DAY AND HALF. BUT ONCE IT FINALLY DOES ALIGN, THE
SYSTEM WILL EXPERIENCE A BURST OF INTENSIFICATION, ROUGHLY BETWEEN
TAU 36 AND TAU 60. THE FORECAST CALLS FOR A PEAK OF 90 KNOTS AT TAU
72, BUT THE ACTUAL PEAK WILL LIKELY OCCUR AROUND TAU 60, AT 95-100
KNOTS. A SHARP SST GRADIENT ALONG THE COAST OF CHINA, AND INCREASED
SHEAR WILL LEAD TO A GENERAL WEAKENING TREND PRIOR TO LANDFALL,
WITH ADDITIONAL RAPID WEAKENING DUE TO LAND INTERACTION AFTER THE
SYSTEM GOES FEET DRY. 

MODEL DISCUSSION: THE GUIDANCE ENVELOPE CONTINUES TO SHRINK WITH
EACH MODEL RUN THIS EVENING. THE GFS HAS NOW COME OVER TO THE ECMWF
CAMP IN TERMS OF THE OVERALL RECURVE SCENARIO, BUT REMAINS ON THE
SOUTHERN SIDE OF THE GUIDANCE PACKAGE. THE ECMWF REMAINS VERY
CONSISTENT WITH A TRACK ON THE NORTHERN SIDE OF THE ENVELOPE,
TAKING THE SYSTEM ABOUT 30NM SOUTH OF OKINAWA AND JUST SKIRTING THE
FAR EASTERN COAST OF CHINA EAST OF SHANGHAI. THE NAVGEM NOW IS THE
ONLY TRACK CONSENSUS MEMBER TAKING THE SYSTEM ON A WESTWARD TRACK
NEAR NORTHERN TAIWAN, THOUGH THE MESOSCALE HAFS-A AND COAMPS-TC
ALSO TAKE THIS TRACK, WHICH HAS IMPORTANT RAMIFICATIONS FOR THE
INTENSITY FORECAST. THE JTWC FORECAST REMAINS VERY CONSISTENT WITH
THE LAST FORECAST, AND LIES CLOSE TO THE MULTI-MODEL CONSENSUS MEAN
WITH MEDIUM CONFIDENCE. INTENSITY GUIDANCE IS A MIXED BAG DUE TO
THE FACT THAT THE BULK OF THE MEMBERS CONSIST OF THE MESOSCALE
MODELS, WHICH ARE TO TAKE A TRACK WELL TO THE SOUTH OF THE GLOBAL
MODELS AND THE TRACK CONSENSUS, ESPECIALLY AFTER TAU 48, RIGHT WHEN
THE PEAK INTENSITY IS EXPECTED. THE JTWC FORECAST GENERALLY TRACKS
THE CONSENSUS MEAN TO TAU 48, THEN DEPARTS ON A LOWER INTENSITY
TRAJECTORY THROUGH TAU 72, BELOW THE MOST AGGRESSIVE OF THE
MESOSCALE MODEL PEAKS. FOR THE REASONS OUTLINED ABOVE, CONFIDENCE
IN THE INTENSITY FORECAST IS LOW. 

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