WDPN32 PGTW 291500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 23W (KONG-REY) WARNING NR 019//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 18.5N 126.1E
   INITIAL INTENSITY: 115 KTS
   GEOGRAPHIC REFERENCE: 472 NM SOUTHEAST OF TAIPEI, TAIWAN
   MOVEMENT PAST 6 HOURS: NORTH-NORTHWESTWARD AT 08 KTS
   SIGNIFICANT WAVE HEIGHT: 46 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A STILL
SOMEWHAT RAGGED EYE FEATURE, THOUGH THE EYE TEMPERATURE HAS
CONTINUED TO WARM AND IS NOW APPROACHING 3 DEG C, INDICATIVE OF THE
INCREASING SUBSIDENCE AND CLEARING OUT OF THE EYE. AT THE SAME
TIME, THE EYE HAS SHRUNK, FROM AN ARCHER ESTIMATED 42NM AT 291013Z,
TO APPROXIMATELY 30NM AT ANALYSIS TIME. A 291013Z GMI 89GHZ
MICROWAVE IMAGE SHOWED A SOLID EYEWALL COMPLETELY SURROUNDING THE
BROAD EYE, WITH WELL-DEFINED SPIRAL BANDS OF DEEP CONVECTION
WRAPPING INTO THE CENTER. THE MICROWAVE IMAGE ALSO SHOWED A MOAT OF
DRY AIR SEPARATING THE EYEWALL FROM A SPIRAL BAND TO THE SOUTHEAST,
SUGGESTING THE EARLY PHASE OF SECONDARY EYEWALL FORMATION (SEF), 
THOUGH THE CIMSS M-PERC PRODUCT ONLY INDICATES A 26 PERCENT CHANCE OF 
AN EYEWALL REPLACEMENT CYCLE (ERC). THE EXTENT OF THE COLDEST CLOUD 
TOPS HAS SHRUNK A GOOD AMOUNT, ESPECIALLY ON THE EASTERN SIDE OF THE 
CIRRUS SHIELD, WHILE THE NORTHERN SIDE HAS ERODED SIGNIFICANTLY WITH 
MUCH LESS CONVECTION THAN SEEN EARLIER. THIS IS LIKELY A REFLECTION OF 
THE DRY AIR MOAT SEEN IN THE MICROWAVE IMAGERY AND THE POSSIBLE START 
OF SEF OR ERC. THE INITIAL POSITION IS ASSESSED WITH HIGH
CONFIDENCE BASED ON AN EXTRAPOLATION OF THE MICROWAVE EYE AND
PLACED IN THE CENTER OF THE EYE IN THE EIR. THE INITIAL INTENSITY
IS ASSESSED WITH HIGH CONFIDENCE, PLACED AT THE AVERAGE OF THE
AGENCY INTENSITY ESTIMATES RANGING FROM T5.5 TO T6.5, AND
CONSISTENT WITH THE BULK OF THE OBJECTIVE ESTIMATES NOTED BELOW. OF
NOTE, THE RAW ADT VALUE AT 1200Z WAS T7.0 (140 KNOTS).
ADDITIONALLY, A 290944Z RCM-2 PARTIAL SAR PASS REVEALED 109 KNOT
MAXIMUM WINDS IN THE SOUTHWESTERN QUADRANT, PROVIDING ADDITIONAL
CONFIDENCE TO THE INITIAL INTENSITY ESTIMATE. THE SYSTEM REMAINS
FIRMLY ENTRENCHED IN FAVORABLE ENVIRONMENT, WITH WARM SSTS, HIGH
OHC, ROBUST RADIAL OUTFLOW ENHANCED BY A DEVELOPING POLEWARD
OUTFLOW CHANNEL AND LOW EASTERLY VWS.

INITIAL WIND RADII BASIS: PERSISTENCE 

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

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T6.5 - 127 KTS
   RJTD: T5.5 - 102 KTS
   RCTP: T6.5 - 127 KTS
   KNES: T6.0 - 115 KTS
   CIMSS ADT: 125 KTS AT 291200Z
   CIMSS AIDT: 115 KTS AT 291200Z
   CIMSS DPRINT: 114 KTS AT 291200Z
   CIMSS DMINT: 111 KTS AT 291013Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: HIGHLY FAVORABLE
   VWS: 5-10 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: STRONG RADIAL
   OTHER FACTORS: ENHANCED POLEWARD OUTFLOW CHANNEL.

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TYPHOON 23W IS FORECAST TO CONTINUE TRACKING
NORTHWESTWARD ALONG THE SOUTHWESTERN PERIPHERY OF THE DEEP STR FOR
THE NEXT 48 HOURS. LANDFALL ALONG THE SOUTHEASTERN COAST OF TAIWAN
IS EXPECTED BETWEEN TAU 36 AND TAU 48. LARGE DEVIATIONS IN THE
EXACT LOCATION AND TIMING OF LANDFALL CAN BE EXPECTED DUE TO
ERRATIC TRACK MOTION THAT IS LIKELY TO OCCUR AS THE SYSTEM
APPROACHES THE COAST OF TAIWAN. BY TAU 48 HOWEVER, THE CENTRAL
VORTEX OF TY 23W IS FORECAST TO HAVE CROSSED THE CENTRAL MOUNTAIN
RANGE (CMR) AND LIE CLOSE TO THE WESTERN COAST OF TAIWAN. SHORTLY
AFTER MOVING BACK OVER WATER IN THE TAIWAN STRAIT, THE SYSTEM WILL
BEGIN TO ROUND THE AXIS OF THE STR AND BEGIN TRACKING NORTHWARD
TOWARDS THE EASTERN COAST OF CHINA. THE CURRENT FORECAST CALLS FOR
THE CENTER OF TY 23W TO SKIRT THE EASTERN COAST OF CHINA, BUT A
FURTHER PENETRATION INLAND IS POSSIBLE DEPENDING ON THE STRENGTH
AND ORIENTATION OF THE STR. TY 23W IS FORECAST TO REEMERGE OVER THE
EAST CHINA SEA (ECS) TO THE SOUTH OF SHANGHAI AROUND TAU 72, AND
BEGIN ACCELERATING NORTHEASTWARD ALONG A REMNANT FRONTAL BOUNDARY
THAT WILL BE DRAPED ACROSS JAPAN AND INTO THE ECS. BY TAU 96, THE
SYSTEM WILL CROSS OVER KYUSHU, THEN SKIRT THE SOUTHERN COAST OF
SHIKOKU AND HONSHU AND PUSH RAPIDLY INTO THE NORTHWEST PACIFIC BY
THE END OF THE FORECAST. IN TERMS OF INTENSITY, THE SYSTEM IS
FORECAST TO CONTINUE INTENSIFYING FOR THE NEXT 12 HOURS, REACHING
130 KNOTS BY TAU 12. A POSSIBLE ERC, LOWERED SSTS AND REDUCED OHC
WILL LEAD TO A GENERAL WEAKENING TREND PRIOR TO LANDFALL, THOUGH
THE SYSTEM WILL STILL REMAIN A POWERFUL TYPHOON AS IT APPROACHES
THE COAST OF TAIWAN. PASSAGE OVER THE CMR WILL SHRED THE SYSTEM
FROM BELOW, WITH A MINIMAL TYPHOON, OR EVEN STRONG TROPICAL STORM,
EMERGING BACK OVER WATER. ONCE PASSING OVER THE TAIWAN STRAIT, THE
SYSTEM WILL UNDERGO ADDITIONAL WEAKENING AS IT WILL START TO
SUCCUMB TO RAPIDLY INCREASING SHEAR AND SIGNIFICANT DRY AIR
ENTRAINMENT. SHEAR IS FORECAST TO EXCEED 30 KNOTS AS THE SYSTEM
MOVES INTO THE ECS AND BEGINS EXTRATROPICAL TRANSITION (ETT). ETT
IS LIKELY TO BE COMPLETED AS EARLY AS TAU 96 AS THE SYSTEM IS
ENGULFED IN DRY AIR, DEVELOPS THERMAL ADVECTION, AND MOVES UNDER THE
STRONG MID-LATITUDE JET STREAM. BAROCLINIC FORCING WILL KEEP
SURFACE WINDS STRONG AS THE EXTRATROPICAL LOW PASSES SOUTH OF
HONSHU, WITH POST-PASSAGE NORTHERLY WINDS BEING PARTICULARLY STRONG
DUE TO TERRAIN FUNNELING.  

MODEL DISCUSSION: DETERMINISTIC TRACK GUIDANCE IS IN GOOD AGREEMENT
THROUGH LANDFALL, AND IN FAIR AGREEMENT THROUGH TAU 72. CROSS-TRACK
SPREAD AT LANDFALL IS JUST 50NM. CROSS-TRACK SPREAD INCREASES TO
175NM BY TAU 72 AS THE MODELS DIFFER IN THE IMPACT THE TERRAIN WILL
HAVE ON BOTH THE TRACK DIRECTION AND THE TRACK SPEED. HOWEVER, ALL
OF THE CONSENSUS MODELS AGREE THAT THE SYSTEM WILL BEGIN TO ROUND
THE RIDGE AXIS AND TURN NORTH, THEN NORTHEASTWARD BETWEEN TAU 48
AND 72. AFTER TAU 72, THE MODELS QUICKLY DIVERGE, PARTICULARLY IN
THE ALONG-TRACK DIRECTION, WITH THE SPREAD OPENING UP TO 820NM BY
TAU 120, BETWEEN THE GEFS ENSEMBLE MEAN (SLOW) AND UKMET ENSEMBLE
MEAN (FAST). THE JTWC FORECAST LIES IN THE CENTER OF THE PACK
THROUGH LANDFALL, THEN MOST CLOSELY FOLLOWS THE GFS DETERMINISTIC
TRACKER WITH HIGH CONFIDENCE THROUGH TAU 72 AND LOW THEREAFTER.
INTENSITY GUIDANCE IS ALSO IN FAIRLY GOOD AGREEMENT, THOUGH THE
HAFS-A IS A SIGNIFICANT OUTLIER, EVIDENTLY PICKING UP ON AN ERC
AND SHOWING ABOUT 15 KNOTS OF WEAKENING BEFORE REGAINING SOME
INTENSITY AFTER TAU 12. THE REMAINDER OF THE MESOSCALE GUIDANCE
SHOWS INTENSIFICATION TO 125-130 KNOTS THROUGH TAU 12 TO TAU 24,
FOLLOWED BY RAPID WEAKENING THROUGH TAU 96 FOLLOWED BY A
STEADY-STATE INTENSITY AS THE SYSTEM COMPLETES ETT. THE JTWC
FORECAST IS CONSISTENT WITH THE HWRF THROUGH THE ENTIRE FORECAST,
WITH MEDIUM CONFIDENCE. 

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