WDPN31 PGTW 291500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 02W (MAWAR) WARNING NR 039//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 19.7N 125.6E
   INITIAL INTENSITY: 100 KTS
   GEOGRAPHIC REFERENCE: 426 NM SOUTH-SOUTHWEST OF KADENA AB
   MOVEMENT PAST 6 HOURS: NORTH-NORTHWESTWARD AT 04 KTS
   SIGNIFICANT WAVE HEIGHT: 38 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A
DEGRADED CONVECTIVE APPEARANCE WITH THE NORTHERN SIDE OF THE STORM
IN PARTICULAR SHOWING CLEAR SIGNS OF SIGNIFICANT EROSION OF THE
EYEWALL. A RECENT 290958Z RCM-2 SAR PASS DEPICTED A 25NM WIDE,
WELL-DEFINED LOW-LEVEL EYE STRUCTURE, BUT A COINCIDENT SSMIS 91GHZ
MICROWAVE IMAGERY SHOWED A CLASSIC DOUBLE EYEWALL STRUCTURE, WITH A
WEAK INNER EYEWALL AROUND 30NM OUT FROM THE CENTER, AND A MORE
PRONOUNCED SECONDARY EYEWALL AROUND 50NM OUT. AN ADDITIONAL
STATIONARY BANDING COMPLEX (SBC) WAS PRESENT IN A BROAD ARC
EXTENDING FROM WEST TO SOUTHEAST OF THE LLCC, INDICATIVE OF ANOTHER
POTENTIAL EYEWALL REPLACEMENT CYCLE (ERC) IN THE OFFING. THE
MICROWAVE IMAGERY ALSO SHOWED A PRONOUNCED REGION OF RELATIVELY LOW
BRIGHTNESS TEMPERATURE STRETCHING SOUTHWARD BUT REMAINING OUTSIDE
THE RADIUS OF THE SECONDARY EYEWALL. RECENT SOUNDINGS FROM
ISHIKAGIJIMA REVEAL AND EXTREMELY DRY AIRMASS BETWEEN 850MB
EXTENDING UP TO 500MB, BEING ADVECTED SOUTHWARD, AND THE LEADING
EDGE OF THIS DRY AIR IS LIKELY ALREADY STARTING TO BE INGESTED INTO
THE CIRCULATION OF TY 02W AND ERODING THE NORTHERN SECTIONS OF THE
CORE. ANALYSIS REVEALS A MARGINAL ENVIRONMENT CHARACTERIZED BY WARM
SSTS AND LOW VWS. THE UPPER-LEVEL PATTERN HOWEVER IS SOMEWHAT ODD,
WITH THE CIMSS AMVS SHOWING CYCLONIC DIVERGENT OUTFLOW AT THE 200MB
LEVEL, WITH A BAND OF EASTWARD OUTFLOW SPLITTING OFF JUST SOUTH OF
OKINAWA. RECENT AMSU SOUNDER MEASUREMENTS REVEAL A VERY STRONG WARM
CORE PEAKING AROUND 200MB, EVEN THOUGH THE SYSTEM IS WEAKENING, AND
LIKELY RESULTING IN THE ATYPICAL OUTFLOW PATTERN.

INITIAL WIND RADII BASIS: SCATTEROMETER AND SAR DATA

CURRENT STEERING MECHANISM: WEAK AND COMPETING STEERING PATTERN.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T5.5 - 102 KTS
   RJTD: T5.5 - 102 KTS
   KNES: T5.0 - 90 KTS
   CIMSS SATCON: 97 KTS AT 291142Z
   CIMSS ADT: 94 KTS AT 291130Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL
   VWS: 5-10 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: MODERATE RADIAL
   OTHER FACTORS: DRY AIR INFLUX FROM THE NORTH. 

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TY 02W HAS CONTINUED TO SLOW DOWN AS IT MOVES
INTO A WEAK AND COMPETING STEERING PATTERN, WITH SUBTROPICAL RIDGES
(STR) CENTERED OVER SOUTH-CENTRAL CHINA AND SOUTH OF TOKYO AND A
WEAKNESS IN THE DEEP-LAYER MEAN DUE NORTH OF THE SYSTEM. NO
SIGNIFICANT CHANGE IN EITHER THE STRENGTH OR POSITION OF THE
COMPETING STR CENTERS IS EXPECTED THROUGH THE NEXT 48 HOURS, AND TY
02W IS FORECAST TO SLOWLY DRIFT NORTHWARD, AND AT TIMES BECOME
QUASI-STATIONARY, GENERALLY MOVING TOWARDS THE WEAKNESS IN THE
RIDGE PATTERN. BY TAU 72, THE STR TO THE EAST IS EXPECTED TO BUILD,
WHILE A MODERATE-STRENGTH MID-LATITUDE TROUGH IS EXPECTED TO PASS
OVER KOREA AND JAPAN, BOTH ENHANCING THE STEERING GRADIENT ON THE
EAST SIDE OF THE SYSTEM AND ENTICING THE SYSTEM POLEWARD INTO THE
WEAKNESS IN THE RIDGE. TY 02W WILL EJECT POLEWARD BY TAU 72, AND
SLOWLY ACCELERATE TO THE NORTHEAST THROUGH TAU 120, THOUGH BY THE
END OF THE FORECAST PERIOD, IT IS EXPECTED TO STILL BE IN THE
VICINITY OF THE RYUKYU ISLAND CHAIN. IN TERMS OF INTENSITY, THE
RECENT INFLUX OF DRY AIR FROM THE NORTH HAS KICKED OFF THE
WEAKENING TREND, EVEN THOUGH CONDITIONS OTHERWISE REMAIN MARGINALLY
FAVORABLE. SSTS ARE ALREADY FAIRLY LOW (28C) AND OHC IS QUITE LOW
AS THE SYSTEM IS APPROACHING A COLD EDDY AND NOW THAT THE SYSTEM
FORECAST TO SLOW TO A CRAWL, UPWELLING WILL OCCUR VERY RAPIDLY AND
RESULT IN A RAPID WEAKENING TREND THROUGH TAU 72. AFTER THE SYSTEM
STARTS TO MOVE NORTHEASTWARD, SSTS WILL CONTINUE TO DECREASE, BUT
THE SYSTEM WILL ALSO TAP INTO A POLEWARD OUTFLOW CHANNEL INTO A JET
MAX OVER JAPAN, OFFSETTING THE DECREASE IN SST FOR A TIME AS THE
SYSTEM PASS BY OKINAWA. HOWEVER, BETWEEN TAU 96 AND 120 THE SYSTEM
BEGINS SUBTROPICAL TRANSITION AND BEGINS TO RAPIDLY WEAKEN ONCE
MORE DUE TO THE DECREASE IN SSTS AND A SHOT OF COOL, DRY AIR FROM
THE NORTH. 

MODEL DISCUSSION: SINCE THE PREVIOUS RUN, THE DETERMINISTIC
GUIDANCE HAS COME INTO BETTER AGREEMENT, PARTICULARLY IN THE
CROSS-TRACK REGIME. THE GALWEM AND UKMET REMAIN FIRMLY ENTRENCHED
ON THE FAR WESTERN SIDE OF THE ENVELOPE THROUGH THE FORECAST
PERIOD, WHILE THE GFS AND GEFS CONTINUE TO LIE ON THE EAST SIDE BUT
HAVE COME CLOSER TO THE REST OF THE PACK WITH THIS RUN. THE
REMAINDER OF THE CONSENSUS MEMBERS INCLUDING THE ECMWF, ECENS AND
NAVGEM ARE CLOSELY PACKED AROUND THE CONSENSUS MEAN. THROUGH TAU
72, CROSS-TRACK SPREAD IS 160NM WITH LESS THAN 50NM OF ALONG-TRACK
SPREAD, BUT THE UNCERTAINTY SURROUNDING THE WEAK STEERING PATTERN
AND HOW THE SYSTEM WILL TRACK WITHIN IT LEADS TO MEDIUM CONFIDENCE
IN THIS TIMEFRAME. AFTER TAU 72, CROSS-TRACK SPREAD REMAINS
CONSISTENT AT 165NM WHEN DISCOUNTING THE NAVGEM AND GALWEM WHICH
KEEP THE SYSTEM BELOW 26N AT TAU 120. HOWEVER, ALONG-TRACK SPREAD
INCREASES DRAMATICALLY, TO NEAR 530NM BETWEEN OUTLIERS, LEADING TO
LOW CONFIDENCE IN THE JTWC FORECAST IN THE EXTENDED TAUS. INTENSITY
GUIDANCE IS IN GOOD AGREEMENT ON THE PACE OF WEAKENING THROUGH THE
ENTIRE FORECAST PERIOD. HOWEVER, THE AMOUNT OF TIME THE SYSTEM
REMAINS OVER THE COLD EDDY COULD LEAD TO A MUCH FASTER RATE OF
WEAKENING, INTRODUCING UNCERTAINTY INTO THE EARLY PORTIONS OF THE
FORECAST, RESULTING IN LOW CONFIDENCE TO THE JTWC INTENSITY
FORECAST. 

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