WDPN32 PGTW 020300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 06W (KHANUN) WARNING NR 024//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 25.8N 127.0E
   INITIAL INTENSITY: 100 KTS
   GEOGRAPHIC REFERENCE: 60 NM SOUTHWEST OF KADENA AB
   MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 04 KTS
   SIGNIFICANT WAVE HEIGHT: 36 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
AFTER PASSING WITHIN 53NM TO THE SOUTH OF KADENA AB, TYPHOON (TY)
06W (KHANUN) HAS CONTINUED TO TRACK GENERALLY TOWARDS THE
WEST-NORTHWEST. HOWEVER, THE STORM TOOK A BRIEF PIT-STOP BETWEEN
ROUGHLY 2100Z AND 0000Z, WITH RADAR DATA SHOWING THE SYSTEM
BECOMING NEARLY QUASI-STATIONARY DURING THIS PERIOD, BEFORE ONCE
AGAIN HEADING OFF TO THE NORTHWEST. RECENT 89GHZ SSMIS MICROWAVE
IMAGERY FROM 012117Z SHOWED A VERY LARGE SECONDARY EYEWALL
APPROXIMATELY 75-90NM OUT FROM THE CENTER AND A CLEAR MOAT
SURROUNDING THE INNER CORE. THE MOST RECENT ANIMATED RADAR DATA
SHOWS THE EYE OF THE SYSTEM PASSING SOUTH OF KUMEJIMA ISLAND BY
0200Z. WINDS AT KUMEJIMA ARE NOT ALL THAT IMPRESSIVE CONSIDERING
THE STATION IS ON THE OUTER EDGE OF THE INNER EYEWALL, BUT
PRESSURES HAVE DROPPED PRECIPITOUSLY, DOWN TO 954MB BY 0200Z. NAHA
CONTINUES TO REPORT SUSTAINED WINDS OVER 50 KNOTS WITH GUSTS AS
HIGH AS 78 KNOTS IN THE OUTER EYEWALL. THE INITIAL INTENSITY HAS
BEEN LOWERED SLIGHTLY, TO 100 KNOTS, WITH MEDIUM CONFIDENCE. THE
INITIAL INTENSITY IS IN LINE WITH THE MAJORITY OF THE AGENCY DVORAK
CURRENT INTENSITY ESTIMATES BUT WELL BELOW THE PREPONDERANCE OF THE
AUTOMATED ESTIMATES WHICH ARE CLUSTERED BETWEEN 112 KNOTS TO 127
KNOTS. CONDITIONS REMAIN GENERALLY FAVORABLE WITH WARMS SSTS, GOOD
POLEWARD OUTFLOW EXTENDING EAST INTO A TUTT-CELL SOUTH OF TOKYO AND
LOW SHEAR.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: SOUTHERN PERIPHERY OF A DEEP-LAYER
SUBTROPICAL RIDGE (STR) CENTERED OVER THE YELLOW SEA. 

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 ADT: 119 KTS AT 012330Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 0-5 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: MODERATE POLEWARD

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: OUTSIDE OF THE BRIEF PIT-STOP SOUTHWEST OF
OKINAWA, TY 06W HAS IN GENERAL CONTINUED TRACKING TOWARDS THE
WEST-NORTHWEST ALONG THE SOUTHERN SIDE OF THE STEERING RIDGE TO THE
NORTH. THE SYSTEM CONTINUES TO SLOW DOWN WHILE CONTINUING TO TREK
FURTHER INTO THE EAST CHINA SEA OVER THE NEXT 24 TO 36 HOURS AS THE
CENTER OF THE STEERING RIDGE SHIFTS TO THE SOUTHWEST AND BLOCKS
FURTHER WESTWARD PROGRESSION. THE SYSTEM IS EXPECTED TO BECOME
QUASI-STATIONARY IN THE VICINITY OF THE 124E LONGITUDE LINE BETWEEN
TAU 36 AND 48 UNDER THE COMPETING STEERING INFLUENCES OF THE
BLOCKING RIDGE TO THE NORTHWEST AND THE NEAR EQUATORIAL RIDGE (NER)
TO THE WEST OF GUAM. AFTER BOUNCING AROUND LIKE A BEACH BALL IN THE
GENERAL ADMISSION SECTION OF DODGER STADIUM FOR 24 HOURS OR SO, THE
NER TO THE SOUTH BUILDS IN AND KICKS THE SYSTEM OUT TO THE
NORTHEAST AFTER TAU 72. AFTER TAU 72, TY 06W WILL PICK UP SPEED
AS IT CONTINUES TO TREK TOWARDS THE EAST-SOUTHEAST, PASSING CLOSE
TO ASAMI OSHIMA BY TAU 120. AS THE SYSTEM CONTINUES TO SLOW DOWN AS
IT TRACKS WESTWARD, IT WILL BEGIN TO UPWELL SIGNIFICANTLY COOLER
WATERS TO THE SURFACE, SOME MODELS SUGGESTING AS MUCH AS -4C OF SST
COOLING. THE UPWELLING WILL LIKELY INHIBIT COMPLETION OF THE
ONGOING EYEWALL REPLACEMENT CYCLE (EWRC). THUS, THE SYSTEM IS
EXPECTED TO SLOWLY WEAKEN FOR THE FIRST 24 HOURS FOLLOWED BY A MORE
PRECIPITOUS DROP-OFF THROUGH TAU 72. IT SHOULD BE NOTED HOWEVER THAT
WHILE THE SYSTEM WILL BE WEAKENING THROUGH THE MAJORITY OF THE
FORECAST, THE WIND FIELD WILL AT THE SAME TIME CONTINUE TO EXPAND. 

MODEL DISCUSSION: DETERMINISTIC TRACK GUIDANCE REMAINS CONSISTENT
WITH THE PREVIOUS MODEL RUN, WITH ALL THE CONSENSUS MEMBERS
INDICATING A SLOWING TRACK TO THE WEST TO TAU 48, THEN A SHARP TURN
TO THE EAST-NORTHEAST BY TAU 72. SOME NEAR-TERM WOBBLES SHOULD BE
ANTICIPATED AS THE EWRC CONTINUES, AND ERRATIC UNPREDICTABLE
MOTION IS EXPECTED ONCE THE SYSTEM BECOMES QUASI-STATIONARY AROUND
TAU 36. AFTER TAU 72, THE GUIDANCE ENVELOPE EXPANDS BOTH IN THE CROSS 
AND ALONG-TRACK SENSE. THE HAFS-A TRACKER NOW SHOWS THE SYSTEM PASSING 
OVER SOUTHERN OKINAWA AFTER TAU 72, WHILE THE GFS AND GEFS ENSEMBLE 
MEAN SHOW A PASSAGE ALONG THE NORTHERN TIP OF THE ISLAND. THE 
REMAINDER OF THE GUIDANCE IS SPREAD ACROSS A 100NM ENVELOPE EXTENDING 
TO THE NORTH. IN THE ALONG-TRACK SENSE, THE ECMWF AND NAVGEM ARE IN A 
HURRY TO GET TO THE JAPANESE MAIN ISLANDS, FAR OUTPACING THE GFS AND 
THE OTHER CONSENSUS MEMBERS, GENERATING A LARGE ALONG-TRACK SPREAD. 
TRACK CONFIDENCE MEDIUM TO LOW IN THE LATER TAUS. INTENSITY GUIDANCE 
IS IN FAIRLY GOOD AGREEMENT, THOUGH HWRF IS AGGRESSIVELY CALLING FOR 
INTENSIFICATION UP TO 115 KNOTS AND REMAINS ABOUT 15 KNOTS ABOVE THE 
CONSENSUS MEAN THROUGH THE REMAINDER OF THE FORECAST, WHILE THE HAFS-A 
TAKES THE OPPOSITE TACK, AND IS ABOUT 15 KNOTS BELOW THE MEAN THROUGH 
TAU 120. THE JTWC FORECAST TRACKS THE MEAN, AS WELL AS THE SHIPS AND 
COAMPS-TC GUIDANCE WITH MEDIUM CONFIDENCE. 

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