WDPN32 PGTW 300900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 06W (KHANUN) WARNING NR 013//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 19.5N 132.7E
   INITIAL INTENSITY: 70 KTS
   GEOGRAPHIC REFERENCE: 499 NM SOUTHEAST OF KADENA AB
   MOVEMENT PAST 6 HOURS: NORTHWARD AT 08 KTS
   SIGNIFICANT WAVE HEIGHT: 29 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
TYPHOON (TY) 06W HAS CONSOLIDATED QUICKLY OVER THE PAST 12 HOURS
WITH A RAGGED EYE EVIDENT IN ANIMATED MULTISPECTRAL SATELLITE
IMAGERY, WHICH SUPPORTS THE INITIAL POSITION WITH HIGH CONFIDENCE.
THE SYSTEM HAS INCREASED 25 KNOTS OVER THE PAST 24 HOURS FROM 45
KNOTS AT 290600Z TO THE INITIAL INTENSITY OF 70 KNOTS DUE PRIMARILY
TO DECREASING NORTHERLY VERTICAL WIND SHEAR, IMPROVING RADIAL
OUTFLOW AND A MOISTENING MID- TO UPPER-LEVEL ENVIRONMENT. ANIMATED
WATER VAPOR IMAGERY NOW SHOWS STRONG EQUATORWARD OUTFLOW AND ROBUST
POLEWARD OUTFLOW, WHICH HAS ALLOWED CORE CONVECTION TO CONSOLIDATE
AND SPIRAL BANDING TO IMPROVE AS DEPICTED IN A 300422Z AMSR2 89GHZ
MICROWAVE IMAGE. THE AMSR2 WINDSPEED IMAGE SHOWS A NARROW BAND OF
60-68 KNOT WINDS OVER THE EASTERN SEMICIRCLE WITH AN OBLONG WIND
FIELD ORIENTED FROM THE SSW TO THE NNE. THIS IMAGE SUPPORTS THE
INITIAL INTENSITY ASSESSMENT OF 70 KNOTS AS WELL AS THE ADJUSTED
WIND RADII. THE MOST RECENT D-PRINT AND D-MINT ESTIMATES SUPPORT THE 
INITIAL INTENSITY ASSESSMENT WITH REALISTIC ESTIMATES WHILE DVORAK 
ESTIMATES RANGE FROM 55 TO 90 KNOTS.

INITIAL WIND RADII BASIS: AMSR2 DATA: DETAILED ANALYSIS OF THE
ASYMMETRIC WIND FIELD REVEALED IN THE AMSR2 WINDSPEED IMAGE.

CURRENT STEERING MECHANISM: DEEP-LAYERED SUBTROPICAL RIDGE (STR)
CENTERED SE OF TOKYO WITH RIDGE EXTENDING SOUTHWARD.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.0 - 65 KTS
   RJTD: T3.5 - 55 KTS
   RCTP: T4.5 - 77 KTS
   KNES: T5.0 - 90 KTS
   CIMSS SATCON: 74 KTS AT 300436Z
   CIMSS ADT: 57 KTS AT 300530Z
   D-PRINT: 72 KTS AT 300700Z   
   D-MINT: 69 KTS AT 300422Z

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

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: THE JTWC FORECAST REMAINS HIGHLY CONSISTENT
WITH THE PREVIOUS JTWC FORECASTS WITH SOME MINOR SHIFTS IN TRACK
NEAR OKINAWA ASSOCIATED WITH POSITIONAL UNCERTAINTY AND SHORT-TERM
TRACK CHANGES. OVER THE PAST 3 DAYS, JTWC FORECASTS HAVE REMAINED
WITHIN A 50NM ENVELOPE JUST TO THE SOUTH OF OKINAWA. TY 06W WILL TURN 
GRADUALLY WEST-NORTHWESTWARD AFTER TAU 24 UNDER THE STEERING 
INFLUENCE OF THE STR POSITIONED TO THE NORTH AND NORTHEAST WITH 
LANDFALL EXPECTED OVER THE EASTERN CHINA COAST NEAR TAU 84. THE 
SYSTEM IS EXPECTED TO WEAKEN RAPIDLY AS IT TRACKS INLAND OVER EASTERN 
CHINA. 

MODEL DISCUSSION: THE 300000Z ECMWF (EPS) AND GFS (GEFS) ENSEMBLES
INDICATE A BIFURCATION IN PROBABILISTIC GUIDANCE WITH TWO DISTINCT
CLUSTERS. THE FIRST CLUSTER SUPPORTS A WNW TRACK INTO CENTRAL CHINA
AND DISSIPATION SCENARIO. THE SECOND CLUSTER REVEALS A POLEWARD
TRACK OVER THE EAST CHINA SEA TOWARD WESTERN JAPAN AND THE KOREAN
PENINSULA (NOTE: THIS COVERS THE NEXT 5 DAYS ONLY). DETERMINISTIC
GUIDANCE REMAINS IN TIGHT AGREEMENT THROUGH TAU 48 WITH A CROSS-TRACK 
SPREAD NEAR OKINAWA RANGING FROM 45NM AT TAU 36 TO 70 NM AT TAU 48. 
ALTHOUGH THE JTWC FORECAST DOES NOT INDICATE RAPID INTENSIFICATION, 
RAPID INTENSIFICATION (RI) IS POSSIBLE OVER THE NEXT TWO DAYS WITH RI 
GUIDANCE TRIGGERED AND THE 300000Z COAMPS-TC ENSEMBLE INDICATING A 10 
TO 20 PERCENT PROBABILITY OF RI. AFTER TAU 48, DETERMINISTIC GUIDANCE 
DIVERGES WITH GFS, AEMN AND JGSM SLOWING AND TURNING POLEWARD WHILE 
ECMWF, EEMN, NAVGEM AND UKMO TRACK THE SYSTEM WNW INTO EASTERN CHINA. 
THE JTWC FORECAST PHILOSOPHY CONTINUES TO FAVOR THE WNW MODEL 
GROUPING AND TRACK OVERLAND. THE MAJOR PROBLEM WITH GFS IS THAT THE 
MODEL IS TRACKING THE SYSTEM INTO THE STR TO THE NORTH WITH NO 
DYNAMIC SHORTWAVE TROUGH EVIDENT IN THE ZONAL MIDLATITUDE FLOW. IN 
FACT, THE MIDLATITUDE WESTERLIES AND BAROCLINIC ZONE ARE DISPLACED 
WELL TO THE NORTH OF 40N WITH A BROAD MIDLATITUDE RIDGE OVER 
NORTHEAST CHINA AND MANCHURIA. GFS RAPIDLY BREAKS THIS STR DOWN AND 
ENVELOPS THE SYSTEM WITHIN A SUBTROPICAL TROUGH WEST OF A NORTH-SOUTH 
ORIENTED STR, WHICH EVENTUALLY DRIVES THE SYSTEM POLEWARD. THIS 
SCENARIO IS POSSIBLE BUT IS CURRENTLY ASSESSED AS A LOW PROBABILITY.    

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