WDPN32 PGTW 040900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 06W (KHANUN)      
WARNING NR 033//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 27.1N 125.0E
   INITIAL INTENSITY: 60 KTS
   GEOGRAPHIC REFERENCE: 154 NM WEST-NORTHWEST OF KADENA AB
   MOVEMENT PAST 6 HOURS: EAST-NORTHEASTWARD AT 04 KTS
   SIGNIFICANT WAVE HEIGHT: 26 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A LARGE
(600NM DIAMETER) SYSTEM WITH TIGHTLY-CURVED BANDING WRAPPING INTO A
DEFINED LOW-LEVEL CIRCULATION CENTER (LLCC), WHICH SUPPORTS THE
INITIAL POSITION WITH HIGH CONFIDENCE. ANIMATED ENHANCED INFRARED
SATELLITE IMAGERY REVEALS DEEP CONVECTIVE BANDING WRAPPING INTO A
BROAD CENTER WITH FLARING, DISORGANIZED CONVECTION NEAR THE CENTER.
ENVIRONMENTAL CONDITIONS REMAIN MARGINAL DUE PRIMARILY TO THE
UPWELLING COOLER WATER OFFSET SOMEWHAT BY THE MODERATE RADIAL
OUTFLOW AND LOW VERTICAL WIND SHEAR. A 040440Z AMSR2 WINDSPEED
IMAGE INDICATES A LARGE (75 TO 85NM DIAMETER) CORE OF LIGHT WINDS
WITH A BROAD SWATH OF STORM-FORCE WINDS OVER THE SOUTHERN
SEMICIRCLE AND A NARROW, LIMITED BAND OF MAXIMUM WINDS (65-70
KNOTS) DISPLACED ABOUT 65NM FROM THE CENTER. THE INITIAL INTENSITY
OF 60 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON THE AGENCY
DVORAK ESTIMATES RANGING FROM 55 TO 65 KNOTS AND THE OVERALL WIND
FIELD STRUCTURE. THE 040443Z D-MINT ESTIMATE OF 67 KNOTS AND THE
040800Z D-PRINT ESTIMATE OF 57 KNOTS REFLECT THE UNCERTAINTY IN THE
INITIAL INTENSITY ESTIMATE.

INITIAL WIND RADII BASIS: AMSR2 DATA, SMAP DATA, SURFACE
OBSERVATIONS

CURRENT STEERING MECHANISM: NEAR-EQUATORIAL RIDGE (NER) POSITIONED
TO THE SOUTH AND SOUTHEAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.0 - 65 KTS
   RJTD: T4.0 - 65 KTS
   RCTP: T3.5 - 55 KTS
   KNES: T3.5 - 55 KTS
   CIMSS ADT: 39 KTS AT 040530Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL
   VWS: 5-10 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: MODERATE RADIAL
   OTHER FACTORS: DYNAMIC OCEAN COOLING

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: TROPICAL STORM (TS) 06W IS ACCELERATING
EAST-NORTHEASTWARD AS ANTICIPATED AND IS FORECAST TO TRACK
EAST-NORTHEASTWARD TO EASTWARD THROUGH TAU 48 ALONG THE NORTHERN
PERIPHERY OF THE NER. DUE TO THE UPWELLING COOL WATER, THE SYSTEM
IS EXPECTED TO WEAKEN SLIGHTLY TO 55 KNOTS BY TAU 12, WHICH IT WILL
MAINTAIN THROUGH TAU 48. AFTER TAU 72, THE GFS AND ECMWF MODELS
CONTINUE TO DEVELOP ANOTHER SYSTEM TO THE EAST AND SOUTHEAST OF TS
06W, WHICH WILL DISRUPT THE STEERING FLOW SUPPORTING THE
CLIMATOLOGICALLY SLOW TRACK SPEEDS OF 5 KNOTS AFTER TAU 48. AFTER
TAU 48, ENVIRONMENTAL CONDITIONS SHOULD GRADUALLY IMPROVE
ESPECIALLY SST VALUES, WHICH WILL INCREASE TO 28-29C, AND POLEWARD
OUTFLOW. THIS SHOULD ALLOW A MODEST REINTENSIFICATION TO 65 KNOTS
BY TAU 96. AFTER TAU 96, TS 06W WILL GRADUALLY WEAKEN DUE TO
FRICTIONAL EFFECTS AS IT APPROACHES WESTERN JAPAN.  

MODEL DISCUSSION: DETERMINISTIC MODEL GUIDANCE IS IN FAIR AGREEMENT
WITH A 130NM CROSS-TRACK SPREAD IN SOLUTIONS AT TAU 72. AFTER TAU
72, THE GUIDANCE DIVERGES SLIGHTLY WITH A 165NM CROSS-TRACK SPREAD
AT TAU 120. THE JGSM TRACKER IS THE WESTERNMOST OUTLIER WITH A
TRACK OVER KYUSHU WHILE NAVGEM IS THE EASTERNMOST OUTLIER WITH A
TRACK OVER SHIKOKU ISLAND. THE REMAINDER OF THE GUIDANCE IS TIGHTLY
CLUSTERED WITH A TRACK BETWEEN KYUSHU AND SHIKOKU ISLANDS. THE 
040000Z ECMWF (EPS) AND GFS (GEFS) ENSEMBLES HAVE COME INTO BETTER
AGREEMENT BUT STILL INDICATE SOLUTIONS WEST OF KYUSHU TO THE KII
PENINSULA SUPPORTING THE MEDIUM FORECAST CONFIDENCE.  

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