WDPN32 PGTW 051500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 06W (KHANUN) WARNING NR 
038//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 27.8N 128.5E
   INITIAL INTENSITY: 55 KTS
   GEOGRAPHIC REFERENCE: 86 NM NORTH-NORTHEAST OF KADENA AB
   MOVEMENT PAST 6 HOURS: EASTWARD AT 08 KTS
   SIGNIFICANT WAVE HEIGHT: 32 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A LARGE
TROPICAL STORM FORCE CIRCULATION WITH DEEP CONVECTIVE BANDING
FEATURES IN ALL QUADRANTS. A 050940Z SSMIS 91GHZ MICROWAVE IMAGE
REVEALS A ROUGHLY 80NM CONVECTIVE DOUGHNUT WITH MINIMAL CORE
CONVECTION. A SERIES OF SCALAR WIND PRODUCTS, SOIL MOISTURE ACTIVE
PASSIVE (SMAP) AND SYNTHETIC APERTURE RADAR (SAR) BOTH INDICATE A
ROUGHLY 80NM RMW WITH VMAX NEAR 55KTS AND SPURIOUS POCKETS OF 60KT
WINDS. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON
EIR AND SSMIS IMAGERY. THE INITIAL INTENSITY OF 55 KTS IS ASSESSED
WITH MEDIUM CONFIDENCE BASED ON SAR AND SMAP PASSES GENERALLY
SUPPORTING 55KTS ALONG WITH AGENCY DVORAK INTENSITY ESTIMATES AND
CIMSS D-PRINT.

INITIAL WIND RADII BASIS: SAR DATA 

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

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.5 - 55 KTS
   RJTD: T3.5 - 55 KTS
   RCTP: T3.0 - 45 KTS
   KNES: T3.0 - 45 KTS
   CIMSS ADT: 32 KTS AT 051130Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 0-5 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: MODERATE EASTWARD
   OTHER FACTORS: IMPROVING SST GRADIENT ALONG THE DIRECTION OF
MOTION

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: TROPICAL STORM (TS) 06W (KHANUN) IS FORECAST
TO CONTINUE TRACKING GENERALLY EASTWARD OVER THE NEXT 36 HOURS
UNDER THE STEERING INFLUENCE OF THE NER TO THE SOUTH. AS TRACK
SPEEDS INCREASE, UPWELLING BECOMES MUCH LESS OF A FACTOR, THOUGH
LOW VERTICAL WIND SHEAR AND WARMING SSTS WILL STILL STRUGGLE TO
FUEL ANY SUBSTANTIAL INTENSIFICATION DUE IN PART TO THE SYSTEMS
LARGE RMW AND SHALLOW CORE CONVECTION. BY TAU 48, THE NER TO THE
SOUTH SHIFTS NORTHEASTWARD AND FORCES 06W TO EXECUTE A SHARP
NORTHWARD COURSE CHANGE. BETWEEN TAUS 48 AND 72, 06W IS FORECAST TO
ONCE AGAIN REACH TYPHOON STRENGTH AS IT APPROACHES SOUTHERN JAPAN.
AS THE SYSTEM MAKES LANDFALL, IT WILL QUICKLY TRAVERSE THE ISLAND
OF KYUSHU, PASSING ROUGHLY 70NM EAST OF SASEBO AND EVENTUALLY
SPILLING OUT INTO THE SEA OF JAPAN. BY TAU 120, THE SYSTEM WILL
INTERACT WITH A PASSING 500MB TROUGH AND ASSOCIATED BAROCLINIC ZONE
WHICH WILL INITIATE EXTRA-TROPICAL TRANSITION (ETT), WHILE AT THE
SAME TIME PROVIDING A ROBUST OUTFLOW CHANNEL. THIS ENHANCED
OUTFLOW, WHEN COMBINED WITH WARM SSTS MAY PROLONG OR SLIGHTLY
ENHANCE THE DURATION OF STORM FORCE WINDS, WHILE AT THE SAME TIME
DELAYING THE EXTRA-TROPICAL TRANSITION.

MODEL DISCUSSION: WITH THE EXCEPTION OF A FEW PERSISTENT TROUBLE
MAKERS TO EITHER SIDE OF THE MULTI-MODEL CONSENSUS, THE BULK OF THE
MODEL GUIDANCE IS IN FAIR AGREEMENT. NVGM AND COAMPS-TC (NVGM
VERSION) REPRESENT THE EXTREME EASTWARD TRACK FORECASTS, WHILE
UK-MET ENSEMBLE AND ECMWF ENSEMBLE REPRESENT THE EXTREME WESTWARD
TRACK FORECAST. THE BULK OF THE REMAINING MODELS TRACK EASTWARD
THROUGH TAUS 36-48 AFTERWARDS MAKING A SHARP NORTHWARD TURN THROUGH
THE FORECAST PERIOD. BASED ON THE PERSISTENT CROSS TRACK SPREADING,
THE JTWC TRACK FORECAST IS PLACED WITH OVERALL MEDIUM CONFIDENCE.
RELIABLE MODEL INTENSITY GUIDANCE IS IN FAIR AGREEMENT THROUGH THE
FORECAST PERIOD WITH A 15KT SPREAD IN SOLUTIONS BY TAU 120. SIMILAR
TO THE TRACK FORECAST, BASED ON THE PERSISTENT SPREAD IN INTENSITY
GUIDANCE, THE JTWC INTENSITY FORECAST IS PLACED WITH OVERALL MEDIUM
CONFIDENCE.

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