WDPN32 PGTW 081500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 06W (KHANUN) WARNING NR 
050//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 30.0N 130.4E
   INITIAL INTENSITY: 50 KTS
   GEOGRAPHIC REFERENCE: 189 NM SOUTH OF SASEBO, JAPAN
   MOVEMENT PAST 6 HOURS: NORTH-NORTHWESTWARD AT 07 KTS
   SIGNIFICANT WAVE HEIGHT: 25 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS DEEP
CONVECTIVE BANDING WRAPPING INTO A BROAD EXPOSED CENTER. PROXY
VISIBLE IMAGERY AND A 080926Z GMI MICROWAVE PASS SHOW MULTIPLE
CONCENTRIC BANDS AROUND THE LLCC. ENVIRONMENTAL ANALYSIS INDICATES
A MARGINAL ENVIRONMENT WITH STRONG EQUATORWARD OUTFLOW, LOW (5-10
KNOTS) VERTICAL WIND SHEAR (VWS) AND WARM (29-30C) SEA SURFACE
TEMPERATURES (SSTS) OFFSET BY DRY AIR ENTRAINMENT. THE INITIAL
INTENSITY IS ASSESSED AT 50 KTS, A BLEND BETWEEN SUBJECTIVE DVORAK
ESTIMATES OF 45 KTS FROM PGTW AND RCTP, SATCON ESTIMATES OF 48 KTS,
AND A 080915Z SAR PASS SHOWING WINDS OF 50-55 KTS IN THE
NORTHEASTERN SEMICIRCLE.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE (STR) POSITIONED TO
THE EAST AND NORTHEAST.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.0 - 45 KTS
   RCTP: T3.0 - 45 KTS
   KNES: T3.5 - 55 KTS
   CIMSS SATCON: 48 KTS AT 080814Z
   CIMSS ADT: 33 KTS AT 081130Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL
   VWS: 5-10 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: MODERATE POLEWARD AND EQUATORWARD

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TS 06W (KHANUN) CONTINUES TO TRACK AROUND THE
WESTERN PERIPHERY OF THE SUBTROPICAL RIDGE (STR) POSITIONED TO THE
EAST AND NORTHEAST, AND WILL CONTINUE TO ACCELERATE NORTHWESTWARD
AS THE STR TAKES OVER AS THE PRIMARY STEERING MECHANISM, THROUGH
THE REMAINDER OF THE FORECAST. BY TAU 24, 06W WILL PASS TO THE WEST
OF KYUSHU BEFORE MAKING LANDFALL TO THE WEST OF BUSAN BY TAU 36.
AFTER WHICH THE SYSTEM WILL RAPIDLY MOVE NORTHWARD INTO
NORTHEASTERN CHINA BY TAU 96. IN TERMS OF INTENSITY, THE SYSTEM
WILL MOVE OVER WARM SSTS, AT THE SAME TIME, OUTFLOW WILL STEADILY
IMPROVE, WITH INCREASED POLEWARD OUTFLOW, WHICH WILL ENABLE
INCREASED CONVECTION. THESE COMBINED FACTORS SHOULD ALLOW THE SYSTEM
TO INTENSIFY TO A PEAK OF 60 KNOTS BY TAU 24. AFTER TAU 36, 06W
WILL SUCCUMB TO THE AFFECTS OF LAND INTERACTION WITH THE KOREAN
PENINSULA AND WILL DECREASE IN INTENSITY TO 30 KTS BY TAU 72. BY
TAU 96, 06W IS EXPECTED TO MOVE OVER LAND IN SOUTHERN CHINA WHERE
DISSIPATION WILL OCCUR.

MODEL DISCUSSION: TRACK GUIDANCE IS IN GOOD AGREEMENT, WITH THE
MINIMAL SPREAD THROUGH THE FORECAST PERIOD. THE JTWC REMAINS
CONSISTENT WITH THE PREVIOUS FORECAST AND LIES NEAR THE MULTI-MODEL
CONSENSUS WITH MEDIUM CONFIDENCE. INTENSITY GUIDANCE IS ALSO IN
RELATIVELY GOOD AGREEMENT, WITH THE MAJORITY OF THE GUIDANCE
SHOWING A PEAK OF 60-65 KNOTS BY TAU 24. OVERALL, THERE IS MEDIUM
CONFIDENCE IN THE JTWC INTENSITY FORECAST WITH INTENSITY GUIDANCE
INDICATING A BRIEF REINTENSIFICATION PHASE THROUGH TAU 24,
AFTERWARD INTENSITY GUIDANCE SHOWS A STEADY DECREASING TREND.

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