WDPN33 PGTW 170900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR SUPER TYPHOON 16W (NANMADOL) 
WARNING NR 019//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 26.7N 132.4E
   INITIAL INTENSITY: 130 KTS
   GEOGRAPHIC REFERENCE: 247 NM EAST OF KADENA AB
   MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 09 KTS
   SIGNIFICANT WAVE HEIGHT: 52 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A LARGE,
WELL DEFINED TYPHOON WITH SPIRAL BANDS OF DEEP CONVECTION WRAPPING
INTO A 16NM PINHOLE EYE. A 170357Z AMSR2 89GHZ MICROWAVE IMAGE
REVEALS THAT 16W HAS A TIGHT, HIGHLY SYMMETRICAL EYEWALL WITH NO
INDICATIONS OF A COMPLETED SECONDARY EYEWALL. THE INITIAL POSITION
IS PLACED WITH HIGH CONFIDENCE BASED ON MSI AND AMSR2 IMAGERY. THE
INITIAL INTENSITY OF 130 KTS IS ASSESSED WITH HIGH CONFIDENCE BASED
ON AGENCY DVORAK INTENSITY ESTIMATES AGREEING ON T6.5-T7.0 AND
CIMSS SATCON AND CIMSS ADT INDICATING 129-131KTS.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: SOUTHWESTERN PERIPHERY OF A DEEP-LAYER
SUBTROPICAL RIDGE (STR)

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T7.0 - 140 KTS 
   RJTD: T7.0 - 140 KTS 
   KNES: T6.5 - 127 KTS
   CIMSS SATCON: 131 KTS AT 170212Z
   CIMSS ADT: 129 KTS AT 170540Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 10-15 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: MODERATE RADIAL

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: STY 16W (NANMADOL) IS FORECAST TO CONTINUE
TRACKING GENERALLY NORTH-NORTHWESTWARD UNDER THE STEERING INFLUENCE
OF A STR TO THE NORTHEAST. THOUGH THE ATMOSPHERIC ENVIRONMENT
REMAINS MARGINALLY FAVORABLE, LOW VERTICAL WIND SHEAR (10-15KTS),
WARM SST (29-30C) AND MODERATE RADIAL OUTFLOW ALOFT, DECLINING
OCEAN HEAT CONTENT VALUES WILL RESULT IN A MARGINAL LOSS IN
INTENSITY BY TAU 12. BY TAU 24, NOT ONLY WILL SST VALUES ALSO DROP
BUT AN APPROACHING COLD FRONT AND ACCOMPANYING SHORTWAVE TROUGH
WILL BEGIN TO BREAKDOWN THE STEERING RIDGE, AS A RESULT 16W WILL
FALL TO AROUND 115KTS AND BEGIN TO EXECUTE A DRAMATIC NORTHEASTERLY
TURN. BY TAU 36, HAVING PASSED JUST SOUTH OF USHIBUKA, JAPAN 16W WILL
BEGIN TO SIGNIFICANTLY WEAKEN AS LAND INTERACTION WITH JAPAN AND
SHEAR VALUES INCREASE. NEAR TAU 48, 16W DRASTICALLY INCREASES TRACK
SPEEDS AND PROGRESSES ALONG THE FRONTAL BOUNDARY AS IT IS RIPPED
APART BY INCREASING SHEAR VALUES AS WELL AS BY JAPAN ITSELF. AS THE
SYSTEM PROGRESSES, IT WILL CONTINUE TO RAPIDLY WEAKEN AND BEGIN TO
INTERACT WITH AND INTEGRATE INTO THE PASSING TROUGH THEREBY
STARTING EXTRA-TROPICAL TRANSITION (ETT). THE REMNANTS OF 16W WILL
EXIT INTO THE PACIFIC OCEAN BY TAU 96 AND COMPLETE ETT BY TAU 120. 

MODEL DISCUSSION: NUMERICAL MODELS GUIDANCE IS IN GOOD AGREEMENT
THROUGH TAU 36, WITH ALL MODELS CLOSELY FOLLOWING THE JTWC FORECAST
TRACK. AFTER TAU 36, ALONG TRACK SPREADING GRADUALLY INCREASES AS
UKMET AND HWRF PULL AHEAD, WHILE ECMWF, COAMPS-TC AND NVGM INDICATE
MUCH SLOWER SPEEDS. FOR THESE REASONS THE JTWC FORECAST TRACK IS
PLACED WITH LOW CONFIDENCE. RELIABLE MODEL INTENSITY GUIDANCE IS IN
GOOD AGREEMENT WITH ALL MEMBERS WEAKENING THE SYSTEM THROUGH THE
FORECAST PERIOD. COAMPS-TC AND GFS SHOW THE MOST AGGRESSIVE
WEAKENING, WHILE DECAY-SHIPS AND HWRF SHOW A MORE REASONABLE
WEAKENING TREND. FOR THIS REASON, THE JTWC FORECAST INTENSITY HAS
BEEN PLACED HIGHER THAN THE MULTI-MODEL CONSENSUS WITH MEDIUM
CONFIDENCE.

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