WDPN33 PGTW 151500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 16W (NANMADOL) WARNING NR 012//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 23.4N 137.3E
   INITIAL INTENSITY: 70 KTS
   GEOGRAPHIC REFERENCE: 549 NM EAST-SOUTHEAST OF KADENA AB,
OKINAWA, JAPAN
   MOVEMENT PAST 6 HOURS: WESTWARD AT 06 KTS
   SIGNIFICANT WAVE HEIGHT: 26 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY SHOWS A LARGE
SYSTEM WITH EXTENSIVE FEEDER BANDS TRAILING TO THE SOUTH ALL THE WAY 
TO THE PHILIPPINES. THE CENTRAL CONVECTION HAS BECOME MORE DENSE WITH
COLDER CONVECTIVE TOPS AS IT MAINTAINED A RAGGED, FORMATIVE EYE.
THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE
FORMATIVE EYE FEATURE IN THE EIR LOOP. THE INITIAL INTENSITY OF
70KTS IS ALSO PLACED WITH HIGH CONFIDENCE BASED ON OVERALL ASSESSMENT 
OF AGENCY AND AUTOMATED DVORAK ESTIMATES AND REFLECTS THE IMPROVEMENT. 
ANALYSIS INDICATES A FAVORABLE ENVIRONMENT WITH LOW VWS AND STRONG 
OUTFLOW OVER WARM SST.

INITIAL WIND RADII BASIS: SCATTEROMETER DATA.

CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE (STR) TO THE NORTH.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.5 - 77 KTS
   RJTD: T4.0 - 65 KTS
   CIMSS SATCON: 75 KTS AT 151047Z
   CIMSS ADT: 75 KTS AT 151140Z

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

ANALYSIS CONFIDENCE:
   INITIAL POSITION: MEDIUM
   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: TY NANMADOL WILL CONTINUE WEST-NORTHWESTWARD
THEN NORTHWESTWARD UNDER THE STEERING INFLUENCE OF THE STR TO THE
NORTH. AFTER TAU 48, IT WILL TURN MORE NORTH-NORTHWESTWARD THEN AROUND 
TAU 72, WILL CREST THE STR AXIS AND ACCELERATE NORTHEASTWARD, MAKE 
LANDFALL OVER KYUSHU, JAPAN, NEAR SASEBO AROUND TAU 78. BY TAU 12O 
WILL BE IN THE SEA OF JAPAN (SOJ) JUST OFF THE COAST OF HONSHU. THE 
FAVORABLE CONDITIONS WILL FUEL A GRADUAL THEN RAPID INTENSIFICATION TO 
A PEAK OF 120KTS BY TAU 48 WITH THE ADDITION OF A POLEWARD OUTFLOW 
CHANNEL. AFTERWARD, INCREASING VWS, LAND INTERACTION, THEN COOLING SST 
IN THE SOJ WILL GRADUALLY ERODE THE SYSTEM. BY TAU 120, THE SYSTEM 
WILL BE REDUCED TO 55KTS AS IT ENTERS THE BAROCLINIC ZONE AND BEGINS 
EXTRA-TROPICAL TRANSITION.  

MODEL DISCUSSION: EXCEPT FOR ONE NOTABLE OUTLIER - NVGM - THAT
DEFLECTS THE VORTEX TO THE LEFT AFTER TAU 48 AND LOOPS IT IN A
QUASI-STATIONARY MOTION, THE REST OF THE NUMERICAL MODELS ARE IN
VERY GOOD AGREEMENT UP TO TAU 72 WITH A GRADUAL AND EVEN SPREAD TO
115NM. AFTERWARD, THE SPREAD INCREASES TO 170 AT TAU 120; HOWEVER,
WITH NOTICEABLE VARIATIONS IN ALONG-TRACK SPEEDS BEYOND TAU 72. IN
VIEW OF THIS, THERE IS HIGH CONFIDENCE IN THE JTWC TRACK FORECAST
UP TO TAU 72 THEN LOW CONFIDENCE AFTERWARD. THE JTWC TRACK IS LAID
JUST TO THE RIGHT OF AND SLIGHTLY FASTER THAN THE MODEL CONSENSUS
TO OFFSET NVGM. THERE IS MEDIUM CONFIDENCE IN THE INTENSITY
FORECAST UP TO TAU 72 WHERE THERE IS SOME VARIABILITY IN THE PEAK
INTENSITY, THEN LOW CONFIDENCE AFTER TAU 72 DUE TO THE LARGE SPREAD
AND VARIATIONS IN THE SPEEDS THAT DIRECTLY AFFECT THE FORECAST
INTENSITIES. 

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