WDPN33 PGTW 142100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 08W (AMPIL) WARNING NR 010//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 27.6N 141.1E
   INITIAL INTENSITY: 75 KTS
   GEOGRAPHIC REFERENCE: 468 NM SOUTH OF YOKOSUKA, JAPAN
   MOVEMENT PAST 6 HOURS: NORTH-NORTHEASTWARD AT 09 KTS
   SIGNIFICANT WAVE HEIGHT: 29 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS WARMING
UPPER-LEVEL CLOUD BANDS WITH A SLOT OF DRY AIR INTRUDING FROM THE
SOUTHWEST STALLING FURTHER INTENSIFICATION DESPITE AN OTHERWISE
FAVORABLE ENVIRONMENT OF LOW VERTICAL WIND SHEAR, WARM SEA SURFACE
TEMPERATURES, AND UPPER-LEVEL DIVERGENCE. A 141917Z F18 SSMIS PASS
REVEALS A DISORGANIZED UPPER-LEVEL CIRCULATION ON THE 91GHZ IMAGE
WITH A FULLY WRAPPED AND ORGANIZED 37GHZ IMAGE ON THE LOW-LEVELS.
THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE
AFOREMENTIONED EIR IMAGERY. THE INITIAL INTENSITY OF 75KTS IS
ASSESSED WITH MEDIUM CONFIDENCE BASED ON A 141557Z GCOM W1 AMSR2
IMAGE DEPICTING WIND SPEEDS BETWEEN 60-65KTS TO THE SOUTHEAST AND
THE AGENCY AND OBJECTIVE FIXES LISTED BELOW.

INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK 

CURRENT STEERING MECHANISM: A COUPLED STEERING ENVIRONMENT ON THE
NORTHWESTERN PERIPHERY OF A SUBTROPICAL RIDGE (STR) TO THE
SOUTHEAST AND THE WESTERN PERIPHERY OF A SUBTROPICAL RIDGE TO THE
EAST.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.5 - 77 KTS
   RJTD: T4.0 - 65 KTS
   RCTP: T4.5 - 77 KTS
   KNES: T4.0 - 65 KTS
   CIMSS SATCON: 63 KTS AT 1900Z
   CIMSS ADT: 49 KTS AT 1930Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 5-10 KTS
   SST: 30-31 CELSIUS
   OUTFLOW: STRONG POLEWARD AND EQUATORWARD

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TYPHOON (TY) 08W IS FORECAST TO TRACK
NORTH-NORTHEASTWARD AS IT COMES PRIMARILY UNDER THE STEERING
INFLUENCE OF THE STR TO THE EAST AND MOVES AWAY FROM THE STR TO THE
SOUTHEAST. THE NORTH-NORTHEASTWARD TRACK WILL CONTINUE THROUGH THE
FIRST 36 HOURS OF THE FORECAST BEFORE ROUNDING THE RIDGE AND
ULTIMATELY TRACKING WEST-NORTHWESTWARD THROUGH THE END OF THE
FORECAST. THE SYSTEM WILL CONTINUE TO INTENSIFY THROUGH FOR THE
FIRST 60 HOURS OF THE FORECAST, POTENTIALLY PEAKING AT 105KTS AS IT
TRACKS JUST SOUTHEAST OF TOKYO BETWEEN TAU 48-60 BEFORE WEAKENING
AS IT ENTERS COOLER SEA SURFACE TEMPERATURES AT TAU 72 AND BEGINS
EXTRATROPICAL TRANSITION. VERTICAL WIND SHEAR WILL ALSO INCREASE TO
UNFAVORABLE LEVELS BETWEEN TAU 72-96, DURING WHICH TIME TY 09W WILL
BECOME BAROCLINIC, ULTIMATELY BECOMING FULLY EXTRATROPICAL BY TAU
96. 

MODEL DISCUSSION: DETERMINISTIC MODEL GUIDANCE TIGHTLY AGREES ON
THE S-SHAPED FORECAST TRACK AS REFLECTED IN A 100NM CROSS-TRACK
SPREAD BY TAU 48 AND A 350NM CROSS-TRACK SPREAD BY TAU 96, HOWEVER
THE GEFS AND ECENS ENSEMBLE GUIDANCE CONSISTENTLY REFLECTS OUTPUTS
FARTHER WEST AND CLOSER TO MAINLAND JAPAN. THE JTWC TRACK LIES JUST
WEST OF THE MULTI-MODEL TRACK CONSENSUS CLOSER TO THE ENSEMBLE
OUTPUT. THE JTWC INTENSITY GUIDANCE INDICATES A POTENTIAL FOR RAPID
INTENSIFICATION WITHIN THE FIRST 24 HOURS WHILE IN A REGION OF LOW
SHEAR, WARM SSTS, AND FAVORABLE UPPER-LEVEL DIVERGENCE. THE PRIMARY
MITIGATING FACTOR FOR RAPID INTENSIFICATION THUS FAR HAS BEEN DRY
AIR ENTRAINMENT FROM THE SOUTHEAST, BUT IF THE SYSTEM BECOMES FULLY
MOIST THEN THE INTENSITY OUTPUT MAY BE HIGHER THAN REFLECTED IN THE
JTWC INTENSITY FORECAST. 

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