WDPN33 PGTW 160900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 08W (AMPIL) WARNING NR 016//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 34.1N 141.1E
   INITIAL INTENSITY: 110 KTS
   GEOGRAPHIC REFERENCE: 100 NM SOUTHEAST OF YOKOSUKA, JAPAN
   MOVEMENT PAST 6 HOURS: NORTH-NORTHEASTWARD AT 06 KTS
   SIGNIFICANT WAVE HEIGHT: 40 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) SHOWS AN INTENSE 
SYSTEM WITH A SYMMETRICAL COLD DENSE OVERCAST (CDO) WITH A SHARPLY-
OUTLINED 22NM EYEWALL. AN ENHANCED INFRARED BD CURVE SATELLITE 
ANIMATION SHOWS SLIGHT WARMING OF THE CDO CONVECTIVE TOPS AND SOME 
LOOSENING OF THE COMPACT FEEDER BANDS. THE INITIAL POSITION IS PLACED 
WITH HIGH CONFIDENCE BASED ON THE EYE FEATURE THAT IS VERTICALLY 
STACKED OVER CLOSELY-CLUSTERED AGENCY AND RADAR FIXES. THE INITIAL 
INTENSITY IS ALSO PLACED WITH HIGH CONFIDENCE BASED ON THE AVERAGE OF 
AGENCY AND AUTOMATED DVORAK INTENSITIES AND REFLECTS THE SLIGHT 6-HR 
DEGRADATION. ANALYSIS INDICATES A FAVORABLE ENVIRONMENT WITH LOW VWS, 
STRONG DUAL OUTFLOW, AND WARM SST. 

INITIAL WIND RADII BASIS: SCATTEROMETER DATA 

CURRENT STEERING MECHANISM: DEEP-LAYER SUBTROPICAL RIDGE (STR) TO THE 
EAST.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T6.0 - 115 KTS
   RJTD: T5.5 - 102 KTS
   KNES: T5.5 - 102 KTS
   CIMSS ADT: 107 KTS AT 160530Z

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

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TYPHOON AMPIL HAS CRESTED THE STR AXIS AND WILL 
BEGIN TO ACCELERATE NORTHEASTWARD. INCREASING VWS AND COOLING SST 
WILL GRADUALLY WEAKEN THE SYSTEM TO 90KTS BY TAU 24. AFTERWARD, A 
MORE RAPID EROSION IS EXPECTED AS THE CYCLONE ENTERS THE BAROCLINIC 
ZONE. CONCURRENTLY BY TAU 36, IT WILL BEGIN EXTRA-TROPICAL TRANSITION 
(ETT) AND BY TAU 48 WILL TRANSFORM INTO A COLD-CORE, STORM-FORCE 
FRONTAL LOW WITH AN EXPANDING WIND FIELD. 

MODEL DISCUSSION: DETERMINISTIC MODEL GUIDANCE IS IN VERY TIGHT 
AGREEMENT WITH A GRADUAL AND EVEN SPREAD TO A MERE 57NM BY TAU 48, 
LENDING HIGH CONFIDENCE TO THE JTWC TRACK FORECAST THAT IS LAID CLOSE 
TO THE MODEL CONSENSUS. GIVEN THE VARIABILITY ASSOCIATED WITH AN ETT, 
THERE IS ONLY MEDIUM CONFIDENCE IN THE INTENSITY FORECAST. 

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