WDPN31 PGTW 041500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 05W (AERE) 
WARNING NR 017//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 31.5N 128.5E
   INITIAL INTENSITY: 25 KTS
   GEOGRAPHIC REFERENCE: 114 NM SOUTH-SOUTHWEST OF SASEBO, JAPAN
   MOVEMENT PAST 6 HOURS: NORTHEASTWARD AT 09 KTS
   SIGNIFICANT WAVE HEIGHT: 10 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY SHOWS TD
05W CONTINUES TO STRUGGLE AS THE LOW LEVEL CIRCULATION (LLC) IS
MOSTLY EXPOSED WITH THE CENTRAL CONVECTION IS SHEARED SOUTHEASTWARD. 
THE INITIAL POSITION AND INTENSITY ARE PLACED WITH HIGH CONFIDENCE
BASED ON EXTRAPOLATION FROM A 040830Z SCATTEROMETER DIRECT PASS.
THE INITIAL INTENSITY IS HELD LOWER THAN PGTW AND RJTD DVORAK
ESTIMATES OF T2.0 (30KTS), REFLECTS THE UNCHANGED 6-HR STRUCTURE,
AND IS CONSISTENT WITH PERIPHERAL SURFACE WIND AND MSLP OBSERVATIONS.
ANIMATED WATER VAPOR IMAGERY INDICATES THAT AN UPPER-LEVEL TROUGH
REMAINS ENTRENCHED OVER THE SYSTEM, INDUCING SUBSIDENCE AND STRONG
NORTHWESTERLY VERTICAL WIND SHEAR.

INITIAL WIND RADII BASIS: NOT APPLICABLE (THERE ARE NO INITIAL WIND
RADII).

CURRENT STEERING MECHANISM: DEEP-LAYER SUBTROPICAL RIDGE TO THE
EAST-SOUTHEAST.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.0 - 30 KTS
   RJTD: T2.0 - 30 KTS
   CIMSS ADT: 34 KTS AT 040840Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY
UNFAVORABLE
   VWS: 20-25 KTS
   SST: 26-27 CELSIUS
   OUTFLOW: MODERATE POLEWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   INITIAL INTENSITY: HIGH
   INITIAL WIND RADII: NOT APPLICABLE

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TD 05W WILL TURN EAST-NORTHEASTWARD THEN
EASTWARD AS IT ROUNDS THE NORTHWESTERN PERIPHERY OF THE STEERING
STR. AROUND TAU 72, TD 05W IS EXPECTED TO MERGE WITH A DEVELOPING
SHORTWAVE TROUGH AND SLOW DOWN OFF THE EAST COAST OF HONSHU. BY TAU
96, A SECONDARY STR TO THE NORTHEAST WILL ASSUME STEERING AND DRIVE
THE CYCLONE NORTHWESTWARD. THE SYSTEM WILL, AT BEST, MAINTAIN ITS
CURRENT INTENSITY UP TO TAU 36 AFTER IT MAKES LANDFALL NEAR SASEBO
THEN INTERACTS WITH THE JAPANESE ISLANDS. AFTER TAU 36, IT WILL
EXIT BACK OVER WATER JUST SOUTH OF OKAZAKI. FAVORABLE DIFFLUENCE
ALOFT AND BAROCLINIC INTERACTION WILL PROMOTE INTENSIFICATION TO A
PEAK OF 35KTS AT TAUS 72 AND 96 AS THE SYSTEM GRADUALLY TRANSFORMS
INTO A SUBTROPICAL LOW.

MODEL DISCUSSION: NUMERICAL MODELS REMAIN IN OVERALL GOOD AGREEMENT
WITH THE CURRENT FORECAST SCENARIO THROUGH TAU 120. SOME SPREAD
REMAINS IN THE ORIENTATION AND SPEED OF THE TRACK AS THE SYSTEM
ROUNDS THE RIDGE AXIS AND INTERACTS WITH LAND. ALSO, AFTER TAU 72 
ANOTHER INCREASE IN SPREAD WITH THE CHANGE IN STEERING MECHANISM.
OVERALL, CONFIDENCE IN THE TRACK AND INTENSITY FORECASTS IS MEDIUM
FOR THE WHOLE DURATION.

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