WDPN31 PGTW 031500

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//

SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 04W (MUN)

WARNING NR 008//

RMKS/

1. FOR METEOROLOGISTS.

2. 6 HOUR SUMMARY AND ANALYSIS.



SUMMARY:

   INITIAL POSITION: 28.3N 145.5E

   INITIAL INTENSITY: 60 KTS

   GEOGRAPHIC REFERENCE: 190 NM EAST-NORTHEAST OF CHICHI JIMA

   MOVEMENT PAST 6 HOURS: NORTH-NORTHEASTWARD AT 07 KTS

   SIGNIFICANT WAVE HEIGHT: 22 FEET



SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:

UPPER-LEVEL OUTFLOW HAS IMPROVED QUICKLY AS INDICATED IN THE CIMSS

COMBINED MESOAMV PLOTS, WHICH INDICATE THE UPPER-LOW PREVIOUSLY OVER

THE CENTER HAS WEAKENED WITH A DEVELOPING POINT SOURCE. ADDITIONALLY,

THE SYSTEM HAS MAINTAINED STRONG EASTWARD, DIFFLUENT OUTFLOW ENHANCED

BY A JET TO THE NORTHEAST, WITH A MOISTENING CORE. CONSEQUENTLY,

ANIMATED ENHANCED INFRARED SATELLITE IMAGERY DEPICTS A COMPACT CORE

AND IMPROVED CENTRAL CONVECTION AND ORGANIZATION, WITH THE SYSTEM

FLIRTING WITH A DEVELOPING WEAK EYE OVER THE PAST FEW HOURS. TWO

RECENT IMAGES ALSO PROVIDE SOLID EVIDENCE THAT TS 04W IS CONSOLIDATING

QUICKLY: A 030751Z WSFM 89GHZ COLOR COMPOSITE IMAGE, DEPICTING A

MICROWAVE EYE FEATURE, AND A 030835Z RCM-3 SAR IMAGE, DEPICTING A

SYMMETRIC CENTER WITH A BAND OF 50-60 KNOT WINDS SURROUNDING THE

CENTER. THE SAR IMAGE DOES SHOW MAXIMUM WINDS AS HIGH AS 72 KNOTS OVER

THE NORTHEAST QUADRANT BUT THESE WINDS APPEAR TO BE TOO HIGH. THE

INITIAL INTENSITY IS ASSESSED AT 60 KNOTS BASED ON THE SAR DATA,

HEDGED ABOVE THE HIGHEST SUBJECTIVE DVORAK ESTIMATE FROM KNES. CIMSS

OBJECTIVE ESTIMATES REMAIN TOO LOW, RANGING FROM 34-48 KNOTS.



INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK



CURRENT STEERING MECHANISM: EXTENSIVE DEEP-LAYERED SUBTROPICAL RIDGE

(STR) PATTERN TO THE SOUTH, EXTENDING NORTHEASTWARD OVER THE EASTERN

PERIPHERY OF THE SYSTEM, WITH A WEAK STR EXTENSION TO THE NORTHEAST.



AGENCY DVORAK AND AUTOMATED FIXES:

   PGTW: T3.0 - 45 KTS

   RJTD: T2.0 - 30 KTS

   RCTP: T2.5 - 35 KTS

   KNES: T3.5 - 55 KTS

   CIMSS SATCON: 45 KTS AT 030900Z

   CIMSS ADT: 34 KTS AT 031130Z

   CIMSS AIDT: 39 KTS AT 031130Z

   CIMSS D-MINT: 48 KTS AT 030810Z

   CIMSS D-PRINT: 44 KTS AT 031130Z



FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE

   VWS: 5-10 KTS

   SST: 26-27 CELSIUS

   OUTFLOW: STRONG EASTWARD



ANALYSIS CONFIDENCE:

   INITIAL POSITION: HIGH

   INITIAL INTENSITY: MEDIUM

   INITIAL WIND RADII: MEDIUM



3. FORECAST REASONING.



SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO

THE FORECAST FROM THE PREVIOUS WARNING.



FORECAST DISCUSSION: TS 04W IS FORECAST TO TRACK NORTHWARD THROUGH

TAU 24 ALONG THE WESTERN PERIPHERY OF THE STR. AFTER TAU 24, THE

SYSTEM IS EXPECTED TO TURN SHARPLY NORTHEASTWARD AS THE STR

REORIENTS IN RESPONSE TO AN APPROACHING SHORTWAVE TROUGH OVER NORTHERN

JAPAN. THE SHORTWAVE TROUGH WILL RAPIDLY PROPAGATE EASTWARD ALLOWING

THE STR TO REBUILD, WHICH WILL DRIVE THE SYSTEM ON A MORE POLEWARD

TRAJECTORY THROUGH TAU 120. ENVIRONMENTAL CONDITIONS ARE IMPROVING,

WHICH WILL SUPPORT A SHORT PERIOD OF INTENSIFICATION, DRIVEN LARGELY

BY THE ROBUST EASTWARD OUTFLOW, WITH A PEAK INTENSITY OF 70 KNOTS

FORECAST BY TAU 24. SST VALUES WILL COOL STEADILY AFTER TAU 24, WITH

VALUES DECREASING TO 24C BY TAU 48 THEN BELOW 20C AFTER TAU 72. AFTER

TAU 60, ENVIRONMENTAL CONDITIONS WILL DEGRADE QUICKLY, WITH INCREASING

VERTICAL WIND SHEAR (VWS) OF 35-40 KNOTS, WHICH WILL LEAD TO RAPID

WEAKENING. THE SYSTEM IS EXPECTED TO TRANSITION TO A SUBTROPICAL

SYSTEM NEAR TAU 120.



MODEL DISCUSSION: DUE TO THE COMPLEX STEERING ENVIRONMENT AND RUN-TO-

RUN INCONSISTENCIES, THERE IS MEDIUM CONFIDENCE IN THE JTWC TRACK

FORECAST THROUGH TAU 72. THERE IS A 70NM CROSS-TRACK SPREAD IN THE

GUIDANCE AT TAU 72, HOWEVER, THERE ARE SIGNIFICANT DIFFERENCES IN

THE ALONG-TRACK SPEEDS. THE 030600Z GEFS RUN, IN PARTICULAR, INDICATES

A WIDE SWATH OF SOLUTIONS FROM CENTRAL JAPAN TO 155E. THE GFS

DETERMINISTIC MODEL HAS JUMPED AROUND ERRATICALLY THE PAST THREE

RUNS, AND NOW SHOWS A DISSIPATING, WEAK SYSTEM TRACKING TOWARD

MAINLAND JAPAN. ALTHOUGH THERE ARE TWO ECENS SOLUTIONS TRACKING TOWARD

MAINLAND JAPAN, THE BULK OF THE ECENS GUIDANCE SUPPORTS A MORE

POLEWARD ORIENTED TRACK WELL EAST OF JAPAN. RELIABLE INTENSITY

GUIDANCE IS MORE COHESIVE, WITH THE BULK OF THE GUIDANCE SHOWING A

BRIEF INTENSIFICATION PERIOD FROM TAU 0 TO TAU 48. HAFS-A INDICATES A

PEAK INTENSITY OF 88 KNOTS BY TAU 60, HOWEVER, THE TRACK IS A

SIGNIFICANT OUTLIER AND SUSPECT. DUE TO HIGH UNCERTAINTY AFTER TAU 72,

THERE IS LOW CONFIDENCE IN THE EXTENDED JTWC FORECAST TRACK.



FORECAST CONFIDENCE:

   TRACK 0 - 72 HR: MEDIUM

   TRACK 72-120 HR: LOW

   INTENSITY 0 - 72 HR: MEDIUM

   INTENSITY 72-120 HR: LOW//

NNNN