WDPN32 PGTW 301500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 19W (JEBI)         
WARNING NR 017//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 29.2N 140.9E
   INITIAL INTENSITY: 45 KTS
   GEOGRAPHIC REFERENCE: 371 NM SOUTH OF YOKOSUKA, JAPAN
   MOVEMENT PAST 6 HOURS: NORTHWARD AT 13 KTS
   SIGNIFICANT WAVE HEIGHT: 20 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED SATELLITE IMAGERY CONTINUES TO REVEAL
IMPROVING NEAR-RADIAL OUTFLOW, ESPECIALLY OVER THE WESTERN SEMICIRCLE, 
WITH CLOUD FILAMENTS ALONG THE WESTERN EDGE OF THE CONVECTION, AND 
ENHANCED POLEWARD VENTING INTO THE WESTERLIES TO THE NORTH. THIS HAS 
ALLOWED THE SYSTEM TO CONSOLIDATE QUICKLY WITH A CENTRAL DENSE 
OVERCAST NOW PRESENT OVER THE LOW-LEVEL CIRCULATION. A 301130Z MHS 
89GHZ MICROWAVE IMAGE REVEALS TIGHTLY CURVED CONVECTIVE BANDING 
WRAPPING INTO A DEFINED LOW-LEVEL CIRCULATION CENTER (LLCC), WHICH 
SUPPORTS THE INITIAL POSITION WITH MEDIUM CONFIDENCE. THE INITIAL 
INTENSITY IS ASSESSED AT 45 KNOTS WITH MEDIUM CONFIDENCE BASED ON THE 
PGTW DVORAK ESTIMATE AND CIMSS OBJECTIVE ESTIMATES RANGING FROM 43-49 
KNOTS. A 300835Z RCM-3 SAR IMAGE SHOWS A SWATH OF 45-50 KNOT WINDS 
OVER THE EASTERN SEMICIRCLE, WHICH SUPPORTS THE INITIAL INTENSITY 
ASSESSMENT. 

INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK 

CURRENT STEERING MECHANISM: LOW- TO MID-LEVEL SUBTROPICAL RIDGE
POSITIONED TO THE EAST, WITH RIDGE EXTENDING POLEWARD

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.0 - 45 KTS
   RJTD: T2.5 - 35 KTS
   RCTP: T2.5 - 35 KTS
   KNES: T2.5 - 35 KTS
   CIMSS ADT: 45 KTS AT 301210Z
   CIMSS AIDT: 43 KTS AT 301210Z
   CIMSS DPRINT: 49 KTS AT 301210Z
   CIMSS DMINT: 45 KTS AT 300857Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 5-10 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: MODERATE POLEWARD AND EQUATORWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: MEDIUM
   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: BASED ON THE IMPROVED ENVIRONMENTAL CONDITIONS
PREVIOUSLY DISCUSSED, TS 19W IS EXPECTED TO INTENSIFY TO MINIMAL
TYPHOON STRENGTH OVER THE NEXT DAY, WITH A PEAK INTENSITY OF 70
KNOTS NEAR TAU 24. THE TRACK FORECAST IS RELATIVELY STRAIGHT-FORWARD, 
WITH A NORTHWARD TRACK THROUGH TAU 24 ALONG THE WESTERN PERIPHERY OF 
THE STR. AFTER TAU 24, THE SYSTEM WILL BEGIN TO INTERACT WITH AN 
UPPER-LEVEL SHORTWAVE TROUGH AND WILL COMMENCE EXTRA-TROPICAL 
TRANSITION (ETT). AS THE SYSTEM RECURVES NORTHEASTWARD AROUND THE STR 
AXIS, IT WILL TRACK UNDER THE JET AND GAIN FRONTAL CHARACTERISTICS, 
COMPLETING ETT BY TAU 48. STEADY WEAKENING FROM TAU 24 TO TAU 48 IS 
EXPECTED AS THE SYSTEM ENCOUNTERS STRONG VERTICAL WIND SHEAR AND 
TRACKS OVER COOLER SST VALUES. TS 19W WILL MAINTAIN A RELATIVELY 
COMPACT REGION OF GALE-FORCE WINDS, PRIMARILY LOCATED OVER THE EASTERN 
SEMICIRCLE, AS IT PASSES EAST OF THE KANTO PLAIN.        

MODEL DISCUSSION: THE CPA TO YOKOSUKA HAS CONTINUED TO FLUCTUATE
WITHIN A 123-149NM RANGE OVER THE PAST DAY DUE TO UNCERTAINTY IN
THE INITIAL POSITION AND MINOR POSITIONAL SHIFTS. THE 300600Z ECMWF
ENSEMBLE (EPS) SHOWS A TIGHT GROUPING OF SOLUTIONS BUT CLEARLY
SHOWS SOME UNCERTAINTY IN THE EXACT TRACK, WHICH COULD LEAD TO SOME
MINOR VARIATIONS IN THE CPAS OVER THE NEXT DAY. THE 300600Z GFS
ENSEMBLE (GEFS) SHOWS A WIDER SPREAD OF SOLUTIONS AND A SLIGHT
SHIFT IN THE ENVELOPE OVER THE EASTERN COAST OF CENTRAL HONSHU.
HOWEVER, THE BULK OF THE SOLUTIONS REMAIN OVER WATER TO THE EAST OF
YOKOSUKA. DETERMINISTIC GUIDANCE COMPRISING THE JTWC TRACK
CONSENSUS (CONW) ALSO SHOWS A TIGHT GROUPING OF MODELS OVER WATER
EAST OF YOKOSUKA, WITH A CROSS-TRACK SPREAD RANGING FROM 50NM AT
TAU 12 TO 66NM AT TAU 24. THE TRACKER CLOSEST TO YOKOSUKA ON THE
WESTERN SIDE OF THE AIDS ENVELOPE IS 70NM FROM THE EAST COAST OF
JAPAN AT CPA.      

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