WDPN32 PGTW 272100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 19W (JEBI) WARNING NR 
006//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 19.4N 144.5E
   INITIAL INTENSITY: 35 KTS
   GEOGRAPHIC REFERENCE: 370 NM SOUTH-SOUTHEAST OF IWO TO, JAPAN
   MOVEMENT PAST 6 HOURS: NORTH-NORTHWESTWARD AT 08 KTS
   SIGNIFICANT WAVE HEIGHT: 12 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY SHOWS THE LOW
LEVEL CIRCULATION CENTER (LLCC) HAS BECOME FULLY EXPOSED AS THE COLD
DENSE OVERCAST IS SHEARED EASTWARD AND CONVECTIVE BUILDUP IS
INHIBITED ALONG THE NORTHWEST FLANK BY THE TUTT CELL TO THE NORTHEAST. 
THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE
BASED ON THE EXPOSED LLCC IN THE EIR LOOP. THE INITIAL INTENSITY OF
35KTS IS ALSO ASSESSED WITH HIGH CONFIDENCE BASED ON OVERALL 
ASSESSMENT OF AGENCY AND AUTOMATED DVORAK INTENSITIES AND REFLECTS
THE 6-HR CONVECTIVE DEGRADATION. ANALYSIS INDICATES A MARGINAL
ENVIRONMENT WITH WARM SST AND MODERATED EQUATORWARD OUTFLOW OFFSET
BY TUTT-INDUCED SUBSIDENCE ALOFT, MODERATE SHEAR, AND DRY AIR 
INTRUSION AT THE LOW LEVELS.

INITIAL WIND RADII BASIS: PERSISTENCE.

CURRENT STEERING MECHANISM: SOUTHWESTERN PERIPHERY OF A DEEP-LAYER
SUBTROPICAL RIDGE (STR) TO THE NORTHEAST. 


AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.5 - 35 KTS
   RJTD: T2.5 - 35 KTS
   RCTP: T2.5 - 35 KTS
   KNES: T2.0 - 30 KTS
   CIMSS SATCON: 38 KTS AT 271529Z
   CIMSS ADT: 34 KTS AT 271730Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL
   VWS: 15-20 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: MODERATE EQUATORWARD
   OTHER FACTORS: TUTT CELL TO THE NORTHEAST CAUSING SUBSIDENCE
ALONG THE NORTHWEST FLANK; DRY AIR INTRUSION AT THE LOW LEVELS ALSO
ALONG THE NORTHWEST FLANK.

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   INITIAL INTENSITY: HIGH
   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 JEBI WILL TRACK NORTHWESTWARD UNDER THE
STEERING INFLUENCE OF THE STR TO THE NORTHEAST. AFTER TAU 36, IT
WILL ROUND THE WESTERN EDGE OF THE STR AXIS, RECURVE AND ACCELERATE
NORTHEASTWARD. THE ENVIRONMENT WILL SLOWLY IMPROVE AS VWS INCREASES
AND THE TUTT CELL MOVES WESTWARD AND OPENS UP A POLEWARD OUTFLOW
CHANNEL, RESULTING IN A GRADUAL INTENSIFICATION TO A PEAK OF 70KTS
BY TAU 72 AS THE SYSTEM APPROACHES THE PREVAILING WESTERLIES, FURTHER 
IMPROVING POLEWARD OUTFLOW. AFTERWARD, INCREASING VWS AND COOLING SST 
WILL BEGIN TO GRADUALLY ERODE THE CYCLONE. CONCURRENTLY BY TAU 96, TS 
19W WILL BEGIN EXTRA-TROPICAL TRANSITION AND BY TAU 120 WILL TRANSFORM 
INTO A GALE-FORCE COLD-CORE LOW.

MODEL DISCUSSION: NUMERICAL MODELS ARE IN OVERALL GOOD AGREEMENT
WITH A GRADUAL AND EVEN SPREAD TO A MERE 110NM BY TAU 72; AFTERWARD,
THE MODEL ENVELOPE SPREADS OUT SIGNIFICANTLY TO OVER 1000NM WITH
AFUM THE EXTREME LEFT-OF-TRACK OUTLIER DRIVING THE VORTEX TOWARD
HOKKAIDO. IN VIEW OF THIS, THERE IS HIGH CONFIDENCE IN THE JTWC TRACK 
FORECAST UP TO TAU 72 THEN LOW CONFIDENCE AFTERWARD. THE CONFIDENCE IN 
THE INTENSITY FORECAST IS MEDIUM UP TO TAU 72, THEN LOW AFTERWARD. 

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