WDPN32 PGTW 280300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 19W (JEBI) WARNING NR 
007//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 20.0N 143.3E
   INITIAL INTENSITY: 35 KTS
   GEOGRAPHIC REFERENCE: 309 NM SOUTH-SOUTHEAST OF IWO TO, JAPAN
   MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 13 KTS
   SIGNIFICANT WAVE HEIGHT: 12 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) SHOWS THE LOW LEVEL
CIRCULATION CENTER (LLCC) HAS REMAINED 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 MSI 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 SUSTAINED 6-HR CONVECTIVE SIGNATURE. ANALYSIS INDICATES A
MARGINAL ENVIRONMENT WITH WARM SST AND MODERATE EQUATORWARD OUTFLOW
OFFSET BY TUTT-INDUCED SUBSIDENCE ALOFT, MODERATE SHEAR, AND DRY
AIR INTRUSION AT THE LOW LEVELS.

INITIAL WIND RADII BASIS: SCATTEROMETER DATA.

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: T2.0 - 30 KTS
   CIMSS ADT: 34 KTS AT 272330Z
   CIMSS DPRNT: 35 KTS AT 272330Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL
   VWS: 15-20 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: MODERATE EQUATORWARD

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 24, IT
WILL ROUND THE WESTERN EDGE OF THE STR AXIS, RECURVE AND ACCELERATE
NORTHEASTWARD. THE ENVIRONMENT WILL SLOWLY IMPROVE AS VWS DECREASES
AND THE TUTT CELL MOVES WESTWARD AND OPENS UP A POLEWARD OUTFLOW
CHANNEL BEHIND IT, RESULTING IN A GRADUAL INTENSIFICATION TO A PEAK OF 
70KTS BY TAU 48 AS THE SYSTEM APPROACHES THE PREVAILING WESTERLIES, 
FURTHER IMPROVING POLEWARD OUTFLOW. AFTERWARD, SUSTAINED DRY AIR 
INTRUSION, INCREASING VWS AND COOLING SST WILL GRADUALLY ERODE THE 
CYCLONE. CONCURRENTLY BY TAU 72, TS 19W WILL BEGIN EXTRA-TROPICAL 
TRANSITION AND BY TAU 96 WILL TRANSFORM INTO A STRONG GALE-FORCE COLD-
CORE LOW.

MODEL DISCUSSION: NUMERICAL MODELS ARE IN OVERALL GOOD AGREEMENT
WITH A GRADUAL AND EVEN SPREAD TO A MERE 96NM BY TAU 72; AFTERWARD,
THE MODEL ENVELOPE SPREADS OUT TO OVER 350NM WITH AFUM THE LEFT-OF-
TRACK OUTLIER. 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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