Tropical Storm KUJIRA Advisory Tue Sep 29

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 15W (KUJIRA) WARNING NR
007//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 15W (KUJIRA), LOCATED APPROXIMATELY 232 NM
NORTH OF MINAMI TORI SHIMA, HAS TRACKED NORTH-NORTHWESTWARD AT 16
KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE
IMAGERY DEPICTS A PARTIALLY-EXPOSED, WELL-DEFINED LOW-LEVEL
CIRCULATION CENTER (LLCC) WITH PERSISTENT DEEP CONVECTION OVER THE
WESTERN SEMICIRCLE. A 280622Z SSMIS 37GHZ MICROWAVE IMAGE REVEALS
SHALLOW BANDING WRAPPING TIGHTLY INTO A DEFINED LLCC, WHICH SUPPORTS
THE INITIAL POSITION WITH GOOD CONFIDENCE. THE INITIAL INTENSITY IS
ASSESSED AT 45 KNOTS BASED ON A PGTW DVORAK ESTIMATE OF T3.0 (45
KNOTS) AND RECENT ASCAT DATA. UPPER-LEVEL ANALYSIS INDICATES A
MARGINALLY-FAVORABLE ENVIRONMENT WITH ROBUST POLEWARD OUTFLOW, WARM
SST (29-30C) AND LOW VERTICAL WIND SHEAR (VWS). HOWEVER, STRONG
CONVERGENCE OVER THE SOUTHERN SEMICIRCLE CONTINUES TO HINDER
CONVECTIVE DEVELOPMENT. TS 15W IS TRACKING NORTH-NORTHWESTWARD UNDER
THE STEERING INFLUENCE OF A SUBTROPICAL RIDGE (STR) POSITIONED TO
THE NORTHEAST.
3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
   B. TS 15W IS FORECAST TO TRACK NORTHWARD TO NORTH-NORTHEASTWARD
THROUGH TAU 24 AS IT ROUNDS THE SUBTROPICAL RIDGE. AFTER TAU 24, TS
15W WILL TURN NORTHEASTWARD AND SHOULD BEGIN EXTRATROPICAL
TRANSITION (ETT) NEAR TAU 36 AS IT INTERACTS WITH MIDLATITUDE
WESTERLIES AND ENCOUNTERS INCREASING VWS (20-30 KNOTS). THE SYSTEM
IS FORECAST TO INTENSIFY TO A PEAK INTENSITY OF 65 KNOTS BY TAU 36.
GRADUAL WEAKENING IS EXPECTED AFTER TAU 36 AS VWS INCREASES TO 30-40
KNOTS AND THE SYSTEM TRACKS OVER COOL SST (24-20C). AS THE SYSTEM
RECURVES EAST-NORTHEASTWARD TO EASTWARD, IT WILL COMPLETE ETT
BETWEEN TAU 60 TO 72 AS IT GAINS FRONTAL CHARACTERISTICS AND BECOMES
EMBEDDED WITHIN THE MIDLATITUDE WESTERLIES. NUMERICAL MODEL GUIDANCE
AND THE ECMWF ENSEMBLE SOLUTIONS REMAIN IN TIGHT AGREEMENT
THROUGHOUT THE FORECAST PERIOD. THUS, THERE IS HIGH CONFIDENCE IN
THE JTWC FORECAST TRACK.//
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