Tropical Storm KUJIRA Advisory 9月28日

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 15W (KUJIRA) WARNING NR
009//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 15W (KUJIRA), LOCATED APPROXIMATELY 730 NM
EAST-NORTHEAST OF IWO TO, JAPAN, HAS TRACKED NORTH-NORTHEASTWARD AT 15
KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE
IMAGERY SHOWS INCREASED POLEWARD OUTFLOW HAS PRIMARILY FUELED THE
DEEPENED CENTRAL CONVECTION THAT REMAINED FAIRLY SYMMETRICAL BUT ALSO
CONTINUED TO OBSCURE THE THE LOW-LEVEL CIRCULATION (LLC). THE INITIAL
POSITION IS PLACED WITH GOOD CONFIDENCE BASED ON A WELL-DEFINED LLC
FEATURE IN THE 281510Z AMSR2 MICROWAVE IMAGE. THE INITIAL INTENSITY OF
45KTS IS AVERAGED FROM THE CURRENT INTENSITY ESTIMATES OF T3.0/45KTS
AND T3.5/55KTS FROM PGTW AND RJTD, RESPECTIVELY, AND REFLECTS THE
IMPROVED STATE OF THE SYSTEM. UPPER-LEVEL ANALYSIS INDICATES A
MARGINALLY-FAVORABLE ENVIRONMENT WITH ROBUST POLEWARD OUTFLOW AND WARM
SST (29-30C) THAT ARE PARTLY OFFSET BY LOW TO MODERATE (10-20KT)
VERTICAL WIND SHEAR (VWS). ALSO, STRONG CONVERGENCE OVER THE SOUTHERN
SEMICIRCLE ASSOCIATED WITH AN UPPER LEVEL TROUGH CONTINUES TO HINDER
CONVECTIVE DEVELOPMENT. TS 15W IS TRACKING NORTHWARD UNDER THE STEERING
INFLUENCE OF A SUBTROPICAL RIDGE (STR) TO THE EAST.
3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
   B. TS KUJIRA HAS CRESTED THE STR AND IS FORECAST TO ACCELERATE
NORTHEASTWARD ON THE POLEWARD SIDE. THE MARGINALLY-FAVORABLE DYNAMICS
WILL WILL PROMOTE FURTHER INTENSIFICATION TO A PEAK OF 55KTS BY TAU 12.
AFTERWARD, INCREASING VWS AND COOLING SSTS WILL CONTRIBUTE TO A GRADUAL
WEAKENING TO 45KTS BY TAU 36. ALSO, BY TAU 12, TS 15W WILL BEGIN
EXTRATROPICAL TRANSITION AS IT INTERACTS WITH MIDLATITUDE WESTERLIES,
BECOMING A STORM-FORCE COLD CORE LOW BY TAU 24. NUMERICAL MODELS REMAIN
IN TIGHT AGREEMENT THROUGHOUT THE FORECAST PERIOD, LENDING HIGH
CONFIDENCE IN THE JTWC FORECAST TRACK.//
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