Tropical Storm MITAG Advisory 9月28日

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 19W (NINETEEN) WARNING
NR 03//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 19W (NINETEEN), LOCATED APPROXIMATELY 791 NM
SOUTH-SOUTHEAST OF KADENA AB, OKINAWA, JAPAN HAS TRACKED WEST-
NORTHWESTWARD AT 14 KNOTS (KTS) OVER THE PAST SIX HOURS. ANIMATED
ENHANCED INFRARED (EIR) SATELLITE IMAGERY SHOWS CONVECTIVE BANDING
WRAPPING INTO THE LOW LEVEL CIRCULATION CENTER (LLCC), SUPPORTING
FAIR CONFIDENCE IN THE INITIAL POSITION. BASED ON THE WIND FIELD
MEASURED IN THE 271233Z METOP-B AND 271159Z METOP-C ASCAT PASSES,
ALONG WITH A DVORAK CURRENT INTENSITY ESTIMATE OF T2.5 (35 KTS) FROM
PGTW, THE INITIAL INTENSITY IS SET AT 35 KTS WITH HIGH CONFIDENCE.
ADDITIONALLY, THE AFOREMENTIONED ASCAT PASSES WERE UTILIZED TO
ESTIMATE THE WIND RADII. UPPER LEVEL ANALYSIS REVEALS THAT TS 19W
REMAINS IN A MODERATELY FAVORABLE (15-20 KTS) VERTICAL WIND SHEAR
(VWS) ENVIRONMENT WITH STRONG EQUATORWARD OUTFLOW AND FAIR POLEWARD
OUTFLOW. HIGHLY FAVORABLE SEA SURFACE TEMPERATURES (SST) OF 30
CELSIUS PLACE THE SYSTEM IN AN OVERALL FAVORABLE ENVIRONMENT FOR
CONTINUED INTENSIFICATION. TRACKING WEST-NORTHWESTWARD, TS 19W IS
BEING STEERED BY A SUBTROPICAL RIDGE (STR) TO THE NORTH OF THE
SYSTEM.
3. FORECAST REASONING.
   A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE
PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. TS 19W WILL CONTINUE TO TRACK WEST-NORTHWESTWARD ALONG THE
PERIPHERY OF THE STR UNTIL TAU 60 WHEN THE SYSTEM WILL TURN
NORTHWARD AS IT RECURVES AROUND THE WESTERN EDGE OF THE STR. WITH A
CONTINUED FAVORABLE ENVIRONMENT, TS 19W WILL INTENSIFY THROUGHOUT
THIS PORTION OF THE FORECAST, REACHING A PEAK INTENSITY OF 100 KTS
AT TAU 72. THE JTWC FORECAST TRACK IS PLACED NEAR THE MODEL
CONSENSUS TRACK AS DYNAMIC GUIDANCE IS IN FAIR AGREEMENT. HOWEVER,
JGSM REMAINS AN EASTERN OUTLIER WITH A 144 NM SEPARATION FROM THE
CONSENSUS BY TAU 72. THUS, THERE IS LOW CONFIDENCE IN THIS PORTION
OF THE JTWC FORECAST TRACK.
   C. BEYOND TAU 72, TS 19W WILL ROUND THE WESTERN EDGE OF THE STR
AND BEGIN TO TRACK NORTH-NORTHEASTWARD. DIVERGENCE ALOFT WILL REMAIN
ROBUST, ALLOWING TS 19W TO MAINTAIN A HIGH INTENSITY (95 KTS)
THROUGH TAU 96. AS THE SYSTEM TRANSITS INTO THE SEA OF JAPAN, THE
ENVIRONMENT WILL BECOME UNFAVORABLE (DRY MID-LEVEL AIR, COOL SST,
HIGH VWS) AND THE SYSTEM WILL BEGIN TO WEAKEN, SLOWLY AT FIRST THEN
MORE QUICKLY. PRIOR TO TAU 120, INTERACTION WITH THE MID-LATITUDE
WESTERLIES WILL ACCELERATE THE TRACK NORTHEASTWARD AND INITIATE
EXTRATROPICAL TRANSITION. FOR THE EXTENDED FORECAST, DYNAMIC MODEL
GUIDANCE IS IN FAIR CROSS-TRACK AGREEMENT (80 NM SPREAD) BUT TRACK
CONFIDENCE REMAINS LOW DUE TO POOR ALONG-TRACK AGREEMENT (520 NM
SPREAD).//
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