WTPN31 PGTW 200300
MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC//
SUBJ/TROPICAL CYCLONE WARNING//
RMKS/
1. TROPICAL STORM 15W (CHOI-WAN) WARNING NR 033
DOWNGRADED FROM TYPHOON 15W
01 ACTIVE TROPICAL CYCLONE IN NORTHWESTPAC
MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
WIND RADII VALID OVER OPEN WATER ONLY
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WARNING POSITION:
200000Z --- NEAR 33.9N 146.8E
MOVEMENT PAST SIX HOURS - 040 DEGREES AT 21 KTS
POSITION ACCURATE TO WITHIN 060 NM
POSITION BASED ON CENTER LOCATED BY SATELLITE
PRESENT WIND DISTRIBUTION:
MAX SUSTAINED WINDS - 060 KT, GUSTS 075 KT
WIND RADII VALID OVER OPEN WATER ONLY
BECOMING EXTRATROPICAL
RADIUS OF 050 KT WINDS - 095 NM NORTHEAST QUADRANT
110 NM SOUTHEAST QUADRANT
095 NM SOUTHWEST QUADRANT
085 NM NORTHWEST QUADRANT
RADIUS OF 034 KT WINDS - 160 NM NORTHEAST QUADRANT
175 NM SOUTHEAST QUADRANT
140 NM SOUTHWEST QUADRANT
140 NM NORTHWEST QUADRANT
REPEAT POSIT: 33.9N 146.8E
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FORECASTS:
12 HRS, VALID AT:
201200Z --- 37.6N 152.7E
MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT
WIND RADII VALID OVER OPEN WATER ONLY
EXTRATROPICAL
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REMARKS:
200300Z POSITION NEAR 34.8N 148.3E.
TROPICAL STORM (TS) 15W (CHOI-WAN), LOCATED 360 NM EAST-SOUTHEAST OF
TOKYO, JAPAN, HAS TRACKED NORTHEASTWARD AT 23 KNOTS OVER THE PAST
SIX HOURS. TS 15W HAS ACCELERATED TO THE NORTHEAST UNDER THE COM-
BINED STEERING INFLUENCE OF THE NORTHWESTERN PERIPHERY OF THE SUB-
TROPICAL RIDGE AND AN APPROACHING MID-LATITUDE TROUGH. RECENT ANI-
MATED MULTISPECTRAL IMAGERY DEPICTS A DETERIORATING TROPICAL STORM
WITH THE DEEP CONVECTION RAPIDLY ERODING ON THE SOUTHERN HALF OF THE
SYSTEM. THE CONVECTION IS BEING ADVERSELY AFFECTED BY DRY MID-
LATITUDE AIR WRAPPING INTO THE LOW LEVEL CIRCULATION CENTER (LLCC)
AND FULLY EXPOSING THE LLCC. ALSO, THE SYSTEM IS EXHIBITING STRONG
BAROCLINIC CHARACTERISTICS SUCH AS WARM FRONTOGENESIS TO THE NORTH-
EAST OF THE LLCC AND COLD FRONTOGENESIS TO THE SOUTHEAST. AN
INCREASINGLY UNFAVORABLE ENVIRONMENT WITH INCREASING VERTICAL WIND
SHEAR ASSOCIATED WITH THE JET STREAM ALOFT, DECREASING SEA SURFACE
TEMP-ERATURES AND COLD AIR ADVECTION ASSOCIATED WITH THE MID-
LATITUDE TROUGH HAVE BEEN THE MAJOR FACTORS IN THE RAPID DECLINE IN
BOTH THE SYSTEM STRUCTURE AND INTENSITY. THIS IS THE FINAL WARNING
ON THIS SYSTEM BY THE JOINT TYPHOON WARNING CENTER (NAVMARFCSTCEN).
THE SYSTEM WILL BE CLOSELY MONITORED FOR SIGNS OF REGENERATION.
MAXIMUM SIGNIFICANT WAVE HEIGHT AT 200000Z IS 30 FEET.//
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