Subject: Pacific-NW: 1. Tropical Storm 11w (eleven) Warning Nr 004

From: SIU Weather Processor <[email-masked]>
Date: Wed, 8 Sep 2010 15:25:12 -0500

WTPN31 PGTW 082100
MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC//
SUBJ/TROPICAL CYCLONE WARNING//
RMKS/
1. TROPICAL STORM 11W (ELEVEN) WARNING NR 004
   01 ACTIVE TROPICAL CYCLONE IN NORTHWESTPAC
   MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
   WIND RADII VALID OVER OPEN WATER ONLY
    ---
   WARNING POSITION:
   081800Z --- NEAR 21.0N 118.9E
     MOVEMENT PAST SIX HOURS - 280 DEGREES AT 05 KTS
     POSITION ACCURATE TO WITHIN 060 NM
     POSITION BASED ON CENTER LOCATED BY SATELLITE
   PRESENT WIND DISTRIBUTION:
   MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   REPEAT POSIT: 21.0N 118.9E
    ---
   FORECASTS:
   12 HRS, VALID AT:
   090600Z --- 21.6N 117.9E
   MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 034 KT WINDS - 030 NM NORTHEAST QUADRANT
                            035 NM SOUTHEAST QUADRANT
                            025 NM SOUTHWEST QUADRANT
                            025 NM NORTHWEST QUADRANT
   VECTOR TO 24 HR POSIT: 320 DEG/ 06 KTS
    ---
   24 HRS, VALID AT:
   091800Z --- 22.5N 117.1E
   MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 034 KT WINDS - 035 NM NORTHEAST QUADRANT
                            040 NM SOUTHEAST QUADRANT
                            030 NM SOUTHWEST QUADRANT
                            030 NM NORTHWEST QUADRANT
   VECTOR TO 36 HR POSIT: 325 DEG/ 06 KTS
    ---
   36 HRS, VALID AT:
   100600Z --- 23.5N 116.3E
   MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER LAND
   VECTOR TO 48 HR POSIT: 335 DEG/ 07 KTS
    ---
   EXTENDED OUTLOOK:
   48 HRS, VALID AT:
   101800Z --- 24.8N 115.6E
   MAX SUSTAINED WINDS - 020 KT, GUSTS 030 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER LAND
    ---
REMARKS:
082100Z POSITION NEAR 21.2N 118.6E.
TROPICAL STORM (TS) 11W (ELEVEN), LOCATED APPROXIMATELY 280 NM
EAST-SOUTHEAST OF HONG KONG, HAS TRACKED WESTWARD AT 05 KNOTS OVER
THE PAST SIX HOURS. ANIMATED INFRARED (IR) IMAGERY REVEALS A
PARTIALLY EXPOSED LOW LEVEL CIRCULATION CENTER WITH DEEP CONVECTION
SHEARING TO THE SOUTHEAST OF THE SYSTEM. THE CURRENT POSITION AND
PAST SIX HOUR MOTION ARE BASED ON ANIMATED IR IMAGERY WITH POOR
CONFIDENCE. THE CURRENT INTENSITY IS BASED ON DVORAK ESTIMATES FROM
PGTW AND KNES OF 35 KNOTS. UPPER LEVEL ANALYSIS INDICATES NORTH-
NORTHWESTERLY VERTICAL WIND SHEAR OVER THE SYSTEM, ASSOCIATED WITH
THE UPPER LEVEL LOW MOVING WESTWARD INTO EASTERN CHINA AND
CONTINUING TO IMPINGE POLEWARD OUTFLOW. TS 11W IS CURRENTLY TRACKING
ALONG THE SOUTHERN PERIPHERY OF A WESTERN EXTENSION OF A LOW TO MID-
LEVEL SUBTROPICAL STEERING RIDGE (STR) STATIONED SOUTH OF MAINLAND
JAPAN. TS 11W IS FORECAST TO INTENSIFY SLIGHTLY AND SLOWLY TURN
POLEWARD AS THE RIDGE IS WEAKENED BY AN APPROACHING MID-LATITUDE
TROUGH. THE SYSTEM IS EXPECTED TO MAKE LANDFALL BY TAU 36 AND
DISSIPATE AS A SIGNIFICANT TROPICAL CYCLONE BY TAU 48. NUMERICAL
MODEL GUIDANCE IS IN FAIR AGREEMENT, WITH THE EXCEPTION OF GFS WHICH
RAPIDLY WEAKENS THE STR AND DRIVES THE SYSTEM POLEWARD FASTER AND
SOONER. GFDN, WBAR, NGPS, ECMWF, AND JGSM MODEL TRACKERS HAVE ALL
SHIFTED SLIGHTLY EASTWARD FROM THE PREVIOUS 12Z TRACKERS, INDICATING
THE STEERING RIDGE MAY WEAKEN SOONER THEN PREVIOUSLY FORECAST. THIS
FORECAST IS CONSISTENT WITH THE PREVIOUS FORECAST AND REMAINS WEST
OF CONSENSUS TO ACCOUNT FOR THE AFOREMENTIONED GFS POLEWARD BIAS AND
UPPER AIR SOUNDINGS FROM HONG KONG, AND SHANTOU, CHINA INDICATING
EASTERLY FLOW. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 081800Z IS 13
FEET. NEXT WARNINGS AT 090300Z, 090900Z, 091500Z AND 092100Z.//

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