Subject: Pacific-NW: 1. Typhoon 15w (megi) Warning Nr 036

From: SIU Weather Processor <[email-masked]>
Date: Thu, 21 Oct 2010 15:46:07 -0500

WTPN31 PGTW 212100
MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC//
SUBJ/TROPICAL CYCLONE WARNING//
RMKS/
1. TYPHOON 15W (MEGI) WARNING NR 036
   03 ACTIVE TROPICAL CYCLONES IN NORTHWESTPAC
   MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
   WIND RADII VALID OVER OPEN WATER ONLY
    ---
   WARNING POSITION:
   211800Z --- NEAR 20.6N 117.9E
     MOVEMENT PAST SIX HOURS - 015 DEGREES AT 04 KTS
     POSITION ACCURATE TO WITHIN 060 NM
     POSITION BASED ON EYE FIXED BY SATELLITE
   PRESENT WIND DISTRIBUTION:
   MAX SUSTAINED WINDS - 090 KT, GUSTS 110 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 064 KT WINDS - 055 NM NORTHEAST QUADRANT
                            055 NM SOUTHEAST QUADRANT
                            050 NM SOUTHWEST QUADRANT
                            050 NM NORTHWEST QUADRANT
   RADIUS OF 050 KT WINDS - 085 NM NORTHEAST QUADRANT
                            085 NM SOUTHEAST QUADRANT
                            075 NM SOUTHWEST QUADRANT
                            075 NM NORTHWEST QUADRANT
   RADIUS OF 034 KT WINDS - 160 NM NORTHEAST QUADRANT
                            160 NM SOUTHEAST QUADRANT
                            150 NM SOUTHWEST QUADRANT
                            150 NM NORTHWEST QUADRANT
   REPEAT POSIT: 20.6N 117.9E
    ---
   FORECASTS:
   12 HRS, VALID AT:
   220600Z --- 21.1N 118.2E
   MAX SUSTAINED WINDS - 085 KT, GUSTS 105 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 064 KT WINDS - 045 NM NORTHEAST QUADRANT
                            045 NM SOUTHEAST QUADRANT
                            040 NM SOUTHWEST QUADRANT
                            040 NM NORTHWEST QUADRANT
   RADIUS OF 050 KT WINDS - 075 NM NORTHEAST QUADRANT
                            075 NM SOUTHEAST QUADRANT
                            065 NM SOUTHWEST QUADRANT
                            065 NM NORTHWEST QUADRANT
   RADIUS OF 034 KT WINDS - 150 NM NORTHEAST QUADRANT
                            150 NM SOUTHEAST QUADRANT
                            140 NM SOUTHWEST QUADRANT
                            140 NM NORTHWEST QUADRANT
   VECTOR TO 24 HR POSIT: 005 DEG/ 06 KTS
    ---
   24 HRS, VALID AT:
   221800Z --- 22.3N 118.3E
   MAX SUSTAINED WINDS - 070 KT, GUSTS 085 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 064 KT WINDS - 030 NM NORTHEAST QUADRANT
                            030 NM SOUTHEAST QUADRANT
                            025 NM SOUTHWEST QUADRANT
                            030 NM NORTHWEST QUADRANT
   RADIUS OF 050 KT WINDS - 055 NM NORTHEAST QUADRANT
                            055 NM SOUTHEAST QUADRANT
                            050 NM SOUTHWEST QUADRANT
                            050 NM NORTHWEST QUADRANT
   RADIUS OF 034 KT WINDS - 135 NM NORTHEAST QUADRANT
                            130 NM SOUTHEAST QUADRANT
                            120 NM SOUTHWEST QUADRANT
                            125 NM NORTHWEST QUADRANT
   VECTOR TO 36 HR POSIT: 350 DEG/ 07 KTS
    ---
   36 HRS, VALID AT:
   230600Z --- 23.6N 118.0E
   MAX SUSTAINED WINDS - 055 KT, GUSTS 070 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 050 KT WINDS - 030 NM NORTHEAST QUADRANT
                            030 NM SOUTHEAST QUADRANT
                            030 NM SOUTHWEST QUADRANT
                            025 NM NORTHWEST QUADRANT
   RADIUS OF 034 KT WINDS - 080 NM NORTHEAST QUADRANT
                            095 NM SOUTHEAST QUADRANT
                            090 NM SOUTHWEST QUADRANT
                            075 NM NORTHWEST QUADRANT
   VECTOR TO 48 HR POSIT: 340 DEG/ 06 KTS
    ---
   EXTENDED OUTLOOK:
   48 HRS, VALID AT:
   231800Z --- 24.8N 117.5E
   MAX SUSTAINED WINDS - 040 KT, GUSTS 050 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER LAND
   VECTOR TO 72 HR POSIT: 345 DEG/ 04 KTS
    ---
   72 HRS, VALID AT:
   241800Z --- 26.4N 117.0E
   MAX SUSTAINED WINDS - 020 KT, GUSTS 030 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER LAND
    ---
REMARKS:
212100Z POSITION NEAR 20.7N 118.0E.
TYPHOON (TY) 15W (MEGI), LOCATED APPROXIMATELY 235 NM EAST-SOUTHEAST
OF HONG KONG, HAS TRACKED NORTH-NORTHEASTWARD AT 04 KNOTS OVER THE
PAST SIX HOURS. ANIMATED INFRARED SATELLITE IMAGERY AND A 211756Z
AMSU 89 GHZ IMAGE INDICATE THAT DEEP CONVECTION HAS ERODED OVER
THE WESTERN SEMI-CIRCLE OVER THE PAST 06 HOURS DUE TO WESTERLY
VERTICAL WIND SHEAR (VWS) BUT THE SYSTEM HAS MAINTAINED A 40NM
RAGGED EYE. THE INTENSITY HAS BEEN DECREASED TO 90 KNOTS BASED ON
THIS WEAKENING AS WELL AS ON THE LOWER DVORAK ESTIMATES RANGING
FROM 77 TO 102 KNOTS (RJTD IS CURRENTLY AT 115 KNOTS). THE CURRENT
POSITION IS BASED ON THE IR IMAGERY WITH GOOD CONFIDENCE. TY 15W
IS CURRENTLY TRACKING SLOWLY NORTHWARD ALONG THE WESTERN PERIPHERY
OF THE MID-LEVEL SUBTROPICAL RIDGE (STR) POSITIONED EAST. THE 21/12Z
500MB ANALYSIS AND SOUNDINGS (E.G., FROM ISHIGAKI-JIMA) INDICATE
WESTERLY FLOW OVER SOUTHEAST CHINA WITH A SHORTWAVE TROUGH OVER
EASTERN CHINA AND SUPPORT A STRONG STEERING STR. THE TROUGH IS
PROPAGATING NORTHEAST AND THE RIDGE IS MAINTAINING STRENGTH,
THEREFORE, THE SYSTEM IS EXPECTED TO CONTINUE TRACKING POLEWARD
THROUGH THE FORECAST PERIOD. DYNAMIC GUIDANCE IS TIGHTLY CLUSTERED
AND SUPPORTS THIS FORECAST. TY 15W IS EXPECTED TO WEAKEN THROUGH
THE PERIOD DUE TO INCREASING VWS AND SHOULD DISSIPATE OVER LAND
BETWEEN TAU 48 AND 72. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 211800Z
IS 34 FEET. NEXT WARNINGS AT 220300Z, 220900Z, 221500Z AND 222100Z.
REFER TO TROPICAL DEPRESSION 16W (SIXTEEN) WARNINGS (WTPN32 PGTW)
FOR SIX-HOURLY UPDATES. REFER TO TROPICAL DEPRESSION 17W (SEVENTEEN)
WARNINGS (WTPN33 PGTW) FOR SIX-HOURLY UPDATES.//

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