Subject: Pacific-NW: 1. Typhoon 15w (megi) Warning Nr 032

From: SIU Weather Processor <[email-masked]>
Date: Wed, 20 Oct 2010 15:48:07 -0500

WTPN31 PGTW 202100
MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC//
SUBJ/TROPICAL CYCLONE WARNING//
RMKS/
1. TYPHOON 15W (MEGI) WARNING NR 032
   01 ACTIVE TROPICAL CYCLONE IN NORTHWESTPAC
   MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
   WIND RADII VALID OVER OPEN WATER ONLY
    ---
   WARNING POSITION:
   201800Z --- NEAR 18.8N 117.4E
     MOVEMENT PAST SIX HOURS - 020 DEGREES AT 05 KTS
     POSITION ACCURATE TO WITHIN 040 NM
     POSITION BASED ON CENTER LOCATED BY SATELLITE
   PRESENT WIND DISTRIBUTION:
   MAX SUSTAINED WINDS - 100 KT, GUSTS 125 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 064 KT WINDS - 055 NM NORTHEAST QUADRANT
                            060 NM SOUTHEAST QUADRANT
                            065 NM SOUTHWEST QUADRANT
                            065 NM NORTHWEST QUADRANT
   RADIUS OF 050 KT WINDS - 085 NM NORTHEAST QUADRANT
                            095 NM SOUTHEAST QUADRANT
                            105 NM SOUTHWEST QUADRANT
                            105 NM NORTHWEST QUADRANT
   RADIUS OF 034 KT WINDS - 160 NM NORTHEAST QUADRANT
                            175 NM SOUTHEAST QUADRANT
                            180 NM SOUTHWEST QUADRANT
                            180 NM NORTHWEST QUADRANT
   REPEAT POSIT: 18.8N 117.4E
    ---
   FORECASTS:
   12 HRS, VALID AT:
   210600Z --- 19.9N 117.7E
   MAX SUSTAINED WINDS - 095 KT, GUSTS 115 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 064 KT WINDS - 045 NM NORTHEAST QUADRANT
                            050 NM SOUTHEAST QUADRANT
                            050 NM SOUTHWEST QUADRANT
                            050 NM NORTHWEST QUADRANT
   RADIUS OF 050 KT WINDS - 075 NM NORTHEAST QUADRANT
                            085 NM SOUTHEAST QUADRANT
                            090 NM SOUTHWEST QUADRANT
                            090 NM NORTHWEST QUADRANT
   RADIUS OF 034 KT WINDS - 150 NM NORTHEAST QUADRANT
                            160 NM SOUTHEAST QUADRANT
                            160 NM SOUTHWEST QUADRANT
                            160 NM NORTHWEST QUADRANT
   VECTOR TO 24 HR POSIT: 015 DEG/ 05 KTS
    ---
   24 HRS, VALID AT:
   211800Z --- 20.8N 118.0E
   MAX SUSTAINED WINDS - 090 KT, GUSTS 110 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 064 KT WINDS - 040 NM NORTHEAST QUADRANT
                            045 NM SOUTHEAST QUADRANT
                            045 NM SOUTHWEST QUADRANT
                            045 NM NORTHWEST QUADRANT
   RADIUS OF 050 KT WINDS - 070 NM NORTHEAST QUADRANT
                            075 NM SOUTHEAST QUADRANT
                            080 NM SOUTHWEST QUADRANT
                            080 NM NORTHWEST QUADRANT
   RADIUS OF 034 KT WINDS - 145 NM NORTHEAST QUADRANT
                            150 NM SOUTHEAST QUADRANT
                            150 NM SOUTHWEST QUADRANT
                            150 NM NORTHWEST QUADRANT
   VECTOR TO 36 HR POSIT: 360 DEG/ 07 KTS
    ---
   36 HRS, VALID AT:
   220600Z --- 22.1N 118.0E
   MAX SUSTAINED WINDS - 075 KT, GUSTS 090 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 064 KT WINDS - 030 NM NORTHEAST QUADRANT
                            030 NM SOUTHEAST QUADRANT
                            030 NM SOUTHWEST QUADRANT
                            030 NM NORTHWEST QUADRANT
   RADIUS OF 050 KT WINDS - 055 NM NORTHEAST QUADRANT
                            055 NM SOUTHEAST QUADRANT
                            060 NM SOUTHWEST QUADRANT
                            060 NM NORTHWEST QUADRANT
   RADIUS OF 034 KT WINDS - 135 NM NORTHEAST QUADRANT
                            135 NM SOUTHEAST QUADRANT
                            135 NM SOUTHWEST QUADRANT
                            140 NM NORTHWEST QUADRANT
   VECTOR TO 48 HR POSIT: 345 DEG/ 06 KTS
    ---
   EXTENDED OUTLOOK:
   48 HRS, VALID AT:
   221800Z --- 23.2N 117.7E
   MAX SUSTAINED WINDS - 060 KT, GUSTS 075 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 050 KT WINDS - 035 NM NORTHEAST QUADRANT
                            035 NM SOUTHEAST QUADRANT
                            040 NM SOUTHWEST QUADRANT
                            040 NM NORTHWEST QUADRANT
   RADIUS OF 034 KT WINDS - 110 NM NORTHEAST QUADRANT
                            105 NM SOUTHEAST QUADRANT
                            105 NM SOUTHWEST QUADRANT
                            110 NM NORTHWEST QUADRANT
   VECTOR TO 72 HR POSIT: 320 DEG/ 04 KTS
    ---
   72 HRS, VALID AT:
   231800Z --- 24.4N 116.6E
   MAX SUSTAINED WINDS - 045 KT, GUSTS 055 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER LAND
   VECTOR TO 96 HR POSIT: 305 DEG/ 03 KTS
    ---
   LONG RANGE OUTLOOK:
   NOTE...ERRORS FOR TRACK HAVE AVERAGED NEAR 250 NM
   ON DAY 4 AND 350 NM ON DAY 5... AND FOR INTENSITY
   NEAR 20 KT EACH DAY.
    ---
   96 HRS, VALID AT:
   241800Z --- 25.0N 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:
202100Z POSITION NEAR 19.1N 117.5E.
TYPHOON (TY) 15W (MEGI), LOCATED APPROXIMATELY 275 NM SOUTHEAST OF
HONG KONG, HAS TRACKED NORTH-NORTHEASTWARD AT 05 KNOTS OVER THE PAST
SIX HOURS. ANIMATED INFRARED SATELLITE IMAGERY INDICATES THAT TY 15W
HAS CONTINUED TO SLOWLY WEAKEN OVER THE PAST 06 HOURS. HOWEVER, IR
IMAGERY DEPICTS AN INTENSE SYSTEM WITH A BANDING EYE AND A 201737Z
AMSR-E IMAGE DEPICTS A LARGE SYMMETRIC MICROWAVE EYE WITH CONVECTIVE
BANDING OVER THE NORTHWEST QUADRANT. ANIMATED WATER VAPOR IMAGERY
DEPICTS EXCELLENT RADIAL OUTFLOW WITH ENHANCED POLEWARD OUTFLOW
ASSOCIATED WITH A MIDLATITUDE SHORTWAVE TROUGH DEEPENING OVER
SOUTHEAST CHINA. THE 20/12Z 500MB ANALYSIS DEPICTS A SHARP
MIDLATITUDE SHORTWAVE TROUGH OVER EASTERN CHINA WITH WESTERLY FLOW
ACROSS SOUTHEAST CHINA AND A SUBTROPICAL RIDGE POSITIONED EAST OF
THE SYSTEM. OVER THE PAST 24 HOURS, THE DYNAMIC MODELS HAVE BECOME
MORE STABLE AND ARE IN GOOD AGREEMENT THROUGH TAU 48, SUPPORTING THE
POLEWARD TRACK. AFTER TAU 48, TY 15W IS FORECAST TO ENCOUNTER STRONG
VERTICAL WIND SHEAR AND SHOULD WEAKEN RAPIDLY AND DE-COUPLE.
SUBSEQUENTLY, MODEL GUIDANCE DIVERGES AND THERE IS INCREASED
UNCERTAINTY IN THE LATER TAUS. THE CURRENT FORECAST FAVORS A
NORTHWESTWARD TURN  INTO CHINA UNDER THE STEERING INFLUENCE OF LOW-
LEVEL NORTHEASTERLY FLOW ASSOCIATED WITH A BROAD HIGH PRESSURE
SYSTEM OVER KOREA/JAPAN. TY 15W IS FORECAST TO WEAKEN SLOWLY THROUGH
TAU 36 BUT SHOULD WEAKEN RAPIDLY THEREAFTER DUE TO THE VERTICAL WIND
SHEAR AND LAND INTERACTION. MAXIMUM SIGNIFICANT WAVE HEIGHT AT
201800Z IS 38 FEET. NEXT WARNINGS AT 210300Z, 210900Z, 211500Z AND
212100Z.//

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