Subject: Pacific-NW: 1. Tropical Storm 15w (megi) Warning Nr 004

From: SIU Weather Processor <[email-masked]>
Date: Wed, 13 Oct 2010 15:32:05 -0500

WTPN31 PGTW 132100
MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC//
SUBJ/TROPICAL CYCLONE WARNING//
RMKS/
1. TROPICAL STORM 15W (MEGI) 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:
   131800Z --- NEAR 11.6N 140.7E
     MOVEMENT PAST SIX HOURS - 245 DEGREES AT 02 KTS
     POSITION ACCURATE TO WITHIN 060 NM
     POSITION BASED ON CENTER LOCATED BY SATELLITE
   PRESENT WIND DISTRIBUTION:
   MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 034 KT WINDS - 050 NM NORTHEAST QUADRANT
                            055 NM SOUTHEAST QUADRANT
                            045 NM SOUTHWEST QUADRANT
                            050 NM NORTHWEST QUADRANT
   REPEAT POSIT: 11.6N 140.7E
    ---
   FORECASTS:
   12 HRS, VALID AT:
   140600Z --- 12.0N 139.8E
   MAX SUSTAINED WINDS - 065 KT, GUSTS 080 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 050 KT WINDS - 035 NM NORTHEAST QUADRANT
                            035 NM SOUTHEAST QUADRANT
                            035 NM SOUTHWEST QUADRANT
                            035 NM NORTHWEST QUADRANT
   RADIUS OF 034 KT WINDS - 080 NM NORTHEAST QUADRANT
                            080 NM SOUTHEAST QUADRANT
                            075 NM SOUTHWEST QUADRANT
                            080 NM NORTHWEST QUADRANT
   VECTOR TO 24 HR POSIT: 300 DEG/ 06 KTS
    ---
   24 HRS, VALID AT:
   141800Z --- 12.6N 138.8E
   MAX SUSTAINED WINDS - 075 KT, GUSTS 090 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 064 KT WINDS - 025 NM NORTHEAST QUADRANT
                            025 NM SOUTHEAST QUADRANT
                            025 NM SOUTHWEST QUADRANT
                            025 NM NORTHWEST QUADRANT
   RADIUS OF 050 KT WINDS - 045 NM NORTHEAST QUADRANT
                            045 NM SOUTHEAST QUADRANT
                            040 NM SOUTHWEST QUADRANT
                            045 NM NORTHWEST QUADRANT
   RADIUS OF 034 KT WINDS - 100 NM NORTHEAST QUADRANT
                            095 NM SOUTHEAST QUADRANT
                            090 NM SOUTHWEST QUADRANT
                            100 NM NORTHWEST QUADRANT
   VECTOR TO 36 HR POSIT: 300 DEG/ 09 KTS
    ---
   36 HRS, VALID AT:
   150600Z --- 13.5N 137.2E
   MAX SUSTAINED WINDS - 095 KT, GUSTS 115 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 064 KT WINDS - 035 NM NORTHEAST QUADRANT
                            035 NM SOUTHEAST QUADRANT
                            035 NM SOUTHWEST QUADRANT
                            035 NM NORTHWEST QUADRANT
   RADIUS OF 050 KT WINDS - 060 NM NORTHEAST QUADRANT
                            060 NM SOUTHEAST QUADRANT
                            055 NM SOUTHWEST QUADRANT
                            060 NM NORTHWEST QUADRANT
   RADIUS OF 034 KT WINDS - 115 NM NORTHEAST QUADRANT
                            110 NM SOUTHEAST QUADRANT
                            105 NM SOUTHWEST QUADRANT
                            115 NM NORTHWEST QUADRANT
   VECTOR TO 48 HR POSIT: 295 DEG/ 12 KTS
    ---
   EXTENDED OUTLOOK:
   48 HRS, VALID AT:
   151800Z --- 14.5N 135.0E
   MAX SUSTAINED WINDS - 105 KT, GUSTS 130 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 064 KT WINDS - 040 NM NORTHEAST QUADRANT
                            040 NM SOUTHEAST QUADRANT
                            040 NM SOUTHWEST QUADRANT
                            040 NM NORTHWEST QUADRANT
   RADIUS OF 050 KT WINDS - 065 NM NORTHEAST QUADRANT
                            065 NM SOUTHEAST QUADRANT
                            060 NM SOUTHWEST QUADRANT
                            065 NM NORTHWEST QUADRANT
   RADIUS OF 034 KT WINDS - 120 NM NORTHEAST QUADRANT
                            115 NM SOUTHEAST QUADRANT
                            115 NM SOUTHWEST QUADRANT
                            120 NM NORTHWEST QUADRANT
   VECTOR TO 72 HR POSIT: 295 DEG/ 10 KTS
    ---
   72 HRS, VALID AT:
   161800Z --- 16.1N 131.0E
   MAX SUSTAINED WINDS - 110 KT, GUSTS 135 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   RADIUS OF 064 KT WINDS - 040 NM NORTHEAST QUADRANT
                            040 NM SOUTHEAST QUADRANT
                            040 NM SOUTHWEST QUADRANT
                            040 NM NORTHWEST QUADRANT
   RADIUS OF 050 KT WINDS - 065 NM NORTHEAST QUADRANT
                            065 NM SOUTHEAST QUADRANT
                            065 NM SOUTHWEST QUADRANT
                            070 NM NORTHWEST QUADRANT
   RADIUS OF 034 KT WINDS - 125 NM NORTHEAST QUADRANT
                            120 NM SOUTHEAST QUADRANT
                            120 NM SOUTHWEST QUADRANT
                            130 NM NORTHWEST QUADRANT
   VECTOR TO 96 HR POSIT: 285 DEG/ 11 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:
   171800Z --- 17.0N 126.7E
   MAX SUSTAINED WINDS - 120 KT, GUSTS 145 KT
   WIND RADII VALID OVER OPEN WATER ONLY
   VECTOR TO 120 HR POSIT: 270 DEG/ 09 KTS
    ---
   120 HRS, VALID AT:
   181800Z --- 17.1N 122.8E
   MAX SUSTAINED WINDS - 120 KT, GUSTS 145 KT
   WIND RADII VALID OVER OPEN WATER ONLY
    ---
REMARKS:
132100Z POSITION NEAR 11.7N 140.5E.
TROPICAL STORM (TS) 15W (MEGI) LOCATED APPROXIMATELY 195 NM
NORTHEAST OF YAP, HAS REMAINED QUASISTATIONARY OVER THE PAST 06
HOURS. RECENT ANIMATED INFRARED SATELLITE IMAGERY SHOWS DEEP FLARING
CONVECTION AND TIGHT FORMATIVE BANDING ASSOCIATED WITH A RAPIDLY
DEVELOPING LOW LEVEL CIRCULATION CENTER (LLCC). WATER VAPOR IMAGERY
SHOWS THE SYSTEM HAS GOOD RADIAL OUTFLOW AND IS DEVELOPING AN
OUTFLOW CHANNEL INTO A TROPICAL UPPER TROPOSPHERIC TROUGH (TUTT) TO
THE EAST. A 131554Z AMSR-E IMAGE SHOWS DEEP CONVECTION OVER THE LLCC
WITH CONVECTIVE BANDING FORMING TO THE SOUTH. THE SYSTEM IS
CURRENTLY TRACKING IN A WEAK STEERING ENVIRONMENT ALONG THE SOUTHERN
PERIPHERY OF THE DEEP SUB-TROPICAL RIDGE (STR). AS AN APPROACHING
UPPER LEVEL, MID-LATITUDE TROUGH MOVES IN FROM THE WEST, THE STR
WILL REORIENT AND ALLOW TS 15W TO BEGIN TRACKING IN A MORE
NORTHWESTWARD DIRECTION (TAU 12 THROUGH 48). DURING THIS PERIOD,
POLEWARD OUTFLOW IS EXPECTED TO BECOME ENHANCED INTO THE DIFFLUENT
REGION AHEAD OF THE TROUGH. THIS, COUPLED WITH HIGH SEA SURFACE
TEMPERATURES, LARGE AMOUNTS OF PRECIPITABLE WATER IN THE AIR COLUMN,
AND EASTWARD OUTFLOW INTO THE TUTT, WILL LIKELY CAUSE THE SYSTEM TO
UNDERGO RAPID INTENSIFICATION (RI). AFTER TAU 48, THE STR IS
EXPECTED RE-BUILD TO THE NORTH AND THE SYSTEM WILL RESUME TRACKING
WESTWARD. MODEL TRACK GUIDANCE IS IN EXCELLENT AGREEMENT.
ADDITIONALLY, MODELS THAT GENERALLY HANDLE RI (GFDN AND COAMPS) ARE
SHOWING SOME RI SIGNALS IN THE NEXT 48 HOURS. MAXIMUM SIGNIFICANT
WAVE HEIGHT AT 131800Z IS 12 FEET.
NEXT WARNINGS AT 140300Z, 140900Z, 141500Z AND 142100Z.
//

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