From owner-wx-tropl@LISTSERV.ILLINOIS.EDU Sat Oct 16 22:20:39 2010 Received: from vacuum.cso.uiuc.edu (vacuum.cso.uiuc.edu [128.174.5.113]) by cozumel.ust.hk (8.13.8/8.13.8) with ESMTP id o9GEKbit012233 for ; Sat, 16 Oct 2010 22:20:38 +0800 Received: from vacuum.cso.uiuc.edu (vacuum.cso.uiuc.edu [128.174.5.113]) by vacuum.cso.uiuc.edu (8.14.2/8.14.2) with ESMTP id o9G400EY028194; Sat, 16 Oct 2010 09:20:16 -0500 (CDT) Received: by LISTSERV.ILLINOIS.EDU (LISTSERV-TCP/IP release 14.5) with spool id 3914509 for WX-TROPL@LISTSERV.ILLINOIS.EDU; Sat, 16 Oct 2010 09:20:15 -0500 Received: from relay03.cites.uiuc.edu (relay03.cites.uiuc.edu [128.174.4.69]) by vacuum.cso.uiuc.edu (8.14.2/8.14.2) with ESMTP id o9GEKF8v014926 for ; Sat, 16 Oct 2010 09:20:15 -0500 (CDT) Received: from weather3.admin.niu.edu (weather3.admin.niu.edu [131.156.8.48]) by relay03.cites.uiuc.edu (8.14.4/8.14.2) with ESMTP id o9GEK9v0002650 for ; Sat, 16 Oct 2010 09:20:15 -0500 (CDT) Received: by weather3.admin.niu.edu (Postfix, from userid 501) id B8417108B0002; Sat, 16 Oct 2010 09:20:08 -0500 (CDT) X-Proofpoint-Spam-Reason: safe Message-ID: <20101016142008.B8417108B0002@weather3.admin.niu.edu> Date: Sat, 16 Oct 2010 09:20:08 -0500 Reply-To: wxmaster@COX.NET Sender: WX-TROPL Tropical Storm and Hurricane WX products From: SIU Weather Processor Subject: Pacific-NW: Subj/prognostic Reasoning For Typhoon 15w (megi) Warning Nr 15// To: WX-TROPL@LISTSERV.ILLINOIS.EDU Precedence: list WDPN31 PGTW 161500 MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 15W (MEGI) WARNING NR 15// RMKS/ 1. FOR METEOROLOGISTS. 2. 12 HOUR SUMMARY AND ANALYSIS. A. TYPHOON 15W (MEGI), LOCATED APPROXIMATELY 580 NM EAST- NORTHEAST OF MANILA, PHILIPPINES, HAS TRACKED WEST-NORTHWESTWARD AT 13 KNOTS OVER THE PAST SIX HOURS. MEGI HAS YET TO DEVELOP A WELL- DEFINED EYE DESPITE A CURRENT INTENSITY OF 105 KNOTS. THIS INTENSITY IS BASED ON A DATA-T AND CURRENT INTENSITY (CI) OF 5.5 FROM PGTW. A CLOUD-FILLED EYE CAN BE EVIDENCED IN CERTAIN INFRARED ENHANCEMENTS, WHICH HAS PROVIDED HIGH POSITION CONFIDENCE. AN UPPER LEVEL INVERTED TROUGH OVER THE PHILIPPINE SEA HAS LIKELY STALLED RAPID INTENSIFICATION BY LIMITING EXPANSION OF DEEP CONVECTION WITHIN THE WESTERN SEMICIRCLE. POLEWARD OUTFLOW HAS IMPROVED AHEAD OF A TRANSITORY MID-LATITUDE TROUGH AND EQUATORWARD OUTFLOW PERSISTS INTO A TROPICAL UPPER LEVEL TROUGH CELL LOCATED NEAR 17N 152E. THE TRACK HAS BEGUN TO FLATTEN TOWARDS THE WEST AS THE SUBTROPICAL STEERING RIDGE STRENGTHENS IN THE WAKE OF A PASSING MID-LATITUDE TROUGH. RISING 500 MB HEIGHTS OVER SOUTHEST ASIA CONFIRM A BUILDING MID- LEVEL RIDGE. 3. FORECAST REASONING. A. THE FORECAST HAS BEEN SLOWED IN THE SOUTH CHINA SEA IN RESPONSE TO THE MAJORITY OF THE CONSENSUS MEMBERS HINTING AT ANOTHER PASSING TROUGH. B. MEGI IS STILL SLATED TO TRACK GENERALLY WESTWARD ALONG THE SOUTHERN PERIPHERY OF THE DEEP LAYER STEERING RIDGE AND GLANCE LUZON SHORTLY AFTER 18/00Z AROUND SUPER TYPHOON STRENGTH, ASSUMING THE UPPER LEVEL TROUGH TO THE WEST FILLS. NOGAPS AND WBAR HAVE WALKED TOWARDS THE MODEL CONSENSUS AND THE OFFICIAL JTWC FORECAST OVER THE PAST 2 RUNS. NEARLY ALL THE TRACKERS INDICATE THE STEERING RIDGE WILL STRENGTHEN OVER THE NEXT 3 DAYS, AND TRACK THE SYSTEM TOWARDS THE WEST. THE SYSTEM WILL WEAKEN CONSIDERABLY OVER THE RUGGED TERRAIN OF NORTHERN LUZON. IF IT TRACKS SOUTH OF TRACK, AS THE LATEST ECMWF AND GFS RUNS SUGGEST, THEN MORE WEAKENING WILL OCCUR. REGARDLESS, REINTENSIFICATION IS EXPECTED IN THE SOUTH CHINA SEA. C. AS STATED IN PARA 3.A. THE TRACK HAS BEEN ADJUSTED BEYOND TAU 72. NEARLY ALL THE MODEL TRACKERS ARE INDICATING A SLOW DOWN AROUND THIS TIME, LIKELY IN RESPONSE TO ANOTHER PASSING TROUGH. +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ To unsubscribe from WX-TROPL send e-mail to LISTSERV@LISTSERV.ILLINOIS.EDU with "unsub wx-tropl" in the body of your message. For help with WX-TROPL write to cnovy@cox.net. For more information on tropical weather products, see the NHC Homepage at http://www.nhc.noaa.gov.