From owner-wx-tropl@LISTSERV.ILLINOIS.EDU Sun Oct 17 22:25:37 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 o9HEPaZI012156 for ; Sun, 17 Oct 2010 22:25:37 +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 o9GB0RdF029155; Sun, 17 Oct 2010 09:25:15 -0500 (CDT) Received: by LISTSERV.ILLINOIS.EDU (LISTSERV-TCP/IP release 14.5) with spool id 3922249 for WX-TROPL@LISTSERV.ILLINOIS.EDU; Sun, 17 Oct 2010 09:25:15 -0500 Received: from relay05.cites.uiuc.edu (relay05.cites.uiuc.edu [128.174.4.40]) by vacuum.cso.uiuc.edu (8.14.2/8.14.2) with ESMTP id o9HEPFov009811 for ; Sun, 17 Oct 2010 09:25:15 -0500 (CDT) Received: from weather3.admin.niu.edu (weather3.admin.niu.edu [131.156.8.48]) by relay05.cites.uiuc.edu (8.14.4/8.14.2) with ESMTP id o9HEP85E029169 for ; Sun, 17 Oct 2010 09:25:15 -0500 (CDT) Received: by weather3.admin.niu.edu (Postfix, from userid 501) id 4F75040501A6; Sun, 17 Oct 2010 09:25:07 -0500 (CDT) X-Proofpoint-Spam-Reason: safe Message-ID: <20101017142508.4F75040501A6@weather3.admin.niu.edu> Date: Sun, 17 Oct 2010 09:25:07 -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 Super Typhoon 15w (megi) Warning Nr To: WX-TROPL@LISTSERV.ILLINOIS.EDU Precedence: list WDPN31 PGTW 171500 MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC// SUBJ/PROGNOSTIC REASONING FOR SUPER TYPHOON 15W (MEGI) WARNING NR 19// RMKS/ 1. FOR METEOROLOGISTS. 2. 12 HOUR SUMMARY AND ANALYSIS. A. SUPER TYPHOON (STY) 15W (MEGI), LOCATED APPROXIMATELY 310 NM NORTHEAST OF MANILA, PHILIPPINES, HAS TRACKED WEST-SOUTHWESTWARD AT 11 KNOTS OVER THE PAST 06 HOURS ALONG THE SOUTHERN PERIPHERY OF THE DEEP LAYER SUBTROPICAL RIDGE TO THE NORTH. MEGI HAS INTENSIFIED TO THE UPPER REACHES OF SUPER TYPHOON STRENGTH. CURRENT DVORAK EYE FIXES FROM PGTW AND RJTD ESTIMATE MAXIMUM SUSTAINED SURFACE WINDS HAVE ELEVATED 10 KNOTS FROM THE PREVIOUS FORECAST TO 155 KNOTS. A STRENGTHENED POLEWARD OUTFLOW CHANNEL HAS SUPPORTED THIS INTENSIFICATION, IN ADDITION TO SUSTAINED EQUATORWARD OUTFLOW INTO A TROPICAL UPPER LEVEL TROPOSPHERIC TROUGH CELL TO THE EAST. EYE TEMPERATURES HAVE REMAINED STEADY AT AROUND 15 DEG CELCIUS AND THE EYE DIAMETER HAS RANGED FROM 20 TO 25 NM. 3. FORECAST REASONING. A. THIS FORECAST REFLECTS A HIGHER INITIAL INTENSITY THAN PREVIOUSLY FORECAST. B. OUTER RAINBANDS HAVE ALREADY BEGUN TO AFFECT LUZON. THE SYSTEM CENTER IS EXPECTED TO TRACK OVER LUZON IN LESS THAN 12 HOURS AND WILL WEAKEN CONSIDERABLY OVER THE RUGGED TOPOGRAPHY. IT WILL EMERGE INTO THE SOUTH CHINA SEA AROUND 18/12Z, REORGANIZE, AND GRADUALLY STRENGTHEN. AROUND THIS TIME THE STEERING RIDGE WILL BEGIN TO WEAKEN AND THE SYSTEM WILL SLOW AND TURN NORTH OF WEST TO THE EAST OF HAINAN. MODEL GUIDANCE HAS COME INTO BETTER AGREEMENT FROM SIX HOURS AGO. GFS REMAINS THE LONE OUTLIER THROUGH THE FIRST 48 HOURS AND STALLS THE CYCLONE OFF THE WEST COAST OF LUZON FOR 1 TO 2 DAYS, THEN JERKS THE TRACK PECULIARLY NORTHEAST. THE REST OF THE MODEL PACKING RIDES THE SOUTHERN PERIPHERY OF THE WEAKENING/RETREATING STEERING RIDGE TO THE WEST THEN NORTHWEST, TO INCLUDE NOGAPS. C. IN THE EXTENDED FORECAST MEGI WILL TURN TOWARDS A BUILDING WEAKENESS IN THE STEERING RIDGE OVER SOUTHERN CHINA. MODEL FIELDS INDICATE A SHORT WAVE TROUGH AS THE SOURCE OF THIS WEAKNESS. THERE IS INCREASED UNCERTAINTY IN THE INTENSITY FORECAST GIVEN THE WIDE RANGE AMONG THE INTENSITY GUIDANCE. NONTHELESS, THE 15Z JTWC FORECAST REMAINS CONSISTENT WITH A REINTENSIFICATION SCENARIO.// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 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.