From owner-wx-tropl@LISTSERV.ILLINOIS.EDU Wed Oct 20 11:02:25 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 o9K32Or9015329 for ; Wed, 20 Oct 2010 11:02:24 +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 o9JJ8YWG022864; Tue, 19 Oct 2010 22:02:12 -0500 (CDT) Received: by LISTSERV.ILLINOIS.EDU (LISTSERV-TCP/IP release 14.5) with spool id 3960110 for WX-TROPL@LISTSERV.ILLINOIS.EDU; Tue, 19 Oct 2010 22:02:12 -0500 Received: from relay08.cites.uiuc.edu (relay08.cites.uiuc.edu [128.174.196.9]) by vacuum.cso.uiuc.edu (8.14.2/8.14.2) with ESMTP id o9K32Cd4016957 for ; Tue, 19 Oct 2010 22:02:12 -0500 (CDT) Received: from weather3.admin.niu.edu (weather3.admin.niu.edu [131.156.8.48]) by relay08.cites.uiuc.edu (8.14.4/8.14.2) with ESMTP id o9K325kT011768 for ; Tue, 19 Oct 2010 22:02:11 -0500 (CDT) Received: by weather3.admin.niu.edu (Postfix, from userid 501) id 13C9940501FD; Tue, 19 Oct 2010 22:02:04 -0500 (CDT) X-Proofpoint-Spam-Reason: safe Message-ID: <20101020030205.13C9940501FD@weather3.admin.niu.edu> Date: Tue, 19 Oct 2010 22:02:04 -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 29// To: WX-TROPL@LISTSERV.ILLINOIS.EDU Precedence: list WDPN31 PGTW 200300 MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 15W (MEGI) WARNING NR 29// RMKS/ 1. FOR METEOROLOGISTS. 2. 12 HOUR SUMMARY AND ANALYSIS. A. TYPHOON (TY) 15W (MEGI), LOCATED APPROXIMATELY 350 NM SOUTH- SOUTHEAST OF HONG KONG, HAS TRACKED NORTHWESTWARD AT 03 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY SHOWS A BANDING EYE WITH A DECREASE IN DEEP CONVECTIVE BANDING ON THE NORTHERN PERIPHERY OF THE SYSTEM. HOWEVER, THE OVERALL SYSTEM SIZE HAS EXPANDED WITH INCREASED CONVECTION IN THE SOUTHERN PERIPHERY. THE CURRENT POSITION IS CENTERED ON THE BANDING EYE FEATURE AS DEPICTED IN THE MULTISPECTRAL IMAGERY AND THE CURRENT INTENSITY IS BASED ON A PGTW DVORAK ESTIMATE OF 115 KNOTS. WATER VAPOR ANIMATION DEPICTS EXCELLENT RADIAL OUTFLOW. TY 15W IS IN A WEAK STEERING ENVIRONMENT, SLOWLY TRACKING ALONG THE SOUTHWESTERN PERIPHERY OF A MID-LEVEL SUBTROPICAL RIDGE WEAKENED BY A DEEPENING MID-LATITUDE SHORTWAVE TROUGH MOVING OVER SOUTHEAST CHINA. 3. FORECAST REASONING. A. THE FORECAST TRACK HAS BEEN ADJUSTED POLEWARD DUE TO A MID- LATITUDE TROUGH, WHICH WEAKENED THE SUBTROPICAL STEERING RIDGE MORE THAN PREVIOUSLY EXPECTED. B. TY 15W IS FORECAST TO TRACK NORTH-NORTHWESTWARD WITHIN THE NEXT 12 HOURS AS THE DEEPENING MID-LATITUDE TROUGH CONTINUES TO WEAKEN AND REORIENT THE STEERING RIDGE. POLEWARD OUTFLOW IS EXPECTED TO ENHANCE INTO THE MID-LATITUDE TROUGH AND ALLOW FURTHER INTENSIFICATION WITHIN THE NEXT 24 HOURS. AFTER TAU 24, TY MEGI SHOULD BEGIN WEAKENING AS IT CONTINUES TO MOVE NORTHWARD INTO AN AREA OF INCREASED VERTICAL WIND SHEAR AND DECREASED OCEAN HEAT CONTENT. C. BY TAU 72, TY 15W IS FORECAST TO MAKE LANDFALL EAST OF HONG KONG. THE SYSTEM SHOULD CONTINUE TO TRACK OVER LAND AND BEGIN TO DISSIPATE AS A SIGNIFICANT TROPICAL CYCLONE BY TAU 120. MODEL GUIDANCE IS SOMEWHAT SPREAD WITH GFS, UKMO, JGSI TRACKING THE SYSTEM MORE POLEWARD AND STAIR-STEPPING IT BACK TO THE NORTHWEST AS THE SUBTROPICAL RIDGE TO THE NORTH RE-BUILDS. ECMWF TRACKS THE SYSTEM MORE TO THE NORTHWEST, TOWARDS HONG KONG. THIS FORECAST IS IN AGREEMENT WITH MODEL CONSENSUS AND TRENDS TO THE LEFT OF MODEL CONSENSUS.// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 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.