From owner-wx-tropl@LISTSERV.ILLINOIS.EDU Wed Oct 20 21:48:25 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 o9KDmO5u021906 for ; Wed, 20 Oct 2010 21:48:25 +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 o9KBitDH000580; Wed, 20 Oct 2010 08:48:12 -0500 (CDT) Received: by LISTSERV.ILLINOIS.EDU (LISTSERV-TCP/IP release 14.5) with spool id 3965675 for WX-TROPL@LISTSERV.ILLINOIS.EDU; Wed, 20 Oct 2010 08:48:12 -0500 Received: from relay01.cites.uiuc.edu (relay01.cites.uiuc.edu [128.174.4.23]) by vacuum.cso.uiuc.edu (8.14.2/8.14.2) with ESMTP id o9KDmCkF012033 for ; Wed, 20 Oct 2010 08:48:12 -0500 (CDT) Received: from weather3.admin.niu.edu (weather3.admin.niu.edu [131.156.8.48]) by relay01.cites.uiuc.edu (8.14.4/8.14.2) with ESMTP id o9KDm6uR019206 for ; Wed, 20 Oct 2010 08:48:12 -0500 (CDT) Received: by weather3.admin.niu.edu (Postfix, from userid 501) id 0FBF64050315; Wed, 20 Oct 2010 08:48:05 -0500 (CDT) X-Proofpoint-Spam-Reason: safe Message-ID: <20101020134806.0FBF64050315@weather3.admin.niu.edu> Date: Wed, 20 Oct 2010 08:48:05 -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 31// To: WX-TROPL@LISTSERV.ILLINOIS.EDU Precedence: list WDPN31 PGTW 201500 MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 15W (MEGI) WARNING NR 31// RMKS/ 1. FOR METEOROLOGISTS. 2. 12 HOUR SUMMARY AND ANALYSIS. A. TYPHOON (TY) 15W (MEGI), LOCATED APPROXIMATELY 285 NM SOUTH- EAST OF HONG KONG, CHINA HAS TRACKED NORTHWARD AT 07 KNOTS OVER THE PAST SIX HOURS. ANIMATED WATER VAPOR IMAGERY SHOWS THE SYSTEM HAS BEGUN TO ERODE ALONG ITS NORTHERN PERIPHERY AS IT GETS EXPOSED TO THE STRONG UPPER LEVEL WESTERLY WINDS. THERE IS ALSO A NOTED DECREASE IN THE DEEP CONVECTION ALONG THE NORTHERN RIM OF THE EYEWALL. THIS IS EVIDENT ON THE 201111Z SSSMI-S MICROWAVE IMAGERY THAT SHOWS A WELL- DEFINED SYMMETRIC EYE WITH CONTINUOUS BANDING ALONG THE SOUTHERN SEMI-CIRCLE. THE CURRENT POSITION IS BASED ON SATELLITE ANIMATION AND EXTRAPOLATED FROM THE ABOVE MICROWAVE IMAGE. THE CURRENT INTENSITY IS BASED ON DVORAK ESTIMATES FROM PGTW, RJTD, AND KNES. UPPER LEVEL ANALYSIS INDICATES TY 15W IS APPROACHING THE BREAK IN THE RIDGE TO THE NORTH CAUSED BY THE SHORT WAVE TROUGH CURRENTLY DIGGING SOUTHWARD INTO SOUTHEASTERN CHINA. 3. FORECAST REASONING. A. THERE IS NO SIGNIFICANT CHANGE TO THE PREVIOUS FORECAST TRACK PHILOSOPHY. B. TY 15W IS EXPECTED TO CONTINUE TRACKING NORTHWARD OVER THE NEXT 36 HOURS IN RESPONSE TO THE AFOREMENTIONED MID-LATITUDE TROUGH. THE VERTICAL WIND SHEAR WILL GRADUALLY INCREASE WITH THE INCREASED UPPER LEVEL WINDS AS THE SYSTEM APPROACHES THE SUBTROPICAL JET STREAM. THIS WILL GRADUALLY ERODE AND WEAKEN THE SYSTEM. AFTER THE TROUGH PASSES TO THE NORTHEAST AFTER TAU 36, THE SUBTROPICAL RIDGE WILL RE-BUILD ALONG THE SOUTHERN BOUNDARY OF CHINA AND STEER THE SYSTEM TO THE NORTHWEST. C. TYPHOON MEGI IS FORECAST TO MAKE LANDFALL EAST OF HONG KONG AROUND TAU 60 THEN RAPIDLY DISSIPATE AS A SIGNIFICANT TROPICAL CYCLONE. MODEL GUIDANCE IS IN LOOSE AGREEMENT WITH GFS AS THE RIGHTMOST OUTLIER. THIS FORECAST IS JUST TO THE LEFT OF MODEL CONSENSUS TO OFFSET GFS.// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 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.