From owner-wx-tropl@LISTSERV.ILLINOIS.EDU Fri Oct 22 22:04:47 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 o9ME4ktm030067 for ; Fri, 22 Oct 2010 22:04:46 +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 o9LJQBrX014749; Fri, 22 Oct 2010 09:04:17 -0500 (CDT) Received: by LISTSERV.ILLINOIS.EDU (LISTSERV-TCP/IP release 14.5) with spool id 3996137 for WX-TROPL@LISTSERV.ILLINOIS.EDU; Fri, 22 Oct 2010 09:04:17 -0500 Received: from relay06.cites.uiuc.edu (relay06.cites.uiuc.edu [128.174.196.8]) by vacuum.cso.uiuc.edu (8.14.2/8.14.2) with ESMTP id o9ME4HoK005993 for ; Fri, 22 Oct 2010 09:04:17 -0500 (CDT) Received: from weather3.admin.niu.edu (weather3.admin.niu.edu [131.156.8.48]) by relay06.cites.uiuc.edu (8.14.4/8.14.2) with ESMTP id o9ME4AJx026960 for ; Fri, 22 Oct 2010 09:04:17 -0500 (CDT) Received: by weather3.admin.niu.edu (Postfix, from userid 501) id 905AA108B0002; Fri, 22 Oct 2010 09:04:10 -0500 (CDT) X-Proofpoint-Spam-Reason: safe Message-ID: <20101022140410.905AA108B0002@weather3.admin.niu.edu> Date: Fri, 22 Oct 2010 09:04:10 -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 39// To: WX-TROPL@LISTSERV.ILLINOIS.EDU Precedence: list WDPN31 PGTW 221500 MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 15W (MEGI) WARNING NR 39// RMKS/ 1. FOR METEOROLOGISTS. 2. 12 HOUR SUMMARY AND ANALYSIS. A. TYPHOON (TY) 15W (MEGI), LOCATED APPROXIMATELY 235 NM EAST OF HONG KONG, HAS TRACKED NORTHWARD AT 06 KNOTS OVER THE PAST SIX HOURS. THE TY HAS CONTINUED TO TRACK ALONG THE WESTERN EXTENT OF A DEEP LAYER STEERING RIDGE TO THE EAST TOWARDS THE CHINESE COASTLINE. LANDFALL IS EXPECTED TO OCCUR IN MUCH THE SAME PLACE AND SAME INTENSITY AS FORECAST TWELVE HOURS AGO. THE SYSTEM HAS BEGUN TO WEAKEN UNDER THE INFLUENCE OF MODERATE VERTICAL WIND SHEAR AND INCREASED SUBSIDENCE. THE CENTRAL CONVECTION HAS SHALLOWED AND CONTRACTED TOWARDS THE CENTER AND THE LARGE EYE HAS BECOME COMPLETELY CLOUD FILLED. THE INITIAL INTENSITY IS BASED ON FALLING DVORAK ESTIMATES FROM PGTW, WHICH INDICATE THE INTENSITY RANGES FROM 77 TO 102 KNOTS. THE CURRENT POSITION IS BASED ON A 221047Z SSMIS MICROWAVE IMAGE, IN ADDITION TO POSITION FIXES FROM PGTW AND RJTD, AND PLACES THE SYSTEM TO THE SOUTH OF A STATIONARY BOUNDARY. COMPARISON OF HIGH AND LOW MICROWAVE FREQUENCIES SUGGESTS THAT THE UPPER LEVEL CIRCULATION IS BEGINNING TO TILT TO THE NORTHEAST OF THE LOW LEVEL CIRCULATION CENTER. 3. FORECAST REASONING. A. THERE IS NO CHANGE IN THE FORECAST PHILOSOPHY. B. TY 15W WILL CONTINUE TO WEAKEN AS IT TRACKS NORTH TOWARDS CHINA. A SHORTWAVE TROUGH IS CURRENTLY DIGGING TO THE WEST OF THE TY AND IS INCITING INCREASED VERTICAL WIND SHEAR AND SUBSIDENCE. THE BASE OF THE TROUGH IS WELL SOUTH OF THE TY'S CURRENT LATITUDE. LANDFALL IS EXPECTED WITHIN TWELVE HOURS NEAR 75 KNOTS. THE SYSTEM WILL QUICKLY DISSIPATE OVER CHINA WITHIN TWELVE TO EIGHTEEN HOURS OF LANDFALL, AND INCORPORATE INTO THE STATIONARY BOUNDARY. ALL THE MODEL TRACKERS BRING THE TY ASHORE WITHIN TWELVE HOURS WITH THE EXCEPTION OF THE EGRR TRACKER. THE 22/1500Z FORECAST LIES NEAR THE PREVIOUS FORECAST AND CLOSE TO THE 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.