From owner-wx-tropl@LISTSERV.ILLINOIS.EDU Thu Oct 21 10:08:25 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 o9L28NBQ028314 for ; Thu, 21 Oct 2010 10:08:24 +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 o9L09QC5000580; Wed, 20 Oct 2010 21:08:13 -0500 (CDT) Received: by LISTSERV.ILLINOIS.EDU (LISTSERV-TCP/IP release 14.5) with spool id 3975343 for WX-TROPL@LISTSERV.ILLINOIS.EDU; Wed, 20 Oct 2010 21:08:13 -0500 Received: from relay10.cites.uiuc.edu (relay10.cites.uiuc.edu [128.174.196.10]) by vacuum.cso.uiuc.edu (8.14.2/8.14.2) with ESMTP id o9L28ChD010009 for ; Wed, 20 Oct 2010 21:08:12 -0500 (CDT) Received: from weather3.admin.niu.edu (weather3.admin.niu.edu [131.156.8.48]) by relay10.cites.uiuc.edu (8.14.4/8.14.2) with ESMTP id o9L286x7014191 for ; Wed, 20 Oct 2010 21:08:12 -0500 (CDT) Received: by weather3.admin.niu.edu (Postfix, from userid 501) id 4F8FB108B0002; Wed, 20 Oct 2010 21:08:06 -0500 (CDT) X-Proofpoint-Spam-Reason: safe Message-ID: <20101021020806.4F8FB108B0002@weather3.admin.niu.edu> Date: Wed, 20 Oct 2010 21:08:06 -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 33// To: WX-TROPL@LISTSERV.ILLINOIS.EDU Precedence: list WDPN31 PGTW 210300 MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 15W (MEGI) WARNING NR 33// RMKS/ 1. FOR METEOROLOGISTS. 2. 12 HOUR SUMMARY AND ANALYSIS. A. TYPHOON (TY) 15W (MEGI), LOCATED APPROXIMATELY 250 NM SOUTHEAST OF HONG KONG, HAS TRACKED NORTHWARD AT 06 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY DEPICTS A LARGE, RAGGED 40NM EYE SURROUNDED BY A FAIRLY SYMMETRIC RING OF DEEP CONVECTION. ANIMATED WATER VAPOR IMAGERY DEPICTS EXCELLENT RADIAL OUTFLOW WITH ENHANCED POLEWARD OUTFLOW ASSOCIATED WITH A MIDLATITUDE SHORTWAVE TROUGH DEEPENING OVER SOUTHEAST CHINA. THERE IS GOOD CONFIDENCE IN THE CURRENT POSITION BASED ON THE EYE. THE CURRENT INTENSITY OF 100 KNOTS IS BASED ON AN AVERAGE OF DVORAK ESTIMATES RANGING FROM 90 TO 115 KNOTS AS WELL AS THE RECENT SATCON ESTIMATE OF 97 KNOTS. 3. FORECAST REASONING. A. NO CHANGE IN FORECAST PHILOSOPHY. B. THE 20/12Z 500MB ANALYSIS DEPICTS A SHARP MIDLATITUDE SHORTWAVE TROUGH OVER EASTERN CHINA WITH WESTERLY FLOW ACROSS SOUTHEAST CHINA AND A SUBTROPICAL RIDGE POSITIONED EAST OF THE SYSTEM. OVER THE PAST 24 HOURS, THE DYNAMIC MODELS HAVE BECOME MORE STABLE AND ARE IN GOOD AGREEMENT THROUGH TAU 48, SUPPORTING THE POLEWARD TRACK. AFTER TAU 36, TY 15W IS FORECAST TO ENCOUNTER STRONG VERTICAL WIND SHEAR AND SHOULD WEAKEN RAPIDLY AND DE-COUPLE. SUBSEQUENTLY, MODEL GUIDANCE DIVERGES AND THERE IS INCREASED UNCERTAINTY IN THE LATER TAUS. THE CURRENT FORECAST FAVORS A NORTHWESTWARD TURN INTO CHINA UNDER THE STEERING INFLUENCE OF LOW- LEVEL NORTHEASTERLY FLOW ASSOCIATED WITH A BROAD HIGH PRESSURE SYSTEM OVER KOREA/JAPAN. C. TY 15W IS FORECAST TO DISSIPATE BY TAU 96.// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 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.