From owner-wx-tropl@LISTSERV.ILLINOIS.EDU Tue Oct 19 22:22:45 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 o9JEMhuR006240 for ; Tue, 19 Oct 2010 22:22:44 +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 o9IMbcWL022864; Tue, 19 Oct 2010 09:22:27 -0500 (CDT) Received: by LISTSERV.ILLINOIS.EDU (LISTSERV-TCP/IP release 14.5) with spool id 3951030 for WX-TROPL@LISTSERV.ILLINOIS.EDU; Tue, 19 Oct 2010 09:22:27 -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 o9JEMRNu008432 for ; Tue, 19 Oct 2010 09:22:27 -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 o9JEMJ0l013811 for ; Tue, 19 Oct 2010 09:22:26 -0500 (CDT) Received: by weather3.admin.niu.edu (Postfix, from userid 501) id AB13C40501A8; Tue, 19 Oct 2010 09:22:19 -0500 (CDT) X-Proofpoint-Spam-Reason: safe Message-ID: <20101019142219.AB13C40501A8@weather3.admin.niu.edu> Date: Tue, 19 Oct 2010 09:22:19 -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 27// To: WX-TROPL@LISTSERV.ILLINOIS.EDU Precedence: list WDPN31 PGTW 191500 MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 15W (MEGI) WARNING NR 27// RMKS/ 1. FOR METEOROLOGISTS. 2. 12 HOUR SUMMARY AND ANALYSIS. A. TYPHOON (TY) 15W (MEGI), LOCATED APPROXIMATELY 395 NM SOUTHEAST OF HONG KONG, HAS TRACKED WEST-NORTHWESTWARD AT 05 KNOTS OVER THE PAST SIX HOURS. ANIMATED INFRARED SATELLITE IMAGERY SHOWS THE SYSTEM HAS MAINTAINED AN EYE THAT HAS BECOME MORE RAGGED AND ENLARGED. ADDITIONALLY, WATER VAPOR ANIMATION DEPICTS EXCELLENT RADIAL OUTFLOW, ESPECIALLY ON THE POLEWARD SIDE. THE CURRENT POSITION AND INTENSITY ARE BASED ON DVORAK EYE FIXES FROM PGTW, RJTD, AND KNES. THESE ARE SUPPORTED BY A 191154Z SSMI-S IMAGE SHOWING A CLOSED MICROWAVE EYE. UPPER LEVEL ANALYSIS INDICATES TY 15W IS APPROXIMATELY 5 DEGREES TO THE SOUTH OF A RIDGE AXIS WITH A MESOCALE ANTICYCLONE DIRECTLY OVER THE SYSTEM. IT IS CURRENTLY TRACKING ALONG THE SOUTHWEST PERIPHERY OF A DEEP-LAYERED SUBTROPICAL RIDGE (STR)TO THE NORTHEAST. TYPHOON MEGI HAS BEGUN TO DRIFT MORE POLEWARD IN RESPONSE TO A MID-LATITUDE TROUGH THAT IS DIGGING SOUTHEASTWARD INTO EAST CENTRAL CHINA. 3. FORECAST REASONING. A. NO CHANGE IN FORECAST PHILOSOPHY, HOWEVER, THE TRACK HAS BEEN ADJUSTED MORE POLEWARD. B. TY 15W IS EXPECTED TO TRACK MORE NORTH-NORTHWESTWARD AFTER TAU 12 AS THE AFOREMENTIONED TROUGH DEEPENS AND DIGS FURTHER SOUTH. ENVIRONMENTAL CONDITIONS WILL REMAIN FAVORABLE FOR A SLIGHT INCREASE IN INTENSITY FROM TAU 36 TO 48. AFTER TAU 48, THE SYSTEM WILL TURN MORE NORTHWESTWARD AS AN EXTENSION OF THE STR TO THE NORTH BUILDS. THE AVAILABLE NUMERIC GUIDANCE ARE IN POOR AGREEMENT WITH JGSM AND EGRR FAVORING A DRASTIC POLEWARD TUG TOWARDS TAIWAN AND ECMWF FAVORING A MORE WESTWARD TRAJECTORY. THIS FORECAST IS TO THE LEFT OF JTWC CONSENSUS WITH BIAS TOWARDS ECMWF. THIS SOLUTION STAYS WITH CURRENT FORECAST PHILOSOPHY FAVORING A LESS INTENSE POLEWARD MOTION ALTHOUGH THE OVERALL TREND HAS BEEN TO THE RIGHT AND POLEWARD OF THE PREVIOUS FORECAST. C. AS THE STR RE-BUILDS NORTH NEAR TAU 48, TYPHOON MEGI IS EXPECTED TO GRADUALLY WEAKEN DUE TO INCREASING VERTICAL WIND SHEAR, AND EVEN MORE RAPIDLY AFTER MAKING LANDFALL NEAR HONG KONG BEFORE 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.