From owner-wx-tropl@LISTSERV.ILLINOIS.EDU Sun Oct 17 11:09:40 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 o9H39d0j010359 for ; Sun, 17 Oct 2010 11:09:39 +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 o9G400YN028194; Sat, 16 Oct 2010 22:09:13 -0500 (CDT) Received: by LISTSERV.ILLINOIS.EDU (LISTSERV-TCP/IP release 14.5) with spool id 3919067 for WX-TROPL@LISTSERV.ILLINOIS.EDU; Sat, 16 Oct 2010 22:09:12 -0500 Received: from relay04.cites.uiuc.edu (relay04.cites.uiuc.edu [128.174.196.5]) by vacuum.cso.uiuc.edu (8.14.2/8.14.2) with ESMTP id o9H39CQm001868 for ; Sat, 16 Oct 2010 22:09:12 -0500 (CDT) Received: from weather3.admin.niu.edu (weather3.admin.niu.edu [131.156.8.48]) by relay04.cites.uiuc.edu (8.14.4/8.14.2) with ESMTP id o9H396Ql000508 for ; Sat, 16 Oct 2010 22:09:12 -0500 (CDT) Received: by weather3.admin.niu.edu (Postfix, from userid 501) id 44FDC108B0002; Sat, 16 Oct 2010 22:09:06 -0500 (CDT) X-Proofpoint-Spam-Reason: safe Message-ID: <20101017030906.44FDC108B0002@weather3.admin.niu.edu> Date: Sat, 16 Oct 2010 22:09:06 -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 Super Typhoon 15w (megi) Warning Nr To: WX-TROPL@LISTSERV.ILLINOIS.EDU Precedence: list WDPN31 PGTW 170300 MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC// SUBJ/PROGNOSTIC REASONING FOR SUPER TYPHOON 15W (MEGI) WARNING NR 17// RMKS/ 1. FOR METEOROLOGISTS. 2. 12 HOUR SUMMARY AND ANALYSIS. A. SUPER TYPHOON (STY) 15W (MEGI), LOCATED APPROXIMATELY 450 NM NORTHEAST OF MANILA, PHILIPPINES, HAS TRACKED WESTWARD AT 12 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY AND A 162254Z SSMIS 91H MICROWAVE IMAGE DEPICT A WELL- DEFINED 15 NM EYE WITH A CONCENTRIC EYE WALL AND EXCELLENT RADIAL OUTFLOW. THERE IS HIGH CONFIDENCE IN THE CURRENT POSITION BASED ON RJTD AND PGTW 17/00Z EYE FIXES. OVER THE PAST 12 HOURS, SUPER TYPHOON MEGI HAS UNDERGONE RAPID INTENSIFICATION. THE CURRENT INTENSITY IS BASED ON DVORAK INTENSITY ESTIMATES 0F 140 KNOTS FROM PGTW AND RJTD, CIMSS SATELLITE CONSENSUS ESTIMATES OF 137 KNOTS AT 16/22Z, AND AN AIRCRAFT VORTEX MESSAGE AT 16/2339Z INDICATING MAXIMUM OBSERVED SURFACE WINDS OF 120 KNOTS, MINIMUM SEA LEVEL PRESSURE OF 908 MB (EQUIVALENT TO 153 KNOT VMAX ON THE KNAFF-ZEHR SCALE), AND MAXIMUM OUTBOUND SURFACE WINDS OF 146 KNOTS. UPPER LEVEL ANALYSIS REVEALS A SLIGHT WEAKENING IN POLEWARD OUTFLOW, HOWEVER EQUATORWARD OUTFLOW INTO AN UPPER LEVEL LOW TO THE EAST REMAINS VIGOROUS. THE TRACK HAS FLATTENED OUT AND STY MEGI IS NOW TRACKING WESTWARD UNDER THE INFLUENCE A DEEP-LAYER SUBTROPICAL STEERING RIDGE. 3. FORECAST REASONING. A. THE FORECAST INTENSITY HAS BEEN INCREASED IN RESPONSE TO THE PAST 12 HOURS OF RAPID INTENSIFICATION. B. STY MEGI IS FORECAST TO CONTINUE TRACKING WESTWARD TO WEST- SOUTHWESTWARD TOWARD LUZON AND MAY INTENSIFY SLIGHTLY WITHIN THE NEXT 12 TO 24 HOURS. THE SYSTEM IS EXPECTED TO MAKE LANDFALL OVER NORTHERN LUZON WITHIN THE NEXT 24 TO 36 HOURS AT SUPER TYPHOON INTENSITY AND WEAKEN CONSIDERABLY AS IT TRACKS ACROSS THE MOUNTAINOUS TERRAIN. AFTER TAU 36, STY MEGI WILL RE-EMERGE IN THE SOUTH CHINA SEA AT TYPHOON INTENSITY AND BEGIN TO STEADILY RE- INTENSIFY. C. NEAR TAU 72, STY MEGI IS FORECAST TO SLOW AND TURN POLEWARD TOWARD A WEAKNESS IN THE SUBTROPICAL STEERING RIDGE ASSOCIATED WITH A SHORTWAVE MID-LATITUDE TROUGH PROPAGATING EASTWARD ACROSS CENTRAL ASIA. NUMERICAL MODEL GUIDANCE HAS COME INTO EVEN BETTER AGREEMENT FROM THE PREVIOUS FORECAST, HOWEVER THERE IS SOME SPREAD IN THE MODELS AFTER TAU 72 AS TO THE TIMING OF THE POLEWARD TURN TOWARD SOUTHERN CHINA. THIS FORECAST IS IN CLOSE AGREEMENT WITH 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.