From owner-wx-tropl@LISTSERV.ILLINOIS.EDU Wed Oct 13 23:03:06 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 o9DF35GH001817 for ; Wed, 13 Oct 2010 23:03:06 +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 o9DB2EVO019087; Wed, 13 Oct 2010 10:02:44 -0500 (CDT) Received: by LISTSERV.ILLINOIS.EDU (LISTSERV-TCP/IP release 14.5) with spool id 3868659 for WX-TROPL@LISTSERV.ILLINOIS.EDU; Wed, 13 Oct 2010 10:02:44 -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 o9DF2iMB013873 for ; Wed, 13 Oct 2010 10:02:44 -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 o9DF2V3k007831 for ; Wed, 13 Oct 2010 10:02:44 -0500 (CDT) Received: by weather3.admin.niu.edu (Postfix, from userid 501) id EB84440501E6; Wed, 13 Oct 2010 10:02:29 -0500 (CDT) X-Proofpoint-Spam-Reason: safe Message-ID: <20101013150230.EB84440501E6@weather3.admin.niu.edu> Date: Wed, 13 Oct 2010 10:02:29 -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 Tropical Storm 15w (megi) Warning Nr To: WX-TROPL@LISTSERV.ILLINOIS.EDU Precedence: list WDPN31 PGTW 131500 MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 15W (MEGI) WARNING NR 03// RMKS/ 1. FOR METEOROLOGISTS. 2. 12 HOUR SUMMARY AND ANALYSIS. A. TROPICAL STORM (TS) 15W (MEGI) LOCATED APPROXIMATELY 200 NM NORTHEAST OF YAP, HAS TRACKED WESTWARD AT 04 KNOTS OVER THE PAST 06 HOURS. ANIMATED INFRARED (IR) SATELLITE IMAGERY AND A 130915Z SSMIS 91 GHZ MICROWAVE IMAGE INDICATE A RAPIDLY DEVELOPING SYSTEM WITH TIGHTLY CURVED CONVECTIVE BANDING WRAPPING INTO A WELL-DEFINED LOW LEVEL CIRCULATION CENTER (LLCC). ANIMATED WATER VAPOR IMAGERY SHOWS GOOD OVERALL OUTFLOW WITH ENHANCED POLEWARD OUTFLOW OVER THE NORTHERN QUADRANT DUE TO A TROPICAL UPPER TROPOSPHERIC TROUGH (TUTT) CELL TO THE NORTHEAST. THE SYSTEM IS CURRENTLY TRACKING WESTWARD ALONG THE SOUTHWESTERN PERIPHERY OF THE SUBTROPICAL STEERING RIDGE (STR). THE CURRENT INTENSITY IS BASED ON THE HIGHER END OF DVORAK ESTIMATES RANGING FROM 30 TO 45 KNOTS FROM KNES, RJTD, AND PGTW. 3. FORECAST REASONING. A. THE FORECAST REASONING HAS NOT CHANGED SINCE THE PREVIOUS PROGNOSTIC REASONING BULLETIN B. TS 15W IS EXPECTED TO STEADILY INTENSIFY THROUGHOUT THE FORECAST PERIOD AS IT TRACKS ALONG THE SOUTHERN FLANK OF THE STEERING RIDGE. BETWEEN TAU 12 AND TAU 24 THE SYSTEM IS EXPECTED TO REACH TYPHOON INTENSITY AND BEGIN TRACKING WEST-NORTHWESTWARD AS AN APPROACHING MID-LATITUDE TROUGH WEAKENS THE RIDGE SLIGHTLY. AFTER TAU 36, THE RIDGE IS EXPECTED TO REORIENT AND RE-BUILD WESTWARD ALLOWING THE SYSTEM TO STAIR-STEP BACK TO THE WEST AND SIGNIFICANTLY INTENSIFY AS POLEWARD OUTFLOW IS ENHANCED BY THE PASSING MID- LATITUDE TROUGH. BETWEEN TAU 48 AND TAU 72, TS 15W IS EXPECTED TO MERGE WITH A TROPICAL DISTURBANCE TO THE WEST. C. AFTER TAU 72, TS MEGI IS FORECAST TO CONTINUE TO INTENSIFY AS IT TRACKS WESTWARD TOWARD NORTHERN LUZON OVER HIGHLY FAVORABLE SEA SURFACE TEMPERATURES AND HIGH OCEAN HEAT CONTENT (OHC). NUMERICAL MODEL GUIDANCE IS IN VERY GOOD AGREEMENT WITH THIS FORECAST TRACK, THEREFORE THIS FORECAST IS CLOSE TO 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.