From owner-wx-tropl@LISTSERV.ILLINOIS.EDU Sun Oct 24 21:35:30 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 o9ODZSOv009212 for ; Sun, 24 Oct 2010 21:35:29 +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 o9OBCYFC021767; Sun, 24 Oct 2010 08:35:14 -0500 (CDT) Received: by LISTSERV.ILLINOIS.EDU (LISTSERV-TCP/IP release 14.5) with spool id 4021337 for WX-TROPL@LISTSERV.ILLINOIS.EDU; Sun, 24 Oct 2010 08:35:14 -0500 Received: from relay02.cites.uiuc.edu (relay02.cites.uiuc.edu [128.174.196.4]) by vacuum.cso.uiuc.edu (8.14.2/8.14.2) with ESMTP id o9ODZEZl005830 for ; Sun, 24 Oct 2010 08:35:14 -0500 (CDT) Received: from weather3.admin.niu.edu (weather3.admin.niu.edu [131.156.8.48]) by relay02.cites.uiuc.edu (8.14.4/8.14.2) with ESMTP id o9ODZ8lu000090 for ; Sun, 24 Oct 2010 08:35:14 -0500 (CDT) Received: by weather3.admin.niu.edu (Postfix, from userid 501) id 01290405001E; Sun, 24 Oct 2010 08:35:05 -0500 (CDT) X-Proofpoint-Spam-Reason: safe Message-ID: <20101024133506.01290405001E@weather3.admin.niu.edu> Date: Sun, 24 Oct 2010 08:35:05 -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 16w Warning Nr 13// To: WX-TROPL@LISTSERV.ILLINOIS.EDU Precedence: list WDPN32 PGTW 241500 MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 16W WARNING NR 13// RMKS/ 1. FOR METEOROLOGISTS. 2. 12 HOUR SUMMARY AND ANALYSIS. A. TROPICAL STORM (TS) 16W (CHABA), LOCATED APPROXIMATELY 690 NM SOUTH-SOUTHEAST OF KADENA AB, OKINAWA, JAPAN, HAS TRACKED WEST- NORTHWESTWARD AT 05 KNOTS OVER THE PAST SIX HOURS. ANIMATED WATER VAPOR SATELLITE IMAGERY SHOWS CONVECTIVE BANDING HAS CONSOLIDATED AROUND THE LOW LEVEL CIRCULATION CENTER. THE SAME ANIMATION SHOWS IMPROVED RADIAL OUTFLOW AFTER THE TROPICAL UPPER TROPOSPHERIC TROUGH TO THE NORTH THAT HAS BEEN RESTRICTING THE POLEWARD CHANNEL MOVED FURTHER WESTWARD. THE INITIAL POSITION IS BASED ON A 241117 SSMI-S MICROWAVE IMAGE WITH POOR CONFIDENCE. THE INITIAL INTENSITY IS AVERAGED BETWEEN PGTW AND RJTD DVORAK ESTIMATES OF 30 AND 42 KNOTS, RESPECTIVELY. TS 16W IS CURRENTLY TRACKING ALONG THE SOUTHERN PERIPHERY OF A LOW- TO MID-LEVEL SUBTROPICAL STEERING RIDGE. 3. FORECAST REASONING. A. THERE IS NO SIGNIFICANT CHANGE IN FORECAST PHILOSOPHY SINCE THE PREVIOUS BULLETIN. B. AN UPPER LEVEL, MID-LATITUDE TROUGH CURRENTLY TRACKING OVER CHINA IS EXPECTED TO DIG SOUTHEASTWARD CAUSING THE STEERING RIDGE TO WEAKEN AND REORIENT. THIS WILL ALLOW TS 16W TO TURN NORTHWARD AROUND TAU 24. CONSEQUENTLY, THE POLEWARD OUTFLOW IS EXPECTED TO INCREASE WITH THE SYSTEM'S INITIAL EXPOSURE TO THE UPPER LEVEL WESTERLIES, FUELING STEADY INTENSIFICATION. C. AFTER TAU 72, TS CHABA IS EXPECTED TO VEER SLIGHTLY TO THE RIGHT AS IT BEGINS EXTRATROPICAL TRANSITION. TOWARDS THE END OF THE FORECAST PERIOD, THE SYSTEM WILL BEGIN TO WEAKEN AS VERTICAL WIND SHEAR INCREASES DUE TO STRONG WESTERLIES ASSOCIATED WITH THE SUBTROPICAL JET STREAM. THE AVAILABLE NUMERIC GUIDANCE IS SPREAD OUT WITH GFS AND WBAR FAVORING AN EARLIER RECURVATURE. GFDN AND UKMO ARE INITIALLY IN UNISON WITH THE PACK BEFORE THEY ABRUPTLY TRACK THE CYCLONE WESTWARD AFTER TAU 36, PRESUMABLY AFTER THE PASSAGE OF THE UPPER LEVEL TROUGH - AN UNLIKELY SCENARIO AT THIS TIME. THIS TRACK FORECAST IS IN THE MIDDLE OF THE MODEL ENVELOPE BUT JUST TO THE RIGHT OF CONSENSUS TO OFFSET THE WESTWARD OUTLIERS.// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 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.