From owner-wx-tropl@LISTSERV.ILLINOIS.EDU Mon Oct 25 10:30:24 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 o9P2UNHp005184 for ; Mon, 25 Oct 2010 10:30:24 +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 o9OBCY0i021767; Sun, 24 Oct 2010 21:30:12 -0500 (CDT) Received: by LISTSERV.ILLINOIS.EDU (LISTSERV-TCP/IP release 14.5) with spool id 4029548 for WX-TROPL@LISTSERV.ILLINOIS.EDU; Sun, 24 Oct 2010 21:30:11 -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 o9P2UBQn004260 for ; Sun, 24 Oct 2010 21:30:11 -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 o9P2U59i024558 for ; Sun, 24 Oct 2010 21:30:11 -0500 (CDT) Received: by weather3.admin.niu.edu (Postfix, from userid 501) id 41DCC405001E; Sun, 24 Oct 2010 21:30:05 -0500 (CDT) X-Proofpoint-Spam-Reason: safe Message-ID: <20101025023005.41DCC405001E@weather3.admin.niu.edu> Date: Sun, 24 Oct 2010 21:30:05 -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 15// To: WX-TROPL@LISTSERV.ILLINOIS.EDU Precedence: list WDPN32 PGTW 250300 MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 16W WARNING NR 15// RMKS/ 1. FOR METEOROLOGISTS. 2. 12 HOUR SUMMARY AND ANALYSIS. A. TROPICAL STORM (TS) 16W (CHABA), LOCATED APPROXIMATELY 590 NM SOUTH-SOUTHEAST OF KADENA AB, OKINAWA, JAPAN, HAS TRACKED NORTHWESTWARD AT 06 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY SHOWS IMPROVED DEEP CONVECTION BANDING WITHIN THE PAST SIX HOURS ALONG THE SOUTHERN AND WESTERN PERIPHERY OF THE LOW LEVEL CIRCULATION CENTER (LLCC). THE INITIAL POSITION IS BASED ON A 241929Z TRMM 36H MICROWAVE IMAGE, WHICH DEPICTS A TIGHTLY WRAPPED LLCC. THE INITIAL INTENSITY IS BASED ON PGTW, KNES, AND RJTD DVORAK ESTIMATES OF 45 KNOTS. ALTHOUGH EQUATORWARD OUTFLOW HAS IMPROVED, AN UPPER TROPOSPHERIC TROUGH IS LIMITING DEEP CONVECTION ALONG THE NORTHEASTERN SIDE OF THE LLCC AND IS HINDERING POLEWARD OUTFLOW. TS 16W IS CURRENTLY TRACKING ALONG THE SOUTHWESTERN PERIPHERY OF A MID-LEVEL SUBTROPICAL STEERING RIDGE. A 240000Z AND 241200Z UPPER AIR ANALYSES INDICATE A MID-LATITUDE TROUGH IS TRACKING OVER NORTHEASTERN CHINA AND DIGGING SOUTHEASTWARD. 3. FORECAST REASONING. A. THE FORECAST INTENSITIES HAVE INCREASED DUE TO CURRENT INTENSIFICATION TRENDS, MODEL GUIDANCE, AND IMPROVED OUTFLOW. B. THE STEERING RIDGE IS FORECAST TO CONTINUE TO RE-ORIENT AND WEAKEN WITH THE PASSING MID-LATITUDE TROUGH, ALLOWING TS 16W TO TURN MORE POLEWARD OVER THE NEXT 36 HOURS. INCREASED POLEWARD OUTFLOW INTO THE TROUGH AND GOOD EQUATORWARD OUTFLOW SHOULD SUPPORT FURTHER INTENSIFICATION. C. AFTER TAU 72, TS CHABA IS EXPECTED TO CONTINUE TRACKING NORTHWARD AND AROUND TAU 96, TURN NORTHEASTWARD AS IT ROUNDS THE SUBTROPICAL RIDGE AXIS. AT THIS TIME, INCREASED VERTICAL WIND SHEAR ASSOCIATED WITH THE MID-LATITUDE WESTERLIES AS WELL AS LOWER OCEAN HEAT CONTENT SHOULD INITIALLY WEAKEN TS 16W AS IT BEGINS EXTRATROPICAL TRANSITION. NUMERICAL MODEL GUIDANCE IS SPREAD IN THE TIMING OF THE TURN NORTHWARD AND THEN NORTHEASTWARD, EXCEPT FOR GFDN WHICH ERRONEOUSLY INTENSIFIES TS 16W AND TRACKS IT WESTWARD. THE MAJORITY OF THE MODELS ARE INDICATING A NORTHWARD TURN WITH NOGAPS AND GFS TURNING THE SYSTEM LATEST AND THEN TRACKING THE SYSTEM TOWARD OKINAWA. THE ECMWF, WBAR, AND UKMO MODELS TURN THE SYSTEM NORTHEASTWARD MORE SHARPLY SOUTH OF OKINAWA, INDICATING THE APPROACHING MID-LATITUDE TROUGH WILL DEEPEN ENOUGH TO INDUCE A RECURVATURE SCENARIO. THIS FORECAST IS IN AGREEMENT WITH THE FASTER TURN NORTHEASTWARD IN ANTICIPATION OF A DEEPER MID-LATITUDE TROUGH AND IS RIGHT OF MODEL CONSENSUS TO ACCOUNT FOR THE GFDN WESTWARD TRACK ERROR.// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 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.