From owner-wx-tropl@LISTSERV.ILLINOIS.EDU Wed Sep 15 10:45:24 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 o8F2jNOl015723 for ; Wed, 15 Sep 2010 10:45:24 +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 o8EMGDbv026844; Tue, 14 Sep 2010 21:45:12 -0500 (CDT) Received: by LISTSERV.ILLINOIS.EDU (LISTSERV-TCP/IP release 14.5) with spool id 3394411 for WX-TROPL@LISTSERV.ILLINOIS.EDU; Tue, 14 Sep 2010 21:45:12 -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 o8F2jCVA015239 for ; Tue, 14 Sep 2010 21:45:12 -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 o8F2j5KO013680 for ; Tue, 14 Sep 2010 21:45:12 -0500 (CDT) Received: by weather3.admin.niu.edu (Postfix, from userid 501) id BEAE2405001E; Tue, 14 Sep 2010 21:45:05 -0500 (CDT) X-Spam-Score: 40 X-Spam-Details: rule=no-quarantine_notspam policy=no-quarantine score=40 spamscore=40 ipscore=0 phishscore=0 bulkscore=4 adultscore=0 classifier=spam adjust=0 reason=mlx engine=5.0.0-1005130000 definitions=main-1009140171 X-Spam-OrigSender: ldm@weather3.admin.niu.edu X-Spam-Bar: **** Message-ID: <20100915024505.BEAE2405001E@weather3.admin.niu.edu> Date: Tue, 14 Sep 2010 21:45:05 -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 Depression 12w Warning Nr 02// To: WX-TROPL@LISTSERV.ILLINOIS.EDU Precedence: list WDPN31 PGTW 150300 MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC// SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 12W WARNING NR 02// RMKS/ 1. FOR METEOROLOGISTS. 2. 12 HOUR SUMMARY AND ANALYSIS. A. TROPICAL DEPRESSION (TD) 12W (TWELVE), LOCATED APPROXIMATELY 380 NM SOUTH OF OKINAWA, JAPAN HAS TRACKED NORTHWESTWARD AT 09 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY SHOWS CONVECTIVE BANDING WRAPPING INTO A LOW LEVEL CIRCULATION CENTER (LLCC) WITH THE MAJORITY OF DEEP CONVECTION IN THE SOUTHEASTERN QUADRANT AND NORTHERN PERIPHERY. THE INITIAL POSITION IS BASED ON A 142138Z CORIOLIS MICROWAVE IMAGE THAT SHOWS CURVED LOW LEVEL CONVECTIVE BANDING. THE INITIAL INTENSITY IS BASED ON THE PGTW DVORAK ESTIMATE OF 30 KNOTS AND DROPSONDE OBSERVATIONS OF 27 TO 30 KNOTS AT 142157Z AND 142209Z RESPECTIVELY. A TROPICAL UPPER TROPOSPHERIC TROUGH (TUTT) TO THE WEST AND NORTH IS CAUSING SUBSIDENCE AND LIMITING POLEWARD OUTFLOW. HOWEVER, THERE IS MODERATE EQUATORWARD OUTFLOW. TD 12W IS LOCATED IN AN AREA OF LOW VERTICAL WIND SHEAR AND GOOD DIVERGENCE ALOFT FAVORABLE FOR DEVELOPMENT. 3. FORECAST REASONING. A. THIS IS THE FIRST ISSUANCE OF THE PROGNOSTIC REASONING MESSAGE. B. TD 12W IS CURRENTLY TRACKING ALONG THE SOUTHWESTERN PERIPHERY OF A LOW- TO MID-LEVEL STEERING RIDGE IN A WEAK STEERING ENVIRONMENT. AROUND TAU 36, TD 12W IS EXPECTED TO CONTINUE SLOWLY TRACKING NORTHWESTWARD AND TURN NORTHWARD AS AN UPPER LEVEL, MID- LATITUDE TROUGH WEAKENS THE STEERING RIDGE TO THE NORTH. TD 12W IS THEN FORECAST TO TURN NORTHEASTWARD, SOUTH OF OKINAWA, AND BEGIN TRACKING ALONG THE NORTHWESTERN PERIPHERY OF A STEERING RIDGE EXTENSION THAT BUILDS IN TO THE SOUTH. AS TD 12W CONTINUES TO TRACK FARTHER NORTH, POLEWARD OUTFLOW SHOULD INCREASE INTO THE MID- LATITUDE UPPER LEVEL TROUGH AND INTO THE TUTT CELL TO THE EAST, WHICH WILL ALLOW FOR INTENSIFICATION. C. BY TAU 96, TD 12W IS EXPECTED TO TURN NORTHWESTWARD AS THE SUBTROPICAL RIDGE TO THE NORTH BUILDS BACK IN. THE SYSTEM IS FORECAST TO CONTINUE INTENSIFYING THROUGHOUT THE FORECAST PERIOD AND REACH TYPHOON STRENGTH BY TAU 96. THE NUMERICAL MODEL GUIDANCE IS IN AGREEMENT IN TRACK PHILOSOPHY, ALTHOUGH DIFFERS IN THE TIMING OF BOTH TURNS TO THE NORTHEAST AND TO THE NORTHWEST. THIS FORECAST IS IN AGREEMENT WITH THE NOGAPS, GFS, AND JGSM MODELS, WHICH TURN THE SYSTEM MORE SLOWLY AND TRACKS THE SYSTEM SOUTH OF OKINAWA. HOWEVER, GFDN PULLS TD 12W FASTER NORTHWARD AND THEN NORTHWESTWARD OVER OKINAWA AS IT ANALYSES THE RIDGE TO WEAKEN AND THEN BUILD BACK IN FASTER THAN THE OTHER MODELS. THIS IS ALSO A POSSIBLE SCENARIO.// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 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.