From owner-wx-tropl@LISTSERV.ILLINOIS.EDU Wed Sep 22 22:35:29 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 o8MEZRs3004101 for ; Wed, 22 Sep 2010 22:35:28 +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 o8M2dXZG028356; Wed, 22 Sep 2010 09:35:13 -0500 (CDT) Received: by LISTSERV.ILLINOIS.EDU (LISTSERV-TCP/IP release 14.5) with spool id 3529203 for WX-TROPL@LISTSERV.ILLINOIS.EDU; Wed, 22 Sep 2010 09:35:12 -0500 Received: from relay08.cites.uiuc.edu (relay08.cites.uiuc.edu [128.174.196.9]) by vacuum.cso.uiuc.edu (8.14.2/8.14.2) with ESMTP id o8MEZCBj007364 for ; Wed, 22 Sep 2010 09:35:12 -0500 (CDT) Received: from weather3.admin.niu.edu (weather3.admin.niu.edu [131.156.8.48]) by relay08.cites.uiuc.edu (8.14.4/8.14.2) with ESMTP id o8MEZ5BP003714 for ; Wed, 22 Sep 2010 09:35:11 -0500 (CDT) Received: by weather3.admin.niu.edu (Postfix, from userid 501) id A84BE405001F; Wed, 22 Sep 2010 09:35:05 -0500 (CDT) X-Spam-Score: 0 X-Spam-Details: rule=no-quarantine_notspam policy=no-quarantine score=0 spamscore=0 ipscore=0 phishscore=0 bulkscore=42 adultscore=0 classifier=spam adjust=0 reason=mlx engine=5.0.0-1005130000 definitions=main-1009220095 X-Spam-OrigSender: ldm@weather3.admin.niu.edu X-Spam-Bar: Message-ID: <20100922143505.A84BE405001F@weather3.admin.niu.edu> Date: Wed, 22 Sep 2010 09:35:05 -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 13w Warning Nr 10// To: WX-TROPL@LISTSERV.ILLINOIS.EDU Precedence: list WDPN32 PGTW 221500 MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 13W WARNING NR 10// RMKS/ 1. FOR METEOROLOGISTS. 2. 12 HOUR SUMMARY AND ANALYSIS. A. TROPICAL STORM (TS) 13W (MALAKAS), LOCATED APPROXIMATELY 300 NM SOUTH OF IWO TO, JAPAN, HAS TRACKED NORTHWESTWARD AT 06 KNOTS OVER THE PAST SIX HOURS. THE SYSTEM CONTINUES TO HAVE A PARTIALLY- EXPOSED, WELL-DEFINED LOW-LEVEL CIRCULATION CENTER (LLCC) WITH SHALLOW CONVECTIVE BANDING WRAPPING TIGHTLY INTO THE SYSTEM CENTER. THE BULK OF THE DEEP CONVECTION IS STILL BEING DISPLACED EQUATORWARD FROM THE LLCC DUE TO NORTHERLY VERTICAL WIND SHEAR ASSOCIATED WITH UPPER-LEVEL CONFLUENT FLOW FORMED BY THE MOVEMENT OF A TUTT CELL NORTH OF THE SYSTEM. MALAKAS HAS TRACKED STEADILY WEST-NORTHWESTWARD ALONG THE SOUTHERN FLANK OF THE SUBTROPICAL STEERING RIDGE, WHICH IS BEGINNING TO WEAKEN AS A DEEPENING MID-LATITUDE TROUGH MOVES THROUGH THE YELLOW SEA. THE CURRENT INTENSITY IS BASED ON DVORAK ESTIMATES OF 35 KNOTS FROM PGTW, KNES AND RJTD AS WELL AS FROM RECENT SATCON ESTIMATES OF APPROXIMATELY 45 KNOTS. THE CURRENT POSITION IS SUPPORTED WITH HIGH CONFIDENCE BY A 221128Z TRMM MICROWAVE IMAGE. 3. FORECAST REASONING. A. THE FORECAST REASONING HAS NOT CHANGED SINCE THE PREVIOUS PROGNOSTIC REASONING BULLETIN. B. ALTHOUGH TS MALAKAS IS CURRENTLY BEING SUPPRESSED BY UPPER LEVEL CONVERGENCE ON ITS NORTHERN FLANK, IT IS IN A FAVORABLE ENVIRONMENT FOR DEVELOPMENT WITH GOOD POLEWARD OUTFLOW INTO A SERIES OF TUTT CELLS TO THE NORTH AND EAST, HIGH OCEAN HEAT CONTENT AND LOW VERTICAL WIND SHEAR. ACCORDINGLY, TS 13W IS EXPECTED TO INTENSIFY STEADILY AS IT APPROACHES THE SUBTROPICAL RIDGE AXIS OVER THE NEXT 24-36 HOURS, REACHING TYPHOON STRENGTH BEFORE 24/00Z AS POLEWARD OUTFLOW INCREASES SIGNIFICANTLY AHEAD OF THE APPROACHING MID- LATITUDE TROUGH. NUMERICAL MODEL GUIDANCE IS IN VERY TIGHT AGREEMENT WITH THIS SCENARIO. THIS FORECAST LIES JUST WEST OF THE JTWC CONSENSUS SINCE THE GFS TRACKER CONTINUES TO REFLECT AN IMPROBABLY SHARP POLEWARD TURN BY TAU 12. C. THE APPROACH OF THE TROUGH WILL ALSO ACT TO FURTHER WEAKEN THE STEERING RIDGE, GIVING THE SYSTEM AN ALLEY TO RECURVE INTO THE MID- LATITUDES. BY TAU 48, EXTRA-TROPICAL TRANSITION WILL BEGIN AS THE SYSTEM NEARS 30 DEGREES NORTH LATITUDE AND STARTS COUPLING WITH THE MID-LATITUDE WESTERLIES. SURFACE AND GRADIENT-LEVEL WIND FIELDS AROUND THE STORM WILL EXPAND AS IT INTERACTS WITH A STRONG BARO- CLINIC ZONE AND COMES UNDER THE INFLUENCE OF A DEEP, NEGATIVELY TILTED TROUGH. THE SYSTEM WILL REMAIN VIGOROUS IN ITS WARM SECTOR AS SEA SURFACE TEMPERATURES REMAIN HIGH THROUGH 35 DEGREES NORTH. THE SYSTEM WILL OCCLUDE AND COMPLETE TRANSITION TO A STORM FORCE EXTRA- TROPICAL LOW BEFORE CROSSING 40 DEGREES NORTH AROUND TAU 72.// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 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.