From owner-wx-tropl@LISTSERV.ILLINOIS.EDU Wed Oct 6 10:04:43 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 o9624gRV013432 for ; Wed, 6 Oct 2010 10:04:42 +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 o959g5du016157; Tue, 5 Oct 2010 21:04:21 -0500 (CDT) Received: by LISTSERV.ILLINOIS.EDU (LISTSERV-TCP/IP release 14.5) with spool id 3759718 for WX-TROPL@LISTSERV.ILLINOIS.EDU; Tue, 5 Oct 2010 21:04:21 -0500 Received: from relay03.cites.uiuc.edu (relay03.cites.uiuc.edu [128.174.4.69]) by vacuum.cso.uiuc.edu (8.14.2/8.14.2) with ESMTP id o9624KQi022499 for ; Tue, 5 Oct 2010 21:04:20 -0500 (CDT) Received: from weather3.admin.niu.edu (weather3.admin.niu.edu [131.156.8.48]) by relay03.cites.uiuc.edu (8.14.4/8.14.2) with ESMTP id o9624E6c005920 for ; Tue, 5 Oct 2010 21:04:20 -0500 (CDT) Received: by weather3.admin.niu.edu (Postfix, from userid 501) id 368D1405016C; Tue, 5 Oct 2010 21:04:14 -0500 (CDT) X-Proofpoint-Spam-Reason: safe Message-ID: <20101006020414.368D1405016C@weather3.admin.niu.edu> Date: Tue, 5 Oct 2010 21:04:14 -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 14w Warning Nr 05// To: WX-TROPL@LISTSERV.ILLINOIS.EDU Precedence: list WDPN31 PGTW 060300 MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC// SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 14W WARNING NR 05// RMKS/ 1. FOR METEOROLOGISTS. 2. 12 HOUR SUMMARY AND ANALYSIS. A. TROPICAL DEPRESSION (TD) 14W, LOCATED APPROXIMATELY 260 NM WEST-SOUTHWEST OF HONG KONG, CHINA, HAS TRACKED EASTWARD AT 02 KNOTS OVER THE PAST SIX HOURS. ANIMATED WATER VAPOR IMAGERY INDICATES SIGNIFICANT SHEARING OF THE SYSTEM IN THE UPPER LEVELS AND MULTI- SPECTRAL ANIMATION SHOWS A SIGNIFICANT DECREASE IN CONVECTION. CORE CONVECTION IN THE SYSTEM HAS NEARLY COMPLETELY ENDED DURING THE PAST SIX HOURS. THE LOW-LEVEL CIRCULATION (LLCC) IS POORLY- DEFINED AND POSTION CONFIDENCE IS LOW. SYNOPTIC OBSERVATIONS FROM HAINAN ISLAND, LEIZHOU PENINSULA, AND COASTAL CHINA CONFIRM THAT THE LOWEST SURFACE PRESSURES ARE IN THE QIONGSHOU STRAIT. A 052220Z MICROWAVE IMAGE INDICATES THAT WHAT CONVECTION REMAINS HAS SHEARED FROM THE LLCC DURING THE PAST THREE HOURS. THE CURRENT INTENSITY IS BASED ON SURFACE OBSERVATIONS WITHIN THE REGION. DUE TO THE RAPIDLY DECAYING DEEP CONVECTION, DVORAK ESTIMATES ARE UNCLASSIFIABLE. 3. FORECAST REASONING. A. THE FORECAST PHILOSOPHY HAS NOT CHANGED SINCE THE PREVIOUS PROGNOSTIC REASONING BULLETIN. B. TD 14W IS IN A WEAK STEERING ENVIRONMENT AND DRIFTING INTO AN INCREASINGLY UNFAVORABLE ENVIRONMENT CHARACTERIZED BY MODERATE TO STRONG VERTICAL WIND SHEAR (VWS) AND DECREASING OCEAN HEAT CONTENT. A 05/12Z UPPER AIR SOUNDING FROM HONG KONG SHOWS A LAYER OF DRY EASTERLIES BETWEEN 925 MB AND 700 MB THAT PORTENDS TO SOME DRIER AIR BECOMING DRAWN INTO THE SYSTEM AT THE BOUNDARY LEVEL. DURING THE PAST 12 HOURS A WEAK SHORT WAVE TROUGH TRACKING OVER SOUTHERN CHINA MOVED EASTWARD AND WAS FOLLOWED BY A DEVELOPING RIDGE. THE ASSOCIATED HEIGHT RISES AND ANTICYCLONIC TURNING ARE ACTING TO SUPPRESS THE POLEWARD OUTFLOW THAT HAS BEEN A KEY IN SUSTAINING THE SYSTEM AS IT TRACKED OVER HAINAN ISLAND. STRONG UPPER- LEVEL WESTERLIES NORTH OF 20N WILL COMBINE WITH GRADIENT LEVEL NORTHEASTERLY FLOW FLOWING OUT OF A 1020 MB HIGH SETTLING OVER SHANGHAI TO PRODUCE VWS VALUES IN EXCESS OF 30 KNOTS. TD 14W IS BOXED IN AN UNFAVORABLE ENVIRONMENT AND ANY EASTWARD MOTION WILL RESULT IN MORE VWS AND FURTHER WEAKENING. THE COMBINATION OF SHEAR ALOFT AND DRYING AT THE BOUNDARY LEVELS WILL WEAKEN AND DE-COUPLE THE STORM BETWEEN TAU 00 AND TAU 12, AND THE SYTEM WILL DISSIPATE OVER WATER BY TAU 12. AVAILABLE DYNAMIC AIDS ARE IN POOR AGREEMENT AS TO TRACK DUE TO LACK OF STEERING FLOW AND WEAK INTENSITY OF THE SYSTEM. THEREFORE THE TRACK FORECAST IS BASED ON A CONSTANT RATE OF MOVEMENT THROUGH TAU 24.// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 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.