From owner-wx-tropl@LISTSERV.ILLINOIS.EDU Thu Oct 14 10:27:57 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 o9E2RugI009122 for ; Thu, 14 Oct 2010 10:27:57 +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 o9DLHefk019087; Wed, 13 Oct 2010 21:27:10 -0500 (CDT) Received: by LISTSERV.ILLINOIS.EDU (LISTSERV-TCP/IP release 14.5) with spool id 3879180 for WX-TROPL@LISTSERV.ILLINOIS.EDU; Wed, 13 Oct 2010 21:27:10 -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 o9E2RA5Q026427 for ; Wed, 13 Oct 2010 21:27:10 -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 o9E2R3kD025701 for ; Wed, 13 Oct 2010 21:27:10 -0500 (CDT) Received: by weather3.admin.niu.edu (Postfix, from userid 501) id AC1F340501E6; Wed, 13 Oct 2010 21:27:03 -0500 (CDT) X-Proofpoint-Spam-Reason: safe Message-ID: <20101014022703.AC1F340501E6@weather3.admin.niu.edu> Date: Wed, 13 Oct 2010 21:27:03 -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 15w (megi) Warning Nr To: WX-TROPL@LISTSERV.ILLINOIS.EDU Precedence: list WDPN31 PGTW 140300 MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 15W (MEGI) WARNING NR 05// RMKS/ 1. FOR METEOROLOGISTS. 2. 12 HOUR SUMMARY AND ANALYSIS. A. TROPICAL STORM (TS) 15W (MEGI) LOCATED APPROXIMATELY 175 NM NORTH-NORTHEAST OF YAP, HAS TRACKED WEST-NORTHWESTWARD AT 07 KNOTS OVER THE PAST 06 HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY SHOWS FLARING CONVECTION IN THE CENTER OF THE STORM WITH DEEP CONVECTIVE BANDING ALONG THE EASTERN AND SOUTHERN SIDE OF THE SYSTEM. UPPER-LEVEL OUTFLOW IS EVIDENT EQUATORWARD AND TO THE EAST INTO A TROPICAL UPPER TROPOSPHERIC TROUGH (TUTT). UPPER-LEVEL ANALYSIS SHOWS THE SYSTEM UNDER THE UPPER-LEVEL ANTICYCLONE WITH AN UPPER-LEVEL TROUGH TO THE NORTHWEST. THE TROUGH AND ASSOCIATED SUBSIDENCE IS PUTTING SIGNIFICANT PRESSURE ON THE WESTERN SIDE OF THE SYSTEM AS EVIDENT BY THE SUPPRESSED CONVECTION WEST OF THE CIRCULATION CENTER AND LACK OF RADIAL OUTFLOW. THE SYSTEM IS CURRENTLY TRACKING WESTWARD ALONG THE SOUTHWESTERN PERIPHERY OF THE SUBTROPICAL RIDGE (STR) TO THE NORTH. THE CURRENT INTENSITY IS BASED ON THE DVORAK ESTIMATE FROM PGTW. 3. FORECAST REASONING. A. THE FORECAST REASONING HAS NOT CHANGED SINCE THE PREVIOUS PROGNOSTIC REASONING BULLETIN. B. IN THE NEXT 12 TO 24 HOURS THE UPPER-LEVEL TROUGH TO THE NORTHWEST OF TS 15W WILL FILL AND RELIEVE THE PRESSURE ON THE WESTERN SIDE OF THE SYSTEM. UNTIL THIS HAPPENS, TS 12W WILL BE SLOW TO INTENSIFY. AFTER TAU 24, A PASSING MID-LATITUDE TROUGH WILL REORIENT THE STR TO THE EAST AND ALLOW FOR THE SYSTEM TO ACCELERATE SLIGHTLY TO THE NORTHWEST. DURING THIS PERIOD, POLEWARD OUTFLOW IS EXPECTED TO BECOME ENHANCED INTO THE DIFFLUENT REGION AHEAD OF THE TROUGH. THIS, COUPLED WITH HIGH SEA SURFACE TEMPERATURES, LARGE AMOUNTS OF PRECIPITABLE WATER IN THE AIR COLUMN, AND EASTWARD OUTFLOW INTO THE TUTT, WILL LIKELY CAUSE THE SYSTEM TO UNDERGO RAPID INTENSIFICATION (RI). ADDITIONALLY, GFDN AND COAMPS-TC ARE BOTH INDICATING RI BETWEEN TAU 24 AND 48. AFTER TAU 48, THE RIDGE IS EXPECTED TO RE-BUILD WESTWARD FOLLOWING THE PASSAGE OF THE MID- LATITUDE TROUGH FORCING THE STORM TRACK TO A MORE WESTWARD TRAJECTORY. C. AFTER TAU 72, TS 15W IS FORECAST TO CONTINUE WESTWARD INTO THE VICINITY OF LUZON. THE ENVIRONMENT REMAINS FAVORABLE FOR CONTINUED INTENSIFICATION FOLLOWING THE PERIOD OF RI, AND THE SYSTEM IS EXPECTED TO DEEPEN FURTHER BEFORE MAKING LANDFALL. NUMERICAL MODEL GUIDANCE SUPPORTS THIS FORECAST TRACK WITH GFDN, GFS, JGSM AND ECMWF ALL IN VERY CLOSE AGREEMENT. UKMO IS SLIGHTLY SOUTH AND FAST AND NOGAPS IS NORTH AND SLOW.// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 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.