From owner-wx-tropl@LISTSERV.ILLINOIS.EDU Tue Oct 26 22:40:28 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 o9QEeRkS021453 for ; Tue, 26 Oct 2010 22:40:27 +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 o9Q50Rcs021767; Tue, 26 Oct 2010 09:40:13 -0500 (CDT) Received: by LISTSERV.ILLINOIS.EDU (LISTSERV-TCP/IP release 14.5) with spool id 4060764 for WX-TROPL@LISTSERV.ILLINOIS.EDU; Tue, 26 Oct 2010 09:40:13 -0500 Received: from relay05.cites.uiuc.edu (relay05.cites.uiuc.edu [128.174.4.40]) by vacuum.cso.uiuc.edu (8.14.2/8.14.2) with ESMTP id o9QEeD4P013295 for ; Tue, 26 Oct 2010 09:40:13 -0500 (CDT) Received: from weather3.admin.niu.edu (weather3.admin.niu.edu [131.156.8.48]) by relay05.cites.uiuc.edu (8.14.4/8.14.2) with ESMTP id o9QEe689021999 for ; Tue, 26 Oct 2010 09:40:12 -0500 (CDT) Received: by weather3.admin.niu.edu (Postfix, from userid 501) id 5D4FC108B0001; Tue, 26 Oct 2010 09:40:05 -0500 (CDT) X-Proofpoint-Spam-Reason: safe Message-ID: <20101026144006.5D4FC108B0001@weather3.admin.niu.edu> Date: Tue, 26 Oct 2010 09:40:05 -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 Typhoon 16w Warning Nr 21// To: WX-TROPL@LISTSERV.ILLINOIS.EDU Precedence: list WDPN32 PGTW 261500 MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 16W WARNING NR 21// RMKS/ 1. FOR METEOROLOGISTS. 2. 12 HOUR SUMMARY AND ANALYSIS. A. TYPHOON (TY) 16W (CHABA), CURRENTLY LOCATED 375 NM SOUTH OF KADENA AB, OKINAWA, HAS TRACKED NORTHWESTWARD AT 05 KNOTS DURING THE PAST SIX HOURS. NEARLY ALL THE DEEP CENTRAL CONVECTION HAD DISSIPATED AROUND 0600Z, BUT IT HAS SINCE REBUILT OVER THE CENTER. A STRONG COLD SURGE CONTINUES TO ADVANCE A MODIFIED POLEWARD AIRMASS EQUATORWARD. THIS SURGE APPEARS TO HAVE HAD LITTLE IMPACT ON THE TY THUS FAR, DESPITE NORTHEASTERLIES BEGINNING TO WEAKLY FILTER IN BENEATH THE CENTRAL CONVECTION. DUAL EXHAUST MECHANISMS PERSIST AND ARE POSITIONED TO AID INTENSIFICATION. VERTICAL WIND SHEAR FLUCTUATES BETWEEN LOW AND MODERATE, WITH THE LOW LEVEL FLOW BEING NEARLY 180 DEGREES OUT OF PHASE WITH THE UPPER LEVEL SOUTH- WESTERLIES. A NARROW EXTENSION OF A DEEP LAYER STEERING RIDGE TO THE EAST HAS CONTINUED TO ADVANCE THE TY NORTHWEST. 3. FORECAST REASONING. A. THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST PHILOSOPHY. HOWEVER, TRACK SPEEDS HAVE BEEN ALTERED, ESPECIALLY IN THE LATER TAUS, TO ACCOUNT FOR A SLOWER CONSENSUS AND A DELAYED TURN TO THE NORTH. B. THE RIDGE EXTENSION WILL BEGIN TO ERODE OVER THE NEXT 06 TO 12 HOURS AND WILL ALLOW THE TY TO TRACK MORE TOWARDS THE NORTH. 500 MB HEIGHT ANALYSIS INDICATES THAT THE RIDGE HAS ALREADY BEGUN TO RETREAT TO THE EAST. AS CHABA TRACKS POLEWARD ALONG THE FLATTENED WESTERN EXTENSION OF THE DEEP LAYER RIDGE, IT WILL CONTINUE TO INTENSIFY, BUT AT A SLOWER RATE. POLEWARD OUTFLOW WILL WEAKEN AS AN UPPER LEVEL TROUGH PULLS TO THE NORTHEAST INTO THE DEEP MID- LATITUDES. IT REMAINS UNCERTAIN WHAT IMPACT THE COLD SURGE WILL HAVE ON THE INTENSITY FORECAST, BUT CURRENTLY THE SYSTEM REMAINS UNSCATHED. TOTAL PRECIPITABLE WATER PRODUCTS SHOW A WELL-ISOLATED SYSTEM THAT CONTINUES TO PULL IN AIR FROM THE DEEP TROPICS. AROUND TAU 48 THE TY WILL SIT JUST SOUTH OF OKINAWA NEAR 90 KNOTS. MODEL GUIDANCE THROUGH THE FIRST 2 DAYS SHOWS A GENERAL SLOW POLEWARD TREND. BECAUSE THE SYSTEM HAS YET TO TURN NORTH-NOTHWEST FROM NORTHWEST THE ENTIRE FORECAST TRACK HAS BEEN SHIFTED SLIGHTLY WEST OF THE PREVIOUS FORECAST. IN ADDITION, THE MODEL CONSENSUS HAS ALSO SHIFTED WEST. C. THE CYCLONE WILL BEGIN TO ACCELERATE AROUND TAU 72 AS IT ROUNDS THE RIDGE AXIS INTO THE MID-LATITUDES, AND WILL ALSO BEGIN TO WEAKEN UNDER INCREASED VERTICAL WIND SHEAR. EXTRATROPICAL TRANSITION WILL ALSO BEGIN SHORTLY THEREAFTER AS THE SYSTEM INTERACTS WITH A BAROCLINIC BOUNDARY RUNNING SOUTH OF JAPAN. THE CYCLONE WILL QUICKLY TRANSITION FROM TROPICAL TO EXTRATROPICAL BY TAU 120, JUST NORTH OF TOKYO. THE FORECAST HAS BEEN SHIFTED FURTHER INLAND OVER HONSHU TO ACCOUNT FOR A CONSENSUS THAT HAS WALKED WEST. GIVEN THE WESTERLIES ALOFT IT IS UNLIKELY THAT THE SYSTEM WILL ADVANCE ANY FARTHER WEST OVER JAPAN THAN ALREADY FORECAST, DESPITE THE GFDN SOLUTION THAT WANTS TO PULL THE SYSTEM INTO THE SEA OF JAPAN. GFS AND ECMWF, THOUGH SOMEWHAT FASTER THAN THE OFFICIAL FORECAST, RESOLVE FORECAST TRACKS THAT ARE CONSISTENT WITH A SYSTEM ENTERING THE MID-LATITUDES, AND HAVE THE CYCLONE ACCELERATING TO THE NORTHEAST AFTER SKIRTING HONSHU.// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 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.