From owner-wx-tropl@LISTSERV.ILLINOIS.EDU Sat Oct 16 11:08:35 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 o9G38YYm021609 for ; Sat, 16 Oct 2010 11:08:34 +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 o9FFhbiR022943; Fri, 15 Oct 2010 22:08:15 -0500 (CDT) Received: by LISTSERV.ILLINOIS.EDU (LISTSERV-TCP/IP release 14.5) with spool id 3909703 for WX-TROPL@LISTSERV.ILLINOIS.EDU; Fri, 15 Oct 2010 22:08:15 -0500 Received: from relay06.cites.uiuc.edu (relay06.cites.uiuc.edu [128.174.196.8]) by vacuum.cso.uiuc.edu (8.14.2/8.14.2) with ESMTP id o9G38F80025716 for ; Fri, 15 Oct 2010 22:08:15 -0500 (CDT) Received: from weather3.admin.niu.edu (weather3.admin.niu.edu [131.156.8.48]) by relay06.cites.uiuc.edu (8.14.4/8.14.2) with ESMTP id o9G388qr007446 for ; Fri, 15 Oct 2010 22:08:14 -0500 (CDT) Received: by weather3.admin.niu.edu (Postfix, from userid 501) id 9468340501A6; Fri, 15 Oct 2010 22:08:08 -0500 (CDT) X-Proofpoint-Spam-Reason: safe Message-ID: <20101016030808.9468340501A6@weather3.admin.niu.edu> Date: Fri, 15 Oct 2010 22:08:08 -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 15w (megi) Warning Nr 13// To: WX-TROPL@LISTSERV.ILLINOIS.EDU Precedence: list WDPN31 PGTW 160300 MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 15W (MEGI) WARNING NR 13// RMKS/ 1. FOR METEOROLOGISTS. 2. 12 HOUR SUMMARY AND ANALYSIS. A. TYPHOON 15W (MEGI), LOCATED APPROXIMATELY 705 NM EAST- NORTHEAST OF MANILA, PHILIPPINES, HAS TRACKED WEST-NORTHWESTWARD AT 15 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY AND A 152017Z SSMIS 91H MICROWAVE IMAGE DEPICT A WELL DEFINED LOW-LEVEL CIRCULATION CENTER WITH TIGHTLY CURVED CONVECTIVE BANDING (TCB) WRAPPING IN FROM THE SOUTHEASTERN QUADRANT. ANIMATED WATER VAPOR IMAGERY INDICATES GOOD EQUATORWARD OUTFLOW, WHILE POLEWARD OUTFLOW HAS YET TO BE ENHANCED BY A PASSING MID-LATITUDE SHORTWAVE TROUGH NORTH OF THE SYSTEM. TY 15W IS CURRENTLY EXPERIENCING SOME DEFORMATION ALONG ITS NORTHWESTERN QUADRANT ASSOCIATED WITH AN UPPER LEVEL LOW, WHICH APPEARS TO BE FILLING SLOWLY. THERE IS HIGH CONFIDENCE IN THE CURRENT POSITION BASED ON THE TCB AND A MICROWAVE EYE IN A PARTIAL 160032Z TRMM 37H MICROWAVE PASS. THE CURRENT INTENSITY IS BASED ON DVORAK ESTIMATES OF 90 KNOTS FROM RJTD, PGTW, AND KNES. 3. FORECAST REASONING. A. NO CHANGE IN FORECAST PHILOSOPHY. B. TY 15W HAS CONTINUED TO TRACK NORTHWESTWARD ALONG THE SOUTHWESTERN PERIPHERY OF THE MID-LEVEL SUBTROPICAL RIDGE (STR) TOWARD A WEAKNESS ASSOCIATED WITH A PASSING MID-LATITUDE SHORTWAVE TROUGH. WITHIN THE NEXT 12 HOURS, AS THE TROUGH CONTINUES TO PROPAGATE NORTHEASTWARD, THE STR IS EXPECTED TO RE-BUILD TO THE WEST ALLOWING THE SYSTEM TO TRACK WESTWARD TOWARD LUZON. POLEWARD OUTFLOW IS EXPECTED TO INCREASE AND THE UPPER LEVEL LOW TO THE WEST OF TY 15W IS EXPECTED TO FILL, RELIEVING THE PRESSURE ALONG THE NORTHWESTERN QUADRANT, AND ALLOWING THE SYSTEM TO UNDERGO STEADY INTENSIFICATION THROUGH TAU 48. TY MEGI IS FORECAST TO MAKE LANDFALL OVER NORTHERN LUZON BETWEEN TAU 48 AND TAU 72 AT OR NEAR SUPER TYPHOON INTENSITY AND SHOULD WEAKEN CONSIDERABLY AS IT CROSSES THE MOUNTAINOUS TERRAIN OF LUZON. UKMO, JGSM, ECMWF AND GFS MODEL TRACKERS REMAIN TIGHTLY CLUSTERED AND CONSISTENT WITH A GENERALLY WESTWARD TRACK OVER LUZON. GFDN HAS CONSISTENTLY INDICATED A WEST- NORTHWESTWARD TRACK TOWARD TAIWAN, WHILE NOGAPS HAS SETTLED ON A POLEWARD TRACK TOWARD OKINAWA OVER THE PAST 3 MODEL RUNS. THE NOGAPS TRACK CONTINUES TO MAKE LITTLE SENSE AS IT APPEARS TO BE EXAGGERATING THE SOUTHERN EXTENT OF THE MID-LATITUDE TROUGH AS WELL AS DRIVING THE SYSTEM INTO A STRONG, BROAD LOW-LEVEL HIGH SITUATED OVER EASTERN CHINA. THE GFDN MODEL SOLUTION ALSO REMAINS QUESTIONABLE AS IT CONTINUES TO TRACK THE SYSTEM INTO A FAIRLY STRONG LOW TO MID-LEVEL STEERING RIDGE SITUATED OVER EASTERN CHINA. BASED ON THIS ANALYSIS, THE CURRENT FORECAST FAVORS A TRACK SLIGHTLY SOUTH AND FASTER THEN MODEL CONSENSUS, SIMILAR TO THE UKMO, JGSM, ECMWF, AND GFS MODEL TRACKERS. C. NEAR TAU 72, TY 15W IS FORECAST TO RE-EMERGE IN THE SOUTH CHINA SEA AT TYPHOON INTENSITY AND TRACK GENERALLY WESTWARD TOWARD HAINAN. THIS FORECAST CONTINUES TO FAVOR THE SOUTHERN CLUSTER OF MODELS.// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 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.