From owner-wx-tropl@LISTSERV.ILLINOIS.EDU Sun Oct 17 05:50:44 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 o9GLohJE018983 for ; Sun, 17 Oct 2010 05:50:43 +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 o9G9BFkK020508; Sat, 16 Oct 2010 16:50:29 -0500 (CDT) Received: by LISTSERV.ILLINOIS.EDU (LISTSERV-TCP/IP release 14.5) with spool id 3917484 for WX-TROPL@LISTSERV.ILLINOIS.EDU; Sat, 16 Oct 2010 16:50:28 -0500 Received: from relay02.cites.uiuc.edu (relay02.cites.uiuc.edu [128.174.196.4]) by vacuum.cso.uiuc.edu (8.14.2/8.14.2) with ESMTP id o9GLoS40016581 for ; Sat, 16 Oct 2010 16:50:28 -0500 (CDT) Received: from weather3.admin.niu.edu (weather3.admin.niu.edu [131.156.8.48]) by relay02.cites.uiuc.edu (8.14.4/8.14.2) with ESMTP id o9GLoL32020764 for ; Sat, 16 Oct 2010 16:50:28 -0500 (CDT) Received: by weather3.admin.niu.edu (Postfix, from userid 501) id A56DA108B0002; Sat, 16 Oct 2010 16:50:21 -0500 (CDT) X-Proofpoint-Spam-Reason: safe Message-ID: <20101016215021.A56DA108B0002@weather3.admin.niu.edu> Date: Sat, 16 Oct 2010 16:50:21 -0500 Reply-To: wxmaster@COX.NET Sender: WX-TROPL Tropical Storm and Hurricane WX products From: LDM Weather Subject: Western Pacific: Synoptic Discussion For The Marianas To: WX-TROPL@LISTSERV.ILLINOIS.EDU Precedence: list 407 FXPQ60 PGUM 162150 AFDPQ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TIYAN GU 750 AM CHST SUN OCT 17 2010 .SYNOPSIS... PGUA WSR-88D SHOWS ISOLATED SHOWERS MOVING THROUGH THE MARIANAS WATERS. CONVERGING FLOW INTO TYPHOON MEGI IS PRODUCING SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS BETWEEN 5N AND 23N FROM 130E TO 135E WHICH IS JUST WEST OF KOROR PALAU. A SURFACE TROUGH IS CREATING SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS WEST OF CHUUK AND SOUTHEAST OF YAP BETWEEN 1N AND 8N FROM 139E TO 151E. TRADE- WIND CONVERGENCE IS GENERATING SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS OVER MUCH OF THE MARSHALL ISLANDS BETWEEN 7N AND 12N FROM 160E TO 180. AN UPPER-LEVEL LOW IS SPARKING SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS BETWEEN 15N AND 25N FROM 148E TO 166E. THIS IS JUST EAST OF THE MARIANAS AND JUST WEST OF WAKE ISLAND. && .DISCUSSION... GFS40 HAS BACKED OFF A BIT ON THE AMOUNT OF RAIN IT IS BRINGING IN TO THE MARIANAS OVER THE NEXT 10 DAYS. SO FOR NOW AM LEAVING THE GRIDS RELATIVELY DRY AS ECMWF-HIRES HAS BEEN SAYING ALL ALONG AND IT NOW SEEMS THE GFS40 IS TRENDING THAT WAY ALSO. THERE WILL STILL BE SOME SHOWERS OF COURSE...AM JUST THINKING THAT ISOLATED WILL COVER IT. THE UPPER-LEVEL LOW MOVING OUR WAY HAS BECOME MUCH MORE CONVECTIVELY ACTIVE IN THE PAST 24 HOURS. NONETHELESS...MOST OF THE ACTIVITY LOOKS LIKE IT WILL SLIDE NORTH OF SAIPAN. INHERITED GRIDS HANDLED THIS DRY SCENARIO WELL...SO NO CHANGES WERE NEEDED. && .MARINE... WEST TYPHOON SWELL WAS REMOVED YESTERDAY...WHICH WITH NEW DATA AND ON FARTHER REFLECTION SEEMS TO BE A FINE IDEA. MEGI IS MOVING TO THE WEST-NORTHWEST AT A FAIRLY HIGH SPEED. THIS IS NOT ONLY WEAKENING THE WEST WINDS THAT MIGHT GIVE US A SWELL BUT ALSO INDUCES A REVERSE DYNAMIC FETCH...LOWERING THE SWELL RATHER THAN RAISING IT. WE STILL MIGHT GET SOME 1 OR 2 FOOT SWELLS...BUT THEY WILL BARELY BE NOTICEABLE. && .EASTERN MICRONESIA... CONVECTION HAS RAPIDLY DISSIPATED NEAR POHNPEI ALLOWING FOR CLOUD COVER TO QUICKLY DIMINISH. LATEST SURFACE ANALYSIS INDICATES AN ELONGATED TROUGH STRETCHING FROM NORTH OF KOSRAE...ACROSS KWAJALEIN AND MAJURO...THEN PASSING THROUGH 10N180. MAJURO CONTINUES TO SIT WITHIN A SMALL AREA FREE OF DEEP CONVECTION. MODELS GUIDANCE SUGGESTS THAT MAJURO MAY ONLY SEE ISOLATED SHOWERS THE NEXT FEW DAYS AS CONVECTION PASSES BY TO THE NORTH. POHNPEI AND KOSRAE WILL LIKELY NOT SEE ANY SIGNIFICANT RAINFALL EITHER WITH CONVECTION STAYING NORTH OF BOTH LOCATIONS. THE PRIMARY FORECAST UNCERTAINTY IS THE SURFACE WIND. GFS40...GFSE AND UKMET ALL DEPICT A BROAD LOW-LEVEL CIRCULATION FORMING ALONG 10N-11N NORTH OF KWAJALEIN BY TUESDAY... WHILE ECMWF JUST SHOWS AN OPEN TROUGH. EITHER WAY...WINDS ARE EXPECTED TO REMAIN UNDER 15 KT. DEPENDING ON THE DEGREE OF DEVELOPMENT THIS SYSTEM EXPERIENCES OVER THE NEXT COUPLE OF DAYS... EAST OR SOUTHEAST WINDS COULD SWING TO THE SOUTH...BUT WINDS WOULD REMAIN LIGHT TO GENTLE. && .WESTERN MICRONESIA... WITH CONVECTION QUICKLY DEPARTING CHUUK...DECIDED TO DROP TO ISOLATED FOR TODAY BUT KEPT THE SLIGHT CHANCE FOR THUNDERSTORMS BASED ON PLACEMENT OF UPPER-LEVEL TROUGH. THE EXPANDING DRY SLOT OVER POHNPEI AND KOSRAE WILL CONTINUE TO ENVELOP CHUUK FOR THE NEXT SEVERAL DAYS SUPPRESSING SHOWER ACTIVITY. THE PRIMARY CONTRIBUTOR TO SCATTERED SHOWERS AT PALAU THROUGH MONDAY NIGHT WILL BE LOW-LEVEL CONVERGENCE OF SOUTH AND SOUTHWEST WINDS FLOWING NORTHWARD TOWARD TYPHOON MEGI. FOR YAP...MODELS MAY BE DOWNPLAYING THE TROUGH WEST OF CHUUK...BUT FOR NOW...DECIDED TO STICK WITH THEM AND CONTINUE ISOLATED SHOWERS AT YAP. DECIDED TO INCREASE SEAS SLIGHTLY FOR BOTH YAP AND PALAU FOR THE NEXT COUPLE DAYS DUE TO THE EFFECTS OF TYPHOON-GENERATED SWELL. WAVEWATCH MODEL DOES NOT YET SHOW ANY EFFECT FROM THE TYPHOON...BUT ALTIMETRY DATA DOES INDICATE THAT SEAS HEIGHTS ARE INCREASING SOME ACROSS MUCH OF THE PHILIPPINE SEA. && .GUM WATCHES/WARNINGS/ADVISORIES... GU...NONE. MARIANAS WATERS...NONE. && $$ STANKO/W. AYDLETT +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 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.