From owner-wx-tropl@LISTSERV.ILLINOIS.EDU Sat Dec 25 04:15:43 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 oBOKFgrD016890 for ; Sat, 25 Dec 2010 04:15:42 +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 oBNIVEcb000588; Fri, 24 Dec 2010 14:15:29 -0600 (CST) Received: by LISTSERV.ILLINOIS.EDU (LISTSERV-TCP/IP release 14.5) with spool id 4863912 for WX-TROPL@LISTSERV.ILLINOIS.EDU; Fri, 24 Dec 2010 14:15:29 -0600 Received: from relay01.cites.uiuc.edu (relay01.cites.uiuc.edu [128.174.4.23]) by vacuum.cso.uiuc.edu (8.14.2/8.14.2) with ESMTP id oBOKFTqW028747 for ; Fri, 24 Dec 2010 14:15:29 -0600 (CST) Received: from weather3.admin.niu.edu (weather3.admin.niu.edu [131.156.8.48]) by relay01.cites.uiuc.edu (8.14.4/8.14.2) with ESMTP id oBOKFM6S026042 for ; Fri, 24 Dec 2010 14:15:29 -0600 (CST) Received: by weather3.admin.niu.edu (Postfix, from userid 501) id 8E0333FE0032; Fri, 24 Dec 2010 14:15:22 -0600 (CST) X-Proofpoint-Spam-Reason: safe Message-ID: <20101224201522.8E0333FE0032@weather3.admin.niu.edu> Date: Fri, 24 Dec 2010 14:15:22 -0600 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 862 FXPQ60 PGUM 242015 AFDPQ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TIYAN GU 615 AM CHST SAT DEC 25 2010 .SYNOPSIS... RADAR AND SATELLITE SHOW SOMEWHAT MOISTER AIR IS IN PLACE TODAY VERSUS THE VERY DRY AIR OF YESTERDAY. TRADE-WIND INVERSION HAS LIFTED TO AROUND 10K FEET...SUPPORTING ISOLATED SHOWERS. A SHEAR LINE CONTINUES TO LINGER NEAR ANATAHAN...BUT IR SATELLITE IMAGERY SHOWS IT BECOMING MORE DIFFUSE. && .DISCUSSION... NO SIGNIFICANT CHANGES TO FORECAST GRIDS OR REASONING. DID REFRESH WIND AND DEW POINT GRIDS. MODEL GUIDANCE SUGGESTS DEEP LAYER RIDGING WILL REMAIN IN CONTROL OF THE WEATHER. PARTLY CLOUDY SKIES AND ISOLATED SHOWERS WILL PREVAIL THROUGH THE FORECAST PERIOD. ANY SHEAR LINES ARE EXPECTED TO REMAIN TO THE NORTH OF SAIPAN AS THE PRIMARY TRADE-WIND CONVERGENCE ZONE IS CONFINED TO SOUTH OF 10N. && .MARINE... TRIMMED A FOOT FROM THE TRADE SWELL HEIGHT TODAY TO INITIALIZE WITH THE IPAN BUOY. STILL EXPECT COMBINED SEAS TO APPROACH 8 FEET BY SUNDAY AS NORTH SWELL ARRIVE. NORTH AND EAST SWELL WILL MAINTAIN MODERATE RIP CURRENT RISK LEVEL SURF ON RESPECTIVE EXPOSURES FOR AT LEAST THE NEXT SEVERAL DAYS. && .EASTERN MICRONESIA... SURFACE RIDGING HAS FINALLY SHIFTED EAST OF THE DATE LINE... ALLOWING MODERATE TO FRESH TRADE WINDS TO FLOW INTO EASTERN MICRONESIA THIS MORNING. BASED ON SATELLITE IMAGERY...THE LEADING EDGE OF THE TRADES IS RIGHT ON TOP OF POHNPEI IN THE FORM OF A SURFACE TROUGH. THIS FEATURE WILL CAUSE SOME PASSING SHOWERS FOR THE ISLAND UNTIL THIS EVENING. FARTHER EAST...A TRADE DISTURBANCE IS CROSSING THE DATE LINE BETWEEN 5N AND 13N. EXPECT THIS DISTURBANCE TO BRING SOMEWHAT WETTER WEATHER FOR MAJURO BY MIDNIGHT TONIGHT...KOSRAE ON SUNDAY AND EVENTUALLY OVER POHNPEI EARLY NEXT WEEK. DID NOT COMMIT TO SCATTERED SHOWERS DURING THIS TIME FRAME AS WATER VAPOR SATELLITE IMAGERY SHOWS STRONG WIND SHEAR AND INCREASING SUBSIDENCE ALOFT OVER EASTERN MICRONESIA. DECREASING QPF AMOUNTS IN SHORT TERM MODEL GUIDANCE ALSO SUPPORT THIS FORECAST SCENARIO. TRADE-WIND CONVERGENCE IN THE WAKE OF THE DISTURBANCE WILL LIKELY PROLONG THE INCREASED SHOWER COVERAGE FOR THE ENTIRE REGION THRU MIDWEEK. A NORTHEAST SWELL IS GENERATING SURF ON CHUUK AND POHNPEI JUST BELOW ADVISORY HEIGHTS. HOWEVER...THE SWELL HAVE ALREADY BEGUN TO GRADUALLY SUBSIDE. SATELLITE-DERIVED SEA HEIGHTS AND LOCAL SURF REPORTS SUPPORT THIS ASSESSMENT. ON THE OTHER HAND...TRADE-WIND ENERGY HEADED WESTWARD FROM THE MARSHALLS WILL EVENTUALLY REACH CHUUK BY SUNDAY EVENING. THIS IS ALREADY EXPECTED TO CAUSE A HIGH SURF EVENT ON KOSRAE BY THIS AFTERNOON...THEREFORE AN ADVISORY HAS BEEN ISSUED. && .WESTERN MICRONESIA... ABUNDANT SUNSHINE IS ANTICIPATED FOR CHUUK TODAY AS LATEST SOUNDINGS INDICATE VERY DRY AIR ABOVE 700 MB. ON SUNDAY THE AFOREMENTIONED SURFACE TROUGH PRESENTLY NEAR POHNPEI WILL TRIGGER A BRIEF PERIOD OF SHALLOW SHOWERS ON SUNDAY. DEEPER MOISTURE WILL FINALLY BEGIN TO SPREAD IN FROM THE EAST TOWARD MIDWEEK... INCREASING SHOWER CHANCES. MOIST SOUTHEASTERLY FLOW ALOFT WILL ENHANCE SHOWERS CAUSED BY CONVERGING SURFACE WINDS ACROSS BOTH YAP AND KOROR THROUGH SUNDAY. TOWARD MIDWEEK...THE ENVIRONMENT OVER KOROR AND YAP WILL ONCE AGAIN BECOME FAVORABLE FOR SHOWER FORMATION AS TRADE CONVERGENCE AND LOW-LEVEL MOISTURE INCREASE. && .GUM WATCHES/WARNINGS/ADVISORIES... GU...NONE. MARIANAS WATERS...NONE. && $$ MCELROY/CHAN +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 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.