From owner-wx-tropl@LISTSERV.ILLINOIS.EDU Sun Nov 21 16:47:12 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 oAL8lBRg008442 for ; Sun, 21 Nov 2010 16:47:11 +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 oAK60wVK000969; Sun, 21 Nov 2010 02:46:58 -0600 (CST) Received: by LISTSERV.ILLINOIS.EDU (LISTSERV-TCP/IP release 14.5) with spool id 4448476 for WX-TROPL@LISTSERV.ILLINOIS.EDU; Sun, 21 Nov 2010 02:46:58 -0600 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 oAL8kw5W004334 for ; Sun, 21 Nov 2010 02:46:58 -0600 (CST) 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 oAL8kp4R007755 for ; Sun, 21 Nov 2010 02:46:58 -0600 (CST) Received: by weather3.admin.niu.edu (Postfix, from userid 501) id C54CE405001E; Sun, 21 Nov 2010 02:46:51 -0600 (CST) X-Proofpoint-Spam-Reason: safe Message-ID: <20101121084651.C54CE405001E@weather3.admin.niu.edu> Date: Sun, 21 Nov 2010 02:46:51 -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 210 FXPQ60 PGUM 210846 AFDPQ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TIYAN GU 646 PM CHST SUN NOV 21 2010 .SYNOPSIS... FRONTAL BOUNDARY AND ASSOCIATED CONVECTION LIE OVER THE NORTHERN CNMI. WEAK LOW-LEVEL VORTICITY CENTER WAS EVIDENT IN AN ENHANCING FIELD OF CUMULUS WEST OF ROTA. A TRADE-WIND TROUGH WAS GENERATING CONVECTION NEAR POHNPEI. WINDS WERE JUST LIGHT ENOUGH AND PWAT JUST HIGH ENOUGH FOR THUNDERSTORMS TO FORM OVER AND JUST WEST OF APRA HARBOR EARLIER THIS AFTERNOON. THE THUNDERSTORMS HAVE SINCE DISSIPATED. && .DISCUSSION... INITIAL FORECAST CONCERN REVOLVES AROUND WHETHER OR NOT CONVECTION IN THE CNMI WILL PROPAGATE FAR ENOUGH SOUTH TO AFFECT THE FORECAST ZONES. SATELLITE IMAGERY AND NEAR-TERM MODEL GUIDANCE BOTH SUGGEST THE SUBTROPICAL RIDGE WILL REMAIN STRONG ENOUGH TO FEND OFF THE CONVECTION. 00Z SOUNDING REVEALS THE INFLUENCE OF THE RIDGING AND SHOWED A PWAT DOWN A BIT FROM THE PREVIOUS SOUNDING TO 1.61 INCHES AND A RELATIVELY LOW TRADE-WIND INVERSION CENTERED AROUND 800 MB. GFS TIME-HEIGHT CROSS SECTION CARRIES EVEN SHALLOWER MOISTURE ON MONDAY...SO WILL ESCHEW PM THUNDER IN THE VICINITY OF GUAM TOMORROW. NEXT POTENTIAL WEATHER MAKER IS THE AFOREMENTIONED TROUGH NEAR POHNPEI. MODE GUIDANCE SUGGESTS THE LIONS SHARE OF THE ASSOCIATED CONVECTION SHOULD PASS SOUTH OF GUAM AROUND WEDNESDAY NIGHT. WILL GO AHEAD AND BRING MOSTLY CLOUDY SKIES IN BEGINNING ON WEDNESDAY EVENING AND LEAVE MOSTLY CLOUDY WORDING IN THROUGH FRIDAY. OTHERWISE...LONG TERM FORECAST LOOKS RELATIVELY UNEVENTFUL. && .MARINE... MARINE SWELL GRIDS MERELY REQUIRED A FEW MINOR ADJUSTMENTS. IPAN BUOY COMES IN WITH A DOMINANT NE SWELL AND A LESSER TRADE-WIND SWELL FROM THE EAST. EXISTING SWELL GRIDS CARRY BOTH COMPONENTS THROUGH THE FORECAST PERIOD IN AGREEMENT WITH WAVE WATCH MODEL GUIDANCE. AS THESE SWELL COMPONENTS CONTINUE TO ARRIVE THEY SHOULD MAINTAIN MODERATE RIP CURRENT RISK LEVEL SURF ON NORTH AND EAST FACING REEFS THROUGH AT LEAST MID WEEK. && .EASTERN MICRONESIA... THE ONLY MAJOR WEATHER FEATURE OVER EASTERN MICRONESIA IS A TRADE-WIND DISTURBANCE MOVING THRU POHNPEI AND KOSRAE THIS EVENING. EXPECT SHOWERS AND EVEN A THUNDERSTORM OR TWO TO CONTINUE OVER BOTH LOCATIONS INTO MONDAY. CONVERGING TRADE WINDS EAST OF THE DISTURBANCE WILL ALSO CAUSE SIMILAR CONDITIONS FOR MAJURO THRU THIS EVENING. THIS AREA OF SHOWERS IS GOING TO SHIFT WESTWARD AND PROLONG SHOWER ACTIVITY OVER POHNPEI INTO TUESDAY BUT SHOULD PASS NORTH OF KOSRAE INSTEAD. AROUND MIDWEEK...ANOTHER TRADE DISTURBANCE CURRENTLY SOUTHWEST OF HAWAII NEAR 6N165W MIGHT ARRIVE AT MAJURO WITH MORE SHOWERS. && .WESTERN MICRONESIA... THE LEADING EDGE OF THE TRADE DISTURBANCE OVER POHNPEI IS APPROACHING CHUUK THIS EVENING AND WILL BRING A PERIOD OF WET WEATHER THRU MONDAY NIGHT. AFTERWARD...DRIER NORTHEASTERLY TRADES SHOULD INTRODUCE GRADUAL IMPROVEMENT AROUND MIDWEEK. FARTHER WEST...A SURFACE TROUGH IS STEADILY DRIFTING WESTWARD TOWARD YAP. HOWEVER THE BULK OF THE PRECIP IS CONCENTRATING ALONG 6N AND MIGHT PASS SOUTH OF YAP DURING MIDWEEK. SURFACE CONVERGENCE NEAR THE SOUTHEASTERN END OF A NEAR-EQUATORIAL TROUGH WILL CONTINUE TO BE ENHANCED BY UPPER-LEVEL DIVERGENCE...AND GENERATE CONVECTION OVER PALAU THROUGH MONDAY. THEN THE SURFACE TROUGH PASSING SOUTH OF YAP WILL AFFECT PALAU WITH MORE RAINY WEATHER THRU MIDWEEK. FINALLY... ISOLATED-SHOWERS REGIME SHOULD RETURN BY THURSDAY AS WEAKER TRADES FROM THE EAST INFILTRATE THE REGION. && .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.