From owner-wx-tropl@LISTSERV.ILLINOIS.EDU Fri Dec 17 14:19:03 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 oBH6J2X0011903 for ; Fri, 17 Dec 2010 14:19:03 +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 oBH0RZRn027712; Fri, 17 Dec 2010 00:18:49 -0600 (CST) Received: by LISTSERV.ILLINOIS.EDU (LISTSERV-TCP/IP release 14.5) with spool id 4802182 for WX-TROPL@LISTSERV.ILLINOIS.EDU; Fri, 17 Dec 2010 00:18:49 -0600 Received: from relay07.cites.uiuc.edu (relay07.cites.uiuc.edu [128.174.4.73]) by vacuum.cso.uiuc.edu (8.14.2/8.14.2) with ESMTP id oBH6Im6F004364 for ; Fri, 17 Dec 2010 00:18:48 -0600 (CST) Received: from weather3.admin.niu.edu (weather3.admin.niu.edu [131.156.8.48]) by relay07.cites.uiuc.edu (8.14.4/8.14.2) with ESMTP id oBH6If4i013491 for ; Fri, 17 Dec 2010 00:18:48 -0600 (CST) Received: by weather3.admin.niu.edu (Postfix, from userid 501) id D92B33FE08A2; Fri, 17 Dec 2010 00:18:39 -0600 (CST) X-Proofpoint-Spam-Reason: safe Message-ID: <20101217061839.D92B33FE08A2@weather3.admin.niu.edu> Date: Fri, 17 Dec 2010 00:18:39 -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 645 FXPQ60 PGUM 170618 AFDPQ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TIYAN GU 418 PM CHST FRI DEC 17 2010 .SYNOPSIS... SATELLITE IMAGERY REVEALS VERY DRY AIR IN PLACE WITH STRONG SUBSIDENCE INDICATED OVERHEAD IN WATER VAPOR IMAGERY. RADAR SCAN SHOWS VIRTUALLY NO RETURNS OVER THE FORECAST DOMAIN. ANIMATED VISIBLE IMAGERY SUGGESTS ISOLATED SHOWERS SHOULD RETURN AROUND MIDNIGHT. A COLD FRONT WAS SLICING BETWEEN IWO TO AND MINAMI TORI SHIMA. && .DISCUSSION... NEAR TERM FORECAST STILL LOOKS RELATIVELY DRY. PLOT THICKENS EARLY NEXT WEEK AS MODELS AGREE ON BRINGING A SHEAR LINE THROUGH THE FORECAST DOMAIN BETWEEN MONDAY AND MONDAY NIGHT. GFS STILL REMAINS THE MOST AGGRESSIVE OF THE SUITE OF MODELS IN REDUCING SURFACE PRESSURES OVER THE MARIANAS AND VEERING SURFACE WINDS AHEAD OF THE SHEAR LINE. GFS ENSEMBLE DOES NOT PERTURB THE WIND FIELD OVER THE FORECAST DOMAIN AS MUCH AS THE 18Z SOLUTION...BUT WIND SPEEDS DO BECOME WEAK. AGREE WITH PREVIOUS SHIFT IN MAINTAINING MORE CLIMATOLOGICAL WINDS IN THE WIND GRIDS DURING THE FIRST HALF OF NEXT WEEK UNLESS MODELS CONVERGE TO THE GFS SOLUTION. FOR NOW...WILL INCREASE CLOUD COVER DURING MONDAY AND TUESDAY TO ACCOUNT FOR THE PROXIMITY OF THE SHEAR LINE. MODEL SOLUTIONS DIVERGE BEYOND MID WEEK...SO WILL ADHERE TO FORECAST CONTINUITY AND MAINTAIN NORTHEAST WINDS...PARTLY CLOUDY SKIES AND ISOLATED SHOWERS DURING THE SECOND HALF OF THE FORECAST PERIOD. && .MARINE... IPAN BUOY CAME IN BETWEEN 3 AND 4 FEET...SO REDUCED PRIMARY SWELL GRID HEIGHT BY A FOOT TONIGHT AND SATURDAY. TAPERING THIS ADJUSTMENT TO THE PREEXISTING MARINE SWELL GRIDS SUGGESTS SURF ON NORTH AND EAST FACING REEFS WILL BUILD 1 TO 2 FEET BY SATURDAY AS WELL. OTHERWISE...STILL EXPECT A NW SWELL TO BEGIN ARRIVING SATURDAY AND BRING SURF ON WEST FACING REEFS TO MODERATE RIP CURRENT RISK LEVELS. && .EASTERN MICRONESIA... LITTLE HAS CHANGED ACROSS THE REGION OTHER THAN THE DEVELOPMENT OF A PATCH OF SHOWERS BETWEEN KOSRAE AND POHNPEI. CONVECTION HAS BEEN SHALLOW AND RELATIVELY SHORT-LIVED. GFS PUSHES THE SHOWERS THROUGH POHNPEI TONIGHT WITH DRIER CONDITIONS ENSUING FOR THE NEXT 5 DAYS. EASTERLY WINDS WILL SHIFT TO THE SOUTHEAST BY MONDAY AT ALL LOCATIONS IN RESPONSE TO A SHEARLINE DROPPING SOUTHWARD TOWARD THE AREA BUT INCREASED SHOWER CHANCES ARE NOT EXPECTED FOR NOW. && .WESTERN MICRONESIA... SCATTERED SHOWERS ASSOCIATED WITH A SMALL MCS ARE BEGINNING TO ERODE AWAY AROUND KOROR AND THEY SHOULD CLEAR OUT BY MIDNIGHT. A WEAK CIRCULATION CENTERED EAST OF YAP RAISES A LITTLE UNCERTAINTY IN THE FORECAST FOR THE NEXT COUPLE OF DAYS. AT THE MOMENT... MODELS ONLY PORTRAY EAST-NORTHEAST WINDS WEST OF THE CIRCULATION. GENERAL TROUGHING APPEARS TO BE RESOLVED BY THE MODELS IN LIEU OF THE CIRCULATION. DECIDED TO GO A LITTLE HEAVIER ON CLOUD COVER OVER YAP FOR THE NEXT COUPLE OF DAYS. CURRENT FORECAST GIVES WEIGHT TO MODEL GUIDANCE AND ASSUMES THE CIRCULATION WILL TROUGH OUT QUICKLY. IF THE CIRCULATION SHIFTS TOO FAR WESTWARD BEFORE FALLING APART...NEAR TERM WIND FORECAST FOR YAP WILL NEED TO BE MODIFIED. UPPER-LEVEL SUBSIDENCE IS OTHERWISE KEEPING DEEP CONVECTION OVER WESTERN MICRONESIA TO A MINIMUM. DRY CONDITIONS WILL CONTINUE ON CHUUK...FOLLOWING THE TREND IN EASTERN MICRONESIA. A COLD FRONT PUSHING SOUTHEASTWARD FROM JAPAN WILL GENERATE A NORTHWEST SWELL ON KOROR AND YAP BY THE WEEKEND. THE NORTHWEST SWELL WILL GRADUALLY BACK TO THE NORTH BY EARLY NEXT WEEK AS THE FRONT DISSIPATES. && .GUM WATCHES/WARNINGS/ADVISORIES... GU...NONE. MARIANAS WATERS...NONE. && $$ MCELROY/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.