From owner-wx-tropl@LISTSERV.ILLINOIS.EDU Sun Dec 19 16:23:05 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 oBJ8N4OC001879 for ; Sun, 19 Dec 2010 16:23:04 +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 oBI60Dnp027712; Sun, 19 Dec 2010 02:22:52 -0600 (CST) Received: by LISTSERV.ILLINOIS.EDU (LISTSERV-TCP/IP release 14.5) with spool id 4820279 for WX-TROPL@LISTSERV.ILLINOIS.EDU; Sun, 19 Dec 2010 02:22:52 -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 oBJ8MpAu011909 for ; Sun, 19 Dec 2010 02:22:51 -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 oBJ8MiHr013127 for ; Sun, 19 Dec 2010 02:22:51 -0600 (CST) Received: by weather3.admin.niu.edu (Postfix, from userid 501) id D2A033FE0866; Sun, 19 Dec 2010 02:22:44 -0600 (CST) X-Proofpoint-Spam-Reason: safe Message-ID: <20101219082244.D2A033FE0866@weather3.admin.niu.edu> Date: Sun, 19 Dec 2010 02:22:44 -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 309 FXPQ60 PGUM 190822 AFDPQ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TIYAN GU 622 PM CHST SUN DEC 19 2010 .SYNOPSIS... A WELL DEFINED SHEAR LINE CONTINUES SINKING SOUTHWARD AND IS CURRENTLY NEARING PAGAN. AN INVERTED SURFACE TROUGH IS LOCATED EAST OF THE MARIANAS ALONG 149E. SHOWERS WERE CONCENTRATING ALONG THE TROUGH AXIS AND WESTWARD AS FAR AS THE MARIANAS. VERY DRY AIR WAS EVIDENT EAST OF THE TROUGH FOR A COUPLE OF HUNDRED MILES. && .DISCUSSION... NO SIGNIFICANT CHANGES TO FORECAST REASONING. MODEL GUIDANCE CONSENSUS STILL SUGGESTS INVERTED SURFACE TROUGH JUST EAST OF THE MARIANAS WILL ENHANCE CLOUD COVER OVER THE FORECAST ZONES THROUGH MONDAY. MODELS ARE NOT BACKING WINDS ENOUGH AHEAD OF THE TROUGH SO HAVE ADJUSTED SHORT TERM WIND GRIDS ACCORDINGLY. MODEL GUIDANCE CONSENSUS ALSO SUGGESTS SHEAR LINE WILL SINK INTO THE FORECAST ZONES ON MONDAY AND TUESDAY. WEAKNESS OF SHEAR LINE BY THIS TIME SUGGESTS WIND FIELD TO THE NORTH OF THE BOUNDARY WILL BE RELATIVELY WEAK. IF NOT...MAGNITUDE OF THE WIND GRIDS OVER THE FORECAST ZONES MAY NEED TO BE BEEFED UP DURING AND JUST AFTER THE TIME FRAME OF THE SHEAR LINE PASSAGE. INHERITED FORECAST MAINTAINS MOSTLY CLOUDY SKIES THROUGH TUESDAY...WHICH LOOKS LIKE A PRETTY GOOD GUESS FOR NOW. MODEL QPFS AND SATELLITE IMAGERY STILL SUGGEST SHOWER COVERAGE SHOULD REMAIN ISOLATED THROUGH TUESDAY...THEN A DRYING TREND IS EXPECTED. HOWEVER...WOULD NOT BE SURPRISED TO SEE SHOWERS BRIEFLY CONCENTRATE ABOVE THE SCATTERED COVERAGE THRESHOLD ON THE MESOSCALE UNTIL THE DRIER AIR ARRIVES. && .MARINE... IPAN BUOY INITIALIZES WITH A MAXIMUM SIGNIFICANT SWELL HEIGHT BETWEEN 3 AND 4 FEET FROM 050 DEGREES AT 12 SECONDS. HAVE BACKED THE SWELL FROM 060 TO 050 DEGREES AND SHAVED A FOOT FROM THE SWELL HEIGHT. WILL TAPER THESE CHANGES INTO THE EXISTING SWELL GRIDS. BASED UPON THIS EXPECT SURF TO BUILD ON NORTH AND EAST FACING REEFS A BIT DURING THE NEXT DAY OR SO IF WAVE WATCH GUIDANCE IS CORRECT. OTHERWISE...NO BIG CHANGES TO THE MARINE SWELL GRIDS. STILL EXPECT MODERATE RIP CURRENT RISK LEVEL SURF TO PREVAIL ON NORTH AND EAST FACING REEFS FOR AT LEAST THE NEXT SEVERAL DAYS. && .EASTERN MICRONESIA... LIGHT SURFACE WINDS ASSOCIATED WITH THE NEUTRAL POINT OF AN UNSEASONAL TROUGH EXTENDING NORTHEASTWARD FROM THE MARSHALLS TO BEYOND THE DATE LINE WILL CONTINUE TO PROMOTE FAIR WEATHER OVER MAJURO INTO TUESDAY. GENTLE NORTHEAST TO EAST WINDS SOUTHEAST OF A STRONG SHEAR LINE NEAR THE MARIANAS ARE ALSO SUPPORTING DRY WEATHER FOR BOTH KOSRAE AND POHNPEI THRU MONDAY EVENING. AS THE TROUGH NEAR THE MARSHALLS GRADUALLY LIFTS NORTHWARD DURING MIDWEEK...THE SURFACE RIDGE EAST OF THE DATE LINE WILL STRETCH WESTWARD AND PROLONG DRY WEATHER FOR THE ENTIRE REGION. && .WESTERN MICRONESIA... A WEAK SURFACE TROUGH IS EXPECTED TO BRING A FEW CLOUDS AND SHOWERS OVER CHUUK THRU MONDAY. BY TUESDAY...THE SAME DRY PATTERN OVER EASTERN MICRONESIA WILL ALSO DOMINATE CHUUK AS WELL. FARTHER WEST...A SHEAR LINE FRAGMENT IS GENERATING SOME WETNESS FOR BOTH YAP AND KOROR. WITH THIS FEATURE SLOWLY SHIFTING WESTWARD... IMPROVEMENT SHOULD BEGIN ON TUE AND LAST INTO AT LEAST FRI. NW-N SWELLS PRODUCED BY NEAR-GALE WINDS NORTH OF THE SHEAR LINE AND COLD FRONT ARE GOING TO CAUSE HIGHER SURF ALONG THE NORTH SHORES OF BOTH THE REPUBLIC OF PALAU AND YAP STATE FOR THE NEXT FEW DAYS...AND FOR CHUUK BY MIDWEEK. SURF HEIGHTS ACROSS PALAU AND YAP SHOULD STAY BELOW ADVISORY LEVELS...BUT COULD REACH ADVISORY CRITERIA ON CHUUK AND NEEDS TO BE MONITORED. && .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.