Issued by NWS Burlington, VT
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-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --000 FXUS61 KBTV 211441 AFDBTV AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BURLINGTON VT 941 AM EST SAT NOV 21 2009 .SYNOPSIS... A LOW PRESSURE SYSTEM CONTINUES TO MOVE EAST THROUGH THE CANADIAN MARITIMES...AND WILL GIVE WAY TO HIGH PRESSURE RIGHT INTO MONDAY BEFORE MOVING OFFSHORE. A COUPLE OF LOW PRESSURE SYSTEMS WILL AFFECT THE REGION TUESDAY...AND AGAIN TOWARDS THE END OF NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/...-- Changed Discussion --AS OF 941 AM EST SATURDAY...QUICK UPDATE TO THE TODAY AND TONIGHT PERIOD...MAINLY TO REFLECT MUCH SLOWER EROSION OF PESKY CLOUD COVER ACROSS THE REGION. CURRENT ACARS DATA FROM CYUL THIS MORNING SHOWING IMPRESSIVE SYNOPTIC LL INVERSION NEAR 900 MB...WHICH IS ACTING TO TRAP RESIDUAL LL MOISTURE ACROSS MUCH OF THE AREA. WITH OROGRAPHICALLY...ALBEIT LIGHT NORHWESTERLY FLOW PERSISTING ACROSS OUR AREA TODAY...HARD TO DISAGREE W/NAM BUFKIT SOUNDING FCSTS SHOWING LL STRATOCU HANGING TOUGH FOR MOST OF THE DAY...ESP IN THE NORTHERN MTNS. THUS HAVE OPTED FOR MORE PESSIMISTIC CHCS OF SUNSHINE TODAY IN THESE AREAS. SOME PEEKS OF SUN MORE LIKELY BY LATER IN THE DAY IN THE LOWER ELEVATIONS AND PORTIONS OF SC VT. BY TONIGHT...CLOUD COVER SHOULD SLOWLY THIN/ERODE AS HIGH PRESSURE AND DEEP LAYER DRYING CONTINUE TO PUSH INTO THE AREA. REST OF FCST IN EXCELLENT SHAPE IN REGARD TO WIND/TEMPS...SO OTHER THAN SKY COVER ADJUSTMENTS NOTED ABOVE NO OTHER CHGS NEEDED ATTM. PRIOR DISCUSSION... REMNANTS OF EXITING SYSTEM CONTINUE TO PINWHEEL DOWN ACROSS THE CWA THIS MORNING...AS LL CLD COVER BLANKETS THE CWA. THIS EXITING LOW OVER THE MARITIMES WILL GIVE WAY TO BROAD SFC RIDGE...WHICH IS CURRENTLY OVER THE MIDWEST. EXPECTING INVERSION TO DEVELOP DURING THE DAY AS RIDGE BUILDS EAST. AS A RESULT...LL CLDS WILL REMAIN OVER MUCH OF THE CWA BFR BREAKING LATE IN THE DAY. ENOUGH MOISTURE WILL BE LEFT OVER FOR MENTION OF --RW OVER HIR TRRN. TEMPS WILL BE CONSTRAINED FROM EXTENSIVE CLDS...SO HAVE STAYED CLOSE TO GUIDANCE. GOING INTO THE EVENING HRS...SKIES WILL CLR OUT ALLOWING FOR TEMPS TO DROP W/RADIATIONAL COOLING.-- End Changed Discussion --&& .SHORT TERM /SUNDAY THROUGH MONDAY/... AS OF 312 AM EST SATURDAY...NICE WX CONTINUES INTO SUNDAY AS RIDGE CRESTS OVER THE REGION. INVERSION WILL REMAIN FOR MUCH OF THE CWA DURING SUNDAY. THIS IS EVIDENT IN LATEST 850 TEMPS THAT WORK UP AND OVER BROAD UPPER RIDGE IN GREAT LKS REGION...AND DOWN UPON THE NORTHEAST. DIFF IS ONLY A FEW DEGREES SO WILL ONLY ETCH UP HIR ELEV...MAINLY IN NNY...HIGH TEMPS FOR SUNDAY THAN IN ADJACENT VALLEY LOCALES. SFC RIDGE WILL BEGIN TO SLIDE OFFSHORE LATE SUNDAY. STILL EXPECT CLRING SKIES OVERNGT FOR RADIATIONAL COOLING...BUT LESS THAN PREVIOUS NGT. WEAK SOUTHERLY FLOW WILL SLOWLY WORK INTO WESTERN PORTIONS OF CWA TOWARDS MORNING. THIS WILL TRANSLATE TO REST OF CWA DURING THE DAY MONDAY. CLDS ON THE INCR MONDAY AS LOW WORKS UP ALONG SE COAST. RIDGE IN PLACE OVER THE NE WILL KEEP SYSTEM AT BAY FOR MONDAY...W/ ONLY SOUTHERN ZONES SEEING SL CHANCE FOR --RW ON NORTHERN EDGE OF APPROACHING SYSTEM. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... AS OF 411 AM EST SATURDAY...AS THE ABOVE MENTIONED SYSTEM MOVES UP THE ATLANTIC COAST THE POTENTIAL FOR SHOWERS IN SOUTHERN ZONES INCREASES MON NIGHT...WITH SHOWERS POSSIBLE IN EASTERN VT AND EVEN CENTRAL/EASTERN DACKS TUESDAY. FOR MID WEEK THERE REMAINS CONSIDERABLE DISAGREEMENT OF GUIDANCE WITH HANDLING OF SHORTWAVE OVER THE HEARTLAND. MORE SPECIFICALLY...WITH THE FUJIWHARA EFFECT BETWEEN THE PRIMARY UPPER LOW AND PACIFIC ENERGY THAT ENTERS THE BROAD TROUGH. THE GFS OFFERS A MUCH MORE PROGRESSIVE SOLUTION...THOUGH HAS BEEN MUCH MORE INCONSISTENT FROM RUN TO RUN. THE ECMWF`S LESS PROGRESSIVE SOLUTION HAS BEEN MORE CONSISTENT AND IS THEREFORE FAVORED. UNDER THE ECMWF SOLUTION THE POTENTIAL FOR WIDESPREAD PRECIPITATION TUESDAY NIGHT AND WEDNESDAY IS MARKEDLY LESS THAN MOS GUIDANCE INDICATES...AS THE RIDGE OF HIGH PRESSURE TRIES TO REMAIN OVER THE REGION. THROUGH DIFFERING SOLUTIONS...BOTH GFS AND ECMWF EVENTUALLY BRING PRECIPITATION INTO THE NORTHEAST AROUND THE HOLIDAY...ESPECIALLY LATE THURSDAY INTO FRIDAY. BOTH ALSO BRING THE FIRST TRUE SEASONAL AIRMASS INTO THE NORTHEAST TOWARD THE END OF THE WORK WEEK. GIVEN THE UNCERTAINTY IN PLACEMENT OF SFC FEATURES AND THUS PLACEMENT OF THE COLD AIR...HAVE MAINTAINED THE RAIN/SNOW FORECAST...EXCEPT AT HIGHER ELEVATIONS WHICH SHOULD BE COLD ENOUGH FOR ALL SNOW. && .AVIATION /15Z SATURDAY THROUGH WEDNESDAY/...-- Changed Discussion --THROUGH 12Z SUNDAY...ABUNDANT LLVL MOISTURE REMAINS OVER THE FORECAST AREA. EXPECT MVFR CIGS AT MOST TAF SITES THROUGH THE MORNING WITH IFR AT KSLK. EXPECT CIGS TO GRADUALLY IMPROVE DURING AROUND 18Z...IMPROVING TO VFR EVENTUALLY SCT LATE THIS AFTERNOON. HIGHER TERRAIN WILL BE OBSCURED IN CLOUDS THROUGH 18Z. SOME AREAS OF SURFACE WIND GUSTS OF 20 KTS OR GREATER THIS MORNING...NOTABLY AT KMPV...BUT WILL DIMINISH BY 14Z. OTHERWISE WINDS WILL BE W TO NW AROUND 10 KTS...DIMINISHING TO LIGHT AND VARIABLE AFTER 02Z SUNDAY. LOOK FOR THE POTENTIAL FOR FOG TO FORM AFTER 05Z SUNDAY AT PRONE LOCATIONS LIKE KMPV AND KSLK WITH MVFR VIS. OUTLOOK 12Z SUNDAY THROUGH WEDNESDAY...MVFR VIS POSSLIBLE AT KMPV AND KSLK WITH BR THROUGH 14Z SUNDAY. OTHERWISE VFR CONDITIONS ANTICIPATED FOR MUCH OF THE PERIOD. SOME SCATTERED SHOWERS AND PERIODS OF MVFR ARE POSSIBLE TUESDAY IN TERRAINE OF SE VT TUE.-- End Changed Discussion --&& .BTV WATCHES/WARNINGS/ADVISORIES... VT...NONE. NY...NONE. && $$ SYNOPSIS...JN NEAR TERM...JMG/JN SHORT TERM...JN LONG TERM...AMF AVIATION...AMF/RJS
