Area Forecast Discussion
Issued by NWS Burlington, VT

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000 FXUS61 KBTV 251722 AFDBTV AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BURLINGTON VT 1222 PM EST TUE NOV 25 2014 .SYNOPSIS... ACCUMULATING SNOW IS FORECAST FROM WEDNESDAY AFTERNOON THROUGH THURSDAY MORNING AS A STORM SYSTEM MOVES UP THE ATLANTIC COAST. SNOW AMOUNTS WILL BE GREATEST IN SOUTHERN AND EASTERN VERMONT, AND TAPER OFF TO THE NORTHWEST. AFTER THE STORM SYSTEM PASSES BY HIGH PRESSURE WILL SETTLE IN OVER THE REGION FOR THE END OF THE WEEK. TEMPERATURES WILL TREND COOLER THROUGH MID WEEK, WITH HIGHS IN THE 40S AND 50S TODAY FALLING INTO THE 20S AND 30S BY THE WEEKEND. && .NEAR TERM /UNTIL 8 PM THIS EVENING/... AS OF 1212 PM EST TUESDAY...NO SIGNIFICANT CHANGES TO THE PREVIOUS FORECAST. THE NORTH COUNTRY IS UNDER DEEP-LAYER SOUTHWEST FLOW WITH A LONGWAVE TROUGH ALONG THE MISSISSIPPI RIVER FROM CANADA TO MEXICO. SHORTWAVE TROUGH HAS PASSED BY TO WEST WITH SURFACE LOW NORTH OF THE GREAT LAKES MOVING NORTHEAST THROUGH QUEBEC. A SURFACE COLD FRONT HAS PUSHED WELL EAST OF THE REGION RESULTING IN TEMPERATURES CLOSER TO SEASONAL LEVELS. NRN NY AND VT WILL HAVE LOW-LEVEL COLD ADVECTION THROUGH THE DAY...WHICH WILL LARGELY OFFSET DIURNAL TEMPERATURE TRENDS. TEMPERATURES WILL ONLY RISE A FEW DEGREES THRU THE DAY...WITH HIGHS IN THE UPR 40S TO LOWER 50S AT LOWER ELEVATIONS...BUT LOCALLY IN THE LOWER 40S TO MID 40S ACROSS THE NRN ADIRONDACKS AND PORTIONS OF THE ST. LAWRENCE VALLEY. STEEP LOW LEVEL LAPSE RATES WILL MAINTAIN MODERATE SWLY WINDS OF 10-20 MPH...WITH A FEW GUSTS 25-35 MPH...HIGHEST IN THE IMMEDIATE ST. LAWRENCE RIVER VALLEY. A FEW DISORGANIZED LAKE EFFECT SHOWERS WILL RESULT IN A CHANCE OF SPRINKLES OF A MTN FLURRY ACROSS SRN ST. LAWRENCE AND FRANKLIN COUNTIES THROUGH THIS EVENING. LITTLE OR NO MEASURABLE PRECIPITATION EXPECTED. && .SHORT TERM /8 PM THIS EVENING THROUGH THURSDAY/... AS OF 409 AM EST TUESDAY...ALL EYES ON THE APPROACHING COASTAL LOW TO BEGIN IMPACTING THE SOUTHERN PART OF THE FORECAST AREA AS EARLY AS MID DAY WEDNESDAY. MODELS HAVE COME NICELY INTO AGREEMENT WITH VERY LITTLE TIMING DIFFERENCES AND SMALL DIFFERENCES IN PLACEMENT OF SURFACE LOW. AS UPPER TROUGH MOVES EAST AND DEEPENS OVER THE EASTERN US THE ATMOSPHERE COOLS TO SUPPORT SNOWFALL. VORT MAX/SHORTWAVE TROUGH AT 500 MB ROUNDS THROUGH THE BASE OF THE LONGWAVE TROUGH IN THE MID SOUTH AT 12Z WEDNESDAY AND BEGINS ITS TURN UP THE COAST. SURFACE LOW SPINS UP OFF THE CAROLINAS AND TRACKS NORTH ALONG THE STALLED FRONT. ECMWF/GFS/NAM ALL BRING THE SURFACE LOW TO 40N LATITUDE AT ABOUT THE SAME TIME 00Z THURS. GFS TAKES IT RIGHT OVER 40N/70W BENCHMARK, WHILE ECMWF AND NAM JUST A LITTLE ON THE INSIDE. ALSO NOT SEEING THE THE DEEPENING OF THE SURFACE LOW THAT THE MODELS HAD IN EARLIER RUNS. TRACK OF THE LOW PUTS THE FORECAST AREA IN THE COLD AIR TO SUPPORT NEARLY ALL SNOW, HOWEVER AT ONSET DURING THE DAY WEDNESDAY SURFACE TEMPS ESPECIALLY IN VALLEY LOCATIONS COULD ALLOW FOR SOME RAIN TO MIX IN. AFTER 00Z THURSDAY WILL BE ALL SNOW WITH PEAK SNOWFALL FROM ABOUT 21Z WED THROUGH 06Z THURS. BUFKIT SOUNDING FOR KVSF ALIGNS MAX RH AND UPWARD VERTICAL MOTION IN THE MIDDLE OF FAVORED -12 TO -18C SNOW GROWTH ZONE FROM 20Z WEDNESDAY TO 06Z THURSDAY. MODELS NOW VERY CLOSE WITH PLACEMENT OF GRADIENTS AND PRECIP AMOUNTS AND USED A MODEL BLEND TO CREATE THE QPF. CAME UP WITH A STORM TOTAL QPF OF .50 TO .75 INCH OF LIQUID ALONG THE CONNECTICUT RIVER VALLEY INTO SOUTHERN VERMONT WITH HIGHEST AMOUNTS IN THE SOUTHEAST. .25 INCH FROM NEWPORT VT THROUGH SOUTHERN CHAMPLAIN VALLEY INTO EASTERN ESSEX COUNTY, AND A TENTH OR LESS TO THE NORTHWEST. USING CLIMO SNOWFALL RATIOS OF ANYWHERE FROM 13-16:1 YIELDED STORM TOTAL SNOW 8-10 INCHES IN THE SOUTH AND 6-8 ESSEX/CALEDONIA/SOUTHERN WASHINGTON/EASTERN ADDISON COUNTIES VT. THIS IS AN UPTICK OVER PREVIOUS STORM TOTAL SNOWFALL AND WARRANTS A NORTHWARD EXPANSION OF THE WINTER STORM WATCH INTO THOSE COUNTIES. SURFACE LOW ACCELERATES NORTHWARD THROUGH THE GULF OF MAINE 06-12Z THURSDAY WITH SNOW ENDING WEST TO EAST. SNOW TO HANG ON LONGEST OVER THE HIGHER TERRAIN AS NORTHWEST FLOW GENERATES UPSLOPE SNOW SHOWERS IN REMAINING LOW LEVEL MOISTURE. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... AS OF 415 AM EST TUESDAY... NO SIGNIFICANT WEATHER EVENTS EXPECTED DURING THE EXTENDED PORTION OF THE FORECAST...BUT IT WILL BE UNSETTLED WITH SEVERAL CHANCES FOR SOME LIGHT PRECIPITATION. BY THURSDAY EVENING...SURFACE LOW WILL BE WELL OUT OF THE PICTURE AS IT MAKES ITS WAY UP THROUGH CANADIAN MARITIMES. UPPER TROUGH REMAINS OVER THE REGION HOWEVER...AND THIS COMBINED WITH LOW LEVEL NORTHERLY FLOW WILL RESULT IN CLOUDY SKIES AND SOME LINGERING UPSLOPE FLOW SNOW SHOWERS. A SHORTWAVE MOVING ACROSS THE REGION FRIDAY MAY GENERATE A FEW MORE LIGHT SNOW SHOWERS OVER THE NORTHERN MOUNTAINS...WITH THE REST OF THE AREA STAYING DRY. RIDGE AXIS SLIDES ACROSS THE AREA FRIDAY NIGHT AND BRINGS A BRIEF PERIOD OF CLEARING SKIES. CLOUDS RETURN BY SATURDAY HOWEVER WITH THE APPROACH OF A WARM FRONT FROM THE SOUTHWEST. CHANCES FOR A FEW SNOW OR RAIN SHOWERS INCREASE LATER SATURDAY INTO SATURDAY NIGHT AS THE WARM FRONT LIFTS NORTH ACROSS THE AREA WHILE LOW PRESSURE PASSES TO THE NORTH ACROSS ONTARIO INTO QUEBEC. COLD FRONT ASSOCIATED WITH THIS SYSTEM WILL THEN BRING A FEW MORE RAIN/SNOW SHOWERS TO THE REGION SUNDAY INTO SUNDAY EVENING. FRONT STALLS TO OUR SOUTH MONDAY WHILE WAVE OF LOW PRESSURE MOVES ALONG THE BOUNDARY...RESULTING IN CONTINUED CHANCE FOR A FEW SNOW/RAIN SHOWERS. TEMPERATURES WILL BE BELOW NORMAL EARLY IN THE PERIOD...THEN MODERATE TO ABOVE NORMAL BY SUNDAY BEFORE COOLING TO SEASONAL LEVELS NEXT MONDAY. && .AVIATION /17Z TUESDAY THROUGH SUNDAY/... THROUGH 12Z WEDNESDAY...MAINLY VFR THRU THE PERIOD. ONLY EXCEPTION IS KSLK WHERE CEILINGS WILL OCCASIONALLY FALL INTO MVFR CATEGORY TODAY. WINDS WILL BE GUSTY AT TIMES TODAY FROM THE SOUTHWEST. EXPECT WIND GUSTS NEAR 30 KTS AT KMSS AND 20-25 KTS ELSEWHERE. TREND WILL BE FOR WINDS TO SLOWLY DIMINISH THIS AFTERNOON INTO TONIGHT. OUTLOOK 12Z WEDNESDAY THROUGH SATURDAY... 12Z WEDNESDAY - 18Z WEDNESDAY...GENERALLY VFR. 18Z WEDNESDAY - 18Z THURSDAY...LOW PRESSURE MOVES NORTHEAST JUST OFF THE NEW ENGLAND COAST WITH IFR IN SNOW/SNOW SHOWERS. 18Z THURSDAY - 00Z SUN...MAINLY MVFR WITH LCL IFR IN SNOW SHOWERS. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...WINTER STORM WATCH FROM WEDNESDAY MORNING THROUGH THURSDAY MORNING FOR VTZ004-007-008-010>012-018-019. NY...NONE. && $$ SYNOPSIS...HANSON NEAR TERM...BANACOS/HANSON SHORT TERM...HANSON LONG TERM...RJS AVIATION...RJS

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