Area Forecast Discussion
Issued by NWS Burlington, VT

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000 FXUS61 KBTV 291129 AFDBTV AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BURLINGTON VT 629 AM EST THU JAN 29 2015 .SYNOPSIS... A WEAK CLIPPER LIKE SYSTEM WILL PRODUCE A WIDESPREAD LIGHT SNOW THIS EVENING INTO FRIDAY...FOLLOWED BY UPSLOPE SNOW SHOWERS AND BITTERLY COLD TEMPERATURES FRIDAY NIGHT. HIGH PRESSURE WILL BUILD IN FOR THE WEEKEND WITH TEMPERATURES MUCH BELOW NORMAL. TEMPERATURES OF 10 TO 15 DEGREES BELOW NORMAL WILL PERSIST INTO THE MIDDLE OF NEXT WEEK. && .NEAR TERM /UNTIL 4 PM THIS AFTERNOON/... AS OF 629 AM EST THURSDAY...COLD MORNING THANKS TO RIDGING ALOFT WITH TEMPERATURES GENERALLY BELOW ZERO WITH COLDEST TEMPS IN THE NORTHEAST KINGDOM AND ADIRONDACKS REPORTING NEGATIVE TEENS. THE RIDGE WILL ERODE TODAY, WHILE AT THE SURFACE A CLIPPER SYSTEM APPROACHING FROM THE GREAT LAKES REGION WILL INCREASE CLOUDS ACROSS THE NORTH COUNTRY. SOUTHERLY WINDS WILL PICK UP AT 5-15 KTS WITH GUSTS DEVELOPING AHEAD OF THE CLIPPER. THIS FLOW WILL RESULT IN WARM AIR ADVECTION WITH 925MB INCREASING TO AROUND -4C. AFTERNOON TEMPERATURES WILL REACH THE M20S TO AROUND 30. THE CLIPPER WILL INCREASE CHANCE FOR SNOW TO SPREAD EASTWARD THIS AFTERNOON...REACHING THE SOUTHWESTERN ST LAWRENCE VALLEY FIRST. && .SHORT TERM /4 PM THIS AFTERNOON THROUGH SATURDAY/... AS OF 629 AM EST THURSDAY...SNOW WILL SPREAD INTO THE ST LAWRENCE VALLEY...AFFECTING THE AFTERNOON/EVENING COMMUTE. A STRONG SOUTH- SOUTHWESTERLY LOW LEVEL JET WILL BRING GUSTY WINDS, RESULTING IN BLOWING SNOW AND REDUCED VISIBILITIES. THIS JET WILL ALSO CAUSE SHADOWING AFFECTS IN THE CHAMPLAIN VALLEY AND NORTHEASTERN SLOPES. AS PWATS REACH AROUND HALF AN INCH TONIGHT, THIS WILL COINCIDE WITH THETA-E RIDGE, SO EXPECT HEAVIEST SNOWFALL TO OCCUR MAINLY BETWEEN 06Z-15Z FRIDAY. THE CENTER OF THE CLIPPER TRAVERSES NEAR THE INTERNATIONAL BORDER EARLY FRIDAY MORNING THEN REDEVELOPS OFF THE SOUTHERN NEW ENGLAND COAST IN THE AFTERNOON AS THE ASSOCIATED MID LEVEL TROUGH BEGINS TO NEGATIVELY TILT. THIS TILTING WILL RESULT IN THE SURFACE LOW SLOWING ITS PROGRESSION AND KEEPING CENTRAL AND EASTERN VERMONT IN SNOW/SNOW SHOWERS INTO FRIDAY AFTERNOON/EVENING. BEHIND THE SURFACE LOW, SOUTHERLY WINDS OVER THE NORTH COUNTRY WILL SHIFT NORTHEAST. THIS COMBINED WITH LINGERING MOISTURE WILL PRODUCE UPSLOPE SNOW SHOWERS WITH FROUDE NUMBERS SHOWING BLOCKED FLOW. WHEN ALL IS SAID AND DONE, EXPECT 3-6 INCHES OF SNOWFALL FOR THE ST LAWRENCE VALLEY, STRETCHING ACROSS THE NORTHERN TIER OF OUR ZONES INTO THE CENTRAL CHAMPLAIN VALLEY, NORTHWESTERN, NORTH CENTRAL AND NORTHEASTERN VERMONT. DUE TO SHADOWING, ESSEX COUNTY NY AND THE SOUTHERN CHAMPLAIN VALLEY AND SOUTH CENTRAL VT LOOK TO RECEIVE 2-4 INCHES. LOCALLY HIGHER AMOUNTS ARE POSSIBLE, ESPECIALLY IN THE IN THE WESTERN ST LAWRENCE VALLEY, AS MODELS DEPICT BEST MOISTURE AND DEFORMATION TO OCCUR IN THIS AREA. THE NW FLOW WILL USHER IN COLDER AIR WITH NON DIURNAL TREND EXPECTED FRIDAY. DRIER AIR WILL ALSO BE FILTERING IN, ALLOWING SKIES TO CLEAR. AS THE SURFACE LOW BECOMES A COASTAL LOW, THE SURFACE PRESSURE GRADIENT WILL INCREASE LATE FRIDAY INTO FRIDAY NIGHT WITH HIGH PRESSURE BUILDING TO OUR WEST. THESE FEATURES WILL RESULT IN VERY COLD TEMPERATURES FRIDAY NIGHT INTO SATURDAY. 925MB TEMPS WILL FALL INTO THE NEGATIVE UPPER TEENS TO AROUND -20C FRIDAY NIGHT, WHICH WILL BE REFLECTED AT THE SURFACE IN TERMS OF SATURDAY MORNING LOWS RANGING FROM -2F TO -17F. THIS COLD AIR WILL COINCIDE WITH NORTHWEST WINDS OF 10-20 MPH, PRODUCING WIND CHILL VALUES OF -20 TO -35. IF MODELS CONTINUE THIS TREND, WIND CHILL HEADLINES MAY NEED TO BE ISSUED. SATURDAY WILL NOT WARM UP MUCH WITH NEW SNOW HELPING TO REFLECT INSOLATION. MAX TEMPERATURES WILL RANGE FROM NEAR ZERO TO 12F. INCREASING SUNSHINE WILL HELP, BUT WINDS WILL BE SLOW TO SUBSIDE. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... AS OF 341 AM EST THURSDAY...MODELS SHOWING AN ARCTIC COLD FRONT TO MOVE THROUGH THE REGION SATURDAY NIGHT...SO HAVE GONE WITH SLIGHT CHANCE POPS FOR SNOW SHOWERS...ALTHOUGH MOISTURE APPEARS TO BE LIMITED WITH THIS FEATURE. A RIDGE OF HIGH PRESSURE WILL SLIDE EAST FROM THE GREAT LAKES ON SUNDAY AND WILL REMAIN THROUGH SUNDAY NIGHT. ECMWF AND GFS MODELS DEVELOP A LOW OFF THE MID ATLANTIC COAST EARLY MONDAY AND TAKE IT SOUTH OF THE BENCHMARK (40N 70W) BY 18Z MONDAY...WITH THE ECMWF FURTHER SOUTH THAN THE GFS MODEL. THE CANADIAN GLOBAL MODEL IS SLOWER THEN THE GFS AND ECMWF AND TAKES A LOW JUST NORTH OF THE BENCHMARK (40N 70W) AFTER 00Z TUESDAY. THE CANADIAN GLOBAL LOOKS TO BE THE OUTLIER AND WAS NOT USED. HAVE LEANED TOWARD THE COMPROMISE GFS SOLUTION FOR MONDAY. THE GFS HINTS THAT THE NORTHERN EDGE OF ANY SNOW ON MONDAY WOULD JUST BARELY MAKE IT INTO SOUTH CENTRAL VERMONT ON MONDAY...SO HAVE JUST GONE WITH SLIGHT CHANCE POPS FOR SNOW SHOWERS IN RUTLAND AND WINDSOR COUNTIES ON MONDAY...WITH THE REMAINDER OF THE REGION REMAINING DRY. IF ECMWF MODEL IS RIGHT...THAN THE ENTIRE FORECAST AREA WOULD REMAIN DRY MONDAY AND MONDAY NIGHT. ANOTHER COLD FRONT WILL APPROACH THE REGION TUESDAY NIGHT AND WEDNESDAY...SO HAVE GONE WITH SLIGHT TO LOW CHANCE POPS FOR SNOW SHOWERS TUESDAY NIGHT AND WEDNESDAY. TEMPERATURES WILL BE WELL BELOW NORMAL FOR EARLY FEBRUARY. && .AVIATION /11Z THURSDAY THROUGH MONDAY/... THROUGH 06Z FRIDAY...A RIDGE OF HIGH PRESSURE WILL MOVE EAST OF THE REGION AND OFF THE NEW ENGLAND COAST BY 18Z THURSDAY. VFR CONDITIONS EXPECTED ACROSS VERMONT AND NORTHERN NEW YORK THROUGH 00Z FRIDAY. BETWEEN 00Z-06Z FRIDAY EXPECTING CONDITIONS TO LOWER TO MVFR/IFR IN DEVELOPING LIGHT SNOW ACROSS VERMONT AND NORTHERN NEW YORK AS A CLIPPER SYSTEM APPROACHES FROM THE EASTERN GREAT LAKES. EXPECTING MAINLY SOUTHERLY SURFACE WIND GUSTS AT OR ABOVE 20 KNOTS TO DEVELOP BETWEEN 21Z-24Z THURSDAY AND CONTINUE THROUGH 06Z FRIDAY. OUTLOOK 06Z FRIDAY THROUGH MONDAY... 06Z FRIDAY-12Z SATURDAY...A CLIPPER SYSTEM WILL MOVE INTO THE REGION...CIGS LIKELY REMAIN MVFR WITH PERIODS OF IFR-LIFR VSBY IN SNOW, MAINLY FROM 06Z FRIDAY THROUGH 06Z SATURDAY. GUSTY NORTHERLY WINDS LIKELY AFTER 21Z FRIDAY. 12Z SATURDAY-00Z SUNDAY...MVFR TRENDS TO VFR AS HIGH PRESSURE BUILDS BACK INTO THE REGION. WINDS TREND LIGHT. 00Z SUNDAY-00Z MONDAY...GENERALLY VFR WITH MVFR SNOW POSSIBLE AS ANOTHER CLIPPER (WEAKER) PASSES THROUGH. 00Z MONDAY-00Z TUESDAY...VFR UNDER HIGH PRESSURE. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...WINTER WEATHER ADVISORY FROM 7 PM THIS EVENING TO 1 AM EST SATURDAY FOR VTZ001>008-010-016>018. NY...WINTER WEATHER ADVISORY FROM 4 PM THIS AFTERNOON TO 7 PM EST FRIDAY FOR NYZ026>031-087. && $$ SYNOPSIS...KGM NEAR TERM...KGM SHORT TERM...KGM LONG TERM...WGH AVIATION...WGH/LAHIFF

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