Area Forecast Discussion
Issued by NWS Burlington, VT

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000 FXUS61 KBTV 300239 AFDBTV AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BURLINGTON VT 939 PM EST THU JAN 29 2015 .SYNOPSIS... A WEAK CLIPPER LIKE SYSTEM WILL PRODUCE A WIDESPREAD LIGHT SNOW TONIGHT 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 7 AM FRIDAY MORNING/... AS OF 932 PM EST THURSDAY... HEADLINES: WINTER WEATHER ADVISORIES CONTINUE TO BE IN AFFECT FOR ENTIRE FORECAST AREA FOR TONIGHT INTO FRIDAY EVENING. NO SIGNIFICANT CHANGES TO THE FORECAST. OBSERVATIONS OVER THE SAINT LAWRENCE VALLEY INDICAT LIGHT SNOW IS BEGINNING TO FALL SO THE BOUNDARY LAYER RH HAS FINALLY SATURATED OVER NORTHERN NEW YORK. THOSE SHOWERS WILL CONTINUE TO DEVELOP AND BRING LIGHT TO MODERATE SNOW OVER THE AREA GRADUALLY MOVING EAST. THE FORECAST IS IN GOOD SHAPE TO HAVE SNOW REACH THE CHAMPLAIN VALLEY IN 05-07Z TIME FRAME WITH 1 TO 1.5 INCHES TO FALL OVERNIGHT BEFORE SUNRISE. TEMPS ARE ON TRACK TO DROP INTO THE LOW 20`S TO MID TEENS OVERNIGHT UNDER OVERCAST SKIES. PREVIOUS DISCUSSION...WV/IR SATELLITE SHOW THE CLIPPER DEVELOPING QUITE NICELY OVER THE GREAT LAKES AND BEGINNING TO WRAP UP. THE MID TO UPPER LEVEL MOISTURE IS QUICKLY INCREASING HOWEVER THAT HASN`T YET REACHED THE GROUND OVER NORTHERN NEW YORK. CURRENT COMPOSITE RADAR AND GROUND TRUTH PRESENT TWO DRASTICALLY DIFFERENT SOLUTIONS RIGHT NOW AS THE SURFACE OBS ARE SHOWING DEWPOINT DEPRESSIONS OF 21 DEGREES AT OGDENSBURG. AT THAT POINT THE LOW LEVEL MOISTURE JUST HASN`T REACHED THE GROUND AND THE METAR IS REPORTED CLEAR BELOW 12,000 FEET. UNTIL THE LOW LEVELS BECOME SATURATED EXPECT THE PRECIP TO ESSENTIALLY BE VIRGA. ADDITIONALLY ACROSS MUCH OF THE ST LAWRENCE VALLEY SURFACE TEMPS ARE IN THE MID TO UPPER 30`S SO ANY PRECIP THAT IS FALLING WILL MOST LIKELY BE A WINTRY MIX OF SNOW OR RAIN FOR THE NEXT HOUR OR TWO. EXPECT OVER THE NEXT 2-3 HOURS THE LOW LEVELS SHOULD SATURATE AND BECOME SNOW SHOWERS FOR MOST OF THE OVERNIGHT HOURS AS THE CLIPPER MOVES EASTWARD. ONLY REAL CHANGES TO THE FORECAST WERE TO UP THE TEMPS OVER THE ST LAWRENCE VALLEY MATCHING OBS AND THEN TREND BACK HOW QUICKLY THE PRECIP MOVES ACROSS THE FORECAST REGION DUE TO THE DRY AIR IN THE VERY LOW LEVELS. THE REST OF THE FORECAST LOOKS ON TRACK TO DROP INTO THE UPPER TEENS TO NEAR 20 ACROSS THE REGION WITH LIGHT TO MODERATE SNOWFALL OVERNIGHT. && .SHORT TERM /7 AM FRIDAY MORNING THROUGH SATURDAY NIGHT/... AS OF 330 PM EST THURSDAY...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 DIGS AND TAKES ON A NEGATIVE TILT. THIS WILL RESULT IN THE SURFACE LOW SLOWING ITS EASTWARD PROGRESSION INTO GULF OF MAINE. THE RESULT WILL BE A TRANSITION OF SYNOPTIC SNOW TO UPSLOPE SNOW OR SNOW SHOWERS ACROSS VERMONT...WHICH WILL CONTINUE INTO FRIDAY NIGHT. THE SNOW WILL TAPER OFF EARLIER ACROSS NORTHERN NEW YORK. BEHIND THE SURFACE LOW AND WITH PASSAGE OF COLD FRONT...SOUTHERLY WINDS WILL SHIFT INTO THE NORTH. THIS COMBINED WITH LINGERING MOISTURE WILL PRODUCE UPSLOPE SNOW SHOWERS WITH FROUDE NUMBERS SHOWING BLOCKED FLOW. WHEN ALL IS SAID AND DONE...EXPECT 3-7 INCHES OF SNOWFALL FOR THE ST LAWRENCE VALLEY...STRETCHING ACROSS THE NORTHERN TIER OF OUR ZONES ACROSS THE CENTRAL CHAMPLAIN VALLEY AND ALL OF NORTHERN VERMONT. DUE TO SHADOWING...ESSEX COUNTY NY AND THE SOUTHERN CHAMPLAIN VALLEY AND SOUTH CENTRAL VT WILL RECEIVE JUST A BIT LESS...WITH 2-5 INCHES EXPECTED. SOME LOCALLY HIGHER AMOUNTS ARE ALSO POSSIBLE...ESPECIALLY OVER THE WESTERN SLOPES OF THE NORTHERN GREEN MOUNTAINS. THE NORTHWEST FLOW WILL USHER IN COLDER AIR WITH NON DIURNAL TEMPERATURE TREND EXPECTED FRIDAY. DRIER AIR WILL ALSO BE FILTERING IN FRIDAY ALLOWING SKIES TO CLEAR ACROSS NORTHERN NEW YORK. PRESSURE GRADIENT WILL INCREASE LATE FRIDAY INTO FRIDAY NIGHT WITH COASTAL LOW DEEPENING AND HIGH PRESSURE BUILDING TO OUR WEST. THESE FEATURES WILL RESULT IN VERY COLD TEMPERATURES FRIDAY NIGHT INTO SATURDAY. 925MB TEMPS WILL FALL TO BETWEEN -10C AND -20C FRIDAY NIGHT...WHICH WILL BE REFLECTED AT THE SURFACE IN TERMS OF SATURDAY MORNING LOWS RANGING FROM A BIT ABOVE ZERO SOUTHERN AND EASTERN VERMONT TO THE TEENS BELOW ZERO ACROSS MUCH OF NORTHERN NEW YORK. COMBINATION OF TEMPS AND WIND WILL LIKELY RESULT IN SOME WIND CHILL ISSUES...WITH POSSIBILITY OF AT LEAST ADVISORIES FOR LATE FRIDAY NIGHT INTO SATURDAY. MAX TEMPS SATURDAY UNDER PARTLY TO MOSTLY SUNNY SKIES WILL BE ONLY IN THE SINGLE NUMBERS TO LOWER TEENS...ALTHOUGH WINDS WILL ABATE DURING THE AFTERNOON. ANOTHER FRONT WILL DROP INTO THE AREA FROM THE NORTHWEST SATURDAY NIGHT. NOT MUCH IN WAY OF AVAILABLE MOISTURE...BUT ENOUGH FOR AT LEAST THE MENTION OF A CHANCE OF SNOW SHOWERS...ESPECIALLY OVER THE NORTHERN MOUNTAINS. && .LONG TERM /SUNDAY THROUGH THURSDAY/... AS OF 254 PM EST THURSDAY...VERY LITTLE CHANGE TO PREVIOUS FORECAST THINKING FOR THE EXTENDED PERIOD AS TODAYS 12Z MODEL SUITE REMAINS IN GOOD AGREEMENT KEEPING ANY MAJOR SYSTEMS AWAY FROM THE NORTH COUNTRY. LINGERING SNOW SHOWERS REMAIN POSSIBLE MAINLY ACROSS THE HIGHER TERRAIN SUNDAY AS AN ARCTIC FRONT PUSHES INTO THE REGION. TRICKY MAX TEMPS FORECAST AT THIS TIME BASED ON FRONTAL PASSAGE TIMING, BUT BASED ON FALLING 925-850MB TEMPS THROUGH THE DAY THINK HIGHS WILL BE EARLY IN THE MORNING AND SLOWLY FALL OFF THROUGH THE DAY. MEANWHILE, STILL MONITORING THE POTENTIAL DEVELOPMENT OF SURFACE LOW PRESSURE OVER THE TENNESSEE RIVER VALLEY LATE SUNDAY INTO SUNDAY NIGHT WHICH WILL INTENSIFY OFF THE EASTERN SEABOARD MONDAY. LATEST TRENDS OF THE 12Z ECMWF AND GFS CONTINUE THE IDEA THAT THIS SOUTH STREAM ENERGY DOESN`T PHASE WITH THE NORTHERN STREAM TROUGH DIGGING THROUGH THE GREAT LAKES WHICH NEVER BECOMES NEGATIVELY TILTED AND REMAINS AN OPEN WAVE AT 500MB. THIS RESULTS IN A MORE WESTERLY TRACK OF THE SURFACE LOW INITIALLY, CAUSING IT TO PASS WELL TO OUR SOUTH AND EAST OF THE BENCHMARK. SO BASICALLY A NON-EVENT FOR US, SIGH. BEYOND MONDAY PATTERN TURNS COLD AND DRY FOR MONDAY NIGHT THROUGH TUESDAY NIGHT AS A STRONG 1030MB HIGH SETTLES OVER THE MID-ATLANTIC AND NORTHEAST. TEMPS WILL STRUGGLE TO WARM INTO THE SINGLE DIGITS TUESDAY AND FALL BELOW ZERO AREA-WIDE BOTH NIGHTS. THIS WILL BE A BRIEF BLAST OF CLOD THOUGH AS THE HIGH SHIFTS EAST OFF THE COAST FOR WEDNESDAY WITH SOUTHERLY RETURN FLOW WARMING TEMPS BACK INTO THE TEENS AND 20S. NEXT CHANCE FOR SNOW COMES WITH A CLIPPER SYSTEM SHIFTING THROUGH THE AREA WEDNESDAY AND WEDNESDAY NIGHT. && .AVIATION /03Z FRIDAY THROUGH TUESDAY/... THROUGH 00Z SATURDAY...PERIODS OF LIGHT SNOW WILL AFFECT TAF SITES THROUGH FRIDAY BRINGING A VARIETY OF FLIGHT CATEGORIES...BUT A PREDOMINANT TREND TO MVFR/IFR. LIGHT SNOW SHOWERS WILL OVERSPREAD THE REGION BETWEEN 00Z AND 04Z...WITH GREATEST COVERAGE AND INTENSITY GENERALLY 06Z TO 12Z. THUS WILL SEE A DOWN TREND IN VISIBILITIES AND CEILINGS TO MAINLY MVFR/IFR. GUSTY SOUTH WINDS UP TO 25 KNOTS WILL GRADUALLY DECREASE TOWARDS MORNING. WINDS WILL TURN TO THE NORTHWEST FROM 5 TO 15 KNOTS WITH SOME HIGHER GUSTS ON FRIDAY...LEADING TO MORE TERRAIN DRIVEN SNOW SHOWERS CONTINUING THROUGH THE DAY...ESPECIALLY BTV/MPV/RUT/SLK. OUTLOOK 00Z SATURDAY THROUGH TUESDAY... 00Z SATURDAY-12Z SATURDAY...SLOW IMPROVEMENT AS SNOW SHOWERS END. GUSTY NORTHWEST WINDS WILL RESULT IN AREAS OF BLOWING SNOW. 12Z SATURDAY-12Z MONDAY...VFR. 12Z MONDAY-00Z WEDNESDAY...MAINLY VFR AS SYSTEM SLIDES SOUTH OF REGION. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...WINTER WEATHER ADVISORY UNTIL 1 AM EST SATURDAY FOR VTZ001>012- 016>019. NY...WINTER WEATHER ADVISORY UNTIL 7 PM EST FRIDAY FOR NYZ026>031- 034-035-087. && $$ SYNOPSIS...RJS NEAR TERM...DEAL SHORT TERM...RJS LONG TERM...LAHIFF AVIATION...MUCCILLI/NASH

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