Area Forecast Discussion
Issued by NWS Burlington, VT

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000 FXUS61 KBTV 212349 AFDBTV AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BURLINGTON VT 749 PM EDT THU MAY 21 2015 .SYNOPSIS... A COLD FRONT WILL MOVE SOUTH FROM CANADA OVERNIGHT AND WILL MOVE THROUGH THE REGION EARLY FRIDAY WITH JUST SOME CLOUDS ASSOCIATED WITH THIS FRONT. MUCH COLDER AIR WILL BE OVER THE NORTH COUNTRY FRIDAY NIGHT INTO EARLY SATURDAY MORNING WITH LOW TEMPERATURES BY EARLY SATURDAY MORNING IN THE 20S AND 30S. A WEAK RIDGE OF HIGH PRESSURE WILL BUILD INTO THE REGION ON SATURDAY WITH HIGHS BY SATURDAY AFTERNOON...MAINLY IN THE 60S. && .NEAR TERM /UNTIL 7 AM FRIDAY MORNING/...
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AS OF 743 PM EDT THURSDAY...A SURFACE COLD FRONT AND DIGGING UPPER LEVEL TROUGH ACROSS SWRN QUEBEC AND SERN ONTARIO WILL SHIFT SEWD OVERNIGHT...APPROACHING THE ST. LAWRENCE VALLEY BETWEEN 10-12Z FRIDAY. GENERALLY LOOKING FOR VARIABLY CLOUDY SKIES OVERNIGHT WITH PREVAILING MID-UPPER LEVEL CLOUDS IN ADVANCE OF THE FRONTAL BNDRY. IT DOES APPEAR BASED ON 18Z NAM MODEL SOUNDINGS THAT SOME STRATUS WILL ACCOMPANY THE COLD FRONT...AND SHOULD SEE THE STRATUS DECK WORK INTO NRN NY TOWARD DAYBREAK. INTRODUCED SOME SPRINKLES ACROSS THE HIGHER ELEVATIONS OF NY/VT DURING FRIDAY MORNING ASSOCIATED WITH FRONTAL PASSAGE. OTHERWISE...NO SIGNIFICANT CHANGES NECESSARY TO THE GOING FORECAST. OVERNIGHT LOWS GENERALLY EXPECTED IN THE LOW-MID 40S...EXCEPT A FEW READINGS IN THE MID- UPPER 30S OVERNIGHT IN THE MORE SHELTERED LOCATIONS WITHIN THE NRN ADIRONDACK REGION...AND FAR NORTHEASTERN VERMONT.
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&& .SHORT TERM /7 AM FRIDAY MORNING THROUGH SATURDAY NIGHT/...
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AS OF 358 PM EDT THURSDAY...EXPECTING COLD FRONT TO MOVE THROUGH THE REGION EARLY FRIDAY...WITH MODELS NOT SHOWING MUCH IN THE WAY OF MOISTURE WITH THIS FRONT...EXCEPT FOR AN INCREASE IN CLOUD COVER. THUS...HAVE ONLY SHOWN 20-30 POPS FOR SPRINKLES ACROSS THE HIGHER ELEVATIONS DURING THE DAY FRIDAY. A CLOSED UPPER LOW WILL PASS OVER NORTHERN AND EASTERN MAINE LATE FRIDAY NIGHT AND EARLY SATURDAY MORNING. TEMPERATURES AT 500 MB BETWEEN 06Z-12Z SATURDAY WILL BE AROUND -32C AND AROUND -7C AT 850 MB BETWEEN 06Z- 12Z SATURDAY. THIS WILL LEAD TO SURFACE TEMPERATURES IN THE MID TO UPPER 20S BY EARLY SATURDAY MORNING ACROSS THE ADIRONDACKS AND EASTERN AND NORTHEAST VERMONT. THUS...HAVE PUT UP A FREEZE WATCH IN THESE AREAS...AS ANY SENSITIVE PLANTS OR VEGETATION WILL LIKELY BE DAMAGED IF LEFT UNPROTECTED. MOS GUIDANCE LOOKS TOO COLD WITH MIN TEMPERATURES AT SARANAC LAKE (KSLK) BY EARLY SATURDAY MORNING WITH BOTH THE GFS AND NAM MOS HAVING MIN TEMPERATURES THERE IN THE UPPER TEENS. HOWEVER...GIVEN THE SHORTER NIGHTS...FEEL MOS GUIDANCE IS TOO COLD THERE...AND HAVE LEANED TOWARD THE WARMER ENSEMBLE MOS GUIDANCE WITH MIN TEMPERATURES AT SARANAC LAKE IN THE LOWER TO MID 20S. TEMPERATURES WILL MODERATE QUICKLY ON SATURDAY...AS SURFACE WINDS SHIFT TO THE WEST-SOUTHWEST WITH HIGHS ON SATURDAY IN THE 60S.
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&& .LONG TERM /SUNDAY THROUGH THURSDAY/... AS OF 315 PM EDT THURSDAY...A DEVELOPING SOUTHWEST FLOW ALOFT WITH EMBEDDED PIECES OF ENERGY AND INCREASED SURFACE INSTABILITY BY THE MIDDLE OF NEXT WEEK...WILL RESULT IN DAILY CHANCES FOR SHOWERS/STORMS. STILL SOME UNCERTAINTY ON TRANSITION PERIOD MONDAY INTO TUESDAY...ASSOCIATED WITH SFC WARM FRNT AND MOISTURE/LIFT. GFS CONTS TO BE 6 TO 12 HOURS FASTER WITH PUSHING RIBBON OF ENHANCED 850 TO 500MB MOISTURE AND WEAK WAA LIFT ACRS OUR CWA ON MONDAY...WHILE 12Z ECMWF DELAYS THIS FEATURE UNTIL TUESDAY. EITHER WAY QPF LOOKS TO BE LIGHT AND GENERALLY < 0.25". WL CONT WITH PREVIOUS FORECASTER IDEA AND KEEP MOST OF OUR CWA DRY ON MONDAY...EXCEPT FOR SOUTHWEST SAINT LAWRENCE VALLEY AND WESTERN DACKS...WILL MENTION CHC POPS. INSTABILITY PARAMETERS INCREASE ON TUESDAY WITH SFC BASED CAPE VALUES BTWN 600 AND 1000 J/KG ASSOCIATED WITH SFC TEMPS WARMING INTO THE UPPER 70S AND LOWER 80S. IN ADDITION...DEVELOPING SOUTH TO SOUTHWEST FLW ALOFT WILL INCREASE DEEP LAYER MOISTURE FIELDS ACROSS OUR REGION...WITH PW VALUES SURGE ABOVE 1.0" BY MIDWEEK...ALONG WITH DEWPOINTS IN THE 50S TO L/M 60S. THIS WILL RESULT IN SOME INCREASE IN THE RELATIVE HUMIDITY VALUES...ESPECIALLY BY WEDS INTO THURS. PROGGED 925MB WARM BTWN 15C AND 17C BY WEDS...SUPPORTING HIGHS WELL INTO THE 80S MOST LOCATIONS. HAVE INCREASED TEMPS BY 3 TO 5 DEGREES ABOVE THE COOLER SUPERBLEND NUMBERS FOR MIDWEEK...ALONG WITH OVERNIGHT LOWS IN THE WARMER VALLEY LOCATIONS. GIVEN THE UNCERTAINTY IN TIMING OF S/W ENERGY IN THE SOUTHWEST FLOW ALOFT AND AREAL COVERAGE OF SHOWERS/STORMS WILL CUT POPS SLIGHTLY FROM SUPERBLEND VALUES AND MENTION 30 TO 40% INSTEAD OF 50 TO 60% POPS FOR WEDS AND THURSDAY. BOTTOM LINE INCREASE CHCS FOR PRECIP BY MIDWEEK...ALONG WITH ABOVE NORMAL TEMPS DEVELOPING. && .AVIATION /00Z FRIDAY THROUGH TUESDAY/... THROUGH 00Z SATURDAY...VFR CONDITIONS WILL PREVAIL AT ALL TAF SITES THROUGHOUT THE PERIOD...THE ONLY SIGNIFICANT CHANGE WILL BE A WIND SHIFT FROM SOUTH TO NORTHWEST BEHIND A SURFACE COLD FRONT ON FRIDAY MORNING. SURFACE ANALYSIS SHOWS WEAK BOUNDARY ACROSS THE NORTHERN GREAT LAKES INTO CENTRAL CANADA...WITH A BAND OF MID LEVEL CLOUDS AND A WIND SHIFT. THIS FRONT WILL IMPACT OUR WESTERN TAF SITES AROUND 12Z FRIDAY AND INTO THE CHAMPLAIN VALLEY/CENTRAL VT TAF SITES BETWEEN 14Z-16Z. A BRIEF PERIOD OF MVFR CIGS ARE POSSIBLE AT SLK AND MSS ASSOCIATED WITH FROPA IN THE EARLY MORNING. WINDS WILL INCREASE FROM THE NORTHWEST AT 10 TO 15 KNOTS WITH GUSTS TO 20-25 KNOTS BEHIND FRONT BY MIDDAY FRIDAY. MID LEVEL CLOUDS WILL CLEAR OUT BY MID TO LATE AFTERNOON. OUTLOOK 00Z SATURDAY THROUGH WEDNESDAY... SFC HIGH PRESSURE BUILDS INTO THE REGION WITH VFR CONDITIONS AND BREEZY NORTHWEST WINDS ON FRIDAY AFTN. NEXT CHANCE FOR SCATTERED SHOWERS AND A RUMBLE OF THUNDER WILL BE EARLY NEXT WEEK WITH POTENTIAL MVFR CEILINGS/VIS IN THE HEAVIER SHOWERS/STORMS. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...FREEZE WATCH FROM LATE FRIDAY NIGHT THROUGH SATURDAY MORNING FOR VTZ003-004-006>008-010-012. NY...FREEZE WATCH FROM LATE FRIDAY NIGHT THROUGH SATURDAY MORNING FOR NYZ029>031-034. && $$ SYNOPSIS...WGH NEAR TERM...BANACOS/WGH SHORT TERM...WGH LONG TERM...TABER AVIATION...BANACOS/MV

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