254 FXUS61 KBTV 191807 AFDBTV AREA FORECAST DISCUSSION National Weather Service Burlington VT 107 PM EST Tue Feb 19 2019 .SYNOPSIS... A large area of high pressure across the Great Lakes region will build eastward into the Northeast, bringing dry, mostly clear, and seasonable cold conditions through Wednesday. Quick moving low pressure passing to the north and west of the St. Lawrence River will bring developing snowfall Wednesday night, ending as a wintry mix early Thursday morning. Snow and sleet amounts will range up to a couple of inches from the Champlain Valley westward across northern New York, with 2 to 5 inches of snow and sleet excepted across north-central into northeastern Vermont. Some melting of this snow and sleet is expected as Thursday afternoon valley temperatures rise into the 40s. Temperatures will remain above normal with drier weather to end the week. && .NEAR TERM /THROUGH WEDNESDAY/... As of 1239 PM EST Tuesday...Forecast in good shape with high pressure remaining in control. Updated the sky forecast to reflect the clear skies in place. Should be a beautiful, sunny late winter afternoon, but bundle up if headed outdoors as wind chills are in the single digits. Previous discussion follows. Previous Discussion... Synoptically quiescent conditions prevail across the North Country as large sfc anticyclone builds ewd from the Great Lakes into the nern CONUS, and eventually shifts east of New England on Wednesday. Some residual stratus clouds persist across n-central into nern VT early this morning per GOES-16 fog product, and could see a few lingering flurries in Vermont's Northeast Kingdom. However, dry N-NW low-level flow will result in clearing conditions areawide toward daybreak with sunny skies expected today. NW winds increasing to 10-15mph will keep temperatures on the chilly side, with highs only in the 15-20F range, except 20-25F across the srn valleys. High pressure builds directly overheard tonight with diminishing winds. Should be ideal radiative cooling conditions with lows in the single digits above zero, and locally zero to minus 10F across the northern Adirondacks and Vermont's Northeast Kingdom. As high pressure shifts to our east on Wednesday, a southerly return flow develops, allowing afternoon highs to reach the mid- upr 20s. Should see a trend toward filtered sunshine Wednesday aftn as mid-upr level cloudiness increases from SW-NE late. PoPs NIL through the near-term period. && .SHORT TERM /WEDNESDAY NIGHT THROUGH THURSDAY/... As of 104 AM EST Tuesday...Little overall change in expected minor snow to mixed precipitation event expected Wednesday night into early Thursday morning. Primary low is still expected to track to our north and west, and secondary low development occurs late and too far east to have any significant impact on our forecast area. Thus, strong 850-700mb WAA will drive isentropic ascent with developing snowfall from SW-NE, likely during the 00-03Z period from BTV south and west, and between 03-06Z across north-central into nern VT. Periods of WAA snows will continue during the overnight hours (PoPs 80-90%), but will see SW 850-750mb winds of 50-60kt advect above freezing/warm layer into the region late. This warm layer results in a transition to sleet across nrn NY and south- central VT 06-09Z, and into the Champlain Valley 09-12Z. Far northeastern VT remains mainly snow based on current NAM/GFS vertical profiles. May see a few pockets of light freezing rain as well, but not expecting much in the way of ice accumulation (trace to a few hundreths). Also appears that synoptic mid- level dry slot works into the region quickly 10-13Z, with a rapid end to any steady precipitation from W-E around or just after daybreak Thursday. The remainder of Thursday will feature isold rain/summit snow showers, with valley temperatures warming well into the 40s. With overall QPF mainly 0.20-0.35", not looking at a major winter event Wednesday night early Thursday morning. General snow/sleet totals of 1-2" expected from the Champlain Valley wwd across nrn NY, and 2-5" of snow/sleet for central into nern VT with colder temperature profiles expected. May see some slow travel for the morning commute on Thursday, especially east of the Greens. Current trends suggest Winter Weather Advisories may be needed for Wednesday night into the morning commute time frame, mainly for central into nern VT. Should see melting and improving road conditions with partial sunshine later Thursday morning into the aftn and temperatures rising into the 40s. Gusty south to southwest winds are also expected Thursday. In the Champlain Valley and nrn NY, will see S-SW winds 15-25 mph with gusts to 35 mph possible with steepening lapse rates and good low-level mixing. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... As of 301 AM EST Tuesday...Surface cold front and shortwave energy aloft shift through the region Thursday night with precipitation generally waning through the night with some upslope snow showers possible across the higher terrain. High pressure follows for Friday and Saturday with dry and pleasant weather expected with temps ranging through the 30s for highs and teens/20s for lows. Next system moves in for Saturday night through Monday and appears to be a rinse and repeat from the mid-week storm with primary low pressure once again tracking from the lee of the Rockies northeast through the Great Lakes Sunday and into southern Quebec Sunday night. Latest GFS/FV3/ECMWF are all in fairly good agreement showing little coastal development which leads to warm air intruding into the region on strong south/southwesterly flow creating some ptype issues. Soundings indicate precip starts as snow Saturday night and briefly changes to a mix of sleet/snow and perhaps freezing rain Sunday morning before transitioning rapidly to all rain by the noon hour as surface temps rise into the 40s area-wide. Could see a break in precip in the warm sector depending on the strength of the mid- level dry slot post warm front passage, and if that does occur it could allow for a period of gusty winds to mix to the surface before the cold front passes Sunday night. Behind the cold front precipitation transitions back to snow and gradually becomes more terrain focused heading into Monday. && .AVIATION /18Z TUESDAY THROUGH SUNDAY/... Through 18z Wednesday...Dry/VFR conditions expected at the TAF sites through the TAF period with the lone exception some MVFR ceilings overnight at SLK. Winds will continue N-NW 7-10kts today and at times gusty east of the Greens, becoming light and variable tonight. Westerly flow aloft will bring some low level moisture into SLK which will lead to a 3-6 hour window of some BKN/OVC 1500 foot ceilings between 03-08z this evening. Outlook... Wednesday Night: Mainly MVFR and IFR, with areas VFR possible. Definite SN, Definite PL, Definite FZRA. Thursday: Mainly MVFR, with areas VFR possible. Chance RA, Chance FZRA, Slight chance SHRA. Thursday Night: Mainly VFR, with local MVFR possible. Slight chance SHSN. Friday: Mainly VFR, with local MVFR possible. NO SIG WX. Friday Night: Mainly VFR, with local MVFR possible. NO SIG WX. Saturday: VFR. NO SIG WX. Saturday Night: VFR. Likely RA, Likely FZRA, Slight chance SN, Slight chance PL. Sunday: MVFR. Definite RA, Definite FZRA. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...None. NY...None. && $$ SYNOPSIS...Banacos NEAR TERM...Banacos/RSD SHORT TERM...Banacos LONG TERM...Lahiff AVIATION...Deal