233 FXUS61 KBTV 220230 AFDBTV Area Forecast Discussion National Weather Service Burlington VT 930 PM EST Sun Jan 21 2018 .SYNOPSIS... Outside spotty light snow or snow showers across northern counties this evening, mainly cloudy skies and dry weather is expected tonight. A storm system tracking through the Great Lakes and St. Lawrence Valley will affect the region Monday into Tuesday with a variety of mixed precipitation and rainfall. Behind this system temperatures return to seasonably cold levels for mid to late week before another round of potentially messy weather arrives by next weekend. && .NEAR TERM /THROUGH MONDAY NIGHT/... As of 927 PM EST Sunday...Current radar shows very light snow angling along the international border this evening with a few flakes here at BTV. Given the lack of deep moisture and forcing...only a few flurries anticipated overnight as temperatures cool back into the mid/upper 20s. Light northwest winds have developed here and our temp has cooled to 31f with mostly cloudy skies. Weak cold air advection will continue under light northerly flow tonight...with cigs continuing to lower. All elements are covered well in current forecast/grids...so no major adjustments needed. Previous Discussion Below: Winter Weather Advisories are now in effect for portions of the area Monday into Monday night. A fairly quiet night remains on tap for the area as this morning's weak cold front remains draped across the area. This boundary separates seasonably mild air in the 30s to around 40 across our area from colder readings in the 20s to our immediate north across southern Quebec and Ontario. For the most part a dry night under variably cloudy skies and continued seasonably mild temperatures are expected as lows bottom out in the 20s to locally near 30 in the Champlain Valley. Very weak overrunning processes streaking just north of the stationary front may produce some spotty on and off sprinkles or light snow through midnight or so along the international border. However, any accumulations should be minor to negligible and generally less than an inch. The weather then turns more active for Monday into Monday night as low pressure tracks from the central plains northeast into the lower Great Lakes. This will drive a more pronounced warm front through our area by later Monday into Monday night with a variety of mixed precipitation. Initially, the cooler airmass off to our north will bleed southward into northern areas Monday morning before background flow trends south/southeasterly over time by Monday evening and especially Monday night pushing temperatures above freezing for many areas. The exception will be the northern St. Lawrence Valley and eastern VT where cooler values will hold more stubborn longer. Using a model-blend for hourly temperature profiles and this morning's GFS thermal profiles to govern p-type it suggests a period of mixed precipitation will arrive with the warm front through the day on Monday and the first part of Monday night before coverage tapers somewhat toward Tuesday morning as we enter the warm sector. The probabilities of mixed precipitation will persist the longest in the aforementioned cooler areas where some light snow/sleet and icing are expected. Using a standard empirical-based methodology for icing it suggests accretions will range from 0.05 to 0.15 inches will localized higher totals in the immediate St. Lawrence Valley from Ogdensburg north toward Massena. Winter Weather Advisories have been issued for these areas accordingly in the Monday afternoon/Monday night time frame. Temperatures will be quite tricky and heavily dependent on elevation, topography and timing though the general idea will be for highs to top out in the 28 to 38 degree range by late in the day Monday with readings slowly rising Monday night. && .SHORT TERM /TUESDAY THROUGH TUESDAY NIGHT/... As of 240 PM EST Sunday...As cold front approaches the North country, rain will spread across the area. Region will be completely in the warm sector behind cold front which lifted across the area Monday night, therefore no further threat for mixed precipitation. Rain will spread west to east across the area, and highest rainfall totals will be across Southern and Eastern Vermont. Maximum temperatures on Tue will reach the mid 30s to upper 40s, a few readings in the 50s would not surprise me. Cold front will push across the area Tuesday night, turning remaining precipitation to snow showers. Temperatures will dip into the teens across Northern New York, with teens and lower 20s across Vermont. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... As of 245 PM EST Sunday...Dry weather returns for Wednesday through Friday night with large ridge of surface high pressure over the region. The coldest day of the week will be Thursday with highs only in the teens. Otherwise temperatures will be closer to seasonal normals with a warming trend headed into next weekend. We will once again be impacted by a warm rain system for the Saturday night through Sunday night timeframe, another system that we will continue to monitor as we get closer to the weekend. && .AVIATION /03Z MONDAY THROUGH FRIDAY/... Through 00Z Tuesday...VFR conditions will trend toward mvfr at slk/mss by 03z...before becoming ifr cigs btwn 06-08z. Surface front draped across our taf sites may help to produce a few very light snow showers overnight...but any impacts to terminal sites will be minimal. Clouds will continue to lower overnight with widespread mvfr conditions expected by Monday Morning...with areas of ifr cigs possible at pbg/mss and slk. A wintry mix will develop between 20-22z on Monday with periods of ifr vis likely at most sites. Light and variable winds overnight will become south/southeast at 5 to 15 knots...except northeast at kmss. Outlook... Monday Night: Mainly MVFR, with local IFR possible. Likely RA, Likely FZRA, Likely PL. Tuesday: Mainly MVFR, with areas IFR possible. Likely RA, Likely FZRA. Tuesday Night: Mainly MVFR, with local IFR possible. Chance SHSN, Chance SHRA. Wednesday: Mainly VFR, with local MVFR possible. Slight chance SHSN. Wednesday Night: Mainly VFR, with areas MVFR possible. NO SIG WX. Thursday: Mainly VFR, with local MVFR possible. NO SIG WX. Thursday Night: Mainly VFR, with areas MVFR possible. NO SIG WX. Friday: Mainly VFR, with local MVFR possible. NO SIG WX. && .HYDROLOGY... As of 324 PM EST Sunday...Widespread rainfall is expected across the area by Monday night into Tuesday. Current data suggests 36-hr rainfall totals ending at 700 pm Wednesday will range from 0.50 to 1 inch across the area. Given the substantial loss of snowpack across lower elevations during last week's storm, and the fact that the warm-up will be of lesser magnitude we are not expecting significant ice movement or water rises on area rivers at this time. This is in close agreement with NERFC guidance and our latest river forecasts. Conditions will continue to be monitored closely over the next 48 hours and will be updated if later information suggests a different scenario than current thinking. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...Winter Weather Advisory from 4 PM Monday to 10 AM EST Tuesday for VTZ003-004-006>008-010-012-018-019. NY...Winter Weather Advisory from 1 PM Monday to 7 AM EST Tuesday for NYZ026>028-030-031-034-087. && $$ SYNOPSIS...JMG NEAR TERM...JMG/Taber SHORT TERM...Neiles LONG TERM...Neiles AVIATION...Taber HYDROLOGY...JMG