296 FXUS61 KBTV 060817 AFDBTV Area Forecast Discussion National Weather Service Burlington VT 317 AM EST Mon Jan 6 2020 .SYNOPSIS... More seasonable temperatures expected for the new week with periods of snow showers possible. A weak front will bring snow showers to the North Country on Monday with 1 to 2 inches in the valley and 2 to 5 inches across the Adirondacks in New York and Greens in Vermont. Another system will track near the region on Wednesday bringing another chance for snow. A brief incursion of Arctic air will occur on Thursday, but will be short lived with strong warming over the weekend. Another next system will begin to impact the region towards Friday and Saturday. && .NEAR TERM /THROUGH TUESDAY/... As of 1020 PM EST Sunday...No changes made to the going forecast except to delay introduction of slight chance of snow in the Saint Lawrence Valley until after midnight. Clear skies have been observed at Ogdensburg, New York and the return of cloud cover is slightly behind schedule. However, a shield of clouds and light overrunning precipitation upstream in western New York is rapidly impinging on the area, so the forecast is generally on track. In Vermont, webcams and other reports show persistent very light, fluffy snow in many locations near and east of the Greens. This should continue for a little while longer under a light northwest flow. Enough subsidence will develop due to weak high pressure moving overhead to end this activity by around 3 AM. Previous Discussion... Weak upper ridging will begin to move in later this evening. Until then, mostly cloudy conditions with brief flurries will continue for some light accumulations across the higher summits. Temperatures are currently in the teens to mid- twenties. A gradual decline in temperatures will continue, especially once a pocket of clearing moves in towards midnight. Clearing will be short lived, and temperatures should level-out as flow becomes south to southwesterly. An occluding front will begin moving in early Monday morning bringing more cloud cover as well. Overnight lows should fall into the single digits to mid teens with the coldest temperatures east of the Greens. Precipitation will begin along the St. Lawrence Valley before sunrise spreading into Vermont later in the morning and covering the region around noon. A weak surface low will try to develop along the occluding frontal boundary in the St. Lawrence Valley. The increased convergence and sfc-850mb lapse rates of about 8.5 C/km should promote moderate to locally heavy snow showers lifting in a band northward, primarily impacting St. Lawrence and Franklin Counties in New York. Greater mid-level winds and better mixing lag behind this band, but an embedded snow squall is possible Monday afternoon. As the low tracks north of the region, better dynamics and instability fail to make it into Vermont. Additionally, the developing 40 kt westerly low-level jet will inhibit snowfall in the Champlain Valley as downslope winds result in terrain shadowing. However, strong orographic lift will produce better snow over the Greens in Vermont as the weak surface low quickly lifts into Quebec Province. Monday's highs should rise into the mid 20s to lower 30s. Heading into Monday evening, a secondary shortwave digs into the North Country, helping to maintain southwest flow a bit longer before ridging sets up into Tuesday. We should see some lake- enhanced showers continue with the best chance for additional snow across southern St. Lawrence County, NY and in Rutland Vermont. A handful of high res models even bring some lake- enhanced showers all the way from Lake Huron, which would place Jay Peak in Vermont favorably as well. All said snow amounts should be 2"-5" across much of Northern New York and higher summits of the Greens, 0.5"-1.0" for the Champlain and lower Connecticut, and 1"-3" for the Northeast Kingdom. Low-level moisture declines after midnights with activity becoming confined to the higher summits after midnight. Overnight lows will struggle to fall with gradient winds and cloud cover. Expect teens to mid 20s for the lows. && .SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/... As of 256 AM EST Monday...Mid/upper lvl trof will be deepening acrs the central Great Lakes into the NE conus during this time period as fast flow aloft continues. Northern stream short wave energy and associated arctic boundary will be crossing our cwa late Tues Night into Weds. The combination of boundary and synoptic scale lift from trof and embedded vort will produce scattered to widespread snow showers on during this time period. The timing of system is slightly faster, which has resulted in less instability for snow squall potential, along with mid/upper lvl clouds from coastal system impacting our central/eastern cwa. Our locally developed snow squall parameter shows limited potential across our western cwa btwn 09z-15z Weds, with cape values < 100 j/kg and some 925mb fgen forcing with approaching arctic boundary. Thinking a general 1 to 3 inches likely with localized higher amounts in the nw upslope areas of the northern dacks and central/northern Greens. Strong llvl caa on brisk nw winds should help to squeeze out remaining moisture in favorable upslope flow on Weds aftn/evening. Strong 1040mb sfc high pres builds into our fa btwn 06z-12z Thurs. The fcst challenge continues to be how quickly we clear overnight Weds into Thur morning. Thinking best area of clear skies/light winds will be SLV/western dacks, where temps should drop into the -5f to -10f range with localized colder values, while CPV and most of VT stay in the 0 to 10f range, with some localized readings near -5f. Thursday is quiet and cool with high pres axis shifting overnight. Highs generally in the teens to lower 20s with mostly clear skies. && .LONG TERM /THURSDAY NIGHT THROUGH SUNDAY/... As of 256 AM EST Monday...The active weather pattern continues as we head into the weekend, with a warming trend expected Thurs Night into Saturday. Still plenty of uncertainty with weekend system, as latest trends have suppressed sfc low pres to our south, resulting a a greatly threat for wintry precip Sat Night into Sunday. GFS/ECMWF/CMC in good agreement with large scale waa developing on Friday associated with strong 850mb southwest jet of 45 to 55 knots. This lift combined with ribbon of mid level moisture will result in a period of light snow/mix changing to light rain on Friday, as temps warm into the mid 30s to lower 40s. Some shadowing is likely in the CPV associated with downslope flw off dacks. Cooler values will be east of the Greens, where deeper valleys will trap cold air near the sfc. Initial surge of moisture should exit our cwa by 00z Saturday, with a decrease in areal coverage of light precip. GFS/ECWMF/CMC have all trended cooler and south with system for late Saturday into Sunday, as northern stream s/w energy helps to push sfc boundary back acrs our cwa on Sat aftn/evening. This will sharpen the low level thermal gradient acrs our cwa as sfc low pres develops in the ms river valley. Deep moisture advection with pws approaching 1.0 and sharp thermal boundary acrs our cwa will result in likely to cat pops on Sat Night into Sunday. Given the very limited run to run consistency and complex thermal profiles acrs our cwa associated with arctic airmass to our north, have continued with the idea of rain/snow for now. Temps very warm on Sat ahead of boundary with many locations well into the 40s, but cool back into the 20s and 30s on Sunday. && .AVIATION /08Z MONDAY THROUGH FRIDAY/... Through 06Z Tuesday...Conditions remain largely VFR across the North Country early this Monday morning with just a pocket of some lake effect clouds bringing 2000 ft ceilings to KBTV. This should persist until about 10Z when the cloud cover moves overhead and temperatures moderate and prevent the lake from steaming further. Snowfall associated with a weak frontal boundary will move into northern New York and southern Vermont around 12Z bringing visibilities down to 2-4 statute miles and ceilings ranging from 1000 to 2000 ft. KPBG, KMPV and KBTV will likely miss out on much of the snow today and have only included a mention of VCSH. These terminals will see ceilings drop to around 3000 ft but should largely remain VFR through the day. Following the passage of the front, we will see winds shift to the south/southwest at 8 to 12 knots with some sites gusting up to 20 knots. This should help to steadily improve any lingering MVFR ceilings later tonight. Outlook... Tuesday: VFR. NO SIG WX. Tuesday Night: Mainly VFR, with local MVFR possible. Chance SHSN. Wednesday: Mainly VFR, with areas MVFR possible. Chance SHSN. Wednesday Night: Mainly VFR, with local MVFR possible. Slight chance SHSN. Thursday: VFR. NO SIG WX. Thursday Night: VFR. Chance SHSN. Friday: Mainly MVFR, with areas VFR possible. Likely SHRA, Chance SHSN. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...None. NY...None. && $$ SYNOPSIS...Haynes NEAR TERM...Haynes/Kutikoff SHORT TERM...Taber LONG TERM...Taber AVIATION...Clay