textproduct: Burlington

WHAT HAS CHANGED

As of 140 PM EST Tuesday...

Confidence in no snow for most of the forecast area on Wednesday and Wednesday night has increased. Southernmost areas still may see light to occasionally moderate snow during this period.

KEY MESSAGES

As of 140 PM EST Tuesday...

1. Mainly dry and colder conditions will return on Wednesday as a low pressure area to our south produces light snow in southern Vermont.

2. Low pressure system tracks from the Great Lakes area then north of our region bringing snow to our forecast area Friday into Friday night.

3. Seasonable weekend conditions expected with additional chances of precipitation. Turning cold to start next week.

DISCUSSION

As of 140 PM EST Tuesday...

KEY MESSAGE 1: Unfortunately for snow lovers, the midweek period looks definitely dry in nearly all of our region following a weak surface cold front that slides through tonight. Aside from a few inconsequential snow showers in north central and northeastern Vermont, this front will primarily serve to shift winds from southerly to northerly, opening the door for much drier air to push into the area. This surface boundary is related to another upper level low diving southeastward in eastern Canada. This system, currently near Hudson Bay, seems to be timed poorly relative to the incoming frontal wave for Wednesday, such that the west side of the trough acts as a block for moisture. The location of this wall through the 12Z model suite has come into better agreement, largely with a consensus in precipitation similar to the HRRR/GFS. As such, forecaster confidence increased to cut back precipitation chances and amounts more substantially across most of northern New York and northern Vermont. Far southern Vermont will still see steady light to moderate snowfall (a Winter Weather Advisory will be in effect in Bennington and Windham counties), and sharply lower amounts are expected moving northward through Rutland and Windsor counties; greatest potential for up to a few inches of snow appear to be right near the border, such as along Route 7 south of Wallingford.

At this point, the deterministic (single value) forecasts should be pretty close to what occurs for snowfall, as probabilistic data has shifted southward in the aggregate, such that a northward jog of snowfall looks unlikely at this point. There are still southern outlier solutions that even totally miss Rutland and Windsor counties. This southern scenario is reflected in modest decreases in PoPs in these areas, where we do expect at least some snowfall. The most northerly push of precipitation may occur in the late afternoon/evening hours when precipitation rates could briefly push 0.05"/hour (0.5"/hour snowfall rate with snow to liquid ratios averaging 10-12:1). This will lead to a period of difficult travel with roads becoming snow covered and slick, in a relatively localized area in southern portions of Vermont. Precipitation chances will taper off tomorrow night as both mid level deformation and frontogenesis depart to the east/southeast. Temperatures and dew points will further lower through Wednesday afternoon and night with modest low level cold air advection; temperatures will likely fall back into the teens overnight for most locations after peaking in the upper 20s to low 30s during the day.

KEY MESSAGE 2: Confidence is increasing that we'll be impacted by a large vertically stacked low pressure system which will weaken as it tracks eastward from the Great Lakes region. Snow will lift into our forecast area from the southwest by Friday afternoon, with a possibility of some mixed precipitation before all precipitation changes to snow and continues into the overnight. The low pressure center stretches out and energy transfers to a secondary low tracking along the New England coast on Friday night. Snow will continue into Friday night, before ending as wrap around snow showers on Saturday. At this time it looks like we will have about a quarter of an inch to half an inch of QPF with this storm system. At this time looks like we can expect about 3 to 6 inches of snowfall potentially, with the heaviest snow between 1 pm Friday and 1 am Saturday. Will continue to monitor this storm system as we get closer to Friday and Friday night and update forecast as things change.

KEY MESSAGE 3: Temperatures will be near normal this weekend but still cold enough to support some winter precipitation through wet-bulbing and dynamical cooling processes. Highs will be near 30, with overnight lows in the teens; slightly warmer temperatures in southern Vermont. Ensemble guidance continues to show some members depicting a potentially impactful coastal system Sunday into Monday. Overall ensemble member timing and track guidance still varies widely, but a few ensemble members draw the coastal system near Benchmark. Current NBM probabilistic guidance shows widespread 20- 30% chance of 4 or more inches of snow across central and southern Vermont. The most likely solution right now keeps the system to our south with the most overrunning precipitation across southern New England, mainly over south and east Massachusetts. Confidence is still low for any precipitation across our area, but this will be something to monitor over the next several days. A digging trough behind the coastal system will drop quite south into parts of the Carolinas. This will return much of the region into a brief cold pattern to start next week with a 50-70% chance for highs on Tuesday to only reach 20F. This supported by a near 100% GEFS chance for 850mb temperatures to be less than -10F, a 40-60% for 850mb temperatures to be less than -20F. While this is not expected to be a cold outbreak by any means, it will be a change from the seasonable weather we will have this week.

AVIATION /18Z TUESDAY THROUGH SUNDAY/

Through 18Z Wednesday...A weak surface trough continues to slide east, with a stationary boundary set up across the St. Lawrence Valley. Lingering moisture along the boundary is leading to LIFR conditions at MSS/SLK primarily due to low ceilings, but intermittent IFR visibilities from patchy dense fog is also contributing to terminal flight restrictions. No precipitation is expected, so any visibility reductions will be driven solely by any patchy fog development. Into Vermont and the Champlain Valley, channeled flow has prevented any similar conditions seen in the St. Lawrence Valley with light southerly flow up to 10 knots, and isolated gusts to 15-20 knots. Ceilings however areawide are generally under 3000ft agl, outside of PBG where some downsloping is helping to prevent any MVFR ceilings. All sites should see prevailing MVFR cigs between 20-04Z. Fog is increasingly unlikely across much of Vermont as the stationary boundary lingers across New York, however, isolated patchy shallow BCFG after sunset cannot be ruled out. A weak cold front will try to dislodge the stationary boundary near midnight tonight. A wind shift from the south/southwest to the west/northwest will take place generally after 06Z with the approach and passage of the cold front. Winds look to remain light to calm overnight with the frontal passage. As the front passes, drier air will mix into any lingering MVFR/IFR ceilings and trend most terminals towards VFR by daybreak tomorrow. EFK/SLK may hold onto MVFR ceilings into 12-14Z tomorrow morning, but beyond 14Z, all sites should see prevailing VFR conditions.

Outlook...

Wednesday Night: VFR. Chance SN. Thursday: VFR. NO SIG WX. Thursday Night: VFR. NO SIG WX. Friday: Mainly VFR, with local MVFR possible. Chance SHSN. Friday Night: Mainly VFR, with areas MVFR and IFR possible. Likely SN. Saturday: MVFR. Chance SN. Saturday Night: MVFR/IFR conditions possible. Chance SN. Sunday: Mainly VFR, with areas MVFR possible. Chance SN.

EQUIPMENT

The KMPV ASOS has suffered a communications failure. The issue has been diagnosed, but there is currently no estimated time of return to service. Terminal Aerodrome Forecasts will continue, but amendments to those forecasts will be suspended.

NOAA Weather Radio station WXM-44, transmitting from Mt. Ascutney, Vermont, on frequency 162.475 MHz is non- operational at this time. NWS technicians have diagnosed the problem, but repairs will likely not be able to occur for quite some time due to circumstances beyond our control. Therefore, the time of return to service is currently unknown. The following NOAA Weather Radio transmitters may be able to provide service during this outage: WWG 50 from Burke Mtn, VT at 162.425 MHz and WNG 546 from Hanover, NH at 162.525 MHz.

The Colchester Reef meteorological station is out of service. This site is not serviced by the NWS and there isn't an estimated return to service at present. Please contact us if you observe winds significantly deviating from the recreational forecast.

BTV WATCHES/WARNINGS/ADVISORIES

VT...None. NY...None.