textproduct: Burlington

WHAT HAS CHANGED

As of 142 PM EST Tuesday...

Introduced freezing rain to the forecast for Thursday night into Friday.

KEY MESSAGES

As of 142 PM EST Tuesday...

1. Light snow this afternoon through midnight with some spotty freezing drizzle possible at the end.

2. More mixed precipitation possible Thursday night into Friday.

3. A period of light freezing rain is possible early Saturday, especially east of the Green Mountains, which could produce slick travel. Then, rain is anticipated by Saturday afternoon and evening.

4. The potential for ice jams and hydrological issues will need to be monitored this weekend due to well above normal temperatures and significant snow melt.

DISCUSSION

As of 142 PM EST Tuesday...

KEY MESSAGE 1: The forecast remains on track for a light nuisance snowfall event this afternoon through midnight as a wave of low pressure tracks west to east along a slow moving warm front south of the forecast area. Clouds and precipitation have kept temperatures below freezing today for much of our southern zones and the southern Adirondacks while northern locales have warmed into the mid-30s. Despite the lack of cold air at the surface though, when precipitation does arrive expect temperatures to wetbulb below freezing supporting snow as the dominant ptype, albeit wet with ratios generally 5-10:1. A general dusting to 2" is expected with isolated amounts up to 4" on the higher terrain of eastern Addison/Rutland counties. Steady snow ends quickly after midnight, however forecast soundings continue to show abundant moisture trapped below a building inversion while drier air moves into the DGZ supporting the chance for patchy freezing drizzle on the tail end of the precip. This will mainly be for mid-slope to higher elevations before sunrise Wednesday where thereafter the entire column drys out and surface temps warm above freezing. There could be a few slick spots on higher elevation passes for the morning commute.

KEY MESSAGE 2: We continue to monitor the evolution and track of another system passing south of our forecast area Thursday through Friday with increasing chances for mixed precipitation across the region. The large-scale synoptic setup features high pressure building south from James Bay driving low-level cold air across the international border Thursday night while weak surface low pressure and a modest shortwave trough move west to east from the Great Lakes to near Cape Cod by Friday morning. The aforementioned warm front from Tuesday continues its slow march northward on Wednesday with 925-850mb temps pushing above 0C and persisting over much of the region through Friday. This scenario supports freezing rain as the dominant ptype across most of the forecast area Thursday night through Friday morning before surface temps warm back above freezing. Where additional uncertainty in the forecast remains is how far north precipitation makes it with medium-long range guidance inconsistent from run to run. The AI versions of the GFS and ECWMF seem to favor a more southern track with little QPF across our northern zones, while their deterministic counter parts are a bit farther north, along with the GEM. The driving shortwave is really just getting it's act together over the WY/CO border this afternoon, so hopefully we'll have a better idea of the track this time tomorrow.

KEY MESSAGE 3: Surface low pressure will slide through or just north of northern New York and Vermont on Saturday and Saturday night, accompanied by strong warm air advection. This would allow surface temperatures to soar into the 50s in the afternoon with nighttime lows in the 30s and low 40s, 15-25 degrees above seasonable normals for early March. A strong low level jet (850mb winds up to 65-70 knots) and weak cold frontal boundary move through Saturday evening/night, producing gusty winds and precipitation. A deep inversion will make precipitation type messy and potentially difficult to forecast Saturday morning. Most models suggest a portion of the arriving precipitation will be in the form of freezing rain at the onset, particularly east of the Greens where cold air looks to pool, then turning to all rain as surface temperatures moderate and stronger forcing arrives with the cold front later Saturday. We also continue to see some elevated instability Saturday afternoon, which could result in rumbles of thunder.

KEY MESSAGE 4: Temperatures are expected to remain 10-20 degrees above seasonal normals through next midweek in persistent southwesterly flow. Highs could reach as high as the upper 40s and 50s, while lows will fall only into the lower and mid 30s. Given the duration of warm temperatures, most of the snowpack below 1500 feet may be melted by early next week, which, combined with some intervals of precipitation, will cause rises on rivers and streams. These rises could be enough to produce localized ice jams and other hydrological issues. In addition, both the NAEFS and GEFS indicate Ausable, Mad, and Otter Creek have a 40 to 60% probability of reaching minor flood stage due to the combination of snow melt and QPF by early next week. We will continue to monitor the potential for both ice jam and main stem river flooding as we head toward the upcoming weekend.

AVIATION /18Z TUESDAY THROUGH SUNDAY/

Through 18Z Wednesday...Mostly VFR conditions prevail across terminals this afternoon, with some MVFR ceilings currently at KRUT. As the afternoon progresses, ceilings are expected to lower across, with more widespread MVFR conditions by 00Z. Light snow will overspread this evening, which will likely bring a period of IFR visibilities to most terminals, other than KMSS and KEFK which are too far north to receive snowfall today. The period of snow will likely be brief, only lasting a few hours, however with increased moisture some IFR ceilings may develop overnight. KSLK and KRUT currently look to be the most likely sites to experience any IFR clouds, but low MVFR ceilings and some reduced visibilities will continue for most of the overnight. Some patchy freezing drizzle may be possible tonight between 05Z and 10Z Wednesday, particularly at KRUT, but confidence was too low to include in the forecast for now. Winds will generally be southerly this afternoon, with some localized gusts of 25 knots, especially at KBTV, before trending light again overnight. Some LLWS will be possible this afternoon, especially at mountain terminals, but it will be fairly short-lived. Flight conditions will gradually improve towards the end of the forecast period.

Outlook...

Wednesday Night: VFR. NO SIG WX. Thursday: Mainly VFR, with local MVFR possible. NO SIG WX. Thursday Night: Mainly MVFR, with local IFR possible. Chance RA, Chance SN. Friday: MVFR. Chance RA, Chance SN. Friday Night: Mainly MVFR, with local IFR possible. Chance RA, Chance FZRA. Saturday: Mainly IFR, with areas MVFR possible. Likely RA. Saturday Night: Mainly MVFR, with areas IFR possible. Chance RA. Sunday: Mainly VFR, with local MVFR possible. NO SIG WX.

EQUIPMENT

The KBTV ASOS has suffered a communications failure. The issue has been diagnosed, but there is currently no estimated time of return to service. The affected communications line is not serviced by the NWS. Terminal Aerodrome Forecasts will continue, but regular observations may not be available.

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.