textproduct: Burlington

WHAT HAS CHANGED

As of 144 PM EST Tuesday...

No significant changes. We continue to monitor the potential for snow squalls Wednesday afternoon and evening.

KEY MESSAGES

As of 144 PM EST Tuesday...

1. Snow will cause hazardous travel on Wednesday, first with widespread light snow in the morning, then scattered snow showers and possible embedded snow squalls during the afternoon and evening.

2. Brief warm up Saturday, cold start to next week.

DISCUSSION

As of 144 PM EST Tuesday...

KEY MESSAGE 1: A clipper system will approach our region tonight with an associated warm frontal boundary providing forcing for widespread light snowfall. Onset of snow will most likely occur late tonight into the predawn hours of Wednesday morning, moving generally west to east across northern New York and then Vermont. With this snowfall, we're expecting slippery travel and low visibilities for the morning commute. Snowfall rates could reach up to 0.50-0.75 inches per hour, most likely across the Green Mountains around 5 AM through 10 AM. After a brief lull in precipitation, attention then turns to the potential for snow squalls in the afternoon and evening. In the upper levels throughout the day Wednesday, models are suggesting cyclonic flow over the Hudson Bay with negative 500mb level height anomalies reaching into the forecast area. The area also sits north of an upper level jet during this period, placing northern New York/Vermont in the region of upper level diffluence. An upper level shortwave will tilt negatively over the forecast area in the afternoon, and high resolution models are indicating surface CAPE values 30 to 70 J/kg during the passage of a cold frontal boundary. In the mid to low levels, the region will be located in the warm sector of the clipper system on Wednesday. Steep lapse rates reach up to the 750mb level on several solutions, including a well-saturated snow growth zone, suggesting snow squalls could be embedded in clusters of snow showers or even a linear organization of squall-like snow showers throughout the afternoon and evening Wednesday. Temperatures in the valleys will likely be near or above freezing while road temperatures, given late February solar angle, rise above freezing ahead of these snow showers. Therefore, some snow squalls could have a flash freeze potential in addition to gusty winds and low visibility. Motorists planning travel Wednesday afternoon should keep an eye on the forecast and prepare for rapidly changing weather conditions if the ingredients come together. Surface temperatures struggle to fall Wednesday night and Thursday despite the cold frontal passage due to the lack of a strong northwesterly flow.

KEY MESSAGE 2: A strong clipper passes by well to the north Friday night into Saturday, causing significant warm air advection. Its pressure looks to drop close to 980 mb, causing a southerly low level jet to pass overhead. Gusty channeled flow in the Champlain Valley and downsloping winds are possible. Temperatures should rise into the 40s for most places, with a run at 50 possible for parts of southern Vermont. The amount of warming looks to depend on the timing and make up of the cold frontal passage on the backside. An earlier passage would prevent the full effects of diurnal heating and some rain/snow showers with a prefrontal trough like the GFS and and about half the GEFS members have would cut back on temperatures, especially for northern areas. Dew points will be low regardless, so melting would be limited and any precipitation would cause notable wet-bulbing. Behind the cold front, it will feel like winter again for a couple days with highs well below freezing and lows looking to be around and below zero.

AVIATION /18Z TUESDAY THROUGH SUNDAY/

Through 18Z Wednesday...VFR conditions should persist through most of the night except at SLK. Ceilings there are currently MVFR and they are expected to mostly stay that way through the afternoon, before that deck scatters this evening. A fast moving round of snow will pass through from west to east late tonight and tomorrow morning. It will last a couple hours as it moves through and should bring a period of IFR visibility to all terminals. It is expected to reach MSS at around 9Z and leave EFK at around 16Z. LLWS is expected to develop around when the snow arrives and end by late morning. Winds will generally be less than 10 KT and northwesterly today, before going light and terrain driven tonight. Southerly winds develop late tonight and continue through the day. The strongest winds will be at BTV and PBG where gusts in the 15-25 KT range are expected.

Outlook...

Wednesday Night: VFR. Slight chance SHSN. Thursday: VFR. NO SIG WX. Thursday Night: VFR. Slight chance SN. Friday: VFR. NO SIG WX. Friday Night: VFR. NO SIG WX. Saturday: Mainly VFR, with local MVFR possible. NO SIG WX. Saturday Night: Mainly VFR, with local MVFR possible. Slight 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.