textproduct: Burlington

WHAT HAS CHANGED

As of 334 PM EDT Thursday...

A winter weather advisory has been issued for parts of northern New York and Vermont for accumulating wet snow Friday into Friday night.

KEY MESSAGES

As of 334 PM EDT Thursday...

1. A clipper system will bring up to 2 to 5 inches of snow to parts of our region Friday into Friday night.

2. A late season snowstorm is becoming more likely Sunday into Sunday night, which could impact the Monday morning commute. A heavy and wet snowfall is possible in portions of the region.

3. Active, winter-like weather will continue through next week, including snow shower chances midweek.

DISCUSSION

As of 334 PM EDT Thursday...

KEY MESSAGE 1: Another clipper system will bring some wet snow to the region Friday into Friday night. This system has good moisture and decent dynamics, which will support some heavy wet snow at times. Storm total QPF will be around a quarter of an inch along the international border up to half an inch in parts of the Adirondacks and central Greens. The temperatures are very tricky with this system. Have relied on hourly temperatures using higher resolution model guidance to get temperatures that will support snowfall rather than a change to rain, though some areas will have a change over to rain. Higher elevations will do the best with this system and some spots will have around 6 inches of wet snow. A shift in the track of this storm could also change the temperatures profiles and amounts of snow expected. Currently looks like the low will track just south of our area which would keep us cold enough for mostly snow. Have issued a winter weather advisory for areas expected to have about 4 inches of snow or more.

KEY MESSAGE 2: Confidence has increased in an impactful snowfall late Sunday into early Monday, as another model cycle shows moderate to heavy precipitation north of a low pressure area tracking eastward from central Pennsylvania to near the southern New England coast. Over 90% of ensemble members fall into clusters/scenarios that show a substantial snowfall for our region with similar upper level patterns, although there are some north-south differences. Will favor the AI-GFS footprint, which is similar to the physical model and the multi-model cluster with the largest number of members, with a swath of heaviest precipitation over south central Vermont and Adirondacks. That being said, typically snow ratios can compensate for lower QPF farther north of the heaviest precipitation, so the current, very wide swath of 10-30% chance of warning level snowfall over the region with the exception of the St. Lawrence Valley looks reasonable. There is a large spread in QPF, so snowfall amounts remain rather uncertain. Mean liquid precipitation in the 0.35" to 0.55" range, with higher amounts south and lower north, point to at the very least Winter Weather Advisory potential.

Right now we show onset of snow being likely Sunday morning, but think the more significant, heavier snowfall could be Sunday night. In fact, blended guidance shows the greatest 24 hour snowfall occurring from 8 PM Sunday through 8 PM Monday, with totals in the 3 to 7 inch range. This discrepancy seems to be tied to precipitation type, as snow becomes more of a certainty by Monday compared to Sunday; some low tracks are a bit farther north and lead to a rain or wintry mix scenario for mainly southern portions of the region before the low pressure area passes to the east and we see colder air infiltrate from the northwest and potential upslope snow commences. Within a relatively narrow zone, snow load could be potentially significant with a heavy liquid amounts approaching 1" in the form of wet snow. At this time, the potential is low but bears watching. Otherwise, impacts would be mainly a travel concern, especially if heavier precipitation occurs early Monday when more traffic is present as opposed to Sunday afternoon/night.

KEY MESSAGE 3: Due to a persistent and strong ridge in the southwestern US, troughiness and cooler than normal temperatures will continue through next Thursday. The next chance of substantial precipitation following the Sunday-Monday snow would be on Wednesday associated with a relatively weak cold front, favoring some upslope snow showers. Relatively high uncertainty exists beyond that event. A somewhat more potent low pressure system and associated mixed precipitation types are possible as early as Thursday. A broad range of storm tracks in model guidance leads to a wait and see approach at this time.

AVIATION /00Z FRIDAY THROUGH TUESDAY/

Through 00Z Saturday...Currently VFR CIGS and VIS at all sites except MVFR CIGS at SLK with 9SM in light snow. Radar imagery and surface observations indicate light snow with VIS generally between 4-6SM along a weakening surface cold front. Used some PROB30 and TEMPO groups for a few hours to indicate the potential for MVFR conditions with frontal passage with winds shifting to northwest and becoming light after midnight. A band of moderate snow with IFR/LIFR conditions is expected to impact our TAF sites between 16Z and 22Z on Friday. Quickly lowering visibilities and ceilings are expected with this snow, with some mix with rain in the valley sites. As precip exits IFR CIGS will linger thru 00z Saturday with northwest upslope winds of 4 to 8 knots.

Outlook...

Friday Night: MVFR/IFR conditions possible. Chance SN, Chance FZRA. Saturday: Mainly VFR, with local MVFR possible. Slight chance SHSN. Saturday Night: VFR. Likely SN. Sunday: Mainly MVFR, with local IFR possible. Definite RA, Likely SN. Sunday Night: Mainly MVFR, with local IFR possible. Likely SN. Monday: MVFR. Chance SN. Monday Night: Mainly MVFR, with areas VFR possible. Slight chance SN. Tuesday: Mainly VFR, with areas MVFR possible. Slight chance SN.

EQUIPMENT

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...Winter Weather Advisory from 8 AM to 11 PM EDT Friday for VTZ003-004-006>008-016>018. NY...Winter Weather Advisory from 8 AM to 11 PM EDT Friday for NYZ026-027-029>031-034-087.