textproduct: Burlington

WHAT HAS CHANGED

As of 131 AM EST Wednesday...A Winter Weather Advisory has been issued for all of northern New York away from Lake Champlain, effective from 7 pm this evening to 7 pm Thursday. Snow amounts of 3 to 7 inches are expected in the Advisory area.

KEY MESSAGES

As of 131 AM EST Wednesday...

1. Widespread rain changing to light to moderate snow late today into Thursday will lead to hazardous travel conditions. Sharply falling temperatures tonight into Thursday will cause any standing water to freeze. This combined with accumulating snow will make for slippery conditions, especially on elevated or untreated surfaces. The Thursday morning commute could be impacted.

2. Bitterly cold temperatures combined with breezy winds will lead to near dangerous wind chills Thursday night into Friday morning.

3. Colder temperatures will continue through next week, with unsettled weather bringing several chances for snow showers, which may lead to slick travel at times.

DISCUSSION

As of 131 AM EST Wednesday...

.KEY MESSAGE 1: Low pressure is currently sliding by to our north this morning, while an upper trough is digging into the Great Lakes. This will give us a mostly dry day, with a few showers possible east of Lake Ontario this morning. Continuing south/southwest flow ahead of the incoming upper trough will result in a relatively mild day for mid January, with temperatures remaining in the upper 30s to mid 40s.

However, this changes late today and overnight as another surface low develops in response to the deepening upper trough. Precipitation will spread eastward ahead of this surface low late today and into our region overnight with the low progged to move almost directly over our forecast area. Colder air will rush in behind the low as flow turns to the west/northwest overnight into Thursday. As noted by the previous forecaster, the arrival for the colder air continues show a slightly slower trend. Still, anticipate rain to quickly change over to snow by midnight across much of northern NY, with it becoming moderate at times later tonight as the low drifts overhead. The colder air and snow will be slower to arrive from the Champlain Valley eastward, with the transition to snow in the higher elevations occurring roughly 3-6 am, then lowering down to the valley floors by 8 am as snow levels drop. Temperatures will initially be near freezing as the changeover occurs, but they'll quick drop into the 20s and even teens from west to east during the day on Thursday. Therefore, any standing water could freeze, leading to black ice, especially on elevated or untreated surfaces. This combined with accumulating snow will make for hazardous travel, including during the Thursday morning commute. Please plan for slow travel and give yourself plenty of time to reach your destination safely.

Snow totals remain uncertain due to continued differences in timing of the changeover from rain to snow and how much we can accumulate when temperatures are marginal. While confidence is high that the greatest snow amounts will be across northern NY, we continue to see a large spread in potential amounts. In the St Lawrence Valley for example, the 25th percentile at Massena is 3 inches while the 75th is almost 8 inches, with the 90th all the way past 10. For northern NY, our forecast of 3 to 7 inches generally lies within the "most likely" range and somewhat close to the mean. As such, we were confident of snow totals averaging 4+ inches to issue a Winter Weather Advisory for all of northern NY outside of the Champlain Valley.

Areas from the Champlain Valley eastward are far trickier as the changeover to snow is later and will occur near sunrise and/or into the daylight hours on Thursday. We'll also start to see drier air intrude during the day Thursday, which could serve to lower overall precipitation amounts. Newport, for example, the 25th percentile is about 1.5 inch, the 75th is nearly 5 inches, and the 90th goes all the way to 7+. Note that our official forecast tends to lie on the lower side for areas from the Champlain Valley eastward through VT, often down near the 25th percentile. Confidence in snow amounts is lower here than further west, and there's the potential for them to go up should things trend colder and/or wetter. Please stay tuned as we continue to refine the forecast going forward.

.KEY MESSAGE 2: West winds will become gusty on Thursday into Thursday night as cold air advection results in steep low level lapse rates and mixing. Given the much colder airmass that is moving into the region, ambient temperatures are expected to drop into the positive and negative single digits by early Friday morning. This combined with breezy winds will create wind chills below zero, with some locations dropping to -15F or even colder Thursday night into Friday morning. If you will be outdoors, please bundle up and dress for bitterly cold conditions.

.KEY MESSAGE 3: After a brief warm up on Saturday, with high temperatures in the 30s, colder air will return late this weekend into next week. By Monday, highs will be closer to climatological normals with below normal temperatures expected mid-week. With these colder temperatures, an active upper level pattern will continue to bring chances for snowfall to the region as several shortwaves rotate through the region. First chances for snowfall arrive on Sunday, with additional chances for snow as the week progresses. Snowfall amounts with any of these system look to be quite modest, with the greatest accumulations expected across northern New York and the spine of the Green Mountains. The wintry and showery weather pattern is expected to persist through much of next week.

AVIATION /12Z WEDNESDAY THROUGH SUNDAY/

Through 12Z Thursday...VFR conditions currently prevail across all terminals this morning, with the exception of a few pockets of MVFR ceilings across northern New York. These conditions are expected to prevail for the next several hours before widespread precipitation spreads across the region. Most terminals should see rainfall at the onset, with precipitation gradually transitioning to snow overnight into tomorrow morning. Conditions are expected to deteriorate to MVFR around 21Z or so, with lower ceilings and some slightly reduced visibilities within rain. After 00Z, IFR conditions are expected to develop due to low ceilings and reduced visibilities due to the precipitation transitioning to snow, with all terminals expected to see a period of IFR. South winds will continue to weaken this morning, with gusts expected to taper off over in the next few hours.

Outlook...

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

EQUIPMENT

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. Use extra caution when navigating the broad waters of Lake Champlain. Please contact us if you observe winds significantly deviating from the recreational forecast.

BTV WATCHES/WARNINGS/ADVISORIES

VT...None. NY...Winter Weather Advisory from 7 PM this evening to 7 PM EST Thursday for NYZ026-027-029>031-034-087.