textproduct: Binghamton

WHAT HAS CHANGED

A little more snow expected from the NW fringes of a coastal low into this evening. Winter Weather Advisories in effect through this evening for Sullivan, Pike, Wayne and Delaware counties. Additional coating to 2 inches expected. Light snow potential increasing along and west of I-81 in the early to mid morning hours Monday. Potential for convective snow showers and isolated snow squalls increasing for Central NY and northern tier of NE PA Monday afternoon and early evening. Wind chills trending a little colder Monday night into Tuesday morning as well, close to Cold Weather Advisory criteria in some locations.

KEY MESSAGES

1) Light snow continues into this evening on NW Fringe of the coastal low. Up to an additional 1-2 inches for advisory area (Pike, Sullivan, Wayne and Delaware Counties).

2) Weak warm front brings period of light snow Monday morning, followed by arctic cold front with snow showers and squalls Monday afternoon and evening. Windy conditions develop, along with very cold wind chills Monday night into Tuesday.

3) Lake effect mainly stays north and west of our forecast area early to mid week. Stronger clipper system approaches Wednesday with snow showers possible.

4) Temperatures briefly rise near freezing Thursday, before another strong cold front brings snow showers and much colder temperatures for the end of the week into next weekend. Lake effect snow possible.

DISCUSSION

KEY MESSAGE 1... Adjusted PoPs, QPF and snow amounts into this evening based on a blend of the latest radar observations, HRRR, RAP and 3km NAM. A surge of moisture will ride back into the area by late afternoon and early evening bringing another steady period of light snow to the Wyoming Valley, Poconos and Caskills. Lingering weak 850mb frontogenesis is evident in this area on the latest 17z SPC mesoanalysis as well. The most likely timeframe for this next steady light snow will be from about 3/4 PM to 7/8 PM, before it then quickly exits east of the area. A few lingering snow showers or flurries could be around until about 10 PM. Additional snow accumulations in and around the advisory counties will be up to about 2 inches.

KEY MESSAGE 2...

Watching a weak warm front that will push west to east across Central NY and far northern tier of NE PA between about 4 AM in the west, reaching I-81 in CNY around 8/9AM, then lifting north and dissipating by late morning. Overall this is a very weak feature, but it may be enough of a lifting mechanism to wring out a 1-3 hour period of light snow, with a dusting to perhaps 1 inch possible.

After a few hour break in the snow, the strong push of much colder air begins filtering into the area on a west-southwest flow. The snow squall parameter is lighting up across the area, up to 5 in spots during the afternoon and early evening hours. This is due to MUCAPE of 25-90 J/kg, 0-2km lapse rates up to 9.5C/km and low level (0.5km agl) winds around 25-30 kts. CAMs are showing scattered convective type snow showers, and small squall segments possible. Accumulations will be light, under 1 inch, but roads and untreated surfaces could become quickly snow covered in spots.

Westerly winds increase Monday afternoon and continue overnight into Tuesday. Current guidance is showing 15-25 mph sustained winds, with gusts of 25-35 mph; a few localized gusts up to 40 mph as possible. These strong winds, falling temperatures and snow showers will bring the potential for areas of blowing snow into the evening hours and perhaps overnight. Wind chills will be very cold between about 5 below to 15 below zero Monday night into Tuesday morning. If confidence increases in these very cold wind chill values some cold weather advisories may be issued.

KEY MESSAGE 3...

A west-southwest flow of very cold air around -20C continues over the area Monday night, Tuesday and Tuesday night. This 250-260 degree flow will keep most of the lake effect snow north and west of our CWA. However, at times the lake band off of Erie could spread light to moderate snow showers across the northern Finger Lakes and even into the I-90 corridor around Syracuse. Minor accumulations up to and inch or two will be possible from this snow shower activity off of Lake Erie. The Lake Ontario snow band will likely remain north of our area most of the time, but it could occasionally scrape northern Oneida County due to minor fluctuations in the wind direction. A few inches of snow are possible across far northern Oneida county over this 36 hour period. Another very cold night Tuesday night, with lows in the single digits, but lighter winds.

The next clipper low pressure system approaches the area later in the day on Wednesday. Out ahead of this system winds are expected to back more southwesterly, lifting the lake effect even further north. Some light snow or snow showers are possible with the weak warm front moving through Wednesday afternoon or evening. Temperatures moderate some, reaching the mid-20s to lower 30s for highs Wednesday.

KEY MESSAGE 4...

Depending on the exact timing of the next strong cold front, temperatures could briefly rise up into the upper 20s to low 30s Thursday, before falling later in the day and evening. As the cold front moves through another round of snow showers are possible. We will have to monitor trends in guidance closely, as behind this front it's possible the overall flow is more due westerly, which could bring some more substantial lake effect into northern portions of our CWA...a lot of uncertainty in this still though. Much colder, arctic air mass is then likely to be around Friday through next weekend. Details on exact temperatures and wind chills still somewhat uncertain, but it will be very cold!

AVIATION /18Z SUNDAY THROUGH FRIDAY/

18Z Update... KAVP remains on the western edge of a system with associated restrictions and light snow, meanwhile snow is done at KBGM but a minor ceiling restriction remains. Remainder of terminals at VFR now through tonight, with KAVP-KBGM eventually joining at VFR later this evening. Another system will be inbound Monday morning, with the front side of it causing a new round of very light snow in the morning for at least the NY terminals with 2-4 mile visibility for a time. Winds will also start picking up out of the southwest, with scattered gusty snow showers/mini- squalls not far behind Monday afternoon.

Outlook...

Monday afternoon-evening...Arctic front passes with scattered gusty snow showers and mini-squalls. These will tend to be brief yet could be quite restrictive as they pass. Though specific terminal timing is low confidence, there is at least medium confidence that the gusty snow showers will occur.

Late Monday night through Wednesday morning...Lake effect snow showers/associated restrictions may visit KSYR-KRME at times but otherwise mainly VFR for all terminals. Low confidence for KSYR-KRME details.

Wednesday afternoon through Thursday...Stronger signal for a low pressure system passing by with restrictions possible from snow showers, especially the NY terminals. Medium confidence.

Thursday night through Friday...Mainly VFR, except intermittent lake effect snow showers possible KSYR-KRME, low confidence.

BGM WATCHES/WARNINGS/ADVISORIES

PA...Winter Weather Advisory until 10 PM EST this evening for PAZ040-048-072. NY...Winter Weather Advisory until 10 PM EST this evening for NYZ057-062.