textproduct: Binghamton

WHAT HAS CHANGED

Winter Weather Advisories have ended across the region along with the threat for accumulating snow.

KEY MESSAGES

1) Light lake effect snow across the Finger Lakes expected this evening and tonight.

2) Cold clipper system with light accumulating snow moves through the Northeast late Tuesday night through the day Wednesday.

3) Another potential winter system is possible late Thursday into Friday, but may move by to the south.

4) Widely varying temperatures this weekend with warm conditions Saturday, followed by a cold blast Sunday.

DISCUSSION

KEY MESSAGE 1...

Cold Canadian air on the back side of the departing, deep coastal low will be drawn south and sewd across the eastern Great Lakes starting this evening and tonight. With 850mb temperatures around -15 to -16 deg C moving across unfrozen Great Lake waters around 0-4 deg C, a brief period lake effect snow showers will develop. The potential for significant snow accumulations will be very low given the relatively shallow depth of the boundary layer and the minimal amount of residence time of any band that does organize over a particular area. The flow pattern will be mostly northwesterly around 290-300 deg this evening, but then back to around 270-280 later tonight...pushing any LES bands to the north.

At this time we are looking at around 2 inches or less into the central and southern Finger Lakes where slight upslope enhancement may help with accumulation. Would not be surprised to see amounts near 3 inches in and around northern Tioga County, especially if there ends up being some Finger Lake enhancement.

There may also be a wind/blowing snow component with this event tonight, with wind gusts 20-25 mph causing some reduced visibilities and also helping to keep secondary roads snow- covered and potentially hazardous.

KEY MESSAGE 2...

The next system is expected to move through late Tuesday and through the day Wednesday in the form of a fast-moving clipper system across the Northeast US.

The challenge with this system will be related to the potential for a mix of rain with the snow during the day Wednesday. A notable push of slightly warmer air is expected to be seen ahead of the short wave, with 850mb temperatures around -7 deg C. These conditions will likely keep the precip all snow Tue night and Wed morning with surface temperatures in the mid to upper 20s. This period is when the majority of the accumulating snow is expected to fall. Ensemble guidance is indicating around a 50-60 pct chance of at least 2 inches of snow...and the higher probabilities really drop off above 4 inches.

The challenge arrives later in the day Wednesday when surface temperatures look to rise into the upper 30s and lower 40s on the back side of trough axis...at least for a brief period of time. These temperatures will cause the lingering light snow to mix with and change to rain...before tapering off Wed evening. There could be weak lake influence Wed night, but with limited snow accumulations at least at this time.

KEY MESSAGE 3...

We are also tracking another short wave rounding the bottom of the long wave trough late Thu into Fri. However, at this time it appears the short wave will dive far enough south to keep most of the significant precipitation (likely in the form of snow) just to our south. Current forecast produces an additional 1-2 inches of snow across our area, but this could very well be too high. Ensemble guidance is in fairly good agreement with the southern track of this wave, but we will continue to monitor the trends through the next 24 to 48 hours as any significant shift northward would be seen soon.

KEY MESSAGE 4...

Behind the departing long wave trough, heights are expected to rise aloft and bring with it a noticeably warmer air mass for a very brief period of time on Saturday. Ensemble guidance is indicating a 60-70% chance of temperatures above 45 deg F on Saturday afternoon. This would be in combination with a fair amount of sun to make it feel even warmer.

Do not get too used to this because on Sunday the cold air is expected to return as another clipper system moves eastward across the northern Great Lakes and into southern Quebec. This system should be mostly a glancing blow for precipitation, but it may open the door to a bout of cold air with high temperatures on Sunday only into the 20s and overnight lows Sun night down into the single digits and teens above zero. Additional rounds of lake effect snow are possible during this time and into early next week as well.

AVIATION /18Z MONDAY THROUGH SATURDAY/

SYR and RME are currently VFR but will fall to MVFR later this afternoon. ITH is also stuck in IFR but should improve to Fuel Alt, though there is some uncertainty when as guidance has ceilings higher than what they are now. Otherwise, MVFR to Fuel Alt ceilings are expected at all sites through most, if not all of this TAF period. Some improvements back to VFR will be possible at AVP and ELM prior to 18z Tuesday.

There is a band of snow moving east to west and could impacting BGM within the next couple of hours with a brief reduction of IFR visibilities. With this band drifting south as it moves west, a quick amendment may be needed for AVP. Otherwise, there will be some lake enhanced snow late today and into part of the overnight hours. RME and AVP should not see this snow but the rest of the terminals will likely see reduced visibilities as this snow moves through.

Gust of 20 to 30 will remain possible through the early evening hours. Winds will remain breezy tonight and tomorrow with gusts 15 to 20 kts.

Outlook...

Late Tuesday night through through Thursday night...Occasional restrictions with a couple waves of snow and/or rain.

Friday and Saturday...Mainly VFR.

BGM WATCHES/WARNINGS/ADVISORIES

PA...None. NY...None.