textproduct: Binghamton

WHAT HAS CHANGED

Increased PoPs this afternoon and evening across CNY and northern tier of NE PA as scattered snow showers and isolated heavier squalls are progged to traverse the area; most activity is over by 8-9 PM EST. Small adjustments to PoPs, QPF and snow amounts for the west- southwest lake effect snow event tonight through Tuesday night. Temperatures and wind chills continue to trend colder Friday night through the upcoming weekend. No confident trend in the potential late weekend winter storm.

KEY MESSAGES

1) Scattered snow showers and isolated squalls possible through early this evening. Much colder, and windy with bitter cold wind chills tonight into Tuesday morning. Cold Weather Advisory in effect for portions of the area.

2) West-southwest flow lake effect event expected tonight through Tuesday night. Minor accumulations off of lake Erie for portions of Central NY (1-2") with northern Oneida County being scraped by much stronger lake Ontario band at times, bringing 2-5 inches here.

3) Clipper system approaches, but ultimately weakens Wednesday into Thursday. Snow showers are still likely across northern portions of the CWA, with minor accumulations possible (especially Oneida and Steuben Counties)

4) Bitter cold arctic outbreak expected later Friday through the upcoming weekend. Snow showers with the frontal passage Friday into Friday night. Watch a potentially expansive winter storm Saturday night through Sunday night. Best guidance is to keep the majority of this system south of the area at this time; something to closely monitor though.

DISCUSSION

KEY MESSAGE 1...

Current water vapor loop shows a well defined shortwave coming into the area this afternoon. MRMS composite reflectivity loop shows snow showers and few snow squalls approaching the area now from the west- southwest. Mesoanalysis shows the snow squall parameter of 3-5 working its way into western portions of the area at this time. RAP forecasts this prime snow squall environment to push east toward I- 81 in the northern tier of PA and CNY by 3-5 PM, then weaken as it reaches the Catskills by 5-8 PM. Snow showers could be briefly heavy,with low visibility gusty winds and a quick inch of snow would be possible locally. The snow squall threat quickly diminishes by around or just after 8 PM in our CWA. Strong west winds of 10-20 mph with gusts of 30-40 mph continue tonight and into Tuesday, eventually diminishing late in the day. 850mb temperatures fall to around -20C by Tuesday morning. Overnight lows will dip down into the single digits and combine with the blustery winds to produce wind chills of 0 to 15 below. Cold Weather Advisories remain in effect from 10 PM this evening until 10 AM Tuesday for all of NE PA and the Central Southern Tier of NY/ SW Finger Lakes of NY (Chemung, Schuyler, Yates & Steuben Counties).

KEY MESSAGE 2...

Behind the arctic frontal passage this evening lake effect snow bands become much better organized off both Lake Erie and Ontario. Through most of the night the flow looks to remain around 250-260 degrees, with minor fluctuations at times. This will keep the lake Ontario band centered on the Tug Hill region, just scraping northern Oneida county at times. The lake Erie band could occasionally extend inland, bringing flurries or light periods of snow to the northern Finger Lakes and in/around the Syracuse metro area. Accumulations overnight will be light just a dusting to half inch south of I-90, with locally up to 2 inches in far northern Oneida county, near the Lewis county line (Boonville, Woodgate, White Lake areas).

On Tuesday, not much changes in the lake effect department as things remain pretty steady state. Small fluctuations in the boundary layer flow may bring the band a touch further south into Northern Oneida County at times, bringing another 1-3 inches locally here (especially in the afternoon). The Lake Erie extension snow band may bring a dusting to an inch or two across parts of Yates, Seneca, S. Cayuga, N. Cortland and S. Onondaga counties; confidence is low to moderate on this though. The flow shifts more southwest, then southerly Tuesday night, with any lake effect snow lifting north of the area after midnight. Snow totals of 2-6 inches are expected across far northern Oneida County through 1 AM EST Wednesday; especially near Boonville/Woodgate and White Lake.

It will be cold on Tuesday with highs in the 10s and dropping back down into the single digits Tuesday night. If skies clear out in the evening it could even drop below zero in a few spots.

KEY MESSAGE 3...

A clipper system tracks into the north central Great lakes Wednesday afternoon and evening, bringing a warm front through our area along with some light snow. South winds increase between 10-20 mph with gusts 25 to 35 mph at times Wednesday afternoon and evening.

Initial front moves through Thursday morning, with more snow showers around through the day; especially across north-central NY. Surface temperatures may creep up into the mid-30s from the Southern Tier south into NE PA as the flow remains southwesterly. The flow slowly shifts more due west Thursday night, and this could bring a better chance for lake effect snow bands to impact areas north of I-90. Accumulations over this 36-48 hour period will be less than 1 inch for most of the area, but a few inches could accumulate in Western Steuben and Oneida counties.

KEY MESSAGE 4...

Model guidance has come into good agreement that a closed 500mb polar low will drop into the Upper Midwest Thursday night into Friday morning, sliding east across the Central Great Lakes on Friday. This will bring an arctic cold front through our area likely Friday afternoon. This front may have snow showers and squalls accompanying it, along with blustery winds. 850mb temperatures drop to around -25 to -29C Friday night, with 1000-500mb thicknesses down to 492dm across Central NY. This type of air mass is capable of bringing extreme bitter cold conditions. Stuck close to the NBM guidance, but hedged slightly lower Friday night (blending in NBM25th and 10th percentile data). This gives actual ambient low temperatures of 0 to 15 below for CNY, with 5 above to 5 below in NE PA; combined with winds, wind chills may reach 5 to 20 below for much of NE PA and CNY...as low as 30 below in northern Oneida. High temperatures on Saturday likely struggle to make it out of the single digits above zero for many locations, with some lower 10s possible for the Wyoming Valley. Another very cold night Saturday night, with similar low temperatures expected as weak high pressure settles overhead. If winds can decouple it could trend even colder.

On Sunday a large, complex winter storm approaches from the south. There remains a great deal of uncertainty in the model guidance. Some guidance is keeping it very suppress, with a wintry mix and snow down across the southern US. Meanwhile some guidance is trying to allow the low to turn the corder and move up along the Mid-Atlantic coast. This more northern solution has the potential to bring some light to moderate snow over northern portions of the Mid-Atlantic. It is too early to tell which solution will win out for our area. Overall the AI-Ensembels remain north of their operational ensemble suites for the most parts, with the 12z ECMWF deterministic being further north as well. Overall, there has not been much of a trend today in most of the guidance. This remains something to watch closely in the coming days.

AVIATION /19Z MONDAY THROUGH SATURDAY/

Flurries continue over much of the region so light snow was added to all central NY terminals though no restrictions are expected. Currently looking upstream into central PA, snow squalls have developed. These will drift northeastward this afternoon and could bring a brief period of LIFR visibilities to some or all of central NY terminals. Given that these squalls are scattered and restrictions may not occur if it does not snow at a terminal, tempo groups were added. Guidance does not have much for AVP but a tempo group was also added there for a snow shower with MVFR visibilities, though brief IFR cannot be ruled out.

By 00z, snow showers should diminish with skies scattering out and VFR conditions continuing through the rest of the TAF period. Lake effect snow will be north of the region and while there are some low chances for snow showers at RME, they are not high enough to mention in the TAFs.

Southwest to west-southwest winds will stay gusty throughout the next 24 hours. Sustained speeds will be 10 to 15 kts with gusts of 20 to 30 kts.

Outlook...

Tuesday Night through Wednesday morning...Lake effect snow showers/associated restrictions may visit SYR-RME at times, though low confidence, but otherwise mainly VFR for all terminals.

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 Saturday...Mainly VFR, except intermittent lake effect snow showers possible SYR-RME, low confidence.

BGM WATCHES/WARNINGS/ADVISORIES

PA...Cold Weather Advisory from 10 PM this evening to 10 AM EST Tuesday for PAZ038>040-043-044-047-048-072. NY...Winter Weather Advisory until 1 AM EST Wednesday for NYZ009. Cold Weather Advisory from 10 PM this evening to 10 AM EST Tuesday for NYZ015-022>024.