textproduct: Binghamton

WHAT HAS CHANGED

Extreme Cold Watch was upgraded to a Warning for Northern Oneida County for Friday night and a Cold Weather Advisory was issued for the rest of the region.

Some initial snowfall totals have been included in the forecast but changes are likely in the upcoming days.

KEY MESSAGES

1) Conditions become much colder heading into the weekend with dangerous low wind chills Friday night into Saturday morning. Lake effect snow also expected tonight into the start of the weekend.

2) A significant winter storm is possible Sunday morning through Monday.

3) The winter storm exits the region Monday with lake effect snow to follow.

DISCUSSION

KEY MESSAGE 1...

Scattered snow showers will come to an end later this afternoon and transition to lake effect snow tonight. The bands of lake effect snow will mainly stay north of the region to start, though model guidance is showing the possibility for light snow extending from Lake Erie into the Finger Lakes region. Then on Friday night, an Arctic cold front will drop in from the north. This will not only bring much colder air but shift the flow out of the northwest leading to lake effect drifting south. Drier air then moves into the region Saturday bringing an end to the lake effect snow.

With the much colder airmass dropping in behind the front, the coldest temperatures of the season will be observed Friday night into Saturday. Overnight temperatures will be near or below zero but blustery winds will bring wind chills down to -10 to -30. For this time period, the Extreme Cold Watch was upgraded to a Warning for N. Oneida and a Cold Weather Advisory was issued for the rest of the CWA. Little relief is then expected Saturday as temperatures will mainly be in the single digits but wind chills will stay below zero for most of the region.

KEY MESSAGE 2...

The main story of the forecast period is the significant winter storm that is expected to impact the region Sunday through Monday. While there is still spread in timing, snow could move in as early as late Saturday night/early Sunday morning and then spread northward throughout Sunday morning as the storm moves into the Northeast. The steadiest snow is expected Sunday and Sunday night. There is plenty of moisture throughout the DGZ and strong Omega throughout the layer as seen in forecast soundings. With signs of banding evident in the forecast, there is potential for localized heavy snowfall but exactly where remains uncertain. Snow-to-liquid ratios will be around 20:1 but could exceed that. In addition, snowfall rates of at least an inch per hour cannot be ruled out.

Confidence remains high that there will be widespread accumulating snowfall of at least 6 inches. The initial first guess at snowfall totals is 10 to 18 inches with the highest amounts across south- central NY, northeastern PA, and the Catskills but this does not include any additional snowfall that could linger into Monday. It is important to note that there remains quite a bit of uncertainty with this system. Model guidance still vary greatly with timing and any shifts in the expected track of this system will also have an impact on the expected totals.

KEY MESSAGE 3...

Upper level trough along with surface low continues to move through the region on Monday, pushing east by Monday evening. This will allow snow to continue to fall with additional accumulations expected. Once the upper level trough is east, northwest to westerly flow and wrap around moisture follows behind with lake effect snow showers expected. There are timing differnces on when exactly the system exits and lake effect snow showers start. GFS is the slowest solution, while the ECMWF and CMC are more on the same page in terms of timing. Cold air advection on Monday will bring 850 mb temperatures to -20 degrees C with surface temperatures only in the mid to upper teens. Gusty winds will also be possible Monday afternoon into the evening, blended NBM 90th into the forecast. While the start of next week will be slightly warmer, conditions will still be frigid and remain below normal through the week. This system will exit Monday afternoon, however, in its wake, wraparound moisture and northwest to westerly flow off the lakes will likely kick off lake effect snow. While the start of next week will be slightly warmer, conditions will still be frigid and remain below normal through the week. Also, with troughing likely remaining over the NE US through at least the end of the month, the pattern will remain favorable for more winter storms.

AVIATION /06Z FRIDAY THROUGH TUESDAY/

Mainly VFR conditions are expected early this morning, but high res. guidance does support some light snow shower activity moving generally west to east that could lead to some intermittent MVFR restrictions generally between 08-12Z for the CNY terminals.

As a cold front crosses the area during the early to mid afternoon, this can lead to additional isolated to scattered snow showers and even some blowing snow around the CNY terminals, especially ITH and BGM. Winds will also become quite gusty both ahead of and behind the frontal boundary with west- northwest gusts of 25-30 knots with locally higher gusts from late morning through the afternoon.

A well defined lake effect snow band downwind of Lake Ontario is expected to drop south late this afternoon and evening. Onset timing of the heavier snow with this band for RME and SYR varies by a few hours among the CAMs, ranging from 19-22Z for RME and 21-23Z for SYR. As this band moves in, there is a high likelihood of IFR or worse visibility. As this band continues to press south, some lower cigs will be possible around ITH and perhaps BGM.

Outlook...

Friday Night through Saturday...MVFR with occasional IFR restrictions continue at or near SYR-ITH-RME overnight, gradually becoming VFR later in the day Saturday. Mainly VFR elsewhere.

Sunday into Sunday Night...Snow overspreads the area, heavy at times leading to IFR or worse restrictions.

Monday...Lingering snow showers and/or lake effect possible with associated restrictions.

Tuesday...Isolated snow showers around, otherwise mainly VFR.

BGM WATCHES/WARNINGS/ADVISORIES

PA...Winter Storm Watch from late Saturday night through Monday evening for PAZ038>040-043-044-047-048-072. Cold Weather Advisory from 7 PM this evening to 10 AM EST Saturday for PAZ038>040-043-044-047-048-072. NY...Extreme Cold Warning from 7 PM this evening to 10 AM EST Saturday for NYZ009. Winter Storm Watch from late Saturday night through Monday evening for NYZ009-015>018-022>025-036-037-044>046- 055>057-062. Cold Weather Advisory from 7 PM this evening to 10 AM EST Saturday for NYZ015>018-022>025-036-037-044>046-055>057- 062.