textproduct: Binghamton

WHAT HAS CHANGED

Issued winter weather advisory for freezing rain for Onondaga Co. as temperatures are in the 20s with dewpoints in the teens and rain in developing shortly.

Upgraded winter weather advisories to winter storm warnings for lake effect snow and blowing snow in north central NY Monday evening to Wednesday morning. Issued winter weather advisories from Southern Cayuga County to Otsego County in NY for lake effect snow and blowing snow for the same times. Issued wind advisory for entire area from Monday afternoon to Tuesday.

KEY MESSAGES

1) Freezing rain expected the remainder of the afternoon and tonight across much of central NY and northeast PA.

2) Strong cold front Monday afternoon/evening with strong winds behind the front Monday night into Tuesday.

3) A prolonged lake effect snow event is expected from Monday night into next week across north central NY. Increasing winds will lead to areas of blowing and drifting snow, with periods of reduced visibility.

DISCUSSION

KEY MESSAGE 1... Freezing rain was spreading rapidly across northeast PA and south central NY. Temperatures were still just below freezing with dewpoints a few degrees lower in the central southern tier and southern Finger lakes. Surface temperatures were solidly in the 20s east of an ITH to Towanda PA line. Strong low-level jet at 850 mb was transporting significant moisture into a warm advection pattern leading to widespread stratiform precipitation. South of NC NY, mainly south of I-90, QPF will be lighter so we expect more freezing rain to accrete on surfaces. Th exception is Oneida county where colder air remains in place leading to around one quarter inch of ice. Road temperatures were hovering below freezing rain as well. So any untreated road surface likely will become very slippery in these areas. Across the northern Finger Lakes where there was downsloping, temperatures have climbed to low to mid 30s already and we are not expecting any significant freezing rain there expect over the higher terrain of southern Cayuga and southern Onondaga Counties. Winter weather advisories are in effect most counties in central NY and northeast PA until late tonight. Main impact will be travel. Temperatures will warm above freezing from west to east overnight and change all the freezing rain to rain. We may be able to drop winter weather advisories from the southern Finger Lakes and points west sooner than advertised. All this precipitation changes to plain rain between midnight and 7 am as 850 mb temperatures aloft climb to around 10C! Rain will eventually drag down warmer and moister air and warm the boundary layer.

KEY MESSAGE 2...

As the deep low progresses into the St. Lawrence River Valley in Southern Canada, a strong cold front moves through later in the day Monday. 850 mb winds behind the front increase to near 50 knots with steep low level lapse rates. Forecast soundings in BUFKIT show some top of boundary layer winds approaching 60 knots. Wind gusts were raised closer to the NBM 90th percentile to match closer to the potential max wind gusts in BUFKIT. Light wrap around snow coupled with the increasing winds will likely lead to areas of blowing snow, especially in the farm country of the Finger Lakes.

KEY MESSAGE 3...

An upper level low will pass north of the region Monday night, with westerly flow transitioning to northwesterly flow as the system continues to rotate. This will advect increasingly cold air into the region, with 850 mb temperatures falling to between -10 to -15 degrees C while lake surface temperatures remain around 4 to 6 degrees C. As northwest flow becomes established and persists, multi- lake connection is likely for much of the week beginning Monday night. Embedded shortwaves rotating around the upper low will periodically move through the region, impacting band orientation and organization and enhancing snowfall rates downstream of the lakes.

Model sounding indicate favorable moisture depth through the dendritic growth zone, especially across north central NY. Snowfall accumulation within the primary lake effect band are expected to range from 7 to 14 inches, with 3 to 6 inches possible south of the main band. Strong winds will accompany this event, increasing Monday afternoon and continuing into Tuesday afternoon. Areas of fresh snowfall will experience blowing and drifting snow, leading to locally reduced visibilities and occasional whiteout conditions.

Winter Storm Warnings have been issued for lake effect snow for Onondaga, Madison, and Oneida counties. A lake effect warning was not issues due to the added impacts of gusty winds and blowing snow. Winter Weather Advisories have been issues south of the Warning area for S. Cayuga, Cortland, Chenango, and Otsego counties.

AVIATION /20Z SUNDAY THROUGH FRIDAY/

Conditions are mainly VFR but as precipitation moves into the region this afternoon, ceilings will fall from west to east. After a forecast update, most terminals are expected to see freezing rain today. Where there was lower confidence on whether there would be freezing rain or just rain, tempo groups were added. SYR will see little to no ice accumulation while other terminals could see at least a glaze on surfaces. Temperatures will climb this evening and overnight, so freezing rain will transition to just rain. Ceilings will be the main restriction going from VFR to IFR/LIFR at most terminals. SYR may just hang onto Fuel Alt ceilings. Visibilities will also be reduced at times when rain/freezing rain is falling. Conditions then improve late in the period as rain slowly comes to an end between 12 and 18z Monday.

Winds are generally light now between 5 and 10 kts. Winds begin to increase later this evening and continue to increase overnight. Gusts will initially be 15 to 20 kts but increase to 25 to 40 by midday Monday. Winds will generally be south- southeasterly for most of the period but become more southwesterly after a front pushes the rain out Monday morning. Low-level wind shear is also expected at all cites. Expected south to southwesterly winds of 35 to 50 kts up to 2000 ft AGL.

Outlook...

Monday afternoon through Tuesday...Cold frontal passage and gusty winds as rain showers change back to lake effect snow showers, especially NY terminals as lake effect becomes dominant. Restrictions possible, especially at the NY terminals.

Wednesday...Lingering lake effect clouds and snow showers for mainly the NY terminals, but cannot rule out some showers making it south to KAVP.

Thursday...Restrictions possible behind a cold front that brings snow showers to the region.

BGM WATCHES/WARNINGS/ADVISORIES

PA...Wind Advisory from 1 PM Monday to 7 PM EST Tuesday for PAZ038>040-043-044-047-048-072. Winter Weather Advisory until 4 AM EST Monday for PAZ038>040- 043-044-047-048-072. NY...Winter Weather Advisory until 7 AM EST Monday for NYZ009-036- 037-046. Wind Advisory from 1 PM Monday to 7 PM EST Tuesday for NYZ009- 015>018-022>025-036-037-044>046-055>057-062. Winter Storm Warning from 7 PM Monday to 7 AM EST Wednesday for NYZ009-018-036-037. Winter Weather Advisory from 7 PM Monday to 7 AM EST Wednesday for NYZ017-044>046. Winter Weather Advisory until 4 AM EST Monday for NYZ018- 022>025-044-045-055>057-062.