textproduct: Binghamton

SYNOPSIS

Cold Canadian air continues to filter into the region with lake effect snow showers expected through Monday. A weak wave of low pressure drops out of Canada Monday afternoon, with with more widespread light snow showers. Warmer conditions develop by midweek with chances for rain increasing on Thursday with an approaching cold front.

NEAR TERM /THROUGH MONDAY NIGHT/

Lake effect snow band is currently unorganized and broken into multi bands this afternoon across Onondaga county and dropping southward into central Cayuga. As flow turns more NNW this afternoon and evening, lake effect snow showers will pick up in coverage across the Finger Lakes region with T850 dropping to near -20C and moisture increases on the back side of the 500/700mb low. A well aligned NNW flow continues this evening, with multiple small lake effect snow bands likely extending across the Finger Lakes and into the Twin Tiers of NY/PA. Although QPF will be light, the SLRs are forecast to be very high and likely above 20:1. Winter weather advisory will remain in effect through Monday morning for Onondaga and southern Cayuga, where an additional 2-4 inches will be possible, further south, the totals will likely be 1 to 2 inches or less across the Southern Tier.

Finally, arctic air tonight combined with gusty winds will create wind chill temperatures below zero for most of the area. A few spots across northern Oneida County and in the Catskills will see wind chill values near -15F early Monday morning, but coverage is not enough to warrant a cold weather advisory for the entire counties. This is also the case across portions of NE PA, where the higher elevations of the Poconos could see wind chill values down to -10F overnight into early Monday morning.

Ridging will build in from the southwest Monday morning and the lake effect snow showers will start to diminish and gradually lift back north. However, another shortwave moves into the area Monday afternoon and evening, bringing a period of light warm air advection snow to most of Central NY and perhaps parts of NE PA. Minor snow accumulations up to about 1 inch are expected from this weak weather system. Monday will feature more cold and below average temperatures as highs only reach into the 20s. Decided to use NBM 25th percentile for temperatures as the NBM has a poor handle on the airmass settling over the region.

SHORT TERM /TUESDAY/

After another chilly start on Tuesday, warm air advection will take hold. Any lake effect will move of our area as flow turns to the WSW. Morning and early after sunshine looks likely, however, clouds will increase during the afternoon as a weak wave / warm front approaches. Temperatures will still be running below average, with highs in the 20s once again to possibly low 30s in the warmer spots.

LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/

The long term period will start out fairly dry with weak high pressure in place midweek. A weak system in Canada will drift eastward Tuesday night and eventually clip the region Wednesday with precipitation for north-central NY. With temperatures climbing into the upper 30s to low 40s and precipitation moving through during the afternoon, rain will be the main ptype but cooler conditions in higher elevations may result in more snow or snow mixing in.

A ridge of high pressure then builds into the region Wednesday night into Thursday. As it does, a low pressure system develops over the upper Midwest. Strong southerly flow will advect in warm air into the region. With above average temperatures in place, precipitation will start out as just rain when as the low tracks to the north late Thursday. Rain then continues overnight as temperatures remain mild but a cold front will being to push through early Friday morning. As it does, precipitation behind the front will become more of a rain/snow mix or just snow. The front exits the region Friday afternoon leaving behind some lingering snow showers. With this event being sensitive to the timing of the front, there does remain uncertainty with the timing of rain transitioning to snow. Besides the precipitation, winds will become gusty. Peak gusts Thursday through Friday morning will likely exceed 30 mph at times. Given the uncertainties, with this forecast, NBM guidance was favored. Winds were increased slightly in the Catskills to coordinate better with neighboring offices.

Behind the late week system, some lake effect snow develops downwind of Lake Ontario thanks to cool, northwesterly flow. It will be short- lived though and comes to an end by Saturday morning with the return of high pressure. Heading into the start of the weekend, a weak low pressure system will track to the north once again. While there is some uncertainty on the southern extent of this system, light rain and snow will be possible for at least some portions of central NY but possibly for northeastern PA as well.

The second half of this week will be warmer than the first half though there will be some colder periods as well. Generally, conditions will be around or above average. Thursday will be the warmest day with highs in the 40s. Single digits and teens make a return Friday night into Saturday morning. The only significant change made to the temperatures this period was for the lows Thursday night.

AVIATION /00Z MONDAY THROUGH FRIDAY/

The near term through 12Z remains a tricky forecast as lake effect snow showers continue. Most of the high res. guidance has the lake effect snow across CNY diminishing around 5Z, but the northwesterly flow off of Lake Ontario isn't expected to start to become more west-northwest and eventually westerly until around 08-12Z, so primarily MVFR restrictions are expected to continue for ITH and BGM, with occasional restrictions possible at SYR and RME through the overnight. There is a plume of steadier snow that is just east of ITH that should hold together to reach BGM within the next hour that can bring IFR or lower restrictions briefly. This zone will be closely monitored in case further amendments are needed.

Beyond 12Z, a band of snow showers is expected to move across SYR and RME through early to mid afternoon. There is the potential for IFR visby with this band during the mid-to-late morning hours, especially at SYR. A weak wave moving through is expected to keep ceiling restrictions in place much of the afternoon tomorrow, except for AVP, then as winds start to turn southwesterly at the end of the TAF period, ceiling should start to gradually lift.

Outlook...

Monday night...Occasional restrictions in the evening with diminishing snow showers, then gradually becoming VFR.

Tuesday through early Thursday... Mainly VFR.

Late Thursday into Friday...Potential frontal passage with rain showers, possibly mixing with or ending as snow showers along with associated restrictions.

BGM WATCHES/WARNINGS/ADVISORIES

PA...None. NY...Winter Weather Advisory until 7 AM EST Monday for NYZ017-018.