Marine Weather and Tide Forecast for Clayton, NY

KEY MESSAGES
1) A warm front will bring light snow this afternoon, before an arctic front brings more impactful snow to parts of the region tonight.

2) Lake effect snow will develop behind the Arctic cold front Saturday through Saturday night, with blowing and drifting of the fresh snowpack.

3) Dangerously cold wind chills between 15 and 35 below zero are expected this weekend.

DISCUSSION
KEY MESSAGE 1...A warm front will bring light snow this afternoon, before an arctic front brings more impactful snow to parts of the region tonight.

WV Satellite imagery this afternoon depicts a deep mid-level trough digging southwards across Ontario Province into the Great Lakes region. This feature will drive a strong Arctic cold front this evening, though out ahead of the main front, an elongated area of sfc low pressure and associated warm front will bring light nuisance snow to much of the region. Regional radar indicates a few breaks in the general light snow upstream, which should work their way into the forecast area through the rest of the afternoon.

The main period of interest for more impactful snowfall will be as the front arrives this evening. Much stronger LLJ energy and height falls/DPVA aloft will result in more vigorous snow shower activity thie evening and tonight. The main areas of concern are from the Genesee Valley to the eastern Lake Ontario shoreline as the main sfc low becomes centered and stregthens over the eastern end of the lake tonight. This feautre, the noted PV intrusion across it, as well as potentially added frictional convergence or instability from Lake Ontario may enhance snowfall and even lead to few snow squalls in the vicinity as it tracks through. A tricky forecast right along the shoreline as the high amount of shear and some ice coverage should limit the inland extent and intensity of lake enhancement, though a noted uptick in QPF among most guidance packages raises enough confidence to include Jefferson County in the Winter Weather Advisory. Fruther west, the more impactful snowfall should remain focused south of Buffalo where upslope enhancement comes into play across the hilltops. The widespread snow showers will transition to lake effect south of Lake Ontario overnight tonight into early Saturday morning.

KEY MESSAGE 2...Lake effect snow will develop behind the Arctic cold front Saturday through Saturday night, with blowing and drifting of the fresh snowpack.

Behind the arctic front Saturday a gusty northwest flow will remain over our region, with gusts upwards to 35 mph. In addition, a shallow and low to the ground snow DGZ zone will support a light lake effect snow response that will only amount to an inch or two of accumulation south of Lake Ontario, but the much greater impact will be from the blowing and drifting of falling, and recently fallen snow. Open county roads could see visibilities greatly reduced from the blowing snow through the day Saturday and into Saturday night.
For which a winter weather advisory will continue.

KEY MESSAGE 3...Dangerously cold wind chills between 15 and 35 below zero are expected this weekend.

Arctic air will arrive on the backside of a strong cold front late tonight through Saturday and cold weather will persist across the region through Sunday. A 40- 50-knot low-level jet with 850 hPa temperatures around -28C will spread across the forecast area late tonight through Saturday. These forecasted values of -28C at 850 hPa would be some of the coldest 850 hPa temperatures ever for the month of February in Buffalo sounding climatology. The lowest 850 hPa temperature measured in February is -28.5C on February 13th 2016.

The core of the coldest air aloft will slowly lift eastward across the North Country into northern New England Saturday night through Sunday.

Strong winds behind the front will exacerbate this cold airmass and create wind chills well below zero. The combination of frigid temperatures and strong winds will create dangerous wind chills across the region. Wind chills as low as 30 below zero are expected to be felt across the higher terrain south of Buffalo, and across the Finger Lakes region late tonight through Saturday, then east of Lake Ontario Saturday through Sunday morning. The flow over the lake waters of Lake Ontario, combined with lake effect clouds may prevent wind chill values from plummeting as much for the northern Niagara Frontier, and counties along the southern Lake Ontario shoreline.

Winds will diminish across the region Saturday night through Sunday, but a still plenty cold airmass with sub zero air temperature readings will promote wind chill values in the negative double digits for our region through Sunday late morning. Cold weather headlines are in effect for the entire region for the weekend.
Though air temperatures Sunday night may be the coldest of the three weekend nights, the surface ridge over our region will bring calm to light winds...with wind chill values possibly remaining above advisory thresholds

An upper level ridge will build into the Plains the start of the work week with a less harsh airmass expected to start the work week.

AVIATION /19Z FRIDAY THROUGH WEDNESDAY/
For the 18Z TAFS light snow with embedded IFR/MVFR flight conditions continues across the TAF region this afternoon. There may be a brief break in the falling snow before an arctic front, coupled with a burst of heavy snow in snow squalls (visibilities less than a mile)
passes across the TAF region, generally between 00Z and 06Z.

Behind this front winds will veer to the northwest and remain gusty, with speeds up to 30 knots across the TAF region through the end of this forecast period which will produce IFR or lower visibilities in blowing snow.

Snow behind the front will transition to lake effect snow on a northwest flow tonight through tomorrow. This will impact KROC with prolonged period of IFR flight conditions in light snow...with a period of IFR flight conditions also anticipated for KIAG/KBUF.

Outlook...

Saturday night through Sunday... Areas of IFR in lake effect snow showers south of Lake Ontario.

Monday through Tuesday...Mainly VFR, trending to MVFR Tuesday afternoon.

Tuesday night through Wednesday... IFR/MVFR in light snow.

MARINE
A strong arctic cold front will pass across the region tonight through Saturday resulting in a period Gales across the far western and central portions of Lake Ontario, and Small Craft Advisories on Lake Erie and the eastern waters of Lake Ontario. This being said, a Gale Warning is in effect for tonight into Saturday morning for the western and central portions of Lake Ontario. Due to the frigid nature of the airmass overhead, along with the strong winds, freezing spray will also be likely on Lake Ontario. Winds and waves will subside later Sunday as surface high pressure builds into the lower Great Lakes.

Please note...Most, if not all of the Lake Erie nearshore waters are now ice covered. Waves have been omitted from the forecast.

BUF WATCHES/WARNINGS/ADVISORIES
NY...Winter Weather Advisory until 7 PM EST Saturday for NYZ001-002- 010>012-019-020-085.
Cold Weather Advisory from 1 AM Saturday to 10 AM EST Sunday for NYZ001>005-010-011.
Winter Weather Advisory until 7 AM EST Sunday for NYZ003>006- 013-014.
Extreme Cold Warning from 7 AM Saturday to 1 PM EST Sunday for NYZ006>008.
Winter Weather Advisory until 1 PM EST Saturday for NYZ007.
Extreme Cold Warning from 1 AM Saturday to 10 AM EST Sunday for NYZ012>014-019>021-085.
MARINE...Small Craft Advisory from 7 PM this evening to 4 PM EST Saturday for LEZ040-041.
Small Craft Advisory from 7 PM this evening to 1 AM EST Sunday for LOZ030.
Gale Warning from 7 PM this evening to 10 AM EST Saturday for LOZ042-043-062-063.
Heavy Freezing Spray Warning from 7 PM this evening to 10 AM EST Saturday for LOZ042-043-062-063.
Small Craft Advisory from 10 PM this evening to 7 AM EST Sunday for LOZ044-045.