Area Forecast Discussion
Issued by NWS Buffalo, NY

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000 FXUS61 KBUF 020232 AFDBUF Area Forecast Discussion National Weather Service Buffalo NY 932 PM EST Mon Mar 1 2021 .SYNOPSIS... Much colder air will pour into the eastern Great Lakes tonight, with lake effect snow showers producing minor accumulations southeast of Lake Erie and Lake Ontario. It will be quite windy tonight, especially southeast of Lake Ontario. This will set the stage for colder weather Tuesday when temperatures will remain below freezing, although high pressure will allow lake effect snow showers to end. We will experience a brief warm up on Wednesday ahead of another cold front, which will bring a return to colder weather to end the week. && .NEAR TERM /THROUGH TUESDAY NIGHT/... Radar imagery showing multiple bands of lake effect snow showers in northwest flow this evening. The most organized band has an upstream connection to Georgian Bay and extends from the Monroe County lakeshore into Wayne County. This band of snow will continue to drift southwest across Rochester through the midnight hour with a few bursts of moderate snow before weakening overnight as a very dry airmass moves into the eastern Great Lakes. Elsewhere a few bands of snow showers are found from central Erie County into the western Finger Lakes, and a few bands of snow showers are across Lewis County. Coverage and intensity will steadily decrease from late evening on. Expansive high pressure over the Upper Mississippi Valley this evening will drift east to the Upper Ohio Valley and Lower Great Lakes during the course of tonight. This will aid in directing very cold air into our region with H85 temps falling to -20C to - 24C. The cold sub arctic air will encourage some nuisance lake effect snow showers southeast of the Lakes on a northwest flow, especially during the first half of tonight, before drier air pushes in causing any lingering lake effect activity to slowly dwindle toward early Tuesday morning. Local accumulations of 1-3 inches are expected southeast of the lakes tonight. Off Lake Erie this will be across the higher terrain of northern Chautauqua and western Cattaraugus counties. Off Lake Ontario the more persistent snow will be from Orleans and Monroe counties eastward across Wayne County and also into the northern Finger Lakes. It will remain quite windy through the first half of tonight as a belt of 40-50 knots of wind just off the deck crosses Lake Ontario and Central NY. This will produce surface wind gusts of 45-55 mph across much of the area east and southeast of Lake Ontario and into the Genesee Valley and western Finger Lakes. The strongest gusts will occur this evening, with winds then gradually diminishing overnight. The fresh cold airmass will also support a wind chill advisory for Lewis county, where wind chills will drop to a little colder than 20 below zero late tonight. High pressure centered over the Ohio valley Tuesday morning will pass by to our south Tuesday afternoon. This will bring an end to any leftover nuisance lake snows early Tuesday. A warm front will move through the area Tuesday night with some light snow possible east of Lk Ontario. && .SHORT TERM /WEDNESDAY THROUGH WEDNESDAY NIGHT/... As a clipper low continues to pass to the north Wednesday morning, lingering chances for light snow across the North Country will dwindle through the day. Otherwise, mostly dry weather along with a brief warmup expected for Wednesday as a warm front slides by to the north of the area. Highs will range from the mid 30s across the higher terrain to the low 40s elsewhere. Temperatures quickly begin to fall shortly after sundown as colder air begins filtering in on a northwesterly flow behind a weak cold front. Cooling 850mb temperatures will slowly raise lake effect chances southeast of the lakes through the night. Latest batch of model guidance has trended a bit slower with bringing in the colder air overnight--if this pattern holds, may not see much in the way of lake effect until closer to Thursday morning. Upslope flow may also trigger some light snow up on the Tug Hill overnight Wednesday as surface temperatures fall into the teens, with mid to low 20s elsewhere. The amplification of an upper ridge over the Intermountain West and downstream blocking over Iceland will force the development of a deep trough over eastern third of the CONUS. Wrap around cold air advection will continue into Thursday as temperatures trend below normal. Despite the cooling temperatures and NW flow aloft, lake effect chances will remain low through the day and evening as the airmass becomes increasingly dry. Increased mixing will allow for some breezier conditions Thursday afternoon and into the evening, particularly south of Lake Ontario. Combined with highs that will struggle to make it out of the 20s even on the lower terrain, wind chills will make temperatures feel closer to the teens and even single digits east of Lake Ontario during the day. Air temperature will bottom out in the teens Thursday night with single digit wind chills, even lower on the higher terrain east of Lake Ontario. && .LONG TERM /THURSDAY THROUGH MONDAY/... Below normal temperatures likely for the first half of this period, then a gradual modification occurs into early next week. While the initial first part of this period will likely feature below normal temperatures, there is some hint that it won`t linger far into the first half of next week. What first looked like several day or longer of cold, has modified and is now advertising the gradual climb to near then above normal temperatures Sunday into next week. However, the degree to which it warms depends on which model of choice is preferred. The GFS is much more aggressive breaking down the Iceland block. This would allow the highly amplified ridge to our west to head east and initiate the faster warming trend. Whereas, the ECMWF keeps the deep trough overhead longer with several shortwaves bringing reinforcing shots of colder air. Have nudged temperatures up a bit from previous forecast reflecting a bit of the change in guidance but not going overly aggressive just yet. && .AVIATION /03Z TUESDAY THROUGH SATURDAY/... Fairly widespread snow showers this evening will give way to more narrow bands of lake effect snow showers by late this evening southeast of the lakes. Off Lake Erie most of this will focus just north and east of KJHW across the western Southern Tier. Off Lake Ontario this will focus from near KROC east and southeast into the northern Finger Lakes. Any snow showers tonight will contain brief/local IFR VSBY and MVFR CIGS, with mainly MVFR/VFR between the bands of snow. It will remain very windy through the first half of tonight with gusts of 35 to 45 knots common along the Lake Ontario shore and Finger Lakes region. Winds will slowly diminish later tonight. Any lingering snow showers southeast of Lake Ontario Tuesday morning will end, with VFR VSBY areawide. Areas of MVFR CIGS will continue through the morning before improving to mainly VFR in the afternoon. Outlook... Wednesday...VFR. Thursday...VFR/MVFR. A chance of snow showers. Friday and Saturday...Mainly VFR. A chance of snow showers. && .MARINE... Strong northwest winds behind a cold front will continue to produce a period of gales on Lake Ontario through this evening. Sustained winds will peak at or a little over 40 knots on the east half of the Lake before slowly diminishing late tonight. Winds are somewhat lower on Lake Erie, with Small Craft Advisory conditions lasting through Tuesday morning. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...Wind Advisory until 1 AM EST Tuesday for NYZ001>008-011>014- 021. Wind Chill Advisory until 10 AM EST Tuesday for NYZ008. MARINE...Small Craft Advisory until 7 AM EST Tuesday for LEZ020. Small Craft Advisory until 10 AM EST Tuesday for LEZ040- 041. Small Craft Advisory until 7 AM EST Tuesday for LOZ030. Gale Warning until 1 AM EST Tuesday for LOZ042>045-062>065. && $$ SYNOPSIS...Hitchcock/RSH NEAR TERM...Hitchcock/JM/RSH SHORT TERM...PP LONG TERM...AR AVIATION...Hitchcock MARINE...Hitchcock/RSH

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