333 FXUS61 KBUF 161805 AFDBUF Area Forecast Discussion National Weather Service Buffalo NY 205 PM EDT Sun Oct 16 2022 .SYNOPSIS... A deep trough of low pressure will become established across the Great Lakes tonight and remain in place through most of the week, bringing chilly and unsettled weather to the region. The trough will bring a few scattered showers at times, and also bring favorable conditions for lake effect rain downwind of Lake Erie and Lake Ontario at times. Most of the precipitation will fall as rain, although some wet snow may mix in across higher terrain each night from Monday night through Wednesday night. Drier and much warmer weather is expected by next weekend. && .NEAR TERM /THROUGH MONDAY NIGHT/... Satellite imagery showing a few areas of mid level clouds persisting this afternoon, most notable across the eastern Lake Ontario region. Meanwhile, sunshine prevails across much of the Southern Tier and Genesee Valley. Highs will reach the upper 50s to lower 60s in most locations. A southwest wind will gust up to 30 mph northeast of Lake Erie. A deep longwave trough will become established across the Great Lakes tonight and Monday as a strong shortwave dives into the deepening trough, forcing a deep closed low to develop over the central Great Lakes Monday. Much colder air aloft will pour into the Great Lakes tonight and Monday, setting the stage for an extended period of lake effect precipitation. The first half of tonight will stay dry. Overnight, DPVA and height falls ahead of the approaching trough will bring increasing large scale ascent. A surface cold front will move into Western NY late tonight, then move east into the eastern Lake Ontario region by later Monday morning. The passing cold front will bring a few light showers to Western NY late tonight, then much of the region Monday. The cold frontal showers will likely become enhanced by Lake Erie across the Buffalo area early Monday morning. Cold frontal and upslope showers will linger much of the day east of Lake Ontario as the cold front slows its eastward progress. Following the passage of the cold front, a band of lake effect rain will develop later Monday morning and continue through Monday night off Lake Erie. Monday through Monday evening boundary layer flow will average 220 degrees, centering the band of lake effect rain quite far north near Grand Island, the Tonawandas, and portions of Niagara County. The rain could become heavy at times and some thunder is possible as cold air deepens and lake induced equilibrium levels rise to over 20K feet. Later Monday night into Tuesday morning boundary layer flow will briefly veer to the WSW following the passage of a low level trough. This will push lake effect south across Buffalo and onshore along much of the Lake Erie shoreline of southern Erie and Chautauqua counties, spreading inland across the Boston Hills and Chautauqua Ridge. Meanwhile for Lake Ontario, boundary layer flow will remain quite southerly Monday and Monday night, directing most, if not all, of the lake effect rain into Canada. Precipitation type will stay all rain Monday through Monday evening as the boundary layer stays mild, although some graupel may develop in heavier convective cells. Later Monday night some wet snow will mix in across the higher terrain of the western Southern Tier as the lake effect moves south and onshore. A minor coating of slush is possible across the higher terrain inland from Lake Erie. Otherwise, the arrival of colder air aloft will keep highs in the mid to upper 40s in Western NY Monday, with low to mid 50s from the Genesee Valley eastward. Lows Monday night will drop into the mid to upper 30s in most locations, with lower 30s across the interior Southern Tier and Lewis County. It will be quite breezy again Monday and Monday night, especially northeast of Lake Erie where winds may gust to 35 mph. && .SHORT TERM /TUESDAY THROUGH THURSDAY/... A deep upper level trough will linger over the Great Lakes region this period, with several embedded shortwaves rounding this upper level low. Each shortwave will oscillate bands of lake effect rain...that could mix with snow Tuesday night and Wednesday night as 850 hPa temperatures become marginally cool enough for higher terrain snow. Deep synoptic moisture will be found closer to the upper level low, with the more defined bands of precipitation off Lake Erie. The band of lake effect rain could become rather heavy Tuesday over metro Buffalo, with a push northward across Grand Island and into Niagara County. Tuesday night and into Wednesday the axis of the upper level low will swing across our region. This will push precipitation farther inland. This moisture increasing over Lake Ontario will also promote an increase in lake response, with lake effect precipitation becoming favored east of this lake Wednesday night and Thursday. The wind flow here will favor the northern Tug Hill, Watertown and through the Saint Lawrence Valley. Temperatures will be below normal this period, especially daytime highs which will be some 10 to 15 degrees below normal. && .LONG TERM /THURSDAY NIGHT THROUGH SATURDAY/... High pressure will build across the mid-Atlantic states Thursday, as the deep trough across the Northeastern states begins to lift off to the north. A few lingering showers are possible Thursday night, with Friday and Saturday expected to be mainly dry and a bit warmer. By Saturday, highs will range from the upper 50s to mid 60s. && .AVIATION /18Z SUNDAY THROUGH FRIDAY/... Areas of mid level clouds will continue this afternoon through this evening with VFR prevailing. A cold front will then move into Western NY late tonight, and cross the remainder of the region Monday. The cold front will bring a few showers by late tonight across Western NY, which will become enhanced by Lake Erie. Expect areas of MVFR CIGS to develop over and east/northeast of Lake Erie late tonight and Monday morning. The cold front will move to the eastern Lake Ontario region later Monday morning through the afternoon, with a period of showers and MVFR CIGS. Meanwhile from the Genesee Valley westward, the showers associated with the cold front will largely end. Lake effect rain will develop over and northeast of Lake Erie with locally heavy rain developing. This band will likely focus just northwest of KBUF most of the time, but may impact KIAG more directly. Outlook... Monday night through Tuesday...Scattered rain showers along with areas of lake effect rain/MVFR from KIAG-KBUF and mainly northwest of KART. The rain will mix with wet snow across the higher terrain both Monday and Tuesday nights. Wednesday and Thursday...Scattered to numerous rain showers along with areas of lake effect rain/MVFR east and northeast of the lakes. The rain will again mix with wet snow across the higher terrain Wednesday night. Friday...Mainly VFR. && .MARINE... Moderate southerlies will bring Small Craft Advisory conditions to Lake Erie for the rest of the afternoon. Winds will then temporarily drop off this evening. A deep trough will become established across the Great Lakes Monday and last through much of the week, with persistent low pressure spinning across the province of Ontario. This will set the stage for an extended period of strong winds on the lower Great Lakes. Small Craft Advisory conditions will develop Monday morning, and then last through Thursday night or Friday. Waterspouts are possible this week, although it may be too windy at times. Waterspouts are most common in and near bands of lake effect clouds when sustained winds are under about 25 knots. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...None. MARINE...Small Craft Advisory until 6 PM EDT this evening for LEZ020- 040-041. && $$ SYNOPSIS...Hitchcock NEAR TERM...Hitchcock SHORT TERM...Thomas LONG TERM...Apffel/Thomas AVIATION...Hitchcock MARINE...Hitchcock