951 FXUS61 KBUF 022023 AFDBUF Area Forecast Discussion National Weather Service Buffalo NY 323 PM EST Tue Feb 2 2021 .SYNOPSIS... A strong low will move slowly northward along the east coast through tonight, reaching the Canadian Maritimes Wednesday. Accumulating snow will spread westward and back into most of the region into tonight, with the greatest accumulations across Central NY and the western Finger Lakes. The snow will end from west to east later tonight and Wednesday as high pressure builds into the eastern Great Lakes. A brief warming trend will arrive Thursday and early Friday before much colder air moves back into the region for the weekend. && .NEAR TERM /THROUGH WEDNESDAY/... Radar update at 145 PM shows widespread moderate snow from the St. Lawrence River valley across the North Country and across much of central NY. Light to moderate snow is as far west as Niagara county. Two main concerns remain into this evening. First issue at hand is problematic strong mesoscale band that keeps forming off and on across North Country on west edge of mid-upper low which is currently vcnty of New York City. Models not handling it well and per radar algorithm and reports from the earlier iteration of this band, it is likely producing snowfall rates of 1-2 inches per hour. Based on radar trends seems like this will break down in the next two hours, but am very uncertain given how the models, even the HRRR, are not handling it well. This heavy snow that has already occurred along with additional snow overnight tonight as another wave of moderate to heavy snow works in from northern New England has led to upgrading Lewis and Jefferson counties to winter storm warning. That warning will run through 15z on Wed. Second issue is from mid afternoon through early evening concerning a period of heavy snow for especially Monroe, Wayne and Ontario counties. This would include Rochester Metro and specifically the commute home this afternoon. All high-res models very insistent on backing swath of moderate to heavy snow over North Country and also eastern Lake Ontario over this area during this time. Based on above comments though, probably should have at least some caution in that idea if the stronger band persists east of Lake Ontario. If this heavier snow moves in though, snowfall rates 1-2 inches per hour would be likely which will result in a very rough commute in the Rochester area. Already started messaging this potential with SPS and on social media for now. We probably will fall just short of warning criteria (7"/12 hours), but wanted to have additional messaging out in addition to the going advisory in place. Appears period of moderate to heavy snow for these areas will last through around 7-8 PM before starting to taper off by late evening. Otherwise, light snow with pockets of moderate snow is expanding across rest of western NY with steadiest snow across northern reaches of the Niagara Frontier. Expect the mainly light snow to linger through late evening before diminishing after midnight as primary shortwave rotating around upper low slides off to the southeast. Rising heights aloft and limited cold air behind the system will lead to improvement from west to east on Wednesday. Snow will persist the longest in the upslope higher terrain areas southeast and east of Lake Ontario. Most additional snow late Wednesday morning through Wednesday afternoon will be light. From west to east here at expected *additional* snow accumulations late this afternoon through Wednesday morning: western NY less than 2 inches, Genesee Valley including Rochester Metro 4-6 inches, northern Finger Lakes into Oswego county 4-6 inches (most over Wayne/Ontario counties) and east of Lake Ontario another 4 to 6 inches. && .SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/... Low pressure will finally exit across the Canadian Maritimes Wednesday night, meanwhile ridging at the surface and aloft will build across the Ohio Valley and eventually nudge into Western New York. There may be a few lingering snow showers east of Rochester Wednesday evening, but after this the high pressure ridge will crest across the region and provide dry weather through Thursday. Low temperatures Wednesday night will generally be in the teens, but single digits are possible across the Southern Tier if the high builds in a bit more quickly. Expect warmer weather Thursday with some breaks of sunshine allowing temperatures to climb well into the 30s. A vertically stacked 976 mb surface low will track across Michigan Thursday night before moving north of the Great Lakes on Friday. This will force a series of frontal boundaries across our area. The initial will be a warm front with associated mid-level warm air advection supporting a round of fairly steady precipitation which will enter Western New York late Thursday night. This will quickly be followed by a cold (or occluded) front which will move from west to east across the area on Friday. Forecast thermal profiles are marginal, suggesting mainly rain across the lake plains where a southerly flow will result in downslope warming. A bit more tricky across the Western Southern Tier and east of Lake Ontario where it will be cold enough to support snow for much of the time. Could see a few inches accumulation, but likely sub-advisory amounts. Some mixed precipitation, such as freezing rain or sleet, cannot be ruled out but suspect increasing winds should help scour out the cold air at the surface resulting in non-diurnal temperature trends Thursday night. Warmest temperatures will be just ahead of the 2nd front Friday morning, then expect temperatures will quickly drop below freezing Friday afternoon behind the front. Expect most of Western New York to remain dry behind the front, with the exception of northeast of Lake Erie where some lake effect snow showers may begin to develop. This system has the potential to produce a period of gusty winds just behind the cold/occluded front Friday, especially northeast of the lakes. How strong the winds are depends on the track of the surface low, which is forecast to move due north of Michigan, keeping it further away from the area. However, would not be surprised to see a few hours with advisory level gusts to 50 mph across the Niagara Frontier on Friday. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... ...COLD WEATHER AND SIGNIFICANT LAKE EFFECT SNOWS POSSIBLE INTO NEXT WEEK... Low pressure will weaken as it gradually gets absorbed by longwave trough across Canada. 850 mb temperatures will drop to around -16c behind the front Friday night resulting in lake induced instability. Meanwhile shortwave will provide ample moisture to support a period of moderate to heavy lake effect snow northeast of the lakes Friday night. This shortwave will exit into New England Saturday, with lake snow expected to taper off Saturday afternoon and evening. This has the potential produce several inches of snow or more, with advisory or even warning amounts possible. Time will be a limiting factor since the moisture provided by the shortwave will be temporary. Slightly warmer air aloft, diminishing synoptic moisture, and increasing shear will cause lake effect snows to diminish Saturday night. The core of arctic air will drop across Western Ontario province on Sunday. As its associated trough axis dives across the Great Lakes, a surface low will pass to our south, with some model disagreement on its track and strength. This could bring a light general snow on Sunday, but in its wake it definitely will be colder heading into next week. GFS/GGEM both drop 850mb temperatures to around -25c, with the 'warmer' ECMWF down to around -20c. This supports highs in the teens for Monday and Tuesday, and even that may be optimistic in some areas if the colder guidance verifies. Bitterly cold wind chills can also be expected. In addition to the cold, this will establish a pattern favorable for lake effect snow. Wind direction and moisture will be key, and its too far out to pin down the details. In general, a prevailing WSW flow will place the traditional snow belts east of the lakes at the greatest risk. However, bands will meander, with the potential to impact the cities of Buffalo and Watertown at times. The WSW flow will diminish the risk for heavy snow for counties immediately south of Lake Ontario, including the Rochester area. && .AVIATION /21Z TUESDAY THROUGH SUNDAY/... Snow is spreading from east to west across the region this afternoon as the circulation around a mature east coast low expands. The moderate snow has reached the lower Genesee Valley, and will continue to spread slowly southwestward rest of afternoon. IFR VSBY and MVFR CIGS will become widespread across most of the region as the snow expands. IFR CIGS will be found across the higher terrain today. The heaviest snow and lowest VSBY is expected to focus from KROC eastward to the eastern Lake Ontario region. There will be a few periods of 1/4SM heavy snow at KROC (20-24z), but most of the time VSBY will stay above airfield minimums. The snow will reach its westernmost extent late this afternoon, reaching KBUF, KIAG, and KJHW for at least a few hours. The snow will then taper off from west to east tonight as the coastal low continues to move northeast towards the Canadian Maritimes. Expect a gradual improvement from IFR VSBY to VFR VSBY from west to east tonight. Areas of MVFR CIGS will linger overnight after the snow ends. Outlook... Wednesday...Light snow east of Lake Ontario with MVFR/IFR VSBY at times. Otherwise areas of MVFR CIGS. Thursday...VFR. Thursday night and Friday...Mainly MVFR. Rain and snow showers likely. Saturday...IFR possible in lake effect snow northeast of Lakes Erie and Ontario. && .MARINE... High pressure will remain anchored from James Bay to central and northern Quebec through Wednesday. To our east, a deep east coast low will move slowly northward just offshore of New England through tonight, reaching the Canadian Maritimes Wednesday. Moderate northeast winds will continue to back to the north this afternoon, and northwest tonight and Wednesday as the coastal low moves slowly northward. This will maintain Small Craft Advisory conditions on Lake Ontario through Wednesday night. Winds are somewhat lower on Lake Erie, but will still be strong enough to produce Small Craft Advisory conditions through late tonight. High pressure will build into the eastern Great Lakes Thursday with diminishing winds. Next period of stronger winds occurs Friday into Friday night with southwest gales looking likely on Lake Erie and a return to Small Craft Advisory conditions for the rest of the waters. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...Winter Storm Warning until 10 AM EST Wednesday for NYZ007-008. Winter Weather Advisory until 10 AM EST Wednesday for NYZ006. Winter Weather Advisory until 7 AM EST Wednesday for NYZ004- 005-014. Winter Weather Advisory until 4 AM EST Wednesday for NYZ003- 013. MARINE...Small Craft Advisory until 7 AM EST Wednesday for LEZ040-041. Small Craft Advisory until 7 AM EST Wednesday for LOZ030. Small Craft Advisory until 7 AM EST Thursday for LOZ042>044. Small Craft Advisory until 10 PM EST Wednesday for LOZ045. && $$ SYNOPSIS...Hitchcock NEAR TERM...JLA SHORT TERM...Apffel LONG TERM...Apffel AVIATION...Hitchcock/JLA MARINE...Hitchcock/JLA