LAKE EFFECT STORM November 17-20, 2022 Maximum Snowfall: Lk. Erie 81.2" (Hamburg); 76.0" (Blasdell 3 SSW) Lk. Ontario 49" (W. Carthage 0.3 ENE; 38" (Croghan 6.2 N) Duration: 60 hours +/- Flake Scale: 5 flakes ***** The first significant lake effect snowstorm of the 2022-23 season was an epic event with snowfall accumulations exceeding six feet off Lake Erie and over four feet off Lake Ontario. Snowfall rates as high as 6 inches per hour contributed to the closing of interstate travel, while the magnitude of the prolonged event led to numerous local and state emergency declarations. After measureable snowfall fell in the area Wednesday into Thursday morning (Nov 16-17), the first substantial lake snows developed Thursday afternoon in the wake of an exiting surface low over the St Lawrence valley. This was a 'primary' low weakening in the midst of a Miller B cyclogenetic event that led to a deep storm over the Canadian Maritimes. Cold air wrapping around the backside of this complex system initially led to disorganized lake snow Thursday afternoon that was largely mixed with rain. This kept daylight hour snow accumulations to a minimum and generally restricted to the higher terrain. After nightfall, the lake snows off Lake Erie quickly organized into a well-defined plume within a 250-260 flow as H85 temps lowered to -9c. Moderate to heavy snow with rates of 1 to as much as 2"/hr fell from Dunkirk across southern Erie county into Wyoming county for much of Thursday night. As is typically the case with a stronger early season lake snow event, the deeper mixed phase layer (>5kft) supported thundersnow within 15 miles or so of the lake. Backing winds ahead of a meso-low then pushed a band of heavy snow northwards to the Buffalo area before the heaviest snow settled to the southern suburbs. Many areas picked up a foot of snow by daybreak, quickly verifying the lake snow warning in place. Off Lake Ontario, a band of heavy snow over Oswego county Thursday evening pushed north to Watertown overnight. While the band was generating snowfall rates over an inch per hour, its transitory nature helped to limit snowfall accumulations. As with the Lake Erie activity, occasional thundersnow was found within the well-organized band between 02-06z. On Friday, Nov 18, a persistent 250 steering flow positioned a stationary band of heavy lake snow over central and southern Erie County. The immediate southern suburbs of Buffalo were targeted with the heaviest snowfall, as a cap in the vicinity of 20kft promoted snowfall rates of 4-6"/hr. The higher snowfall rates were often accompanied by rumbles of thunder. While travel restrictions were already in place for the New York state Thruway, the intensity of the snowfall eventually led to the closure of the New York state Thruway south of Buffalo and even led to decision to relocate Sundays NFL game in Orchard Park. Meanwhile, a 250 flow off Lake Ontario supported a 25 mile wide band of moderate to heavy lake snow that was centered over central Jefferson County and extended across northern Lewis County. This band brought over a foot of snow to the Watertown area with snowfall rates occasionally reaching 3"/hr. Again, thundersnow within the heart of the band was not uncommon. Another shortwave approached the Lower Great Lakes Friday evening. During the course of the night, the well-defined band of moderate to heavy lake snow that extended from the Chautauqua county lakeshore across southern Erie County to Wyoming steadily marched north, passing through the Buffalo metro area after midnight with a burst of snow that deposited in excess of a foot of accumulation in this period alone! A very similar scenario unfolded east of Lake Ontario, however that band was somewhat more cellular and disorganized. Fresh nighttime accumulations across Jefferson and northern Lewis County were closer to six inches. On Saturday, the steering flow had backed to 220-230 degrees over both lakes. The impressive Lake Erie snow band over the Buffalo area early in the morning pushed to the north across Niagara County and even spent several hours being centered over the Niagara Peninsula. This gave a much needed break to Buffalo and its immediate southern suburbs, while nearly a foot of snow fell over areas to the north that had seen little to no real accumulation up to this point. Meanwhile, the Lake Ontario snow band made its way north of Watertown, spending most of Sunday over the Thousand Islands region and Kingston, Ontario. Late Saturday evening, the Lake Erie band over the Lower IAG River began to push south as a reinforcing cold front approached from the northwest. The band pushed through the BUF metro area with snowfall rates of 3-5 inches an hour, enhanced by the synoptic forcing of the cold frontal boundary. Many areas picked up another half foot to 10 inches of snow. By late Saturday night, the band had re-oriented itself over the Southern Tier. The band remained strong on a 260-270 flow until after daybreak when some stripping away of the mid-level environmental moisture and 280-290 flow encouraged the activity to become much more cellular and disorganized for Sunday. As the cap lowered below 8kft Sunday night, the lake snows off Lake Erie finally tapered off to scattered nuisance snow showers and flurries. The band over the Thousand Islands acted very much the same. It was positioned well north of Watertown Saturday evening then slowly dropped south during the course of the night. It generated 2-4 inch/hour snowfall rates as it made its way to the Tug Hill by daybreak. The band continued south where it impacted Oswego County with another six inches or so of accumulation on Sunday. The long duration of this event, combined with average snowfall rates of 1 to 3 inches per hour (as high as 6"/hr), resulted in a high impact event. The New York state Thruway (I-90) from Rochester to the Pennsylvania line was shut down for a period, and there were numerous local and state emergency declarations. The NFL and local officials even decided to relocate a Buffalo Bills game to Detroit. While these significant impacts were experienced in both the Buffalo and Watertown metropolitan areas, they may have been somewhat minimized by the lead time and accuracy of the headlines and by the event extending through a weekend period. This event was clearly a Five ***** star event. Here are some one and two day snowfall records that were set. 2 Day Event ... Erie County: 58.2" 2.7 mi WSW Elma (11/20/22) 1 Day Event ... Genesee County: 28.3" 2.5 mi SE Alden (Darien) (11/19/2022) 2 Day Event ... Genesee County: 46.6" 2.5 mi SE Alden (Darien) (11/19/2022)