LAKE EFFECT STORM
November 20-23, 2000
Flake scale: *****
Maximum Snowfall: Lk.Erie: (Stockton) 31" ; Lk. Ont: (Parish ) 28".
Duration: 60 Hours
Prime Feature: Extreme intensity over Buffalo, frequent lightning. Timing was crippling.
Lake Effect Storm "Chestnut" was a powerful, intense storm which crippled much of the Buffalo metro area. The storm was most intense on the first day when winds were southwest...but also remained quite potent on 21st and even 22nd as winds veered around to west and northwest. It was the most widespread and significant November lake effect storm since 1996 when a long lasting storm dropped over 3 feet over Chautauqua county.
The event began around midday on Monday Nov. 20th . A cold front approached the region with a few snow showers...which blossomed into heavy "thunder snowpellet showers" with winds on a 220-230 flow during the morning...mainly focusing on areas north and west of Buffalo. But winds veered slightly as this initial front drifted through...and a strong band set up and intensified on a 240 flow across the northern half of the metro area by 2 pm. The band drifted a few miles south...then stalled between 5 and 9 pm. Finally it broke apart as a stronger trof moved through.
Snow fell at the rate of 2-4 inches per hour for several hours within this band...and it focused on the most densely populated area of upstate New York. The timing could not have been worse...from about 1 to 9 pm. Most workers tried to leave work early but by 4 pm the city and nearby Amherst and Cheektowaga were clogged with traffic which came to a standstill. Thousands spent the night in autos or stores and many schoolchildren as well as buses became trapped. It was the most disruptive storm in the Buffalo area since the Blizzard of ‘77.
As for the meteorology...the storm was a classic in all aspects and the most intense we have ever observed. The dynamics were extreme. We had a very deep layer of moist and unstable air for this time of the year. There was no capping subsidence inversion, well aligned winds with little shear...a very warm lake at 10 (C) and an 850mb temperature of -12(C). A compact but strong large scale low pressure system was bearing down on the region from the Upper Great Lakes. Aloft, there was a strong short wave with a 500mb vorticity center of 28 crossing the southern Ontario. From the standpoint of cloud microphysics, there was a large cloud area that had optimum temperatures for dendritic snow crystal growth. As a result of the depth of the unstable layer and the tremendous thermodynamics and favorable microphysics, there was abundant lightning...approx every 5 minutes for 8 hours or more.
Snowfall during this initial phase was as high as 2 feet in a narrow strip about 3 miles wide from downtown Buffalo to north Cheektowaga and south Amherst to Clarence center! Over a foot fell within an area from Kenmore to central Amherst to Akron on the north...and south Buffalo to Lancaster to Alden on the south. In many respects this storm acted more like a wintertime Flash Flood over Buffalo and its adjacent suburbs.
The storm wasn’t over yet though. The coldest November air in many years continued to pour across the lower Lakes for the next few days...keeping the lake machine going in high gear. The flow turned west to northwest on Tuesday (21st) and heavy lake snows continued over Chautauqua and Cattaraugus counties...and even extended unusually far east into Allegany county. Lake snows set up strongly over Oswego county as well and drifted down into the Syracuse area.. The bands then lifted north again on Wednesday ahead of another cold front with several inches into southern Erie county and an intense band lifted across Oswego into Jefferson county later in the day. The flow turned northwest and north after the frontal passage late Wednesday and brought several inches of fluffy snow to the south shore of Lake Ontario...including the Rochester area.. The event finally shut down early on Thanksgiving Day (23rd) as strong subsidence and high pressure crested over the region.
"Chestnut" was a classic and severe lake effect storm. It should be used as a model for future study. Not only for the unusual meteorological aspects...but for the critical timing issue which led to a total paralysis of a metropolitan area of a million people.
It easily ranks as a 5-Star Storm. *****
Lake Erie Snow Spotter Reports
|New Albion||30 inches|
|Jamestown||18 to 22 inches|
|Amherst||8 to 24 inches|
Lake Ontario Snow Spotter Reports
|West Monroe||26 inches|
|North Osceola||24 inches|
|Oswego||12 to 24 inches|
|Watertown||8 to 16 inches|