With even only seasonably cold air arriving, the evolving scenario would be favorable for significant lake effect snowfall to occur to the lee of the eastern Great Lakes, in part because of the exceptionally warm LSTs previously shown. The 24-hour forecast from 00 UTC 24 December 2001 for the same fields previously shown (valid 00 UTC 25 December 2001) can be seen by clicking again on the "Display Graphic" button below.
24-hr fcst valid 00Z 25 Dec 2001 at 500, 700, 850-hPa, SLP and 1000-500
hPa thickness.
We see that there is broad, deep cyclonic flow over the entire Great Lakes area, after the passage of a cold front and a vigorous mid-tropospheric short-wave disturbance. Additionally, these ingredients are present for the production of heavy lee-side lake effect snows:
Before this time, the lake effect snow event downwind from Lake Erie had already begun in earnest. Radar reflectivities (set to clear air mode for better observation of snow) between 08 UTC and 18 UTC on 24 December 2001 can be seen by clicking on the "Display Graphic" button below. Note that as the lake effect event evolved, the band nearest the KBUF radar site showed up best in clear air mode.
Radar from KBUF, 08:06 UTC to 18:08 UTC 12/24/01
In the animation, the location of the Buffalo NY observations is shown in the first animation panel with a white "X". Initially, lake effect snow bands can be seen developing on the north shore of Lake Erie; surface observations indicated snow showers occuring in this area (not shown), with winds generally from about 220-230°. The winds then backed to a 210-220° direction. Through late-morning, the lake effect snow bands gave up to 6" of snow to the Niagara peninsula, Niagara County, NY (including Niagara Falls) and far northern Erie County, NY. The winds then began to veer to 240-250° by early afternoon, a direction favorable for a single heavy lake effect snow band to affect the Buffalo metropolitan area, shortly after the last panel in the radar animation.
Observations over the period from 18 UTC 24 December 2001 through 09 UTC 25 December 2001 can be seen for the Buffalo airport by clicking on the "Display Graphic" button below:
METAR observations from Buffalo NY, 18Z 12/24/01 - 09Z 12/25/01
It can be seen from the observations that the lake effect snow band that earlier was over the Niagara Peninsula moved over the observation point between 18 and 19 UTC. Subsequently, convective clouds could be seen from the site as the single lake effect snow band was intensifying (from observations: moderate cumulus visible in all quadrants between 20 UTC and 21 UTC).
At 21:42 UTC, a burst of moderate snow occurred, and by 23:00, continuous heavy snow was falling as the single lake effect snow band intensified off of Lake Erie. The heavy snow continued past 6:00 UTC 25 December, with 1.99" of water equivalent measured from 23:00 UTC 24 December through 9:00 UTC 25 December, 2001. Snowfall rates were from 2-5" per hour. During the three hours ending 3:00 UTC 25 December, 0.99" of liquid equivalent precipitation and 12" of snow fell!
As the wind continued to veer more to the west, the single lake effect band shifted further south and affected the southern Buffalo suburbs with significant snowfall. Later that morning, the band weakened as it shifted north again with backing winds, dropping an additional 1-3" of snow over Buffalo proper. All told, 25.2" of snow was recorded at Buffalo for the first 24 hours of this event, the third greatest 24-hour total ever recorded. Over most of the Buffalo metropolitan area, however, the snowfalls and water equivalents were on the order of 8-12" and 0.5-1", respectively.