Lake Effect Summary - December 3-5, 2007
Maximum Snowfall: Lake Erie 15"
(Warsaw); Lake Ontario 21" (Constantia)
Duration: 48 hours +/-
Feature: Unusually strong northwest flow event.
Rare lake effect totals across Finger Lakes and Allegany basin. Major Rochester and Syracuse event.
The first true arctic airmass of the season swept into western and central New York on the heels of a major synoptic storm during the first
few days of December. The synoptic event dropped 3 to 5 inches of snow across most of the area early on the 2nd, and was followed by a
drenching rain from about Rochester westward overnight on 2-3rd. This melted nearly all of the newly fallen snow. Areas to the
held held onto freezing rain overnight.
A strong west to northwest flow followed the storm early on the 3rd and changed to rain to snow from west to east between 6 am and
noon. The snow…upslope at first, then increasingly lake enhanced, was heavy at times across higher elevations south of Buffalo during the
afternoon and evening of Monday 3rd where several inches fell. Very strong northwest winds brought intense streamers in from Lake
Huron and they crossed Lake Erie and weren't even wrung out as they usually are by the Chautauqua ridge. Rather, they extended well down into
Pennsylvania. This process continued into Tuesday before weakening.
Over on Lake Ontario, the upslope snow evolved into many multiple band streamers by late Monday which continued through most of Tuesday. In
addition, some wraparound moisture from the departing coastal storm swung across Lake Ontario into the Genesee Valley and Finger Lakes too.
This resulted in unusually heavy accumulations well inland, over places which usually avoid much lake effect, like the mid Genesee Valley
and Finger Lakes. Snowfall was heavier inland than near the lakes due to the fast wind speeds.
The activity wound down late Tuesday (4th) as the inversion lowered, but lighter winds focused one last pure lake effect area from
Niagara to Wayne counties on Tuesday evening, dropping another 2 to 4 inches before weakening further after midnight. Finally, as a clipper
approached the Ohio Valley from the northwest, winds turned northerly and "tea kettle" snow developed along the Lake Erie shore of Chautauqua
county during the predawn hours Wednesday morning and dropped a few inches down toward Erie. Strong ridging and shear squashed any organized
activity Wednesday as a clipper passed well to our south,giving areas from the Ohio Valley to Maryland some decent snows.
Again, the most impressive feature about this event were the unusually heavy accumulations so far away from the Lakes. Places like Avon,
Olean and Geneva caught their heaviest lake effect totals in many years. The event was not totally lake effect, as it could be argued that
much of the snowfall was upslope and wraparound induced, but substantially enhanced by the lakes.
The event was an impressive northwest flow event with unusually large extent. It affected a large population including the Rochester and
Syracuse metro areas. It therefore earns three *** stars.
Off of Lake Erie...
Off of Lake Ontario...
||6 - 14 inches
||10 - 15 inches