Lake Effect Storm Copperhead November 20-23, 2008
Maximum Snowfall: Lake Erie 18"
(Mayville); Lake Ontario 14" (West Monroe)
Duration: 72 hours +/-
Prime Feature: Marginal multi-faceted event.
After a quick passage of a synoptic "clipper", the lake effect machine got into high gear once again on Thursday (20th) as a west to
northwest flow set up off Lake Erie and brought narrow streamers of heavy snow into Chautauqua county. Several inches fell during the
afternoon. Meanwhile, a weak secondary front/wind shift dropped south across New York and set up from near Erie PA across the Commonwealth
all the way to near Philly. A band of heavy snow set up along this convergence line, fed at its western end by Lake Erie. This band dropped
just to the south of Chautauqua County during the evening, after 6 to 8 inch totals. Then, winds turned northerly and even NNE and another
band set up on a NNE-SSW trajectory from Dunkirk to Ripley which became heavy overnight and early Friday morning as winds backed to north
and NNW, impinging on the ridge. 6 to 12 inches fell during this phase along the lakeshore.
The flow turned strong northwest later Friday and remained so through Saturday. This flow was unusually cold for November but very dry, so
multiple bands formed off Lake Ontario on a 320 flow and continued for 36 to 48 hours. Snowfall was generally 3-6 inches in any 12 hour
period, with two day totals maxing out around a foot from eastern Wayne to western Oswego counties. Further west, a strong single plume
from Lake Huron meandered across Chautauqua county through Saturday with rates of an inch per hour, but it was very narrow and did not stay
in one place too long, so additional accumulations at any one spot did not exceed 6 or 8 inches. The band drifted into far western Cattaraugus
county at times.
Winds backed and cap crashed with warm advection ending the activity off Erie by Sunday morning and Sunday afternoon off Ontario with the
last of the flurries Sunday night up by Watertown.
Total snowfall for the entire event exceeded a foot over most of Chautauqua county but little to the north and east. 8 to 14 inches fell for
the period from Wayne to Oswego counties but little over the Tug as flow was too NNW. Several inches fell west through the Rochester area
with 1 to 3 inches back to northern and eastern suburbs of Buffalo during a few minor NNW "Niagara River" streamers. In fact, with the very
cold air and 330 flow, there may be some influence from the huge heat island of Toronto? The narrow bands seem to initiate directly downwind
of Toronto near the mouth of the Niagara River and drift sown into Buf's north and east suburbs, enhancing on the upslope and dropping an
inch or two. We see this several times each winter on a cold 330 flow.
The event was spread out and relatively modest in overall snow amounts. It therefore earns two ** stars.
Off of Lake Erie...
Off of Lake Ontario...