LAKE EFFECT STORM BLACKFOOT
Thurs-Fri. December 16-17, 1999
After an unusually long absence of wintry weather...enough cold air swept into the region to ignite the Lake effect machine. Both Lakes produced some significant amounts, with totals exceeding a foot in a few spots. This storm was as close to a “typical” event in location and coverage as you will ever see...with heaviest amounts in higher elevations of ski country south of Buffalo...and over the Tug Hill east of Lake Ontario. Little or no snow fell from Buffalo northward or along the NY-Pennsylvania border. And...the amounts were very elevation oriented...with much of the snow melting along the Lake Erie shore of Chautauqua county while inland elevated areas had much more accumulation.
The activity began during the morning of the 16th off Lake Erie as colder air swept in behind a storm system pulling away over James Bay. The Lake temp was still near 45 (7c)...and 850 temps dropped to -6 by 12z...creating marginal instability. Other ingredients were present: deep low and mid level moisture, lack of wind shear, and an approaching vort max. But...surface temps were very mild and the activity began as rain or a mix of rain and snow. The precipitation initially was cellular and oriented on a 230 flow across the Niagara Peninsula but gradually settled southward and developed into a single or band over the north side of Buffalo by 10 Am. Some thunder was reported at this time. This band then dropped fairly rapidly across the metro area...limiting accumulations to an inch or so...before slowing down and settling over southern Erie...Wyoming...and the northern portions of Chautauqua and Cattaraugus counties late in the afternoon and evening. Snow fell heavily at times within this area...and even extended east at times into Livingston and Ontario counties. The area weakened later in the evening as the inversion began lowering and drifted north...almost to Buffalo again...before shearing off to the east and south again Friday morning and dying off by Friday afternoon with low inversion and lighter surface winds.
Snowfall totals were close to a foot in a strip from the Chautauqua-Cattaraugus-Erie county border...across extreme southern Erie and into southern Wyoming Counties. Perrysburg had 14", Springville 11", Warsaw, Colden, and Wales 10". About 6" fell near the lakeshore in Fredonia...3-6" also fell eastward across much of Livingston county with 2-4" in the Bristol Hills of southern Ontario county. Amounts dropped off quickly toward Buffalo with 4-6" in Orchard Park...2" in Lancaster...and about an inch in Buffalo. There also was a sharp cutoff to the south...with less than 2" in Jamestown...Salamanca and Wellsville.
Off Lake Ontario...activity began later...and was disorganized during Thursday afternoon with some locally heavy rain./..sleet...and snow showers. Lake bands became better organized overnight...dropping a few inches on the Tug Hill...weakened toward morning...then really intensified on a westerly fetch during Friday morning with 1-2" per hour over the Tug Hill. The activity began weakening and drifting north Friday afternoon. Snowfall totals were more limited here...with Montague catching 17", Highmarket about 10-12", but less than 6" at Lowville and only a couple inches over most of Oswego and Jefferson counties.
As for forecast guidance...the MM5 did fairly well with the timing and placement...although the Erie band moved across Buffalo much faster than the model indicated...limiting time to an hour instead of 3 to 5...this affected accumulations here. The main band did not drop as far south as model indicated either. Overall though...except for the Buffalo area...the forecasts were quite good. We mentioned potential of this event 3-5 days ahead (and nailed it within 6 hours in a 5 day forecast); had timely Outlooks and Watches...and did verify all warnings.
Flake Rating - ***