Winter Season Summary 2011 - 2012

The 2011-12 winter will long be remembered for warmth and lack of snow, and in some locations near record setting snowfall departures. The winter was very mild and the November through March timeframe consistently had well above normal temperatures. Cold blasts were few and short lived and the snow that did fall quickly melted. Many areas were green for much of the winter as widespread synoptic snows were also few and light.

Snowfall

Much of the country east of the Rockies this winter fell short of their seasonal snowfall normal. This was true across the Eastern Great Lakes region as well, with many areas less than 50 percent of their typical winter snowfall totals.

The lake effect season again was off to a slow start. The first event occurred in mid November, and only two events through December.

For the winter season, there were eight lake effect "events" which is two fewer than average. The most impressive lake effect event occurred at the end of January when a localized area south and east of Lake Ontario received impressive two-feet plus of snow in a relatively short period of time. For our major metropolitan areas, Rochester had a significant lake effect snowstorm of a foot, which was its first in several years of this magnitude. Fortunately it fell at the most opportune time, the weekend, with minimal impact on the city.

Heaviest snowfall was over Oswego and the Tug Hill where 100+ inches of snow fell, mainly on frequent light to moderate lake effect snow events. Across Western New York, a few higher elevations of the Chautauqua ridge and hills of Wyoming County also reached the 100 inch mark with all other locations well below normal.

Seasonal snowfall at the two primary climate locations of Buffalo and Rochester were well below normal. Lack of snow combined with the above normal warmth greatly limited the duration of snow through the winter with the longest stretch of one inch or more of snow on the ground in Buffalo being 5 days, and 6 days for Rochester.

Temperatures

Temperatures in November through March remained 5.0 F or greater all five months for both Buffalo and Rochester. This was the warmest November through March timeframe in the recorded history for both Buffalo and Rochester. With the persistent warmth the amount of days the temperature remained below freezing was abnormally low with only 17 such days in Buffalo and 19 days in Rochester; and of these days, only 4 were found to be consecutive. The warmest March in history closed out the epic winter season.

Hemispheric Pattern

The Winter of 2011-12 proved to be historically mild and relatively snow free across Western and North Central New York. Some of the main contributors to this were an abnormally deep and persistent Icelandic Low and a strong Azores High that encouraged a fast zonal upper level flow across Eastern North America and the North Atlantic. This stronger than normal zonal flow kept Arctic air bottled up over the high latitudes while flooding much of the lower 48 with mild Pacific air. Normally, the jet stream over North America exhibits a higher amplitude. The corresponding meridional component to the jet stream this past winter was very weak.

While Icelandic Low's are quite common during the winter months, they periodically give way to persistent areas of high pressure. These high pressure systems are associated with ridging that extends from the North Atlantic poleward across Greenland. These 'Greenland blocks' can persist for weeks at a time and act as a barrier to the upper level flow exiting North America. The blocking pattern enables closed lows to develop over Eastern Canada, which in turn encourages intrusions of Arctic air over the Great Lakes region. This is often referred to as the negative phase of the North Atlantic Oscillation (NAO).

During this past winter, a Greenland block was virtually non-existent as low pressure was very persistent in the vicinity of Iceland. In fact, the strength and persistence of the resulting positive NAO had not been witnessed since the winter of 1999-2000 when we experienced one of our top 30 'warmest' winters (out of more than 140 winters). That particular winter was also one that featured relatively little snow.
 
While our winters are often correlated to what is happening over the Equatorial Pacific (El Nino / La Nina), this is past winter was just more evidence that the Great Lakes region is heavily influenced by the strength and phase of the North Atlantic Oscillation.

Here are some statistics for Buffalo N.Y.

Snowfall: 36.7 inches (Normal 94.7)
Greatest Daily Snowfall: 6.4 inches on Jan 13, 2012
Days with 1" or greater Snowfall 8 (Normal 26 Days)
Days with 1" or greater Snow cover 22 (Normal is 71 Days)

Rankings

Least Snow (since 1884)

1 1889-90 22.4
2 1918-19 25.0
3 2011-12 36.7
4 1921-22 39.8
5 1948-49 40.1

Days with 1" or Greater Snowfall (since 1884)

1 2011-12 8
2 1889-90 8
3 1934-35 10
4 1918-19 11
....
8 1948-49 12 (tie)

Days with 1" or Greater Snow Cover (since 1893)

1 2011-12 22
2 1918-19 29
3 1948-49 31
4 1921-22 32

Days Freezing or Below (since 1871)

1 2011-12 17
2 1931-32 27
3 1881-82 29

Here are some statistics for Rochester N.Y.

Snowfall: 59.9 inches (Normal 99.5)
Greatest Daily Snowfall: 10.3 inches on Jan 12, 2012
Days with 1" or greater Snowfall 18 (Normal 25 Days)
Days with 1" or greater Snow cover 29 (Normal is 76 Days)

Rankings

Least Snow (since 1884)

1 1932-33 29.2
2 1918-19 36.0
3 1952-53 41.7
....
19 1982-83 59.9
2011-12 59.9 (tie)

Days with 1" or Greater Snowfall (since 1910)

1 1932-33 11
2 1918-19 12
3 1920-21 12
4 1943-44 12
....
9 2011-12 18 (tie)
1939-40 18

Days with 1" or Greater Snow Cover (since 1893)

1 2011-12 29
2 1932-33 35
3 2001-02 38
4 1952-53 39

Days Freezing or Below (since 1871)

1 2011-12 19
2 2001-02 25
3 1932-33 28

November 2011

While the month was tranquil on average, there were a few notable weather events in Western New York in November. On the 14th there were two EF2 tornadoes in the Chautauqua County towns of Westfield and Fredonia. These are the first two tornadoes on record in Western New York in the month of November going back at least 50 years. There were also two lake effect snow events, one November 11th and another on the 17th (Ayrshire) across Ski Country and the Southern Tier well south of Buffalo. In both cases temperatures quickly warmed to melt the snow a day or two later.

December 2011

December 2011 will be long remembered for the incredible lack of winter weather. Temperatures were well above average with only a handful of days cold enough to support lake effect snow. There was practically no snow for the month, and the ground remained green for many areas for the month. This was a continuation of similar conditions in November, making this fall and early winter through December 31st one of the least snowy starts to winter on record. Snowfall was woefully low throughout Western and Central New York, even in the normally snowy lake effect snowbelt locations of the Southern Tier.

January 2012

This was the first month that actually resembled winter in terms of snowfall. Temporary surges of arctic air did bring more significant lake effect snows to the Southern Tier and to the ski resorts. West and northwest flow brought several lake effect snow events to areas south and east of Lake Ontario with many areas having their greatest monthly snowfall totals this month. There were three named lake effect events this month. Unfortunately, a significant warm up late in the month helped to erode a lot of the snowpack.

February 2012

Winter continued its sparse appearance this month. Several lake effect events occurred in February, including one on a northwest flow in mid February that brought over a foot of snow to the Rochester metropolitan area, the largest snowfall event in Rochester for the year. Greatest snow totals for the month were found south of the Lake Ontario shoreline and the mid month lake effect event aided in Rochester finishing with above normal snowfall for the month. Another late month lake effect snow event with upstream connections to Georgian Bay and Lake Huron brought a foot of snow to the Ski country regions of Western New York.

March 2012

March will be remembered for the incredible and long duration warmth through the month. Temperatures well above normal were not conducive for lake effect snow, and synoptic storms were few and minor. Areas outside the eastern Lake Ontario region finished with less than a half a foot of snow, which is well below normal while parts of the Tug Hill were able to reach the one foot mark.

April 2012

It looked like most of the region would finish April with no accumulating snow, however a late season storm moved across the eastern Great Lakes with snow falling across the region the third week of the month. This was an elevation driven event with up to 6 inches falling on the Tug Hill, while parts of the southern tier reached over 12 inches of snow. Snow even accumulated at lower elevations of metro Buffalo, Rochester and Watertown. However the strong late April sun angle quickly melted the snow.