Thursday, December 15, 2005

White Christmas? Be careful with early predictions

In a follow-up of the last posting, Lake Mendota didn't actually freeze on the 8th as had been suggested. Apparently the very warm fall did have enough effect. I believe the lake froze over during the early morning of last Monday the 12th, which puts it later than in 2000, but I haven't seen confirmation on exactly what day it froze.
Onto the new topic, Madison has received ample snowfall so far this December, 14.4 inches so far, way more than any other time in the last ten Decembers except for the extremely snowy December of 2000. This caused the Wisconsin State Journal a couple of days ago to write a story speculating about how a white Christmas appears very likely this year. They asked NBC-15 meteorologist David George if he thought we would have a white Christmas, and he said that it appeared almost certain.
In Madison we received a heavy, wet, 4.5 inches of snow yesterday (12/14) that packed down on top of the snow already on the ground to give a snow depth of 8 inches. With the cold weather so far this month, it would seem that 8 inches would be easily sufficient to last until Christmas, just ten days away.
But......model runs have been hinting at a strong warmup just before Christmas for the last few days. Today, that trend has continued and become more pronounced. Long-range forecasts should always be taken with a grain of salt, but it now looks possible that we could have temperatures near 50 from the 22nd through the 25th. If so, our chances of a white Christmas would be seriously jeopardized. If all of the snow were to melt fairly early in that period, it's possible that we could have record highs on Christmas in the mid to upper 50s.

Wednesday, December 07, 2005

Lake Mendota will likely freeze tonight

If Lake Mendota freezes tonight, it would be the earliest freeze in 28 years, since the winter of 1977-1978, even more remarkable after the significantly above normal summer and fall in Madison. While unusually early by recent standards, it would only put this year in a four-way tie for 19th earliest freeze since records have been taken in 1853. It’s likely that the urbanization of the area around Lake Mendota has accounted for some of the delay of average ice-in date, but it’s questionable how much (negligible, 1 day, 1 week?).

Lake Mendota Earliest Freeze Dates

1.) Nov. 23, 1880-1881
2.) Nov. 25, 1857-1858
3.) Nov. 29, 1873-1874
4.) Nov. 30, 1872-1873
5.) Dec. 2, 1861-1862
5.) Dec. 2, 1869-1870
7.) Dec. 3, 1929-1930
8.) Dec. 3, 1976-1977
9.) Dec. 4, 1893-1894
10.) Dec. 5, 1886-1887
11.) Dec. 6, 1856-1857
11.) Dec. 6, 1926-1927
13.) Dec. 7, 1859-1860
13.) Dec. 7, 1936-1937
13.) Dec. 7, 1937-1938
13.) Dec. 7, 1942-1943
13.) Dec. 7, 1972-1973
13.) Dec. 7, 1977-1978
19.) Dec. 8, 1858-1859
19.) Dec. 8, 1864-1865
19.) Dec. 8, 1876-1877
19.) Dec. 8, 2005-2006?

Records are from the UW-Madison Limnology Department, http://lter.limnology.wisc.edu/mendota_ice.htm#recent