What Goes Into The Snowfall Prediction
November 14, 2011, 10:07 PM
SIOUX FALLS, SD -
The research is done and the number is in. So, how much snow will the Sioux Falls area get this season?
When putting a winter forecast together, there are many things I look at to try to get a handle on how much snow we'll get. A lot of them range from local to global weather patterns. This year is no exception.
While this year started wet and it looked like we were going to mimic another record year for precipitation, the rains slowed down in August and almost completely stopped in September. But not everyone had the rain shut off. Just west of Sioux Falls, heavier rains fell in October. I looked into what the winters brought after a dry September and October, but I also need to be aware of the wet weather just west of the city and how that takes into account.
This autumn, we're flirting with a record-dry fall. Of the top 10 driest autumns on record, Sioux Falls has averaged 33.9". The highest total was in 1955 and 1956 with 60.5 inches. The lowest was 1967 and 1968 with 9.1". But the autumn months go from September through November and we've had an active start to November, so will a dry autumn have that much of an effect on the snow? At the moment, I'd say no.
Something else that stands out is the current drought in Texas. Texas suffered similar droughts in the late 1940s to the middle 1950s.
The drought there has my attention because it has an effect on some of the upper-air patterns. From the Texas drought years of 1950 through 1956, Sioux Falls averaged 42.2" of snow, just an inch or two above average for the season. I have to be honest; the upper-air patterns of the early and middle 1950s will be looked at closely.
One of the big factors when putting a winter forecast together and one that is probably heard of the most is whether this will be an El Nino or La Niña winter. Both have certain characteristics about the weather patterns not only in the United States, but around the globe.
This winter will be another La Nina. While last year was also a La Nina, this time it's not as established but it's present and the forecast is for a strengthening La Nina through the spring. Since 1950, La Nina winters are all over the board from as little as 9.1" in 1967 and 1968 to as much as 60.5" in 1955 and 1956.
So here it is. Even though we will get snow early in the year, I think the most will fall in January or February. While we could have a couple of temperature swings, once we get a snow base, expect winter's chill to stay. For this reason, I think a majority of the winter will be colder than average.
As far as snow goes, let's go above average again this year, but just barely with a season total of 43.2".
Click on the play button below to see more of the fall weather we've experienced in KELOLAND.
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