A Taste Of Spring in December...How Common is it?
by Angela Schilling, Meteorologist
December 16, 2011 10:25 PM
A Christmas wish list oftentimes includes presents and toys but this year if you wanted a warm December, you just might have gotten your wish. The average temperature for this time of year is in the upper 20’s and we’ve been quite spoiled with temperatures above freezing numerous times this year. We’re just over a week away from Christmas and we’ve already been close to 50 degrees once, and this weekend we’ll get our second go at it in Sioux Falls.
March is typically our snowiest month but after all it is December and it wouldn’t be winter without snow in the Northern plains either. On average we get around 8 inches of snow in Sioux Falls and 5 inches in Pierre for the month of December. Last year was a much different set up with even a blizzard around the second week of December. As a matter of fact Sioux Falls received measurable snowfall above a trace nine times last year during the month of December alone. As far as 2011 we’ve only picked up around .3 inches of snow in Sioux Falls so far with a couple of freezing rain/drizzle events to speak of.
It’s not only the lack of snowfall, which makes this year seem uncommon compared to others but it’s also the temperatures. Over the last several years we’ve only been above 40 degrees a couple of times during the month of December, and this year we may do a little bit better. However, it is not uncommon for us to see several days above 40 degrees during the month of December. Four years ago in 2006 we saw 9 days above 40 degrees and 14 in 2002. Last year we reached 48 degrees on December 9th, but that was about all we could muster besides 41 on December 10th as well.
This weekend we have a couple of opportunities to top 40 degrees, some of us could even reach 50, especially along the Missouri River. So here’s the reason why…first of all we have a huge ridge in place in the upper levels of the atmosphere, which causes air to sink and compresses as it reaches the surface. When you compress air it tends to heat up. Also, we have an area of low pressure just to our west at the surface, with an associated warm front. Just like it sounds a warm front brings warm air along with it. Our winds will also be coming out of the west-southwest on Saturday and south on Sunday, both of which are warming patterns for us here in the Northern Plains.
Highs on Saturday will be a little bit cooler west of the James, but still well above average. All of the warm air will slide east of the James on Sunday, allowing highs to reach the upper 40’s.