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Will the rest of the winter be snowy? A statistical look...

Matt Ross @ 12:00 AM

For both snow lovers and snow haters alike, I think this is the question on many minds as we wind up January. Do I know the answer? No. However, I think there are clues that can help guide us. There are many ways to approach this topic, and certainly in my opinion, there is no substitute for the short and medium range model analyses, pattern recognition, and forecasts provided by the contributors on this website. That being said, I will take a statistical approach to the question.

Today's forecast is pretty straight forward. We'll be in between clippers -- so the weather will be non descript. Look for partly cloudy skies with a high near 40. Still keeping an eye on the weekend -- when there could be some storminess. Dan will have more details on that tomorrow.

One of the biggest issues with using statistical constructs to analyze weather is the determination of what is trivial versus what is meaningful. I may come up with one conclusion based on a set of data, while another set of seemingly meaningful data will lead to an opposite conclusion. There are ways to limit the triviality of data, but when it comes to weather it isn't easy, particularly in light of the fact that accurate records only go back to the late 1800's, thus limiting sample size. Nevertheless, we can try to come up with relevant, or at the very least, interesting ways of looking at possible weather outcomes.

So far this winter(through January 23rd) we have received 3.9" at DCA. Let us assume that we end January with 5" or less for the winter(I know, big assumption given several possibilities over the next week). Official snowfall records have been kept in DC since 1887-88, or 117 winters. Of those, 16 winters have had 3-5" at the end of January(average was 4.4"). This is about 4.5" shy of where we should be at the end of January(around 9"), or only 50% of normal. However, these 17 winters averaged 9.5" in February/March/April, about 2" above normal for that time period or about 130% of normal. Consequently, these 16 winters which averaged only about 50% of normal at the end of January, finished the winter at 14.1" or almost 90% of normal(16.2" is the seasonal average since the official measuring station was moved to DCA in the early 1940's). Certainly by no means conclusive and in fact potentially irrelevant come next Monday, January 31st should we get another decent snowfall, but for now another piece of hope for DC snow lovers.

I forgot to mention that this is my first submission. I will be contributing here on occasion, and my bio should be up shortly. Matt.

Photograph taken at 19th Street and Park Road on 1/22

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