Daily independent weather forecasts for the Kansas City area

Wednesday, March 23, 2005

Snowfall in Kansas City

Often times, you hear that snow is one of most difficult things for a meteorologist to forecast. As the snowfall we saw yesterday reinstates that point, the question becomes... Why?

One of the more difficult parts of forecasting snow is the fact that it doesn't take much moisture to fall from the clouds to create a large amount of snow. The amount of moisture that is required to fall from the clouds to produce one inch of snow is generally equivalent of 1/10th inch of rain. If it is colder, that equivalence can go up to 15-1, 20-1, or even 30-1! So what would be the difference between drizzle or sprinkles and a little light rain can make a huge difference as to how much snow can fall.

The vast majority of our snow in Kansas City comes from storms coming out of the west or southwest. These storms often pump in much more warm air than their northwesterly, Alberta Clipper, counterparts. This often requires your local meteorologist to forecast where the rain-snow line will be. The heaviest snowfall usually occurs in a narrow band just north of this point of changeover, but one usually doesn't need to go much further north from the storm to escape the snowfall completely. So, if the track of your typical snowstorm differs by as little as 30 miles, it can make a world of difference with regards to snowfall amounts.

At least we don't get lake-effect snow. Lake-effect snow bands can be so localized, that you can travel 5 miles either side of the heaviest snow, and see absolutely no snowfall. When I was a meteorologist in South Bend, IN I often had to forecast lake-effect snow (which I love to do). I remember one storm that dumped 13-15 inches of snow west of town, but if you traveled to the next city to the west (approx 10 miles), no snow was reported. Now that's fun to forecast... it would drive our news director in South Bend crazy, because she only had ears for the heaviest, most extreeme number we said. So if we forecasted 12 inches of snow in Colorado, we would get the traditional "I thought you said we were going to get 12 inches of snow here?"

Anyway, I mentioned in yesterday's podcast that March snowstorms are not that unusual. In fact, today is the anniversary of the largest snowfall in Kansas City history. 25 inches of snow fell between March 23 and 24 in 1912. In fact, we average 3.8 inches of snow during the month of March. It can indeed snow in March! Will we see any more this year? There is a storm that will be heading our way this weekend that will bring snow across Nebraska. It won't take much more cold air around here to bring the snow to the city. ... but I don't think that will happen. :^)

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