Long Term Flood Concerns Increase With Snow Pack

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WEST MICHIGAN (February 8, 2014) — By now all of us have realized that this is no normal winter. We’re breaking temperature records, wind chill records, and snowfall records. We already had the seventh snowiest January in Grand Rapids history, and we’ll probably end up in the top five snowiest seasons ever! Breaking the 100-inch mark is almost a done deal!

You don’t need to be a meteorologist or weather geek to realize there’s moisture locked up in all that snow…and plenty of it. In fact, the National Weather Service took a core sample from their office by the Gerald R. Ford International Airport and determined we have approximately 4.6 inches of liquid equivalent within about 23 inches of snow pack. So what does it all mean? Well if we can’t melt this snow off in a slow, gradual process, West Michigan could be in for some serious flooding. The water has to go somewhere and the ground is frozen, so our rivers and tributaries would fill quickly. The frozen ground simply acts as pavement and moisture cannot percolate in to the ground. That said, I’m not expecting any major prolonged warm up anytime soon, but how fast the snow melts and where it goes is certainly a hydrologic concern.

National Weather Service hydrologists say “the snow pack, how much water is in the snow pack, ice coverage, and ice thickness on rivers across Lower Michigan are all above normal for this time of year. These factors all increase the risk for flooding from snow melt and ice jams.”

Of course, we haven’t even thought about the possibility of a warm up along with rain falling (or heavy thunderstorms) instead of snow. That too, will exacerbate the problem. You can click here to read the entire NWS article and get more facts and figures. You’ll recall it was just Spring 2013 (last year) that we experienced record flooding across the area, especially along the Grand River basin. It’s never too early to start thinking about the “what if ” scenario.

The attached photo shows what one inch of liquid equivalent water will yield in total snow fall. Generally, snow ratios are about 10:1…that is for every one inch of liquid water, you’d get 10 inches of snow. That said, it’s only a general rule and is NOT constant. It’s dependent on many things…not the least of which is temperature. In colder temperatures the ratio goes up as the graphic shows. For example, that same one inch of liquid water may yield 15 inches of snow in 20 degree temperatures, but only 10 inches of snow in 30 degree temperatures. In fact, I’ve seen lake-effect snow ratios in really cold (Arctic air) on the order of 30:1 or rarely 40:1.

The best case scenario is to slowly melt off this snow with gradual, brief warm ups and minimal added precipitation. Unfortunately, it usually never happens that way. Get the complete West Michigan forecast at www.fox17online.com/weather. 

 

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