The flood threat on the Mississippi, particularly North of St. Louis, is increasing every time a big snow hits Minnesota and another big snow just hit.
12"-19" of snow fell (again) on the Minneapolis area and that snow will eventually melt and come downstream on the Mississippi. Kristen talked about The most recent Spring Flood Outlook (Click here) in her latest blog and I think it's worth emphasizing the serious flood threat to areas North of the St. Louis metro along the Mississippi River.
The National Weather Service has already predicted a high probability of moderate to major flooding along the Mississippi River North of St. Louis (from near to North of Grafton, IL and especially from Winfield, MO and North). In fact, straight from the flood outlook, "THESE PROBABILITIES ARE INDICATING GREATER CHANCES OF SIGNIFICANT FLOODING ALONG THE MISSISSIPPI RIVER THAN IN ANY SPRING
FLOOD OUTLOOK ISSUED OVER AT LEAST THE PAST 8 YEARS." And consider that in 2008 we had major flooding in this area.
So when will this snow pack melt and release downstream? I looked at a forecast model of temperatures over the next 16 days, and I don't see it happening in the next 2 weeks. Perhaps a warmer pattern develops around or after March 10th for the Northern United States. Until then the snow will compact and melt a little, but largely remain frozen. If that snow we're to melt quickly coupled with heavy Spring rains, it would exacerbate the flood threat.
As for the St. Louis area, the Mississippi River will run high when that snow melt comes downstream but the metro flood threat on the Mississippi is low. Typically in St. Louis the flooding impact comes from smaller rivers that back up, like the Meramec or River Des Peres and other smaller creeks and rivers. At this point that threat is low.