ELEVATED RISK FOR SPRING FLOODING...
River flooding continues for much of the region. Rain, warmer temperatures and rapid snow melt the last couple of weeks has led to flooding along the Cedar, Iowa, Wapsi and others. However, with no snow left in the local area many have already reached their crest and are falling except the Mississippi which is slowly rising from snow melt up north making its way down stream.
NOAA (National Oceanic and Atmospheric Administration) released its 2019 Spring Flood Outlook and it's definitely concerning especially along the Mississippi River. They suggest nearly two-thirds of the lower 48 states face an elevated risk for flooding through May.
The potential is there for moderate to major flooding in at least 25 states. The areas of greatest risk include the upper, middle and lower Mississippi River basins including the mainstream Mississippi River, the eastern Missouri River, and Red River of the North. On the map below, moderate flooding is indicated by the red color and major by the purple which highlights much of the Mississippi River basin especially from southeast Minnesota south to the Quad Cities.
Record snow across a large area of the country has set the stage for the elevated flood risk. In fact, the upper Mississippi River basin has received rain and snow more than 200% above normal.
The outlook is based on several factors: current snowpack, drought, soil moisture, frost depth, streamflow and precipitation.
A wet fall for many areas saturated the soil heading into winter. Deep frost depth limits water infiltration thereby generating more runoff from rain and snow melt than soil that is not frozen.
The image below is the latest frost depth from the North Central River Forecast Center where a few inches to as much as 36 inches or more remain in parts of Minnesota. That is aided by several inches of snow still on the ground.
Snow cover is still extensive in the upper Midwest. However, warmer temperatures and rain lately have melted much of it away in northern Iowa and southern Minnesota where a few inches are still left. Further north, into Minnesota and central/northern Wisconsin up to a foot or more still blanket the frozen ground.
Take a look at the snow cover from just one week ago on the image below. Big difference.
A considerable amount of water remains in the left over snow all throughout the Mississippi River watershed as you can see below. As much as 2-6" of water is waiting to get released into the river system.
The snowpack will take a big hit with some rapid melt this weekend as temperatures warm above normal into the 40s and 50s. Below is the GFS model and its forecasted highs for both Saturday and Sunday.