National Weather Service United States Department of Commerce

Above Average Spring Flood Risk

What's New?

There has been average to well above average precipitation across Wisconsin this Winter. Most of this precipitation has come from snow with an increasing snowpack throughout the state with above to well above average liquid water equivalent. Soil moisture remains historically high in the 99th percentile across the state with streamflow much above normal across the state as well. In addition, according to the CPC seasonal outlook, March/April/May have slightly increased chances for above average precipitation.

What Does This Mean?

With the ground being unable to accept much additional water increased runoff is expected, which will increase flooding potential. In addition, runoff into rivers that already high further increases potential for river flooding. Minor flooding is generally expected, however more impactful flooding is possible, especially with rapid snowmelt and/or heavy rains. Overall this suggests an above average risk for spring flooding across Wisconsin. 

Note: River flooding in Wisconsin typically occurs in March and April when we have a rapid snowmelt and/or heavy rain. But, it can happen any time of year when we get heavy rain.

 

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Typical Spring Flood Risk Factors Include:

(Red if already going to factor into 2020 Spring Season)

  • High river levels
  • High soil moisture
  • Normal to above normal winter precipitation
  • Deep snowpack with high liquid water equivalent
  • Quick rate of snowmelt
  • Deep frost depth
  • Heavy rain

 

Potential Impacts This Spring:

  • Rivers freezing at elevated levels
  • Ice jams, including locations that are not usually affected by ice jams
  • Spring flooding, especially with any heavy rain on frozen ground or a rapid snowmelt
  • Backwater/inundation flooding of river mouths near Lake Michigan
  • Soil damage
  • Delay or prevention of crop planting
  • Travel impacts due to road or bridge damage

Preparedness/Early Actions:

  • Get a NOAA Weather Radio to be alerted to flash flood warnings and river flood warnings
  • Monitor weather forecasts for heavy rain potential
  • Monitor river levels and forecasted river levels online: (National Site, USGS, MKX)
  • Consider flood insurance, especially if you are in a flood prone area - (may require 30 day notice)
  • Prepare (Flood Ready, Flood Safety
  • Make sure your sump pump is working and consider a backup.
  • Have a professional install check-values to prevent floodwaters from backing up into the drains of your home
  • Keep important documents in a waterproof, elevated container
  • Finish any outdoor projects that may be affected by heavy rain or flood waters

 

Contact information:

Sarah Marquardt,

NWS Milwaukee/Sullivan Service Hydrologist

Sarah.Marquardt@noaa.gov