Key Points - issued 3/9/23
What Changed
Monitor rivers levels here: Current River Levels and Short Term Forecast River Levels
Flood Outlook as of March 9, 2023
River flooding in Wisconsin typically occurs in March and April when there is a rapid snowmelt and/or heavy rain. But, it can happen any time of year when there is heavy rain.
Seasonal Flood Probability Graphics
Seasonal Flood Probability Table
Current River Levels and Short Term Forecast River Levels
Flood Risk Factors
Current Conditions (images auto update)
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Snow Water Equivalent | Streamflow Compared to Normal | Soil Moisture Percentile |
Flood Risk Factors (as of March 9, 2023)
SnowPack
Mild temperatures this winter resulted in rain at times and a lower than normal snowpack. The water content of the snowpack is around 0.25 inches for the Upper Fox River eastward to Sheboygan and close to 0 for the rest of southern Wisconsin. Average is around one half inch to one inch. An additional 0.5 to 1 inch is expected March 8-9 which will bring the snow water content closer to normal for this time of year. If amounts end up being higher than this forecast, the flood risk could be higher.
Snow water content in the Wisconsin River basin is 4-6 inches in the headwaters, 2-4 inches in the central portion of the basin, and around 0.5 inch in the lower portion of the basin. These values in the headwaters are well above average, contributing to the elevated risk.
Streamflow and River Levels
Streamflow values have been close to average to slightly above average at times this winter. Recent melting snow and rain resulted in rivers running above normal. This means there is less room in rivers to collect runoff from melting snow and spring rain.
Soil Moisture
Soil moisture is above average across all of southern Wisconsin due to a wet winter and wet February. The ground is somewhat saturated leaving little room to absorb additional water.
Frost Depth
Frost depth values are a few inches to 0, which is shallower than normal for this time of year. This helps to decrease the flood risk somewhat because the ground can absorb melting snow and spring rain. However, there will still be a moderate amount of runoff because the vegetation is still dormant.
Rivers and Ice
Mild temperatures over the past two weeks have allowed some melting of ice in rivers, further lowering the ice jam risk. There are many areas with open water, although some rivers and lakes do have some ice cover, so flooding due to ice jams is still a threat. Ice jams occur when rivers rise due to melting snow and rain and ice starts to break up and move downstream in the river. Sometimes it jams up resulting in some flooding. The most susceptible areas for ice jam related flooding are at bridges, river bends or other areas with restrictions in the river channel where ice chunks can collect and cause flooding.
Looking Ahead (images auto update)
7 Day Precipitation Forecast |
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Extended outlooks from the Climate Prediction Center:
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How To Prepare Safety
Preparedness/Early Actions:
How To Stay Safe During a Flood:
Briefing Slides
Feb 9, 2023 Webinar Recording and Slides
Feb. 24, 2023 Slides
Mar. 9, 2023 Webinar Recording and Slides
Information about the spring flood outlook across the entire Upper Mississippi River basin here.
If you have any questions or comments about this spring flood outlook please contact:
Sarah Marquardt
Senior Service Hydrologist
National Weather Service Milwaukee
sarah.marquardt@noaa.gov
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