Historic 2019 Flooding

Historic flooding occurred last year across significant parts of the Mississippi, Missouri, Arkansas, and Tennessee River Basins and their tributaries. 

All-time-high records were set at 43 communities. The repeated heavy rainfall resulted in 11.2 million acres of unplanted fields.  

Economic damages exceed $16 billion dollars.

Early Thoughts on Spring Flooding 2020

First, a lot that can change before spring. In fact, early spring weather is typically quite dynamic and the overall potential for spring flooding can change significantly within weeks. 

However, there are some interesting observations that can be made at this time as to the potential for spring flooding. Let’s review these important indicators. 

Soil Moisture

Soils are unusually wet (blue) across a large part of the Upper Mississippi Basin. This soil moisture is now likely “locked-in” until spring due to frozen ground.

Soils are also unusually wet over parts of the Ohio due to recent heavy rainfall. 

Current wet soil anomalies point towards an enhanced vulnerability for spring flooding. 

Current Vulnerability: Above Average

Snow Cover

Snow Water Equivalent (SWE) is actually a bit higher than last year at this time over the Upper Mississippi. 

However, there is a lot of time for SWE to change, either increasing or decreasing vulnerability, over the next two months. 

Current Vulnerability: Neutral

2020

Last Year

Stream Flow

Streamflow is running quite high, in many cases above flood stage, over the eastern half of the nation. In fact, around 178 communities are currently above the flood stage. 

This can change, increasing or decreasing the overall vulnerability, over the next two months depending on precipitation.

Current Vulnerability: Well Above Normal

Blue and black dots = well above normal streamflow

 

Outlooks and Models

Perhaps the most important variable as to the potential for spring flooding is future precipitation — especially snowfall.

NOAA’s outlook for below-normal temperature and above-normal precipitation over the next three months over the Upper Midwest points towards an increasing snowpack.

The outlook for above-normal precipitation over the Ohio river points towards a continuation of above-normal soil moisture and higher than normal streamflow.

Current Vulnerability: Above Normal

NOAA February – April Temperature Outlook

NOAA February – April Precipitation Outlook

 

Current Vulnerability Assessment

Soil Moisture: Above Normal
Snow Water Equivalent: Neutral
Streamflow: Well Above Normal
Outlooks: Above Normal

Again, keep in mind that these vulnerabilities are (other than outlooks) snapshots of current conditions and are likely to change as we progress through the winter months and near spring.

The National Weather Service will be issuing official outlooks later this winter as well. 

BWO will keep you informed on changing vulnerabilities, and NWS outlooks, as we near spring.