TERRY’S TAKE: 2013 SPRING FLOOD OUTLOOK
The final spring flood outlook of the year was released by the National Weather Service in the Quad Cities March 7th. I’ll post it below in a condensed form. The interesting thing is that coming off one of the worst droughts in our history (many say the worst since the 1930′s) the outlook calls for an average to slightly above average risk of flooding.
Back on December 1st when we had compiled a 12″ rainfall deficit, I would have been shocked to see that sort of assessment. However, since then we have seen 7.38″ of precipitation and gotten stream and moisture levels close to normal. With a nice snow pack and an active weather pattern ongoing, the threat could increase even further if storms and melting snows combine the right way.
There are a number of factors hydrologists look for and with the aid of graphics, you can see the 9 parameters that are considered vital in creating the outlooks scattered throughout this post. I have also provided the text summary from the NWS outlook below.
Highlights for eastern Iowa, northwestern Illinois, and far northeastern Missouri:
- The spring snowmelt flood potential is near to slightly above normal for the area tributary rivers across northwestern and western Illinois and far northeastern Missouri.
- The potential for spring snowmelt flooding is near to below normal for the area tributary rivers across eastern Iowa as well as the mainstem Mississippi River from near Dubuque, Iowa downstream to Gregory Landing, Missouri.
- Change from the previous outlook has been an increase in the snowpack across the upper Mississippi River Basin overall. The increased snowpack and its liquid water equivalent have increased the spring flood outlook probabilities slightly since late February.
- Current conditions as of March 7, 2013:
- Above normal winter season precipitation and snow depth
- Near to below normal soil moisture
- Deep frost
- Near to below normal stream levels
Important factors to watch in the coming weeks:
- Additional precipitation with the ongoing active weather regime
- Frost depth that could interfere with the absorption of snowmelt and rainfall
- Potential for ice jam flooding during the melt period