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Wisconsin Manure Management Advisory System

During the last week of February, you may have noticed that some basins in southern Wisconsin showed up red in the forecast, but without the snowmelt hashmarks. That means that the model expected rain to be running off frozen fields...and that made us wonder. While precipitation was in the forecast, it was supposed to be mostly or all snow, and snowmelt was certainly possible given the forecast temperatures.

To make a long story short, when our NWS team members examined the event model, they found that it did not indicate snowmelt when the snowpack captures and freezes some of the rainfall that occurs and passes the rest to the soil. In this case there is a net gain to the snowpack, so, technically speaking, snowmelt is not occurring. However, water is still being conveyed to the soil through the snowpack, so we thought it made sense to alter the logic to categorize events like this as being partially due to snowmelt And indeed, with very similar conditions over the past 24 hours, we now see that wherever the map is alerting us to forecast runoff, there is a snowmelt component.

The effort to tune and improve the forecast is ongoing, and we hope you'll help. If you see something on the page that doesn't jibe with your sense of what's really going on, please don't be shy -- tell us! Even if the forecast turns out to be "right", that doesn't mean you were "wrong"; it means that we need to improve the presentation, and we welcome your suggestions for doing so. Likewise if there is a problem with the forecast, we need to know about it before we can fix it.

For questions about and problems with the forecast, contact Mark Jenks; for website problems (broken links, etc.), Rick Wayne is the guy. Contact info for the whole team is here.. Thanks for your help!

We hope you evaluated the RRAF over the last several days as Wisconsin saw a January rain and thaw event. How do you think the RRAF performed? Did you see runoff in your fields when the RRAF indicated high risk? Did you have the opposite situation where you had no runoff and conditions were still good to spread although you were under high risk? let us know via our contacts page or, better yet, by submitting a survey!

Were you in a basin that was showing no risk although all the watersheds around you were highlighted red for high risk? Maybe you are wondering how could that be? If so, be sure to see the previous Blog post which describes some of the reasons you may be seeing that behavior on the RRAF.

The RRAF team conducted an on-the-fly evaluation of some of these basins that were consistently "blue" during the last few days and wanted to share with you some of their findings. The good news is that these basins were very close to being categorized as high risk as well. As discussed in the previous blog post, category thresholds were in play during this runoff event. These basins needed just a bit more melting, or bit more rain to knock them over to the high risk category.

In the future, the RRAF team will continue to evaluate and update the model to provide the best decision support tool we can for your nutrient management.

Winding down from Wisconsin's first widespread runoff event in 2013, it's a good time for some additional background about the RRAF.

1. Source Model

The RRAF is derived from the North Central River Forecast Center's (NCRFC) Sacramento Soil Moisture Accounting Model (SAC-SMA) calibrated and used for operational river forecasting. Each of the variously-sized watersheds on the map can respond differently to rainfall and snowmelt to generate runoff into their streams.

2. Spatial Scale Challenge

Replicating runoff you see on your fields with much-larger modeled watersheds (the average RRAF watershed is 192,000 acres) is an obvious challenge. And it's key to realize that the SAC-SMA is a lumped model, yielding just one runoff value per watershed. This might seem alarming, however, the RRAF team has compared the model versus observed runoff from Edge-of-Field sites at several Discovery Farms sites and small watersheds gauged by the U.S. Geological Survey (USGS) and have found that the RRAF can do a decent job in detecting risky runoff conditions for producers.

3. Watersheds have "On/Off" Behavior

To define simple categories of risk, thresholds had to be chosen. Crossing a threshold essentially turns the basin's runoff risk "on or off". As mentioned above, the model watersheds can have slight differences in how they behave and this is why we can see some basins having high risk and a neighboring basin in low or medium risk.

4. Model Basin Boundaries versus Nature

The RRAF's watersheds act like distinct puzzle pieces, whose defined boundaries separate each watershed and its risk value from its neighbors. Why is this important? In real life, as you travel across the landscape, changes are continuous and gradual. So if your farm is near the boundary inside a low-risk watershed, with high-risk ones nearby, this should tip you off that you might be in near risky conditions as well.

5. The RRAF is only one part of the decision making process

The RRAF is meant to be a tool for producers to use in planning manure and nutrient applications. However, it is a model, and thus includes assumptions and limitations inherent in all weather and watershed models. Producers must rely on their own knowledge of the local conditions and fields in addition to any model guidance when making application plans.

6. Future RRAF Plans

The RRAF is the only decision support tool of its kind currently available, and this is Version 1. The RRAF team is dedicated to continually monitor and improve the RRAF over time. However, you can help as well. Did the RRAF work great for your area lately? Let us know by sending us a note via our contacts page or submitting a survey. Did the RRAF bust on a forecast lately? Help us improve the tool and let us know that as well.

In the near future the RRAF team will begin the planning stages on implementing the second generation RRAF tool. This version could include a much finer resolution model and perhaps provide an even better forecast tool for using in your decision making process. Stay tuned and let us know what you think of the RRAF!

The NWS River Forecast Center runs their forecast model three times per day; once in the evening, once in the early morning, and again later in the morning with updates and accuracy enhancements from the experienced human forecasters.

Up until now, we have incorporated the two morning forecasts; we are currently working on a new automated uptake system that will enable us to use all three.

Watch this site for the evening forecast, once we have everything working it should appear around 7 PM local time.

Winter is here, at least for the RRAF! Cold weather and snow in Wisconsin have yielded frozen and/or snow-covered soils for much of the state. So the forecast is now looking 10 days out for runoff risk, with special alerts for snowmelt (see the legend above the map).

Runoff Risk Advisory Forecast Tool Being Developed

The ability to predict the risk of runoff on a particular day can greatly assist Wisconsin producers, manure haulers, and nutrient applicators when making decisions about when to land apply manure or other nutrients. The Wisconsin Department of Agriculture, Trade and Consumer Protection (DATCP), United States Geological Survey (USGS), National Oceanic and Atmospheric Administration (NOAA), National Weather Service (NWS), National Resources Conservation Service (NRCS), University of Wisconsin (UW), and others are collaborating to develop a risk assessment tool that identifies when there is a high likelihood for surface runoff and, therefore, when to avoid spreading nutrients on agricultural fields.

The Runoff Risk Advisory Forecast map currently shows this assessment of day-to-day runoff risk occurring across Wisconsin using National Weather Service forecast models that consider predicted precipitation, soil moisture, snow melt forecasts and actual individual watershed basin characteristics. However, because all of these conditions can and do vary across a watershed basin, persons intending to apply manure or other nutrients should always apply their knowledge of local conditions when deciding whether or not to spread on a specific field. This tool is a work in progress, continuing to be refined as better weather forecasting data and field runoff information becomes available.

 

The forecast map is updated 3 times each day to account for changes in weather forecasts and soil moisture conditions over short time periods. The forecast tool can be found on the Wisconsin Manure Advisory System website link below.

http://www.manureadvisorysystem.wi.gov/app/runoffrisk.

We need your input to help improve the tool and make it as useful as possible. When visiting the website, please take a few moments to complete the National Weather Service survey, located in the lower right hand portion of the screen, to provide feedback on the forecast’s usefulness to you.

Contacts:
Mark Jenks
WI Dept. of Agriculture, Trade and Consumer Protection
262 521-5011
Mark.Jenks@Wisconsin.gov
Sara Walling
WI Dept. of Agriculture, Trade and Consumer Protection
608-224-4501
Sara.Walling@Wisconsin.gov

As we gain experience with the forecast, we can see where the model results fail to agree with reality on the ground, and update the model. The basins WI15C, WI14C, WI13C, WI12C (in Douglas, Bayfield, Ashland, and Iron Counties) are all up on the northwest coast of the state and have frequently been outliers for our risk forecast. We expect that the new parameters will bring them more in line. Next up is basin PDSW3 near Prairie du Sac, which may already be responding better by the time you read this. We are watching some other basins that seem to average out fine over time, but respond more slowly than their neighbors (NEWW3 near New London, SHIW3 near Shiocton, and RAYW3 near Raymond).