Grassland Production Forecast

Outlook

  • Grass-Cast Maps
  • About Our Maps
  • Introductory Video
  • How to Read the Maps
  • Grass-Cast Handout
  • Science Webinars
  • Acknowledgements
  • Historical Productivity
Select an area:

% Change in Grassland Production for Your Area this Summer Compared to Its 38-yr Average

For the 3 maps (scenarios) below: "If precipitation between now and August 31st is above (left map), near(middle), or below (right)normal, we estimate that grassland production in your area(at lbs / acre of peak biomass) will be ____ % more or less than its 38-year average."

To determine which of the above maps is more likely for your location, check the monthly and seasonal precipitation outlooks by visiting NOAA at: https://www.cpc.ncep.noaa.gov/products/forecasts/.

To see which map (scenario) is more likely to occur in your area, please visit NOAA's long-range precipitation outlooks at: https://www.cpc.ncep.noaa.gov/products/predictions/long_range/interactive/index.php

% Change in Grassland Production for Your Area this Summer Compared to Its 36-yr Average

For the 3 maps(scenarios) below: "If precipitation between now and August 31st is above (left map), near (middle), or below (right) normal, we estimate that grassland production in your area this SUMMER (at lbs / acre of peak biomass on September 30th) will be ____% more or less than its 36-year average."

The above maps estimate peak standing biomass on September 30th for the summer growing season, depending on precipitation now through August 31st. To check the precipitation outlook for your specific location, please visit NOAA’s outlooks at: https://www.cpc.ncep.noaa.gov/products/forecasts/.

To see which map (scenario) is more likely to occur in your area, please visit NOAA's long-range precipitation outlooks at: https://www.cpc.ncep.noaa.gov/products/predictions/long_range/interactive/index.php

Download 8.5 x 11-inch Handout Download Maps
Select an area:

% Change in Grassland Production for Your Area this Summer Compared to Its 38-yr Average

% Change in 2020 Predicted ANPP compared to 1982-2019 mean ANPP Assuming ABOVE Normal Precipitation through August (%)

% Change in 2020 Predicted ANPP compared to 1982-2019 mean ANPP Assuming NEAR Normal Precipitation through August (%)

% Change in 2020 Predicted ANPP compared to 1982-2019 mean ANPP Assuming BELOW Normal Precipitation through August (%)

Percent (%)

  • < -30
  • -30 to -15
  • -15 to -5
  • -5 to +5
  • +5 to +15
  • +15 to +30
  • > +30
  • No Data

To see which map(scenario) is more likely to occur in your area, please visit NOAA's long-range precipitation outlooks at:

https://www.cpc.ncep.noaa.gov/products/predictions/long_range/interactive/index.php

Print Maps

% Change in Grassland Production for Your Area this Summer Compared to Its 36-yr Average

% difference in predicted 2020 Summer (June-August) ANPP compared to 1984-2019 mean ANPP Assuming ABOVE Normal June-September Precipitation (%)

% difference in predicted 2020 Summer (June-August) ANPP compared to 1984-2019 mean ANPP Assuming NEAR Normal June-September Precipitation (%)

% difference in predicted 2020 Summer (June-August) ANPP compared to 1984-2019 mean ANPP Assuming BELOW Normal June-September Precipitation (%)

Percent (%)

  • < -30
  • -30 to -15
  • -15 to -5
  • -5 to +5
  • +5 to +15
  • +15 to +30
  • > +30
  • No Data

To see which map(scenario) is more likely to occur in your area, please visit NOAA's long-range precipitation outlooks at:

https://www.cpc.ncep.noaa.gov/products/predictions/long_range/interactive/index.php

Print Maps

Grass-Cast: A New, Experimental Grassland Productivity Forecast for the Great Plains

Every spring, ranchers face the same difficult challenge—trying to guess how much grass will be available for livestock to graze during the upcoming summer. An innovative new Grassland Productivity Forecast or “Grass-Cast” can help producers in the Great Plains reduce this economically important source of uncertainty.

This new experimental grassland forecast is the result of a collaboration between Colorado State University, U.S. Department of Agriculture (USDA), National Drought Mitigation Center, and the University of Arizona. Funding for this project was provided by the USDA Natural Resources Conservation Service (NRCS), USDA Agricultural Research Service (ARS), and the National Drought Mitigation Center.

Grass-Cast uses almost 40 years of historical data on weather and vegetation growth— combined with seasonal precipitation forecasts—to predict if rangelands in individual grid cells (whose size is 10 km x 10km, or ~ 6 miles x 6 miles) are likely to produce above-normal, near-normal, or below-normal amounts of vegetation.

As with any forecast, Grass-Cast’s accuracy depends on how far into the future we try to look, according to ARS economist Dannele Peck, Director of the USDA Northern Plains Climate Hub. Its accuracy improves with time as the growing season unfolds, so it should be consulted more than just once during the growing season. Grass-Cast is updated every two weeks to incorporate newly observed weather data and emerging trends in the forecast, such as the flash drought in the western Dakotas and eastern Montana in 2017.

Grass-Cast also provides a view of rangeland productivity in the broader region, to assist in larger-scale decision making—such as where grazing resources might be more plentiful if a rancher’s own region is at risk of drought.

Grass-Cast provides ranchers and land managers with an indication of productivity in the upcoming growing season relative to their area’s more nearly 40-year history. Ranchers and land managers should use this information in combination with their local knowledge of soils, plant communities, topography, and management to help with decision-making.

It should be noted that Grass-Cast cannot tell the difference between desirable forage species and undesirable species. So it is important for producers to know what proportion of a pasture is occupied by weeds, and how well those weeds respond to rain (or lack of rain) compared to the desirable species. Producers should monitor these different vegetation types to see if one is responding to the weather better than the other. Furthermore, Grass-Cast does not directly account for local management practices, such as grazing intensity in previous years. Producers should therefore adjust Grass-Cast’s grid-level productivity estimates accordingly.

Producers should not rely on Grass-Cast as a sole source for making management decisions. Similarly, public land managers should not use Grass-Cast as a sole source of information for setting stocking rates, determining turnout dates, or other aspects of lease agreements, allotments or permits.

Watch for updates on the Grass-Cast website or on Twitter (@PeckAgEc). Project Contact: Dannele Peck, Director of the USDA Northern Plains Climate Hub, at dannele.peck@ars.usda.gov or 970-744-9043.

Example

An example set of Grass-Cast maps, produced on April 29th for the summer of 2019, are shown below. The left map shows, for each grid-cell (~6 miles x 6 miles in size), how much vegetation is expected to grow (compared to the grid-cell’s 38-year average) if precipitation in May-June-July-August (MJJA) is above-normal. A grid-cell in dark blue, for example, is expected to have 30% more pounds per acre than its average. A grid-cell in green is expected to have near-average (5% less or more) pounds per acre. The middle map shows how much vegetation is expected to grow if MJJA precipitation is nearnormal. A grid-cell in yellow, for example, is expected to have 5% to 15% less vegetation than its average. The right map shows expected vegetation if MJJA precipitation is below-normal. A grid-cell in red, for example, is expected to have 30% less vegetation (or worse) than its average. For grid-cells in white or gray, no forecast is available due to insufficient data or weak statistical relationships.

Example Grassland Productivity Forecast (“Grass-Cast”) maps for summer 2019, produced on April 29, 2019 (see Grass-Cast website for the most up-to-date maps). These three maps show the forecasted percent change in grassland production compared to a grid-cell’s 38-year average. Left map: percent change in pounds per acre if precipitation in May-June-July-August (MJJA) of 2019 is above-normal. Middle map: percent change in production if MJJA precipitation is near-normal. Right map: percent change in production if MJJA precipitation is below-normal. To see which map (scenario) is more likely to occur in your area, please visit NOAA's long-range precipitation outlooks at: https://www.cpc.ncep.noaa.gov/products/predictions/long_range/interactive/index.php.

For Example: In the maps above, much of the grid-cells in north-central Montana are medium-blue (left map), green (middle map), and orange (right map). If May-Jun-Jul-Aug precipitation is abovenormal (left map), those medium-blue grid-cells in north-central Montana rangelands are expected to have 15 to 30% more pounds per acre of vegetation than their 38-year average. If MJJA precipitation is near-normal (middle map), those green grid-cells in north-central Montana are expected to have near-normal production, anywhere from 5% less to 5% more than their 38-year average. If MJJA precipitation is below-normal (right map), those orange grid-cells in north-central Montana are expected to have 15 to 30% less production than their 38-year average. For areas in gray, Grass-Cast is not available due to insufficient data or weak statistical relationships.

Printable Version

How to Interpret the Maps

Video Transcript

How to Use the Zoomable Maps

Video Transcript

How to Interpret the Maps (full version)

Video Transcript

How to Read the Maps (with Dannele Peck)

Video Transcript

Grass-Cast Handout

Select an area:

Science Webinars

Select an area:

Great Plains

This webinar on the scientific methods underlying Grass-Cast was presented by Dannele Peck (Director, USDA Northern Plains Climate Hub) on April 2, 2019, for rangeland specialists with USDA NRCS in Kansas. Unlike previous webinars (provided below), it describes why Grass-Cast uses 3 maps instead of just 1. It also explains how to interpret the 3 maps for a specific area of interest. Fast-forward to minute 44:15 for this explanation.

This webinar on the scientific methods underlying Grass-Cast was presented by Dannele Peck (Director, USDA Northern Plains Climate Hub) through the USDA Climate Hub 'brown bag' series on March 14, 2018.

This webinar about the science behind Grass-Cast was presented by Dr. William Parton (Professor and Senior Research Scientist, Natural Resources Ecology Lab, Colorado State University) for the North Central Climate Adaptation Science Center's ReVAMP Check-in Series, on June 26, 2018.

Southwest

Grass-Cast for the Southwest (Part 1): How to Interpret the 3 Grass-Cast Maps. Presented by Dr. Dannele Peck (Director, USDA Northern Plains Climate Hub) on May 14, 2019 for rangeland specialists in the Southwest region. Go to minute 4:53 for the motivation behind Grass-Cast. At 8:29 learn about the 4-step process for making Grass-Cast. Jump to 15:39 to understand why Grass-Cast shows 3 maps. At 18:20 learn how to interpret the 3 Grass-Cast maps for your location.

Grass-Cast for the Southwest (Part 2): Why Separate Forecasts for Spring & Summer? Presented by Dr. Melannie Hartman (Senior Research Associate, Colorado State University) on May 14, 2019 for rangeland specialists in the Southwest region.

Grass-Cast for the Southwest: Remote Sensing’s Role in the 4-Step Grass-Cast Process. Presented by Dr. William K. Smith (Assistant Professor, University of Arizona) on May 14, 2019 for rangeland specialists in the Southwest region.

Acknowledgements

Development of the Grassland Productivity Forecast or "Grass-Cast" was funded in part by the:

USDA Agricultural
Research Service

USDA Natural Resources
Conservation Service

National Drought
Mitigation Center

Historical Productivity

Want to know the 38-year (Great Plains) or 36-year (Southwest) average productivity (pounds per acre) estimated by Grass-Cast for grasslands in your county or grid-cell? Which year had the highest pounds per acres, or the lowest? Click on the following links to learn!

Great Plains

Southwest