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Experimental Runoff Risk Data for Great Lakes States - Version 2


  • The data provided here is an experimental service of the National Weather Service (NWS) at this time.  



  • We encourage you to fill out the survey at the following link to provide the NWS your thoughts on providing runoff risk guidance:  RRAF Survey



The development of experimental runoff risk guidance has been a multi-agency collaborative effort consisting of many federal and state agencies and academia.  As part of National Oceanic Atmospheric Administration’s participation in the Great Lakes Restoration Initiative, the North Central River Forecast Center (NCRFC) and its neighboring River Forecast Centers are working together to develop and provide experimental runoff risk analysis data.  The state partners use the experimental runoff risk guidance for optimized application of nutrients which is expected to support safe water quality and healthy ecosystems in the nation’s streams, lakes, and coastal waters, such as the Great Lakes and the Gulf of Mexico.


Runoff Risk Technical Information


The experimental runoff risk analysis data is based on event thresholds set by the state agencies and available as daily runoff risk grids for each state representing the maximum risk from midnight to the following midnight window out to 10 days. The data is generated using the HL-RDHM model (version 3.5.11) running the Sacramento Soil Moisture Accounting model with Heat Transfer and Enhanced evapotranspiration (SAC-HTET). The model is driven with 7-days of forecast precipitation and 10-days of forecast temperatures. The model runs at least once a day on an hourly time-step out to 10 days. Various model states are analyzed to produce the runoff risk data.  Iterative comparisons of simulated high resolution (4km x 4km) model states against observed edge-of-field (EOF) runoff thresholds are then used to develop the risk potential for surface runoff.


The model data is produced in native XMRG format and the NWS polar stereographic projection. NCRFC converts these files to geoTIFF format and also reprojects them to the Google Mercator projection (EPSG: 3857). This process results in a 2km x 2km grid in geoTIFF format.


The category levels for the runoff risk grids include No, Low, Moderate, and/or High Risk.  Each cell is assigned a value of categorical risk ranging from 0 to 4. A value of  0 or 1 represents no risk for that day. A value of 2, 3, or 4 represents either low, moderate, or high risk respectively for that cell. 









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