COLORADO BASIN RIVER FORECAST CENTER
  NATIONAL WEATHER SERVICE / NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION

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Colorado Basin River Forecast Center - Colorado River, Green River, San Juan River, Eastern Great Basin, Lower Colorado CBRFC Modeled Lower Zone Soil Moisture Images
Image Desciption
The Colorado Basin River Forecast Center uses the Sacramento Soil Moisture Accounting Algorithm (Sac-SMA) to simulate basin runoff from rain and snowmelt driven events. Sac-SMA divides the soil response into fast responding upper zone (approximately the top 20-50 mm of soil) and the longer term lower zone (generally deeper than 50 mm.) The fall lower zone portion of the model helps to determine the volume of runoff during the spring and summer months by indicating a basin's antecedent condition prior to melt. Images linked below are a snap shot of the date's lower zone contents as a percentage of the average contents on that date. The daily average values for each elevational sub-area within the river basin are derived from the calibration process during which the model parameters are adjusted to match the historical observed stream flow. In the Upper Colorado and Lower Colorado this period is water years 1981 through 2010. Forecasters may use these images to help explain atypical basin responses from ESP.

It should be noted that once the melt has commenced, lower zone free supplemental will indicate higher total contents. This is not indicative of the longer term soil moisture influence on ESP.

More information about the Sac-SMA Model.
Daily Model Inches to Saturation Images

Operational Model Soil Moisture - Percent of Average
Most of these images show only areas that are significant contributors to the spring runoff volume (generally the higher elevations). Some of the older maps show additional areas.

November 15, 2018

November 16, 2017

November 16, 2016

November 15, 2015

Older Maps