Experimental Gridded Soil Moisture Forecast Products
These experimental images are intended to be used as 30, 60, 90, and 180 day drought forecast tools for the ABRFC basin. They are created empirically from our current hydrologic model data, and based on a priori grids of the Sac-SMA hydrologic distributed model used at ABRFC. The forecasts are based on our HEFS (Hydrologic Ensemble Forecast System), and are forecasts of the soil moisture anomaly compared to average for that period. More information can be found about HEFS here. The forecasts are not directly based on any measured data, but derived from soil types, land use, antecedent precipitation, and forecast data from HEFS. On a very basic level, the hydrologic model takes rainfall at the surface, moves it slowly through the upper zones of the soil, and stores it in the lower zones. Typically, water in the upper zones moves through to the lower zones (or out through evaporation) on a time scale of days to a few weeks. The upper and lower zones have a variable depth and capacity, but generally, the upper zone is the first few inches of soil while the lower zone is the next few feet. The upper zone images below can indicate short-term wetness or dryness, while the lower zone images can indicate long-term wetness or dryness.
Each row of images shows the upper zone (short-term) and lower zone (long-term) forecast conditions at different time scales as a percentage full of those zones with respect to the 16 year (1996-2011) average.
Click on each image for a closer look.
File created: 2018-05-23 16:16Z