Forecast Note
Forecasts in this publication are now being referenced to the 1971-2000 median value. Median represents the mid point of all the April-July volumes observed during this 30 year period. Half of the observed volumes are above this value, and half below this value. Historically forecasts were represented as a percent of the 1971-2000 average (or mean) value. However, the average values were skewed by a few very wet years and are not considered the best metric on which to reference forecasts.

The following conditions influenced this month's forecasts:

Precipitation:
Seasonal October-January precipitation is near 130 percent of average in the Virgin Headwaters, and ranges from 120 to 160 percent of average basin wide.

January precipitation was near 200 percent of average in the Virgin Headwaters, and 190 to 350 percent of average throughout the remainder of the basin.

Snow:
Snowpack increased across higher elevations of the Virgin River Basin during January. As of February 1st snowpack, expressed as water equivalent contained in the snow, ranged from 140 to 260 percent of average.

Virgin River Basin Snow Plot.

Soil Moisture:
Below average modeled soil moisture conditions existed entering the winter season. Below average soil moisture conditions still exist at higher elevations where snowpack has persisted throughout the winter.

Climate Forecasts:
El Nino climate conditions suggest increased chances of precipitation in this area. The El Nino influence was accounted for in generation of these forecasts.

Forecast Summary:
Drier soil moisture conditions tend to reduce forecast volumes. However, above average precipitation is anticipated over the next couple of months due to the presence of El Nino climate conditions. This combined with much above average snowpack has resulted in an increase in forecasted runoff volumes from those issued in January. April-July runoff volumes are expected to be near 200 percent of median, which is 125 percent of average.

Differences between the full period forecasts and the residual forecasts may not exactly equal the actual observed volumes due to rounding conventions (see Definitions section).