Streamflow Forecast

The spring–summer streamflow forecast for the Southwest, issued on March 1, shows below-average flows for basins in the Mogollon Rim region of Arizona and New Mexico basins and near- to above-average flows for most of the Upper Colorado River Basin (Figure 12). Streamflow forecasts become more accurate as the winter progresses. However, spring storms can still have a large effect on actual spring streamflows.

In the Upper Colorade River Basin, winter precipitation has been above average. As a result, there is a 50 percent chance that inflow to Lake Powell will be about 116 percent of the 1971–2000 average for April–July, or 9 million acre-feet, which is a slight increase from the forecast issued on February 1. Dry conditions in most of Arizona are reflected in the streamflow forecast for the state; spring streamflow in the Little Colorado, Verde, Salt and Gila rivers are 18, 42, 22, and 23 percent of median, respectively.

In New Mexico forecasts for the Rio Grande Basin range from 30 percent of average for the Rio Pueblo de Taos below Los Cordovas to 82 percent of average for the El Vado Reservoir inflow.  Flows for the Rio Grande at Otowi Bridge are forecast to be around 63 percent of average. For the Canadian River Basin, forecasts range from 40 percent of average for the Conchas Reservoir Inflow to 78 percent of average for Ponil Creek near Cimarron.

Since the water year began October 1, most of Arizona and New Mexico have received below-average rainfall, particularly in southern regions of both states where rain and snow have totaled less than 50 percent of average. The dry southern regions reflect the influence of La Niña events, which often deflect the storms north. In January, most of New Mexico and Arizona received scant precipitation; it was the driest January on record for New Mexico, according to the NOAA-Climate Prediction Center.