April 2016 Colorado Drought Update from CWCB

Recent precipitation delivered 103 percent of average April precipitation to-date, helping to boost overall snowpack and alleviate drought conditions across parts of Colorado. Regions of the central mountains and Front Range saw as much as 3 inches of precipitation, Monte Vista received a quarter of their average annual precipitation in just one storm. With short and long term forecasts favoring continued precipitation, and good reservoir storage, water providers have no immediate concerns. Agricultural producers are also in good shape with many looking to increase production this season to compensate for low commodity prices.

Statewide water year to-date precipitation as reported from NRCS is at 98% of average, with the southern portion of the state experiencing drier conditions than the northern half. Currently 2 percent of the state is classified as experiencing moderate drought, while 25 percent is classified as D0.

Despite recent precipitation, much of the state has seen above normal temperatures in March and April. Forecasts indicate that warmer temperatures are likely to continue into the spring.

Statewide NRCS SNOTEL water year-to-date precipitation is 98 percent of normal. The Upper Rio Grande has the lowest year-to-date precipitation at 87 percent of average, while the South Platte has the highest at 112 percent of average.

Reservoir storage statewide remains above normal at 111 percent. The Arkansas and Yampa/White basins have the highest storage levels in the state at 120 percent of average; the Upper Rio Grande has the lowest storage levels at 94 percent, just slightly below normal.

The Surface Water Supply Index (SWSI) as of April 1st is near or above average across the majority of the state. At this time of year the index reflects reservoir storage and streamflow forecasts. The lower Arkansas has seen large increases in storage over the last year and has some of the highest SWSI values in the state. The most recent storm increased statewide snowpack that was previously declining. The state as a whole remains near normal at 95 percent for the snow accumulation season.

Streamflow forecasts are slightly below normal across many regions of the state with most forecasts ranging between 70-89 percent of average. The North Platte has the highest forecast in the state at 111 percent of average while the Purgatoire has the lower at just 69 percent of average.

The long term experimental forecast favors above average probability of precipitation through spring, with eastern Colorado favored more than the rest of the state. The strong El Nino event is likely to dissipate over the coming months but it is unclear if persistent La Nina conditions will develop. La Nina events tend to result in drier conditions across Colorado, but more so during later years of long-lived events.

The Pacific Decadal Oscillation tied its record high in March after more than two years above normal, which would tend to inhibit the development of a strong La Nina event or lessen its impacts.