Snowpack through the first quarter of the water year (October- September) was above normal for nearly the entire state and well above normal in the San Juan Mountains. A cool and wet December helped to alleviate abnormally dry conditions over the majority of the state. Long-term forecast favor the state for continued above average snow accumulation over the coming months; and with 45% of the snow accumulation season still remaining, water providers have no immediate concerns.
The 2015 calendar year was the warmest on record globally, the second warmest on record nationally and the 3rd warmest on record in Colorado. Colorado ended the year 2.9 degrees Fahrenheit above the 100 year average for temperature. January to-date has been below average for temperature statewide.
Statewide SNOTEL water year-to-date precipitation is 104% of normal. Both November and December saw above average precipitation statewide, with nearly all basins receiving above average precipitation in both November and December. The Yampa/ White basin is the exception to this, but as of January 19th was at 98% of normal snowpack.
Reservoir Storage statewide is at above normal at 110%. The Arkansas basin has the highest storage levels in the state; the Upper Rio Grande has the lowest storage levels, just slightly below normal. However, the Rio Grande levels are the highest they have been since 2009.
The Surface Water Supply Index (SWSI) is near or above average across the majority of the state, with the southern half of the state faring better than the northern. At this time of year the index reflects reservoir storage and streamflow forecasts. January 1st forecasts were normal to above normal in all basins, except the Yampa/White. Still, forecasts within the Yampa/ White ranged from a maximum of 103% on the Laramie River near Woods, to a minimum of 80% on the Little Snake River near Dixon.
El Niño conditions remain strong and should continue through spring. A recent large westerly wind anomaly may help keep the El Nino going and even cause a second peak. Assuming conditions persist as expected precipitation chances will be increased in March and April.
Long term projections indicate a transition to La Nina conditions later this year. While La Nina conditions typically result in lower precipitation especially across the southern portion of the state; the first year following large El Nino events, like we are currently experiencing, is more often associated with good snow accumulation totals than not.
Recent storms have alleviated some regions of abnormally dry conditions across the state. With 45% of the snow accumulation season remaining and strong storage levels, water providers have no immediate concerns.
The Climate Prediction Center’s three month forecast for February through April indicates wetter than average conditions across the entire state. This coincides with University of Colorado, CIRES & NOAA-ESRL PSD statistical forecasts for the spring. Historically, Colorado’s largest snowstorms along the Front Range have occurred during the spring months of El Nino years.
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