Snowpack news: April to June forecast for inflows to Lake Powell = 52% of avg. #ColoradoRiver

From InkStain (John Fleck):

The April-July runoff forecast into Lake Powell, on the Arizona-Utah border, is just 52 percent of the long term mean, according to new numbers out today from the Colorado Basin River Forecast Center.

That is roughly 1.3 million acre feet less water flowing into Lake Powell than the forecast of just a month ago, the result of a hot, dry March. That means at the end of said runoff period, Powell will be roughly 13 feet lower than it would have been otherwise, according to my half-assed amateur calculation (danger, danger, journalist doing math! – the pros at the Bureau of Reclamation will give us a more reliable number next week).

From the Pagosa Springs Sun (Renita Freeman):

The Natural Resources Conser- vation Service (NRCS) reported that the San Juan River Basin was at 51 percent of median on April 1, com- pared to 63 percent in the March 1 report. Snowpack reports generated by the National Resource Conserva- tion Service (NRCS) show that the San Juan Basin snowpack was down 19 percent from last month.

According to data provided by SNOTEL, the report listed three measurements. The first was the Upper San Juan, with snow depth of 37 inches, and a current median of 47 percent compared to 74 per- cent last year. Vallecito, with a snow depth of 22 inches, was listed at 53 percent as compared to 90 percent median for last year, and Wolf Creek Summit, with a snow depth of 43 inches, was listed at 56 percent as compared to 76 percent median last year.

According to the Colorado Water Supply Outlook report on the United States Department of Ag- riculture site, “Forecasts of any kind are not perfect. Streamflow forecast uncertainty arises from three primary sources: (1) uncer- tain knowledge of future weather conditions, (2) uncertainty in the forecasting procedure, and (3) er- rors in the data. The forecast, there- fore, must be interpreted not as a single value but rather as a range of values with specific probabilities of occurrence.”

From the Estes Park Trail-Gazette (Pamela Johnson):

Snowpack in the South Platte River basin sits at 89 percent of average, while the Upper Colorado basin is recording 78 percent of average at automated sites. Numbers from sites that are measured manually will be released within the next few days, but cumulative snowpack figures have remained below average over the past months…

In Loveland, only 0.37 inches of precipitation fell in March, or 23 percent of average, according to Wendy Ryan, assistant state climatologist at Colorado State University. Over the past three months, 2.24 inches was recorded in Loveland, or 85 percent of normal. During the same time, Loveland’s temperatures were 2.4 degrees above average, according to Ryan…

Brian Werner, spokesman for Northern Water, said storage levels in the Colorado-Big Thompson Project and other local reservoirs remain at all-time highs.

From (Whitney Wild):

Coming off the snowiest February on record, the National Weather Service calls March a dud. The dry spell melted the statewide snowpack from 87 percent of average at the end of February to 69 percent as of Thursday.

“When we talk about snowpack, and we talk about drought, and we talk about how much rain is going to fall, the state doesn’t act all in sync,” NWS meteorologist Bob Glancy said…

In southwest Colorado, the reservoirs are below average and well-below capacity. North of the metro-Denver area, reservoirs are above average but slightly below capacity.

Meanwhile here’s a report about the low snowpack from Bruce Finley writing for The Denver Post:

Colorado’s mountain snowpack is running low — around 69 percent of average — raising concerns about low stream flow during summer and potential strain on water supplies. A relatively hot, dry March took a toll, melting away snowpack from 87 percent at the end of February. The latest data under review by the federal Natural Resources Conservation Service survey team on Thursday showed statewide snowpack at 69 percent of average, with snowpack in southwestern Colorado basins dropping to 55 and 58 percent of average.

In the closely watched Colorado River Basin, snowpack was measured at 76 percent, the early data show. The South Platte River Basin, which supplies metro Denver and northeastern Colorado, had snowpack at 88 percent of average. The Arkansas River Basin was at 83 percent of average…

Water storage in reservoirs statewide measured at 90 percent of last year’s level on March 1. Federal hydrologists had yet to compile the latest water levels in reservoirs.

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