Record inflow on North Fork of Colorado River

Yesterday's flow of 995 cfs on the North Fork of the Colorado River broke an all-time record, according to records kept by the USGS since 1953.

The previous record was 976 cfs on June 30, 1957. As it turns out, we've been comparing this year's snowpack to 1957 for some time.

Our models suggest there's still plenty of gas in the tank in terms of snowpack, so record-level flows are likely to continue for another day or two.

The North Fork of the Colorado River discharges into Shadow Mountain Reservoir.

Weekend forecast: Peaking rivers, some records

A cocktail of increased temperatures on top of big snowpack may swell area rivers over the weekend. 

The Colorado Basin River Forecast Center recently put out a forecast expecting peaks on all of the high-elevation watersheds in their area this weekend. The center based its forecast on current cool temperatures, which have prevented snowmelt, along with predicted upcoming high temperatures that would kickstart more runoff.

If you had a bird's eye view, the CBRFC's forecast would have you seeing simultaneous peaks in several Upper Colorado basin rivers: the Fraser, Williams Fork, Upper Colorado into Granby, and Blue into Dillion.

The Colorado River at the Cameo gage (between De Beque and Palisade) may have its second peak, possibly higher than the one we saw June 7.

The center is most concerned about Northern Utah, Northwestern Colorado and Southwestern Wyoming. A few streams in Utah and Wyoming, for example, are expected to hit record flows. The forecast also stated that flooding is occurring and will likely continue to occur along rivers where there's still high-elevation snow.

The CBRFC does not forecast Northern Water's East Slope tributaries, but we expect the climate to have similar effects on our snowpack.

Cool temps set stage for record-breaking year

So far, May has been much cooler than normal, keeping our deep snowpack chilled in place. The chart housed here shows inflows to Willow Creek Reservoir reached 950 cfs on Thursday but have since fallen off.

Today (May 24) is the average date for peak inflow to Willow Creek Reservoir. The latest weather forecast suggests that it will be at least another week and maybe considerably longer before we see this year's peak inflows. In fact, we're still adding to the snowpack at a time when we should be nearly melted out!

Right now, we're watching temperature trends very closely. Any sort of sustained warmth will trigger rapid snowmelt.

We're starting to run out of superlatives to describe this year's snow season. It'll be one for the record books in nearly all respects, and we'll be talking about it for years to come.

May 1 forecast brings increased runoff expectations

Northern Water released its May streamflow forecast last week. The May 1 snowpack breaks records for the Blue River, Upper Colorado, Willow Creek, Cache la Poudre and Big Thompson basins. And it's not just in our area - many SNOTEL sites across the Western U.S. broke records for snow water equivalent accumulation this year.

The first SNOTEL stations were established 30 years ago; hydrologically speaking, that's not a very long period of record. So although this year's record snowpack is notable, should we consider it exceptional?

We might want to consider it. A much longer-standing record has been smashed too: the Snow Course at Cameron Pass, which has been around since 1936. The chart here shows the May 1 snow water equivalent, which has 17 percent more water than the previous record (1986)!

However, a record-breaking snowpack doesn't necessarily translate into record-breaking runoff, especially in Northern Water's East Slope watersheds. We need precipitation on top of melting snow to break those records. Still, two of our West Slope basins, the Upper Colorado and Willow Creek, are expected to produce record-breaking runoff this year from snowmelt alone.

Granby releases increase Friday

Beginning at 8 a.m. Friday, outflow from Lake Granby will increase by 50 cfs every two hours until outflow reaches 430 cfs in the late afternoon.

The flow of 430 cfs will be maintained indefinitely. It is the maximum that operators can release out of the valves that sit toward the bottom of Granby. If more water needs to be released, it will come down the spillway at the top of the reservoir, but only after the reservoir rises to the spillway's elevation.

The Colorado Basin River Forecast Center is predicting inflow to Lake Granby to be the largest on record. Northern Water's models agree.

Join us: Runoff season meeting April 13 in Granby

Want to learn more about the 2011 runoff season? Join Northern Water and Reclamation at a public meeting, 6 p.m. Wednesday, April 13 at the Granby Library, 55 Zero Street, in the Community Meeting Room.

Granby Library, from gcld.org

We'll share forecasted runoff and streamflows for spring and summer, along with potential operational changes to the Colorado-Big Thompson and other projects. We'll also answer questions you may have about what to expect this season.

Although inflows are a moving target, we will be working to provide the public with as much information as we can, as soon as we can, during this meeting and throughout the season.

Lake Granby releases increase starting tonight

The April 1 forecasts (the latest available) are indicating a greater inflow to Lake Granby this year than forecasters previously expected. Accordingly, operators are going to make a pre-emptive release of stored water in Lake Granby. Pre-emptive releases help operators balance inflows into a reservoir with the flows going out, and they can curb the need to ramp up releases at faster rates.

Outflow from the reservoir will increase from the current 20 cfs to 80 cfs this evening. Additional increases are scheduled through this week until a rate of 200 cfs is reached; that rate will continue until further notice.

It could be an epic year

Northern Water published its April streamflow forecast today. We expect the flows to be even higher than what we projected a month ago - so high that some of us are using words like "epic" to describe the West Slope snowpack.

Many of our forecasting tools are struggling because of a lack of a key type of data: comparable years. Our forecasters look at similar water years to estimate what kind of runoff to expect, and for many of the basins Northern Water monitors, we have less than a handful of "comparables" available to analyze.

For example, Willow Creek only has one year on SNOTEL record that compares to this year: 1986. That year the seasonal runoff (April through July) on Willow Creek was 85,600 acre feet - 170 percent of average. This year we're not far behind with an anticipated runoff that's 160 percent of average.

The Colorado River Basin Forecast Center has a nice tool for following this year's snowpack and how it matches up to 1986. We're less than an inch away from a record snowpack for Willow Creek ... and the National Weather Service is calling for more snow later this week!

Northern Water forecast: Above-average runoff

Northern Water issued its second 2011 streamflow forecast on March 7. It anticipates above-average seasonal runoff throughout our district collection and service areas. This is in stark contrast to the dry conditions on the eastern plains.

We compute forecasts for eight basins, all of which either directly supply the C-BT and/or Windy Gap projects or provide native water supplies for Northern Water constituents. Updated forecasts will be published in April and May.

We began developing our streamflow forecasting program in 1999. At first, our forecasting tools were used to provide estimates of supply and demand to the Board as they set the quota allocation in April each year. Now, using customized technologies and tools we developed in-house, we also compute short-term streamflow forecasts to support operational decision-making for our West Slope Collection System.