Willow Creek releases will reach 1,200 cfs today

We expect releases from Willow Creek Reservoir to reach 1,200 cfs today. This is our preferred maximum release rate. Once that rate of outflow is reached, we will allow the reservoir to start filling.

Flows below Willow Creek Reservoir

Temperatures yesterday were higher than forecasted, and they have been today too. We expect inflows to Willow Creek Reservoir to continue to climb today and in the coming days.

Flows above/into Willow Creek Reservoir

NWS predicts hot temperatures next week; could create flood conditions

The National Weather Service is starting to sound the alarm about warm weather next week, which could trigger rapid snowmelt and possible flooding. From today's forecast discussion (issued 3:33 p.m. today by the Denver/Boulder office):

BY MONDAY...UPPER TROUGH OUT WEST PASSES TO THE NORTH OF THE STATE AND WINDS TURN WESTERLY WHICH WILL START THE BIG WARM UP INITIALLY EAST OF THE MTNS. TUESDAY AND BEYOND...MODELS SHOW STRONG AND STEADY WARMING AS THE HOT UPPER RIDGE OVER TEXAS EXPANDS NORTHWARD OVER THE REGION. COULD SEE TEMPERATURES ON THE PLAINS BY MID TO LATE WEEK IN THE UPR 80S/LOWER 90S...WITH HIGH COUNTRY TEMPERATURES IN THE 70S/LOWER 80S. BUT IT'S THE NIGHT TIME TEMPERATURES IN THE 40S/LOWER 50S IN THE HIGH COUNTRY THAT WILL BE ON MOST CONCERN AS THESE READINGS WILL ACCELERATE THE MELTING OF THE RECORD SNOWPACK... LEADING TO HEAVY RUNOFF AND POTENTIALLY SIGNIFICANT FLOODING ON MANY HIGH COUNTRY STREAMS AND CREEKS.

HYDROLOGY...NO CONVECTION EXPECTED THROUGH THE NEXT 24 HOURS OVER THE FOURMILE CANYON AREA. 

TEMPERATURES WILL CLIMB ABOVE NORMAL NEXT WEEK WEDNESDAY WITH HIGHS IN THE 50S TO 60S...IN THE MOUNTAINS WITH 70S TO LOWER 80S IN THE MOUNTAIN VALLEYS. THESE ABOVE NORMAL TEMPERATURES WILL PERSIST THROUGH NEXT WEEKEND. OVERNIGHT LOW ARE EXPECTED TO REMAIN ABOVE FREEZING IN THE MOUNTAINS. THIS WILL RESULT IN RAPID SNOW MELT OF THE EXTENSIVE SNOWPACK. LOW LYING AREAS NEAR MOUNTAIN RIVERS AND CREEKS CAN EXPECT FLOODING WITH WIDESPREAD FLOODING POSSIBLE LATE NEXT WEEK AND NEXT WEEKEND.

This forecast discussion changes every 12 hours as new forecasts are published.

Looking ahead to extreme runoff

Even though it's called "forecasting," predicting runoff doesn't come with a crystal ball, in part because we cannot know Mother Nature's next move.

We do know now that we have record-setting snowpack in the high country. But we don't know exactly how that snowpack will translate into streamflow. A sudden heat wave or another soggy spring storm can alter the picture in unexpected ways.

Northern Water has a suite of tools to forecast water supplies. However, most of those tools were designed to predict total streamflow volume, or the total amount of water runoff will add to stored supplies. These models were not explicitly designed to predict or analyze flood flows. Similarly, Northern Water does not own or operate any facilities designed for the sole purpose of flood protection.

However, there are some other good places to look for flood flow information:

• The National Weather Service maintains models that predict flood flows. Their Advanced Hydrologic Prediction Service provides real-time information and, for a few locations, expected flow forecasts.
• Across the country, designated basin forecast centers provide detailed information about river flows. For areas west of the Continental Divide, the Colorado Basin River Forecast Center has a comprehensive website that details short-term forecasts, water supply forecasts and estimates of peak flow magnitudes and dates.
• For areas east of the Continental Divide, the Missouri River Forecast Center has a website that mostly duplicates the Advanced Hydrologic Prediction Service material. This week, the map on their home page has been lit up with flooding problems across the northern plains.

This 2011 Runoff Update site originally focused on the unusual runoff expected in Northern Water's West Slope watersheds. As the snow has piled on, we will also use this site to communicate runoff conditions on the East Slope.

Historically, Colorado flood events causing property damage and loss of life were the result of torrential rains and cloudbursts, not snowmelt. But with a record-setting snowpack still in place this week - a time by which most of our snow has normally melted - we can't afford to discount the possibility of damaging floodwaters.

Staying informed is one way to stay safe.

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.

Make your own streamflow dashboard page

Would you like to be able to see all of your favorite streamflow gages on one page? Colorado's Division of Water Resources has a Web page that allows you to do just that.

Here are step-by-step instructions for creating your own Northern Water Gage Page.

1. Go to this link and click on the "My Stations" link at the bottom right.

2. Select stations of interest and, one by one, move them from the left side ("Available") box to the right side ("Current Station List") box. Here's a list of stations to get you started. This list will allow you to watch key canyon gages on the East Slope and key collection system flows on the West Slope:

ADATUNCO, ALVA B. ADAMS TUNNEL AT EAST PORTAL NEAR ESTES PARK
BOCOROCO, BOULDER CREEK NEAR ORODELL
SVCLYOCO, SAINT VRAIN CREEK AT LYONS, CO
BTABESCO, BIG THOMPSON RIVER ABOVE LAKE ESTES
BTCANYCO, BIG THOMPSON RIVER AT MOUTH OF CANYON NEAR DRAKE
CLAFTCCO, CACHE LA POUDRE AT CANYON MOUTH NEAR FORT COLLINS
CLANSECO, NORTH FORK CACHE LA POUDRE RIVER BELOW SEAMAN RESERVOIR
COLNGBCO, COLORADO RIVER NEAR GRANBY
COLBAKCO, COLORADO R BELOW BAKER GULCH, NR GRAND LAKE, CO
FRAGRACO, FRASER RIVER AT GRANBY, CO
COLAWICO, COLORADO RIVER AT WINDY GAP, NEAR GRANBY, CO
WILABVCO, WILLOW CREEK ABOVE WILLOW CREEK RESERVOIR
WILWCRCO, WILLOW CREEK BELOW WILLOW CREEK RESERVOIR

3. If you want the list to be in a particular order, use the arrow buttons to sort.

4. After you've populated your Current Station List and sorted it, enter a name in the box at the bottom of the screen (you can keep the name "My Stations" if you like) and click "Save."

5. After you save the list, a "Current Conditions" page appears. This is a list of all of your stations with the current values. Bookmark this page!

6. Click on the "Graph(s)" tab to see 10-day graphs for all of your gages.

7. Add or remove gages any time by going to the "Edit List" tab. Remember to save your changes.

Thank you, DWR - this is a great tool!

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.

Morning spike in Willow Creek releases

Operators tested the outlet works at Willow Creek Reservoir this morning. They initially released 900 cfs and then went up to 1,200 cfs for a brief period. This was a test to check operations for the releases we anticipate making. It was successful, and we're back to passing inflows.

The graph here shows the spike in flow that occurred this morning.

Warm weather triggers increased snowmelt

Warm weekend temperatures increased the inflow to Willow Creek Reservoir. Right now we are holding the reservoir's elevation steady at around 8,092 feet and passing inflows right through. The highest release so far this year was 782 cfs at 9:45 this morning.

Releases from Lake Granby are holding steady at about 400 cfs. Below the dam at Lake Granby there are small side tributaries that add to the flow of the river, so flows can be higher by the time they reach the "Y Gage" (listed as "Colorado River near Granby, CO" on the USGS website). Saturday evening was a good example: the flows were at 600 cfs, so the tributaries likely contributed about 200 cfs. The flow has not been as high since then.

The schematic shown with this post shows the various stream gages below Willow Creek Reservoir and Lake Granby. The releases from Granby and Willow Creek reservoirs, along with the flow of the Fraser River, all add to the Colorado River's flow as measured below Windy Gap Reservoir. Today, that flow went above 2,000 cfs for the first time this year. The flows are affected by Denver Water's diversions; they aren't diverting much Fraser River water right now because it has been so cold.