The National Weather Service’s “Hydrological Outlook” advisory says there is a high probability of localized flooding in mid-elevation watersheds as the state warms.
Most of Utah is under a “hydrological outlook” as Salt Lake City prepares to hit the early 80s early next week, according to the National Weather Service.
The warning was issued around 1.30pm Thursday afternoon and warns of “significant increases” in waterways due to increased snowmelt. The service urged caution, as cold water will flow rapidly in rivers, streams and streams – so even short periods of time in the water can cause hypothermia.
There is a high possibility of localized flooding in some mid-elevation watersheds in northern Utah early next week, the service said. A high-pressure system moving through the state will also result in temperatures 15 to 20 degrees above normal and accelerate the melting of Utah’s record snowpack.
In Salt Lake City, forecasters are expecting a sunny weekend with a high of 83 degrees on Monday. Temperatures then cool down with a chance of Thursday showers and a forecast high of 70 degrees.
The Salt Lake City Public Utilities Office is bracing for increased power flows amid higher temperatures and anticipates the city’s systems will be able to accommodate snowmelt. Drain experts will also continue to monitor and clean the city’s drainage system “around the clock,” Public Utilities director Laura Briefer said in a statement.
Emigration Creek and Red Butte Creek are the city’s main areas of focus right now, said Brian McInerney, a hydrologist who advises the city on flooding. City Creek, Big Cottonwood, Mill Creek and Little Cottonwood canyons have such a large amount of snow cover that it “will take a while” for them to release meltwater, he added.
“They’re not mature yet, so we’re not seeing a big spike,” McInerney said. But we’ll see the lower elevation watersheds like Red Butte and Emigration faster, but we still don’t have flooding.”
Officials expect the highest flows will occur towards the end of May and early June.
“What we’ve seen so far is that the flows can’t rise even though it’s hot because they’re not isothermal and don’t provide meltwater,” McInerney said. “So think of a drop of water at the top [of the mountains] comes into the sun, melts and starts trickling through the snowpack making it about – and I measured that two days ago – 35 centimeters down. And then it freezes again because the pack is cold so water doesn’t get into the ground or into the streams.”
Controlled releases from Mountain Dell and Little Dell reservoirs will result in higher discharges from Parleys Creek and will be visible in Parleys Nature Preserve, Sugar House Park and Hidden Hollow, officials said. These controlled releases help reduce runoff pressure on the city by maintaining upstream capacity in the Parleys watershed, officials said.
Salt Lake City residents can call 801-483-6700 to report flooding.