That means rivers and streams swollen with runoff, forecasters say.

It also means the tranquil mountain waters will transform for the next few weeks into potential drowning-death traps.

The mountain snow is ripe to melt, according to Brian McInerney, a hydrologist for the National Weather Service in Salt Lake City. With weekend temperatures expected to climb into the high 80s, and perhaps low 90s in northern Utah, the next two weeks looks likely to be the peak runoff period for Mill Creek, Big and Little Cottonwood creeks, and the Weber, Bear and Logan rivers.

"It should be ready to roll," said McInerney.

Plus, dust from the storms in April and last year's Milford Flat fires, which lowers the snow's reflectivity, has the potential to speed up the melt-off, McInerney said.

Flowing rivers are expected to be running at their highest and fastest beginning around Tuesday. They will come to the top of the stream banks and perhaps a bit higher, McInerney said.

"The streams are going to be dangerous," he said, noting that Utah rivers often claim lives during the peak runoff.

Ditto, said Randy Julander, snow survey supervisor for the federal Natural Resources Conservation Service. "The water is going to be high, it's going to be fast, and it's going to be cold."

This year's peak runoff will be "100 percent different from last year," Julander added. By this time in 2007, the meager snowpack already had melted into the streams and the peak flows had passed, he said.

Neither Julander nor McInerney sounded an alarm about flooding. It would take a lot of unexpected rain for flooding to be a problem this year, they said.

The snowpack would have to be bigger - drier-than-normal March and April put a check on precipitation levels - and soil moisture would have to be greater for flood risk to be higher.

For people on the bigger rivers, including the Colorado, the hearty runoff will only add to the fun.

"If you're rafting the Colorado, you're going to be having fun," said Julander. "But it's not going to be death-defying."

Meanwhile, Bob Parenti, director of the Utah Safety Council, restated the warning about avoiding the fast-flowing streams during the high-runoff period, which will include the Memorial Day holiday this year.

"Parents need to be extremely careful," Parenti cautioned, noting that the dangerous undercurrents can be hard to miss in fast-flowing water. "It's best this time of year to stay away."

fahys@sltrib.com

* Avoid fast-moving water.

* Watch children closely.

* Call 911 immediately if someone is swept in.

* Stay safe while trying to help.

Source: Utah Safety Council