Here it comes.
This week’s blast of statewide warm weather will kick-start a deluge of melting snowpack that will likely cause some minor flooding.
Monday morning, the National Weather Service issued a flood watch for the East River near Almont, the Green River in Uintah County and the Yampa River in Moffat County. Isolated flooding was reported on the Rio San Antonio near Manassa, and a creeping landslide along Archuleta County’s East Fork of the San Juan River was threatening a gas line.
The Elk River north of Steamboat Springs is expected to reach flood stage this week. And a record snowfall above Aspen is raising flood concerns along the Roaring Fork River, which has yet to begin surging with any whitewater.
“I think with these next four, five, six days of really warm weather, things are going to start to bust loose,” said Tom Ley, chief hydrographer for Colorado’s Division of Water Resources.
The Colorado Flood Task Force meets once a month every spring to study weather forecasts, streamflow projections, snowpack averages and reservoir capacities as it tries to predict problem flooding.
During the first two meetings, southern Colorado emerged as a hot spot for flooding, but a warm, dry April there has eased that threat. In the central and northern mountains, meanwhile, a cool April and plenty of new snowfall sustained and even added snowpack, raising the possibility of flooding in river basins considered safe only a month earlier.
The Gunnison River basin’s snowpack, for example, climbed from 128 percent of average on April 1 to 141 percent of average in mid-May, a time when snowpacks typically begin to dry out.
The East River, which feeds the Gunnison River and runs through Crested Butte, saw its snowpack climb from a barely manageable 147 percent of average in early March to 205 percent of average in early May.
Gunnison County’s emergency-management team on Friday sent out reverse-911 calls to all residents along the East River, warning them to watch for a surge that could slip the banks.
“We were just telling them to be prepared,” said Gunnison County emergency-services manager Scott Morrill. “We’ve been waiting. Now we get to see what it’s going to do.”
Reservoirs across the state are draining in anticipation of the pending surge in snowmelt. And this week’s warm weather — with predicted lows in the mountains not dipping below freezing — is already reducing high-elevation snowpack by as much as an inch a day.
“It seems to me local emergency managers in several counties will be on high alert this week,” said Tom Browning, chief of the state’s Watershed Protection and Flood Mitigation team.
Jason Blevins: 303-954-1374 or jblevins@denverpost.com
