Monsoon finally here, weather experts say
respite from extreme fire danger and partially greening parched vegetation and lawns.
The National Weather Service predicts the moisture will continue through midweek. The widely dispersed rains – torrential at times Monday afternoon – created some localized flooding in Avon, washing out gullies and causing mudflows at the base of Metcalf and Nottingham Roads in Avon and elsewhere.
Interstate 70 travelers found the driving a bit dodgy, too, having to slow because of poor visibility and lots of spray. Several auto accidents were reported.
“It looks like we are in the monsoonal pattern now,” said the National Weather Service’s John Kyle. “The 90-day forecast, August through October, is for an above-normal chance of above-normal precipitation.”
Monsoonal flows draw moisture from the gulfs of California and Mexico into the Rocky Mountains, where the moisture typically produces heavy afternoon rains and thunderstorms.
The rains are expected to make little headway, however, on ending the region’s worst drought on record. The flows of local streams are still just 20 percent of normal, with watering restrictions still in place.
The rains should reduce reliance on irrigation, however, and help flows of local streams, which are now at record lows.
The Eagle River last week in Avon, for example, was flowing at 38 cubic feet per second, or cfs, just 20 percent of normal. Without precipitation, the flow of the river could reach 15 cfs, a level typical for the low-flow months of January and February.
Temperatures, meanwhile, have been above normal, while precipitation has been below normal. June’s precipitation at Avon was just 0.08 inches; normal precipitation is 1.07 inches. July saw 0.98 inches of rain; 1.9 inches is normal.
The rain is good news, however, for local fire crews who have been stretched thin by plenty of fires across the region. Dry conditions created the worst fire season Colorado has experienced, burning more than 425,000 acres. Eagle County so far has seen nearly two-dozen fires, most of them less than five acres in size. Last week a 1,700-acre blaze, believed to have been started by a construction crew, burned near El Jebel in the southwestern part of the county, destroying three structures.
The area’s extreme fire danger fortunately is somewhat reduced by the recent rains.
“It all depends on how long and intense this surge of moisture is and what the weather does,” said Holy Cross District Ranger Cal Wettstein.
But the rains aren’t a quick fix. The fire danger could return, he said,
“The added complexity of this is a lot of the shrubs have been hit hard with dry conditions and lost foliage and a lot of grasses have cured,” he said. “It’s not a simple matter of just because we have rain the fire danger going away. The danger is still there.”
Ironically, the local water districts just last week increased water restrictions, created a target river flow of 25 cfs at Avon and severely limited lawn sprinkling. The heavy rains Monday caused the Eagle’s flow to jump from 58 cfs to 70 cfs, still just 36 percent of mean flow.
Boulder hydrologist Bob Weaver of Hydroshpere, a consultant to the local water authorities, said the rains will provide only short-term relief. Streams and rivers depend on snowmelt for 70 percent of their water, he said.
Some rains this summer have produced impressive spikes in river flows, but those have been short in duration, typically less than 72 hours. July 4 rains, for example, briefly tripled the flow of the Eagle.