Below are my notes from yesterday’s meeting:
Water Supply
Nolan Doesken (Colorado State Climatologist) reported that, “Warm weather has kicked in.” There was an early heat wave in March which resulted in some minor flooding in the Wet Mountain Valley. Runoff has started and the, “green up is well underway,” he said. A heavy wet snow in early March really helped the Yampa Valley in Routt and Moffat counties.
The eastern slope and Sangre de Cristo Mountains have been wetter than average. He added that, “Grand Lake is the poster child for dry conditions in Colorado…No matter what happens across the state it seems to miss Grand Lake.”
Reports by weather station: Burlington still tracking at near record moisture; Akron is close to average; Fort Collins has had good moisture; and Kassler was tracking at near record moisture but is now at the average; Boulder is down to near average moisture for the water year.
Mike Gillespie (NRCS) reported that snowpack in the South Platte Basin is well below average at 75% of average on April 20. The peak was 89% of average on April 9. Storage in the basin is at 102% of average.
Clear Creek and the Poudre River are expected to have below average runoff this season.
Klaus Wolter (University of Colorado) reported that, “El Nino is starting to founder…It probably peaked in January.” He said that Colorado can expect 1-2 inches of moisture over the next two weeks from two storms. The cool temperatures over the next two weeks, “will slow snowmelt.”
Thomas Ley (Colorado Division of Water Resources) reported that streamflow in the Poudre is dropping as is the South Platte at Kersey. He felt that the reason was probably an increase in diversions with the start of irrigation season.
Flood Risk
As at the March meeting the National Weather Service representative rates the risk of flooding from snowmelt as very low. Conditions, “are not indicating any flooding due to snowpack.”
A representative from the Colorado Water Conservation Board asked all municipalities to send comments on the proposed new floodplain rules. Here’s the link: http://cwcb.state.co.us/NR/rdonlyres/98D13420-A1B5-4910-8EA2-345D2C53853A/0/FINALDRAFT2010Rules.pdf
Doesken took the opportunity to remind people that flooding does not always depend on high runoff in the streams. He said that Colorado’s largest flood occurred in 1999 (Pueblo County?) on April 30 in what had been a very dry year.
The CWCB flood threat webpage (http://www.hdrwebprojects.com/COSWP/) is still not active but CWCB staff indicated it would be up and running by May 1.
More CWCB coverage here.