Flood risk depends on snow, rain, temps
Date posted: March 27, 2014
SHERIDAN — The National Weather Service has issued a hazardous weather outlook for the northeast Bighorn Mountains and Sheridan foothills as a storm system moves through the region and produces wet, heavy snow and rain.
Wet snow and colder temperatures could be hard on young livestock, the outlook said. This morning, 2 to 4 inches of snow was reported from Sheridan to Dayton, and another 1 to 2 inches was expected.
Moving into the weekend, temperatures are expected to reach daytime highs from the mid-40s to lower 60s before another storm system moves in and drops a mixture of rain and snow.
There is a moderate potential for flooding due to snowmelt along the Little and Big Goose Creeks near Sheridan and Clear Creek near Buffalo, Wyoming National Oceanic and Atmospheric Administration Hydrologist James Fahey said in a report issued this week.
Flood potential is higher in the central and southern Bighorn Mountains.
Fahey said mountain snowpack and associated snow water equivalents across Wyoming continue to be above average at 130 percent of median.
Snow water equivalents at peak snowmelt runoff elevations of 8,000-9,500 feet are highest in the northern third of Wyoming, measuring 135 to 160 percent of median.
Flood potential outlooks are based on snow water equivalents in mountain snowpack, how basins respond to snowmelt, extent of burn scars from 2012 and 2013 fires, amount of bark beetle kill, soil moisture trends and likely temperature and precipitation trends for the season.
County Emergency Management Coordinator Dave Coleman said stream gauges are currently about average for the season, but that he and his team are watching them closely. The latest reading of the Goose Creek guage in Sheridan was 2.19 feet. Flood stage is 7.5 feet. The latest reading at the Tongue River gauge near Dayton was 1.83 feet. Flood stage there is 6 feet.
Coleman said it’s too early to fill sandbags because the bags are biodegradable and can start decaying in the sun.
However, the county does have 30,000 empty sandbags on hand, with more available from the Wyoming Office of Homeland Security. Volunteers from the Girls’ School and Normative Services are lined up to help should need arise.
At this point, Coleman said it’s a matter of watching, waiting and being as ready as possible for any flooding that may occur.
“The melt hasn’t started on the mountain yet. If it goes as a normal spring where it’s cool at night and warms up during the day, we could have normal runoff. If it would get hot and stay warm for a number of days plus rain on top of that, the potential for flooding certainly exists,” Coleman said.
“It’s a guessing game right now. It’s all contingent upon Mother Nature.”
In the meantime, Coleman and his team have been holding conference calls with the National Weather Service out of Billings, Mont., and the Office of Homeland Security in Cheyenne to make sure communication lines remain open.
The weather service in Billings does forecasting for the Sheridan area and has said it will monitor weather trends and keep Coleman and other government officials up-to-date. Homeland Security in Cheyenne has been keeping a close eye on flood potentials around the state following the flooding that occurred due to ice jams in Big Horn County earlier in March.
Sand and sandbags are available at no charge at the Road and Bridge Shop at 48 Short Road Monday through Thursday from 6 a.m. to 4 p.m. For help outside of normal hours or for more information, call the Sheridan County Public Works office at 674-2920.
• The U.S. Geological Survey WaterAlert service sends text or email messages regarding flood potential. Sign up to receive alerts online at maps.waterdata.usgs.gov/mapper/wateralert/.