Wyoming Drought Information
by National Weather Service – Riverton, Wyoming
January 15, 2013
2012 was the driest and warmest for Wyoming in last 118 years. Wyoming received less than one-half its 20th century average of precipitation from March through September 2012. Extreme or severe drought continues to covers much of the state.
2012 was the driest on record for Wyoming dating back to 1895. Statewide average precipitation for the year was only 8.08 inches which was 61 percent of the 20th century statewide average of 13.17 inches. 2012 shatters the previous driest year on record set in 1988 with 8.55 inches of precipitation. This record deficit, and the onset and worsening of drought conditions, was largely created from March through September 2012 when the statewide average precipitation was only 4.54 inches, or 48 percent of the 20th century average of 9.40 inches. This also set a new record for the driest seven month period March through September by over one inch of precipitation. The previous record for this period was 5.67 inches in 1960.
2012 also goes down as the warmest on record for Wyoming since 1895 with a statewide average temperature of 45.6 degrees Fahrenheit, which was 5.1 degrees above the 20th century of 41.5 degrees and breaks the previous warmest year on record of 1934 with an average temperature of 45.0 degrees. Once again, the seven month period of March through September 2012 accounted for the record heat with an average temperature of 56.9 degrees, 5.2 degrees above the 20th century average of 51.7 inches for Wyoming during this period, and shattering the old record for this period of 55.6 set in 2007.
The latest U.S. drought monitor for Wyoming released on January 3rd showed worsening drought conditions across east central Wyoming and some improvement across the far west since early December. Exceptional drought persisted across most of Goshen, Niobrara and Weston counties, creeping into eastern Converse and southeast Campbell counties. A small area of exceptional drought also emerged over central Sweetwater county. Extreme drought covered most of central Wyoming with severe drought remaining across the northeast, southeast and southwest corners of the state. Moderate drought covered most of northwest Wyoming except for Grand Teton and Yellowstone National Parks and the Jackson Hole Valley, which were classified as abnormally dry.
River and stream flow conditions
No river basins in Wyoming were in hydrologic drought conditions during the 28-day watch period for December 2012.
Fire weather impacts
No fuels were classified as critical in any areas across west and central Wyoming. Cooler temperatures, more abundant precipitation and mountain snow cover had moderated fuel conditions in autumn.
Below are the cumulative precipitation amounts from selected locations across west and central Wyoming for January – December 2012.
Location precipitation % average
Big Piney, 2.69 inches, 42% (severe drought)
Buffalo, 8.90 inches, 66% (severe drought)
Casper, 7.88 inches, 63% (extreme drought)
Evanston, 5.35 inches, 45% (severe drought)
Greybull, 2.35 inches, 31% (extreme drought)
Lander, 6.60 inches, 52% (extreme drought)
Riverton, 3.28 inches, 35% (extreme drought)
Rock Springs, 3.01 inches, 35% (extreme drought)
Sheridan, 9.53 inches, 67% (severe drought)
Worland, 2.91 inches, 38% (extreme drought)
Bedford 3 SE, 21.54 inches, 101% (moderate drought)
Billy Creek, 8.57 inches, 68% (severe drought)
Bitter Creek 4 NE, 3.70 inches, 53% (extreme drought)
Fossil Butte National Monument, 9.11 inches, 83% (severe drought)
Green River, 6.72 inches, 81% (extreme drought)
Jeffrey City, 4.07 inches, 40% (extreme drought)
Moose, 18.80 inches, 86%
Old Faithful, 26.44 inches, 104%
Powell Field Station, 4.01 inches, 59% (severe drought)
Riverton (Downtown), 3.98 inches, 47% (extreme drought)
Thermopolis, 4.55 inches, 39% (extreme drought)
The outlook for January shows a 33 to 40 percent chance of below normal temperatures across northern Wyoming or roughly north of a Lusk to Worland to Cody line. The rest of Wyoming has equal chances for above, below or normal temperatures or no significant climate signal.
The northwest portion of the state, or roughly west of a Cody to Cokeville line, has a 33 to 40 percent chance of above normal precipitation in January. The rest of the state has equal chances for above, below or normal precipitation.
The three month outlook for the January, February and March shows a greater than equal chance of above normal temperatures across the far south or roughly south of a Baggs to Kemmerer line. The rest of Wyoming has equal chances of above, below or normal temperatures. The precipitation outlook for this three month period shows a greater than equal chance for above normal precipitation across the northwest, north of a Lovell to Alpine line, and equal chances for above, below or normal precipitation or no significant climate signal across the rest of Wyoming.
The U.S. seasonal drought outlook released on January 3rd showed that drought conditions were likely to persist through March 2013 across all areas in Wyoming currently classified as moderate /d1/ drought or worse.
Development of El Nino conditions stalled out in September in the Pacific Ocean. Enso neutral conditions were observed in November. Enso-neutral conditions are favored through winter 2012-13 and into spring 2013.
Hydrologic summary and outlook
Snowpack data for January 9th
Percent of Average (based on 1981-2010 normals)
Drainage Basin, Snow Water Equivalent (SWE)
Snake River Drainage Basin, 103% Percent of Average
Madison Drainage Basin, 101% Percent of Average
Yellowstone Drainage Basin, 101% Percent of Average
Wind River Drainage Basin, 94% Percent of Average
Big Horn Basin Drainage Basin, 82% Percent of Average
Shoshone River Drainage Basin, 105% Percent of Average
Powder Drainage Basin, 88% Percent of Average
Tongue Drainage Basin, 69% Percent of Average
Belle Fourche Drainage Basin, 62% Percent of Average
Cheyenne Drainage Basin, 65% Percent of Average
Upper North Platte Drainage Basin, 71% Percent of Average
Sweetwater Drainage Basin, 94% Percent of Average
Lower North Platte Drainage Basin, 29% Percent of Average
Laramie Drainage Basin, 65% Percent of Average
South Platte Drainage Basin, 62% Percent of Average
Little Snake River Drainage Basin, 78% Percent of Average
Upper Green Drainage Basin, 96% Percent of Average
Lower Green Drainage Basin, 97% Percent of Average
Upper Bear Drainage Basin, 92% Percent of Average
Reservoir Data For January 9th
Boysen Reservoir, 69.8% full
Buffalo Bill Reservoir, 66.6% full
Bull Lake Reservoir, 50.9% full
Pathfinder Reservoir, 40.9% full
Upper Green River Basin
Big Sandy Reservoir, 18.0% full
Fontenelle Reservoir, 55.0% full
Flaming Gorge Reservoir, 80.0% full
Upper Snake River Basin
Grassy Lake Reservoir, 83.0% full
Jackson Lake Reservoir, 72.0% full
The drought monitor is a multi-agency effort involving NOAA’s National weather Service and National Climatic Data Center, the USDA, state and regional center climatologists and the National Drought Mitigation Center. Information for this statement has been gathered from NWS and FAA observation sites, state Cooperative Extension Services, the USDA, USACE, and USGS.
Drought Impact Reporter To report effects of the drought in your area, click here and go to the drought impact reporter and click on submit a report.
Drought information for media
National Weather Service Riverton drought page
USGS Wyoming Drought Watch
U.S. drought monitor
NOAA drought page
Climate Prediction Center (CPC)
NW Advanced Hydrologic Prediction Service (AHPS)
Water Resource Data System (WRDS)