Greater Yellowstone Network Climate of 2008

Gray, Stephen; Nicholson, Christopher; Ogden, Michelle

A report regarding the climate patterns observed in the Greater Yellowstone Network during 2008. Information such as methods and strategies of the study is included, as is data concerning precipitation, temperature, snowpack, streamflow, and drought status. This report describes the climate of 2008 for parksin the Greater Yellowstone Network (GRYN; BighornCanyon National Recreation Area, Grand TetonNational Park, and Yellowstone National Park) andsurrounding areas. It focuses on temperature and precipitation,while providing supplemental informationon snowpack, streamflow, and the regional droughtstatus. The report includes a series of maps that conveyGRYN area climatic conditions, as well as records fromindividual observing stations used to highlight variabilityat finer-scales within the GRYN.Compared to the standard climatological referenceperiod (currently 1971–2000), the GRYN received 87%of average precipitation in 2008. Although the GRYNarea was slightly drier than 1971–2000, it was less drythan in 2007 when the area received ~80% of averageprecipitation. May 2008 was especially notable forbringing major improvements to the area’s moisturestatus. Bighorn Canyon in particular received largeamounts of precipitation as a string of storms movedthrough the area from 22 May to 27 May. July wasdry throughout the GRYN area, with parts of Yellowstoneand Bighorn Canyon receiving less than 25% ofaverage precipitation. Yellowstone and Grand Tetonhad lower-than-average precipitation in August andSeptember. Large storms in late December closed theyear on a wet note.Compared to 2007—an especially hot year by mostmeasures—temperatures in 2008 were much closerto average. The GRYN was generally cold in January2008, but lower-than-average temperatures were especiallyprominent in Yellowstone and Grand Teton. AtOld Faithful in Yellowstone, for example, the maximumtemperatures in January were 6.1°F below average,while maximum temperatures at Moran in GrandTeton were 4.5°F below average. Spring and early summer2008 were cool to near average across the GRYNarea. July and August were warm in Yellowstone andGrand Teton, with maximum daily temperatures rangingfrom 2°F to 4°F warmer than average. Stations inYellowstone and Grand Teton reported a large numberof days exceeding 80°F in 2008. November 2008 wasmarked by very warm temperatures, with the Mammothstation in Yellowstone recording minimum dailytemperatures for the month at 9.3°F above average.Most stations recorded near average temperatures inDecember 2008, though key locations in Yellowstonewere generally ~2°F cooler than long-term means.The climate of 2008 brought near average snowpackto the GRYN, making it one of the wettest wintersthe GRYN area has experienced in the last 7–9 years.GRYN area stream conditions were characterized bynear-average to slightly higher-than-average discharge.Unlike many years in the past decade, highcountrysnowpack persisted into the early summer, leading tonear or slightly above average flows later in the summer.Persistent snowpack combined with residualmoisture from late May storms helped the area avoidthe onset of severe drought conditions later in thesummer and fall.

Greater Yellowstone Network Climate of 2008

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