83rd Annual

Wednesday, 12 February 2003: 2:30 PM
Climate Assessment of the 19992002 drought in Colorado
Klaus Wolter, NOAA/ERL/CDC and CIRES, Boulder, CO; and R. Pielke Sr., M. Hoerling, S. Jain, and N. Doesken
After record-setting precipitation in April 1999, and an above-average monsoon during July-August of that year, Colorado, and much of the southwestern U.S. gradually developed drought conditions that reached extreme proportions during 2002. The most recent drought has now surpassed the severity of the 1976/77 and 1980/81 drought years, and is embedded in a larger-scale western drought which rivals the peak drought years of the 1930s and 1950s.

In this paper, we present an analysis of the meteorological and hydrological aspects of this event, ranking it against historic droughts as documented in precipitation records, snowpack data from snow course and SNOTEL sites, streamflow, and reservoir levels through the last century. We also explore a theory for the origin of the drought, in particular its relation to the larger scale drought afflicting much of the West and Eastern seaboard.

Several of the authors of this paper have been involved in the Colorado Drought Task Force that has assessed the impacts of the evolving drought on a monthly basis. This task force was originally established by the Governor of Colorado in response to the droughts of the late 1970s. The State Climatologist has been responsible for a monthly assessment of the precipitation anomalies over Colorado, and scientists at the Climate Diagnostics Center (CDC) have performed research and briefed the task force on climate variability within Colorado, and linkages to climate variability elsewhere, in particular El Nino. Through years of such outreach and applied research, trust was developed and the drought task force now uses both diagnostic and predictive climate information on a regular basis, examples of which will be presented.

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