May 2009 Climate Summary

For a printable version of the climate summary which includes more figures, data tables, and state summaries, click here.

Temperature Summary

Temperatures across the High Plains Region were near normal with common average monthly temperature departures ranging from 2°F (1.1°C) above normal to 2°F (1.1°C) below normal.  The exceptions were North Dakota and Colorado where average monthly temperature departures were as large as 6°F (3.3°C) below normal and 8°F (4.4°C) above normal, respectively.  The cool temperatures in North Dakota were not record breaking however, Cheesman, CO recorded its 4th warmest May with an average temperature of 55.0°F (12.8°C), which was 6.8°F (3.8°C) above normal.

Precipitation Summary

May 2009 was a month of record setting dryness across the High Plains Region as a weak precipitation pattern dominated.  Most of the Region received less than 70% of normal precipitation and large swaths received less than 50% of normal precipitation.  Ultimately, several locations across the region recorded the driest May on record.  This month’s extreme dry location was Wamego 4W, KS which broke a 108 year record by receiving only 0.52 inches (13.2 mm) of precipitation.  The old record of 0.92 inches (23.4 mm) was set back in 1901.  

While the vast majority of the High Plains Region was dry, western Colorado, and small portions of Kansas, Nebraska, and North Dakota received above normal precipitation.  This month’s extreme wet location was Leadville, CO.  The Leadville Lake County Airport recorded its wettest May with 2.66 inches (67.6 mm), or 422% of normal precipitation.  Of this monthly total, 0.82 inches (20.8 mm) fell in one day (May 31), which set a daily record.  Interestingly, this daily record was over 1000% of the previous record of 0.07 inches (1.8 mm) set back in 1983.

Climate Outlook

ENSO-neutral conditions are present and based on trends in both forecasts and observations, the ENSO-neutral conditions are expected to continue through the summer months.  The temperature outlook indicates a higher probability of above normal temperatures for Colorado, Wyoming, and a small portion of western Nebraska, and a higher probability of below normal temperatures for North Dakota and the majority of South Dakota.  Elsewhere in the region, equal chances of above, near, or below normal temperatures are predicted.  The precipitation outlook indicates a higher probability of above normal precipitation for western Colorado.  Elsewhere in the region, equal chances of above, near, or below normal precipitation is predicted.  More information about these forecasts can be found here.

Drought Watch

May was another dry month for portions of the High Plains Region with many locations currently 3-6 inches (76.2-152.4 mm) below normal for the year.  The combination of cool temperatures and ample soil moisture staved off drought conditions, but stress on some emerging crops is now evident.  Since last month, the abnormally dry conditions (D0) in eastern Nebraska and north-central Kansas have expanded to include much of South Dakota and a portion of the Nebraska panhandle.  In the western portion of the High Plains Region, drought conditions have improved.  In south-central Colorado moderate drought conditions (D1) have been downgraded to D0 and portions of the D0 in both Wyoming and Colorado have been erased.  According to the U.S. Seasonal Drought Outlook released on May 21, drought conditions in Colorado and Wyoming are expected to improve through August 2009.