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September 2012 Climate Summary

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Source/Author: Natalie Umphlett - High Plains Regional Climate Center 10/05/12

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September 2012 Climate Summary  

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

Temperature Summary

While most the High Plains Region had near normal average temperatures, September 2012 continued to be dry. Most locations in the Region had average temperatures which were within 1.0-2.0 degrees F (0.6-1.1 degrees C) of normal. The largest temperature departures occurred in a few areas of Wyoming, where average temperatures were over 4.0 degrees F (2.2 degrees C) above normal, and an area along the border of northeastern Kansas and southeastern Nebraska where average temperatures were 2.0-3.0 degrees F (1.1-1.7 degrees C) below normal. Unlike the majority of this year, the temperatures this month were not record setting; however a small number of locations did break into the top 10 warmest Septembers on record. Lander, Wyoming had its 6th warmest September on record with an average temperature of 63.2 degrees F (17.3 degrees C). In 1990, Lander had its warmest September with an average temperature of 64.8 degrees F (18.2 degrees C) (period of record 1891-2012). Even with some below normal temperatures this month, 2012, as a whole, has continued to be one of the warmest on record for much of the Region. For instance, the average temperature in Topeka, Kansas was 0.5 degrees F (0.3 degrees C) below normal this month, but this year’s January 1-September 30 time period still ranked as the warmest. The average temperature in Topeka for that time period was 64.4 degrees F (18.0 degrees C), which easily beat the 1934 record of 62.3 degrees F (16.8 degrees C) (period of record 1887-2012).

Precipitation Summary

September was yet another dry month for the majority of the High Plains Region. Precipitation totals which were less than 50 percent of normal were widespread. In addition, a large area of central and northern South Dakota and pockets of North Dakota, Nebraska, and Wyoming received at most 5 percent of normal precipitation. This dearth of precipitation caused many new records to be set this month. Aberdeen, South Dakota had its driest September on record with only 0.01 inches (0 mm) of precipitation which was 2.18 inches (55 mm) below normal. The old record of 0.05 inches (1 mm) was set back in 1979 (period of record 1893-2012). Interestingly there were numerous stations across South Dakota that received no measurable precipitation this month. One of these locations was Pierre, South Dakota which tied with 1893 for its driest September on record (period of record 1893-2012).

The dry weather continued to have an impact across the Region. According to the U.S. Army Corps of Engineers, the Missouri River had record low inflows this month of just 0.3 million acre feet. The previous record occurred in 1919 with 0.4 million acre feet (period of record 1898-2012). In addition, water and feed shortages for livestock were common and many producers continued to cull livestock. The dry weather did help with crop dry down and by the end of the month, the corn harvest was well ahead of average in Nebraska and the Dakotas.

The only areas of the Region which received above normal precipitation were central and southeastern Colorado, and southwestern and eastern Kansas. These areas had precipitation totals ranging from 110 percent of normal to 300 percent of normal. Denver, Colorado had its 5th wettest September on record with 2.95 inches (75 mm). The record held at 4.67 inches (119 mm), set back in 1961 (period of record 1872-2012). Heavy rainfall in Colorado actually caused problems in areas that had been affected by the wildfires this summer. According to InciWeb, rain caused rock and mud slides in the High Park Fire burn area, west of Fort Collins, Colorado. In addition, numerous trees had also fallen and this combination of rock, mud, and trees caused multiple closures of roads in that area. Luckily, according to The Coloradoan, no property damage or injuries were reported.

Climate Outlook

ENSO-neutral conditions continue and weak El Niño conditions are likely to develop later this fall. For the next three months, the temperature outlook indicates a higher probability of above normal temperatures for the entire High Plains Region, with the highest probability being in the southeastern half of North Dakota, most of South Dakota, the majority of Nebraska, and northeastern Kansas. The precipitation outlook indicates equal chances of above, near, or below normal precipitation for the entire High Plains Region. The seasonal outlooks combine the effects of long-term trends, soil moisture, and when applicable, the El Niño Southern Oscillation cycle (ENSO). More information about these forecasts can be found here.

Drought Watch

According to the U.S. Drought Monitor, there have been significant changes in drought conditions over the last month in the High Plains Region. By the end of September, about 99 percent of the Region was under moderate (D1) to exceptional (D4) drought, with nearly 24 percent of the Region in the D4 designation. In contrast, at the end of last month, only 15 percent of the Region was in D4. D4 areas expanded to include most of the state of Nebraska, a small portion of eastern Wyoming, southeastern South Dakota, northeastern Colorado and much of the western and central parts of Kansas. By the end of the month, just over 75 percent of Nebraska was in D4 drought. Extreme drought conditions (D3) also expanded in Nebraska, North Dakota, South Dakota, and Wyoming. In addition, every part of the Region had at least some sort of drought designation or either abnormally dry conditions (D0). About the only improvements occurred in eastern Kansas, where the remnants of Hurricane Isaac helped downgrade drought conditions there. According to the U.S. Seasonal Drought Outlook released September 20th, drought conditions were expected to improve in the far southeastern corner of Kansas and develop in central North Dakota and northern South Dakota. All other areas of drought in the Region were expected to persist through the end of the year.

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