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September 2013 Climate Summary

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Source/Author: Natalie Umphlett - High Plains Regional Climate Center 10/07/13

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September 2013 Climate Summary  

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

Temperature Summary

September 2013 was quite warm across the High Plains Region - even a mid-month cool down could not drop the monthly average temperatures to below normal. A large area of the Region stretching from central Kansas and eastern Colorado to the Canadian border had average temperatures of at least 4.0 degrees F (2.2 degrees C) above normal. Even some pockets of Nebraska, Wyoming, and the Dakotas had temperature departures of up to 8.0 degrees F (4.4 degrees C) above normal. As a result, many locations ranked in the top 10 warmest Septembers on record. For instance, Huron, South Dakota had its 3rd warmest September on record with an average temperature of 68.4 degrees F (20.2 degrees C), which was 6.7 degrees F (3.7 degrees C) above normal (period of record 1881-2013). Extremely warm temperatures at the beginning of the month also led to many daily records. The highest temperature in the Region occurred in Beaver City, Nebraska on the 8th with 109 degrees F (42.8 degrees C). Not only did this set a new record for the day, this also tied with September 3, 1947 for the highest September temperature on record (period of record 1893-2013). Another extreme location was Denver, Colorado which tied for its highest September temperature of 97 degrees F (36.1 degrees C) on both the 5th and the 6th (period of record 1872-2013).

Precipitation Summary

Precipitation was the big story this month in the High Plains Region. Copious amounts of rain fell across Colorado, Wyoming, much of North Dakota, northern South Dakota, western Kansas, and the panhandle of Nebraska where precipitation totals of 200-400 percent of normal were common. Most of the precipitation fell in one week – the 9th through the 15th. Precipitation totals even topped 400 percent of normal in north-central and northeastern Colorado, southern Wyoming, northwestern Kansas, and an area along the southwestern border of the Dakotas. While the destructive flooding in Colorado grabbed the headlines, other areas in the Region received large amounts of precipitation and flash flooding as well (For more information on Colorado’s historic precipitation, please see page 3). Some areas actually did miss out on the rains and received less than 50 percent of normal precipitation. Those areas included southeastern Kansas, northeastern Nebraska, and parts of central and southeastern South Dakota.

Numerous records were set this month – daily, monthly, and even some all-time records were just completely smashed. One example is from Goodland, Kansas which received 6.49 inches (165 mm) of precipitation. This new record for September was 5.27 inches (134 mm) above normal, or a whopping 532 percent of normal precipitation! The old record of 5.39 inches (137 mm) was set back in 1973 (period of record 1895-2013). 4.11 inches (104 mm) of the monthly total fell on the 12th and just obliterated the old daily record of 0.85 inches (22 mm). The rainfall on that day went down as the second highest one-day rainfall total on record and came just short of the record 4.15 inches (105 mm) that fell on June 28, 1989. Interestingly, even with the extremely heavy rainfall, Goodland was still running a precipitation deficit for the year. Wyoming had its share of records as well. Cheyenne, Wyoming set a new record for wettest September with 6.95 inches (177 mm) of precipitation which was 470 percent of normal. The old record of 4.52 inches (115 mm) also occurred in 1973 (period of record 1871-2013). Just like Colorado, the bulk of the precipitation (5.79 inches / 147 mm) fell during the week of the 9th-15th. The heaviest day for Cheyenne was the 13th with 1.37 inches (35 mm) and this snuck past the old record of 1.06 inches (27 mm) received in 1996.

Climate Outlook

ENSO-neutral conditions were still present at the end of September and are likely to continue into the winter. For the next three months, the temperature outlook indicates a higher probability of above normal temperatures for roughly the southwestern halves of Colorado and Wyoming. Equal chances of above, near, or below normal temperatures exist for the rest of the Region. Meanwhile, the precipitation outlook indicates a higher probability of above normal precipitation in only one area of the nation including northern Wyoming, most of Montana, northern Idaho, northeastern Oregon, and eastern Washington. Equal chances of above, near, or below normal precipitation exist for the rest of the 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

Many changes were in store for the U.S. Drought Monitor over the past month. At the end of August, approximately 64 percent of the Region was in moderate (D1) to exceptional (D4) drought, but by the end of the month this was down to just under 50 percent. Colorado had the largest improvements and experienced a decline in drought coverage from about 94 percent to just under 65 percent. Unfortunately, much of the rain that fell caused towns, roads, bridges, and farmland to become inundated in one of the worst floods in at least 35 years. All D4 conditions were eliminated in Nebraska and Kansas and only a small portion remained in eastern Colorado. Moderate to heavy rain also fell in southern Wyoming, western Nebraska, and western Kansas, improving drought conditions there as well. One of the only areas in the Region that showed declines was northeastern South Dakota where recent heat and dryness led to a one category degradation to severe drought (D2) there. According to the U.S. Seasonal Drought Outlook released September 19th, current drought conditions should persist everywhere in the High Plains Region through December 2013. No improvements were expected.

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