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The temperature at Nowata, Oklahoma, fell to -31°F (-35.0°C) at 7:40 a.m. CST (GMT - 6) on 10 February 2011, establishing a potential new minimum temperature record for the state of Oklahoma. This replaced the old record of -27°F (-32.8°C) set at Vinita on 13 February 1905, at Watts on 18 January 1930, and at Guthrie on 4 January 1947. The temperature at several other Oklahoma weather stations fell to -27°F or colder on 10 February 2011, breaking or tying the previous state record; these were at Bartlesville Municipal Airport (-28°F), Blackwell 4SSE Mesonet (-27°F), Medford 1 SW Mesonet (-27°F), Miami (-28°F), Pryor Mesonet (-28°F), and Ralston (-29°F). The purpose of this article is to describe the circumstances of the new recordcold temperature at Nowata following the manner of previous reviews of state or regional cold records.
The Nowata station is located in Nowata County (36°44'37"N, 95°36'28"W) at 206-m elevation above sea level. The station is part of the Oklahoma Mesonet (www.mesonet.org) and was established on 1 January 1994. The Oklahoma Mesonet consists of 120 automated weather stations that transmit data in near-real time to the Oklahoma Climatological Survey at the University of Oklahoma. Temperature is measured 1.5 m above the soil surface with a Thermometrics thermometer with accuracy of 0.5°C, and housed in an aspirated radiation shield. This is similar to the temperature sensors in the U.S. Climate Reference Network that Lin and colleagues (in a 2005 study) found to be a few tenths of a degree cooler than a nonaspirated thermometer of the maximumminimum temperature system (MMTS) while temperatures were cooling at night over snow-covered ground. Lin and colleagues attributed the small "bias" to the nonaspirated MMTS thermometer. The area within 1,000 m of the station is open, flat terrain with agricultural land use (Fig. 1). The station is not in a valley or depression that might contribute to the development of extreme cold, as exists at some other locations of state cold records.
Severe winter weather was widespread across Oklahoma during the first 10 days of February 2011. A snowstorm on 31 January.1 February brought high winds and 30.48 cm of snow from Oklahoma City to Tulsa and Bartlesville,...