It took a bit of convincing, but Mother Nature finally gave the okay for fall to arrive during the final week of October. That change in seasons took the state from a warm, dry pattern that had persisted for the past three months to much more seasonable and rainy weather. Two successive storm systems at the end of the month brought heavy rains to much of southern and western Oklahoma, halting the advance of the flash drought that began during the heat of August. Those areas saw between 3-7 inches of rain, and in some areas of south central Oklahoma, more than 9 inches of moisture fell. Unfortunately, parts of northern and eastern Oklahoma came out on the short side with amounts of 2 inches or less. Areas of Grant and Garfield counties saw less than an inch for the month.
Statewide, the Oklahoma Mesonet recorded an average of 3.43 inches, 0.11 inches below normal but still ranked as the 42nd wettest October since records began in 1895. To demonstrate the contrast in fortunes, south central Oklahoma recorded an average of 6.41 inches while the north central region received 1.61 inches. Those values rank as the 16th wettest and 45th driest on record for those areas, respectively. The Panhandle more than doubled the northeast’s meager total with an average of 3.89 inches, 2.19 inches above normal and ranked as its ninth wettest October on record. Madill led the Mesonet during October with 9.67 inches while Breckenridge had the lowest total of 0.9 inches. The National Weather Service’s (NWS) cooperative observer at Madill reported 11.13 inches for the month. October’s statewide average brought the year-to-date total up to 41.95 inches, 10.02 inches above normal and the fifth wettest January-October on record. That total stood about 2.4 inches behind 1915’s record total of 44.27 inches. Tishomingo leads 2015’s totals on the Mesonet thus far with 67.4 inches with McAlester close behind at 66.1 inches. Many stations across the southeastern section of the state have seen from 50-65 inches of rain for the year thus far.
The autumnal weather to end the month cooled the state down a bit, but the statewide average for the entire month still finished 2 degrees above normal at 62.9 degrees. High temperatures during the first three weeks of the month were much closer to September normals than October. The highest temperature recorded during October was 97 degrees at several locations over several days during the middle of the month. The first freeze of the season occurred on the 25th when numerous stations in the northwest dropped to 32 degrees or less. The lowest temperature reported during the month was 31 degrees at four different stations on the 25th and 26th. The warm October helped boost the first 10 months of 2015 to the 43rd warmest on record at 63.5 degrees statewide, 0.4 degrees above normal.
Drought peaked during the month’s third week with over 36 percent of Oklahoma in at least moderate drought according to the Oct. 20 U.S. Drought Monitor report. The subsequent heavy rain events at the end the month helped reduce the area of the state in drought to 18 percent by the Oct. 27 report. More of the state was expected to be removed from drought when the final week’s rains were considered in the first Drought Monitor report for November. The state was completely free of drought from June 2 through August 4 before the flash drought conditions began in mid-August.
The NWS’ Climate Prediction Center’s precipitation outlook for November continued to reflect the influence of El Niño with increased odds of above normal precipitation across the Southern Plains and Oklahoma. That same pattern held for their outlooks through winter into early spring as well. The temperature outlooks indicated increased odds for below normal temperatures throughout that period save for November, where above normal temperatures were expected for the northeastern two-thirds of the state.