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Dry September Diminishes Drought Recovery

Hopes were high for much-needed rainfall across Oklahoma after August's disappointing totals. June and July were exceedingly wet, lending optimism that August's step back would be but a brief interruption. Unfortunately, that script did not play out as written and September became yet another dry month in the now four-year-old drought. According to preliminary data from the Oklahoma Mesonet, the statewide average rainfall total was 2.6 inches, 1.3 inches below normal and the 46th driest September since records began in 1895. Of the 48 months since the drought began back in October 2010, 34 have been drier than normal, amounting to a deficit of over 30 inches during that span. Hugo led all Mesonet sites with 8.7 inches of rain during September while Buffalo received a scant 0.3 inches. August and September combined for a statewide average of 3.9 inches, 2.6 inches below normal and the 22nd driest August-September on record in the state. Much of the state had less than 4 inches of rain throughout the two months, with many of the stations across western Oklahoma receiving less than 2 inches. The January-September statewide average reflected the dry start to the year, coming in at 21.7 inches, 6.7 inches below normal and the 18th driest such period on record.

Not surprisingly, temperatures across the state were a bit above normal with the lack of rainfall and accompanying storm systems. The statewide average as measured by the Mesonet was 73.1 degrees, 0.7 degrees above normal and the 63rd warmest September on record. Grandfield led all Mesonet sites with 102 degrees on Sept. 1. The lowest temperature of the month was 40 degrees from several locations on the 12th and 13th. The August-September temperature was also 76.9 degrees and 0.5 degrees above normal. The first nine months of the year were substantially cooler, again a reflection of the chilly winter through early spring as well as the below normal temperatures of June and July. The January-September statewide average temperature was 61.9 degrees, 1.1 degrees below normal and ranked as the 21st coolest such period on record.

The last U.S. Drought Monitor report of the month, released on Sept. 25, gave a clear indication that drought was once again gaining strength. Drought impacts began to worsen across most of western and northern Oklahoma where farm ponds, vegetation and soils showed increasing signs of water stress. By the end of September, more than 49 percent of the state was considered in at least "severe" drought, and 14 percent of that area was in the more significant "extreme" and "exceptional" drought categories. The Drought Monitor’s intensity scale slides from moderate-severe-extreme-exceptional, with exceptional being the worst classification. Soil moisture appeared to be critically low across much of the western half of the state according to data from the Oklahoma Mesonet, including the important wheat-producing north central region. The Oklahoma Field Office of the USDA's National Agricultural Statistics Service (NASS) reported 54 percent of the state's topsoil and 77 percent of the subsoil to be in "short" or "very short" condition. Eighty percent of the state's pastures and rangeland were rated from "fair" to "excellent," a benefit of the rains that occurred from late May through July.

Widespread improvement in the drought conditions might be at least a month away. The National Weather Service's Climate Prediction Center (CPC) expected drought to either persist or intensify through October, at least in those areas where drought is already in place,  according to the latest U.S. Monthly Drought Outlook. Development of drought across eastern Oklahoma was not expected. The October precipitation and temperature outlooks from CPC lacked a definitive direction other than increased odds for above normal precipitation across far northeastern Oklahoma. The first half of October looked to be on the warm and dry side according to CPC's medium-term outlooks, although their October-December outlooks released in mid-September gave increased odds of above normal precipitation for most of the state. The October-December temperature outlook provided no clear direction, with equal odds of above-, below- and near-normal conditions.

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