By Gary McManus
Associate State Climatologist,
Oklahoma Climatological Survey
Fresh off the heels of yet another dry month in western Oklahoma, the latest map from the U.S. Drought Monitor indicates an intensification of the ongoing drought in that part of the state.
Exceptional drought, the Drought Monitor’s most severe classification, now covers the extreme southwestern corner of the state and the western Oklahoma Panhandle. The Drought Monitor’s intensity scale ranges from “abnormally dry” to “exceptional.” Most of the remainder of western Oklahoma is covered by extreme to severe drought. Central Oklahoma has a mixture of extreme to moderate drought while the eastern one-third of the state is now free of drought thanks to recent heavy rains.
According to the Drought Monitor, the impacts of exceptional drought include widespread crop and pasture losses and shortages of water in reservoirs, streams and wells.
Much of southwestern Oklahoma and the western Panhandle received less than 20 percent of normal rainfall during April.
The Oklahoma Mesonet site at Hollis recorded less than a tenth of an inch for the month. Boise City in the far western Panhandle eclipsed a dubious record by stretching its streak of consecutive days without at least a quarter-inch of rain on any single day to 223.
The record for that area is 218 days from September 1988 to April 1989. In contrast, the ironically named Westville along the Arkansas border totaled nearly 15 inches of rain as the surrounding areas dealt with flood concerns.
The dry conditions during April continue a string of dry months and mounting rainfall deficits in the western half of the state.
From December 2010 through April 2011, southwestern and west central Oklahoma received 1.67 inches and 1.74 inches of rainfall, respectively. That ranks as the driest such period on record for those areas dating back to 1895. Central Oklahoma fared little better with 4.63 inches, their third driest such period on record.
Widespread damage and destruction of the winter wheat crop has already occurred in the western half of the state. Wheat in southwestern Oklahoma and the western Panhandle has been particularly hard hit.
A recent unofficial estimate of this year’s wheat harvest indicates it could be nearly half of last year’s 126 million bushels.
Additionally, the livestock industry has been hurt by the loss of pasture, hay, and stock ponds. The wildfire season continues to be extended in western Oklahoma thanks to a delayed green-up as vegetation continues to die or remains dormant due to the lack of moisture.
Outlooks from the National Weather Service’s Climate Prediction Center for both the short- and long-term periods are not promising for western Oklahoma. Increased chances of below normal rainfall are indicated through May for much of the state, especially in the southwest.
The latest U.S. Seasonal Drought Outlook indicates the persistence or intensification of drought for the western half of Oklahoma through July. Improvement is possible in central and southeastern Oklahoma.