By Gary McManus, Oklahoma Climatological Survey
The cumulative effect of the last two weekend’s rainfall events was enough to draw some of the state out of exceptional drought. Unfortunately, those that missed out on those two rainfall events were drawn into the U.S. Drought Monitor’s worst drought category. This morning’s U.S. Drought Monitor report showed that parts of northeastern and central Oklahoma improved from exceptional drought to extreme drought, including the state’s two most populous cities in Oklahoma City and Tulsa.
Exceptional drought shrunk from 48 percent of the state to 37 percent. The area of extreme/exceptional drought remained at 90 percent,however. The entire state remains in at least severe drought. That’s the same extent as this time last year, but at that time 67 percent of the state was in exceptional drought. The severe/exceptional and extreme/exceptional drought areas were less one year ago at 79 percent and 85 percent, respectively.
The two rainfall events that allowed for the improvements this week combined to bring 3-5 inches of rain though those areas.
Rainfall out to 30 days has added just a tad more to those totals, and helped a bit more in other areas.
Also, areas that missed out on appreciable rainfall through the last month, and therefore increased in intensity from extreme to exceptional … north central and southwestern Oklahoma, particularly. The western two-thirds of the Panhandle have also been dry. Dry weather in the Panhandle is reaching a critical point rather quickly as well. Without additional moisture, drought will continue to worsen in that area.
Soil moisture responded quite well to the rains down to the 10-inch level on the Mesonet. The topsoils across the state moistened up quite nicely. More importantly, the soil down to 10 inches moistened up at 10 inches across central and northeastern Oklahoma. Typical during significant droughts, the lower soil levels still remain unsatisfied.
There is still the hope for moisture from the remnants of Hurricane Isaac, but the forecasts still show the best chance is in far eastern Oklahoma. Should Isaac shift to the west, that heavier rainfall will also shift more in our direction.
A bit further out, the prospects for another cold front and associated rainfall are just beginning to show up on CPS’ 6-10 and 8-14 day outlooks with increased odds of above normal rainfall and near normal temperatures in the offing.