News•May 29, 2014

Rains Slightly Ease Southern Plains Drought

Over the better part of a week, a slow-moving low-pressure system dumped rain across parts of Oklahoma and Texas, including parts of the region suffering the most from drought. The storm brought them at least a modicum of relief according the latest U.S. Drought Monitor.

“Basically, the rain fell exactly where it was most needed,” Victor Murphy, the climate services program manager with the National Weather Service’s Southern Region, said in an email.

A comparison of drought conditions in Texas and Oklahoma for the weeks of May 20 and May 27.
Credit: U.S. Drought Monitor

But it will take much more than a few days of rain to make serious strides toward ending a drought that has been years in the making. Unusually dry and hot conditions settled into place in October 2010, then persisted through wet season after wet season, due to factors like La Nina and other climate patterns that influence the region’s weather. What percentage of any single drought or other event climate change is responsible for is difficult to tease apart, but the steady rise in average temperatures as greenhouse gases accumulate in the atmosphere exacerbate the impacts of droughts. And places that are already dry are only expected to get drier.RELATED100 Percent of California Now in Highest Stages of Drought
Warming Temperatures Could Dry Out One Third of Planet
Ongoing Coverage of Historic Drought in U.S.

A number of drought-stricken areas saw heavy rainfall with the highest seven-day totals stretching from central Texas through the Texas Panhandle and southwest Oklahoma. Southeast and northeast Oklahoma also got a good soaking, though those areas have been less affected by the drought.

Because of this infusion of rain, the weekly update to the U.S. Drought Monitor saw a reduction in the portion of Texas covered by the highest stage of drought from 25 percent to about 11 percent. The portion covered by the two highest stages fell from 40 to 32 percent. But the area covered by any stage of drought barely shifted, remaining around 70 percent.

Oklahoma saw its coverage of exceptional drought drop from about 34 to 26 percent and extreme and exceptional drought combined from 61 to 55 percent. The total area covered from drought likewise stayed relatively constant, around 80 percent.

Rainfall amounts (in inches) across Oklahoma over the 10 days from May 19 to May 29, 2014.
Credit: Oklahoma Mesonet

Not every community that needed rain got it during this rainfall event, though. Murphy said Wichita Falls, Texas, was the one major city that missed out on rain.

The city, located in the north-central part of the state, recorded just 0.31 inches of rain over the past 7 days. Other areas of the Southern Plains saw closer to 5 inches over that time.

The city has received only 47 percent of its normal rain for the year — the same percentage it was at before the rains swept through, Murphy said — and has declared a Stage 5 Drought Catastrophe. The declaration means absolutely no outside watering is allowed and other serious restrictions have been placed on the use of city-supplied water.

And while drought improved somewhat elsewhere, it’s not a total recovery.

“(It) still means those counties are in a really bad drought. Just not record bad at this point,” said Michael Brewer, the author of this week’s Drought Monitor and a scientist with the National Climatic Data Center.

The rain will help to put a bit more water into reservoirs, increase the flow of water in some streams, and the moisture in the soils.

“The biggest improvement will be in soil moisture and some greening up of the vegetation across the area,” Gary McManus, Oklahoma’s state climatologist, told Climate Central. “That will help prevent or reduce the extreme fire danger that we've seen continue into spring from our normal fire season which usually ends in early spring or late winter.”

Rainfall totals across Texas over the seven days ending on May 29, 2014.
Credit: Vincent Murphy/NOAA

But just how long these benefits will last depends on whether or not the area sees any more rain in the next few weeks and months and how hot the summer season gets, as heat dries out the soils and increases the demand for water.

“If the rain stops, the drought will worsen,” Brewer said.

Without more rain, Brewer said the recent improvements could disappear in a matter of weeks.

The forecast tools from the National Oceanic and Atmospheric Administration make it clear that even normal precipitation over the next few months are unlikely to end the drought, Brewer said, because areas are running at such a large deficit. Some places, including Wichita Falls, are as much as 40 inches of rain in the hole.