| The Drought Monitor |
The Drought Monitor – a partnership of the U.S. Agriculture Department, the National Oceanic and Atmospheric Administration and the National Drought Mitigation Center – considers lake levels, soil moisture, stream flows, groundwater storage and precipitation deficits in producing a weekly nationwide assessment. The classifications: |
Scant rainfall. Shrinking reservoirs. Thirsty soil. Across North Texas, another dry spell is settling in.
Some two years after rains ended a prolonged and brutal drought, the Dallas area is back in D-land – and the situation is likely to persist if not worsen in the months ahead, climate scientists say.
The latest report of the U.S. Drought Monitor shows "moderate" or "severe" drought in the region and most of northern Texas. Drought conditions exist in two-thirds of the state, up from 25 percent one month ago.
And "extreme" or worst-case "exceptional" impacts are spreading across most of south-central Texas, particularly around Austin and San Antonio, in what is shaping up as a record drought there.
"It's going to keep expanding unless we see a major shift in weather patterns," said Dr. Steve Quiring, a climatologist at Texas A&M University.
Forecasts call for a chance of rain in the Dallas area Feb. 9 and 10.
The U.S. Climate Prediction Center foresees drought conditions continuing or developing across most of the state. Forecasters expect the La Niña weather pattern to persist through April, with cooler-than-normal water temperatures in the equatorial Pacific Ocean tending to weaken the tropical jet stream and keep rain-producing storms north of Texas.
In Texas, "we're going to continue to see this drought intensify and expand," said Brian Fuchs, a climatologist with the National Drought Mitigation Center in Lincoln, Neb. "Much of the state is very vulnerable."
He and others at the center produce the Drought Monitor with peers from the U.S. Agriculture Department and National Oceanic and Atmospheric Administration. The report draws on lake levels, soil moisture, precipitation and other factors in its weekly assessment.
Despite last year's unusually wet November and March, rainfall at Dallas/Fort Worth International Airport, the area's official recording station, has been almost 11 inches below normal since May 1.
Complementing the dry-out, average temperatures at the airport have been above normal for 18 consecutive months. And when winds kick up, so does the potential for wildfires.
For now, area water restrictions imposed during the drought of 2005-06 are a memory, although cities keep pressing ahead with water conservation programs. Some prohibit outdoor watering part of the year, as does Dallas from 10 a.m. to 6 p.m. April 1 to Oct. 31.
Most Dallas-area reservoirs are slowly dwindling and stand 75 to 90 percent full, eight months after many were in flood stage.
But compared with lake levels in autumn 2006, the situation is buoyant. That's when Lavon Lake, primary supply for the North Texas Municipal Water District, fell to 36 percent of its capacity (it now stands at 81 percent), after prompting water restrictions and talk of rationing. The district serves about 1.6 million people in Collin, Dallas and six other counties.
The Wylie-based district's water supply should be more stable for droughts to come with the addition of two new sources. Water purchased from the Sabine River Authority is being piped from Lake Tawakoni to Lavon. And the district plans to soon begin recycling some of its treated wastewater into Lavon as well.
By one measure, the Palmer Drought Index, North Texas needs 3 to 6 inches of rain to return to "near normal" soil conditions. The decline in soil moisture and livestock water hasn't reached the gravity of droughts past. Still, farmers' and ranchers' concerns are mounting.
"It's really a tough situation for producers," said Glen Moore, an agriculture extension agent in Ellis and Navarro counties south of Dallas. Winter wheat is struggling and yields will probably be down without rain soon, he said.
To the north, in Collin County, farmer Butch Aycock says stock tanks are drying up and winter wheat is lagging, limiting livestock grazing and forcing herds to hay. "It's not a big issue in the area yet," he said of the blooming drought.
Jackie McMahon, another longtime Collin County farmer, agrees.
"We're not in dire straits yet," he said. "But we're just a month from corn planting, and we need some subsurface moisture."
Only time and nature will tell whether the current dry spell will rival the last parching. One thing's for sure, North Texas rainfall has been strikingly variable in recent years. And from another perspective, it's been amazingly consistent.
The sixth-wettest year on record (2004) gave way to the fifth-driest year (2005). The fifth-wettest year was 2007, followed by below-normal rainfall in 2008. But for the last five years combined, annual rainfall at D/FW has averaged 34.69 inches – almost matching the 30-year norm of 34.73.
"Precipitation amounts may well be 'average' over a long stretch of time. However, are we ready to deal with the variability that occurs in the shorter terms?" said Victor Murphy, climate service program manager for the National Weather Service in Fort Worth. "It just shows why you need to have well-informed planners to deal with events that happen day to day, as well as year to year."
For now, the area's "moderate" drought isn't that unusual, occurring on average every five to 10 years, Murphy said.
"The impacts aren't that dramatic, but if we don't get some rainfall soon, we could lapse into a severe or extreme drought," he said.
On average, the Dallas area gets more than 40 percent of its yearly precipitation in March through June. And heading into the growing, lawn-sprinkling season with a moisture deficit, the area needs at least normal springtime rains to stave off a drought that could "equal or exceed" that of 2005-06, Murphy said.
"Those will be the months that we bust out of the drought or fall deeper into it."