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Water + Weather for December 2020 Posted on January 08, 2021


Dr. Mark Wentzel – Hydrologist, Texas Water Development Board

Hi everyone, and welcome to the Texas Water Development Board's latest Water and Weather Report. I'm Dr. Mark Wentzel, a hydrologist in the Surface Water Division here at the agency. And today, we're going to take a look at conditions for our state at the end of December 2020.

As Texas ended 2020, 81 percent of the state was in drought. That's a modest three percentage point improvement from late November, but much worse than the start of the year when only 38 percent of the state was in drought. 

Let's take a look at some of the big water and weather headlines at the end of 2020. La Niña conditions are reducing rainfall across the state. These conditions are expected to continue at least through the end of spring of 2021. The northern tip of the Panhandle and the upper Gulf Coast, from Houston to the Louisiana border, are the only drought-free areas in the state. West Texas remains the area of the state most severely impacted by drought. Statewide, storage in our water supply reservoirs ended the year at 80 percent, about one and a half percentage points below normal for this time of year.

To see how the conditions vary, let's take a virtual road trip on I-10, from east to west across our state, via images from Google Maps and data from the National Weather Service. We'll be making three stops on our trip, Houston, San Antonio, and El Paso. In an average year, we'd expect annual rainfall totals along our route to drop from a little over 50 inches in Houston, to about 29 inches in San Antonio, to less than 9 inches in El Paso.

How did we do this year? On this chart, we're looking at 2020 monthly rainfall data for Houston in red, along with maximum, minimum, and average monthly values in gray and black. In the Houston area, we finished the year with an annual rainfall total of more than 60 inches, about 10 inches more than average. In October, Houston received less than 20 percent of normal rainfall, which brought the area close to drought, but they finished the year with average rainfall in November, and nearly twice average rainfall in December. This part of the state, from the Louisiana border to Houston, is one of only two areas of the state that are drought-free.

As we head west on I-10, conditions get much drier. Midway across the state, San Antonio recorded about 21 inches of precipitation in 2020, 8 inches less than normal. In fact, the seven-month period from June to December was the third driest such period in 126 years. The U.S. Drought Monitor currently shows this area in drought, with about half the area in extreme drought.

As we had farther west, drought conditions continue to intensify. Near the I-10, I-20 junction in Reeves County, we are in a part of the state that the U.S. Drought Monitor considers to be in exceptional drought, the most severe drought category.

By the time we get to El Paso, things are slightly improved, with a mix of severe and extreme drought covering the landscape. El Paso's rainfall total for 2020 was just under 6 inches, about 70 percent of normal. But the second half of the year was much drier. In fact, El Paso ended the year with the driest August through December in the last 126 years. Without additional precipitation, this area could soon join much of West Texas in exceptional drought.

That concludes our virtual road trip across the state at the end of 2020. But what might 2021 hold for us? According to the National Weather Service, the early months of 2021 are expected to be drier and warmer than usual for Texas, bringing drought to the entire state by the end of March. Beyond March, there is some good news. A 50 percent chance that La Niña conditions dissipate during the April to June time period, which could bring us some drought relief. 

That concludes our report. Until next time, I hope you all stay healthy and safe.

This article is posted in Weather / Water Supply .