Water + Weather for August 2020 Posted on September 14, 2020
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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 here in the Surface Water Division at the agency. And today, we're going to be taking a look at conditions for our state at the end of August 2020. This month I'm once again coming to you from my home office.
As shown in this map of precipitation as a percentage of normal, August was exceptionally dry for many areas of the state. Orange and red areas received half or less of their normal precipitation. Green and blue areas got more than normal rainfall. Only a small portion of the state received normal or above rainfall: the eastern edge of the state battered by Hurricane Laura, the lower Red River Valley, and a few other scattered areas. For the second consecutive month, much of West and Central Texas received less than half of normal precipitation.
The U.S. Drought Monitor map for conditions as of August 25 shows a significant increase in drought. At the end of July, drought covered 34 percent of the state in large patches scattered across the Panhandle and West and Central Texas. At the end of August, those patches have expanded and merged leaving only isolated pockets of drought-free area in those parts of the state. Overall, 57 percent of the state is now in drought, up 23 percentage points from the end of July. Statewide, our surface water supplies are a little lower than what we would expect for this time of year. The dark line on this chart shows how storage this year compares to minimum, maximum, and median values for the day of the year from data going back to 1990. Also displayed are lighter lines that show how we did in 2019 and 2018.
We began August at 83.6 percent of capacity, right about normal for the time of year. During the month, water supply storage dropped. Not much of a surprise by itself, but this year we lost more than expected, ending the month with storage at 80.5 percent of capacity, about two percentage points below normal for this time of year. What else can we expect? The latest seasonal drought outlook from the National Weather Service anticipates continued drought development across our state. By the end of November, we can expect all but far East and coastal Texas to be experiencing drought conditions. Why so pessimistic? Much like a lot of the bad news we've received in 2020, the cause is something a long way from Texas. This time it's La Niña conditions, unusually cool sea surface temperatures in the Eastern Pacific thousands of miles to our south. La Niña conditions are expected to develop this fall and extend into the winter, which typically leads to hotter and drier than normal conditions for Texas.
That concludes our Water and Weather report. In summary, August rainfall was well below normal across much of the state. At the end of August, moderate or worst drought is impacting 57 percent of the state, up from 34 percent at the end of July. As we approach the end of summer, our surface water supplies are slightly below average for the time of year. Going forward, drought conditions are expected to persist and expand to cover most of the state by the end of November. Thanks for viewing. And until next time, I hope you all stay healthy and safe.