Water + Weather for September 2020 Posted on October 13, 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 take a look at conditions for our state at the end of September 2020.
As shown in this map of precipitation as a percentage of normal, September brought plentiful and, in some cases, excessive rainfall to much of Central, Eastern, and Coastal Texas. For example, Hobby Airport in Houston received more than 13 inches of rainfall for the month, about 250 percent of normal. Meanwhile, the Muleshoe National Wildlife Refuge west of Lubbock received only four one-hundredths of an inch for the month, less than 2 percent of normal. This rainfall pattern improved drought conditions in Central, Coastal, and East Texas but degraded conditions in West Texas and the Panhandle.
The U.S. Drought Monitor map for conditions as of September 29 shows a significant decrease in drought. At the end of August, drought covered 57 percent of the state in a large, almost continuous patch that covered most of West Texas, the Panhandle, and Central Texas. September's rainfall has banished drought from East and Coastal Texas in all but two patches in Central Texas. Unfortunately, 32 percent of the state remains in drought, with 3 percent of the state reaching exceptional drought. After some much-needed drought relief for the eastern half of the state in September, what can we expect going forward?
The latest Seasonal Drought Outlook from the National Weather Service for conditions through the end of the calendar year is not very optimistic. Instead, they anticipate that drought will expand to cover the few drought-free spots in West Texas and the Panhandle and quickly return to most of Central and Eastern Texas. Why so pessimistic?
Unfortunately, sea surface temperatures in the Pacific Ocean far to our south are cooler than normal this fall and are expected to remain that way through the winter. Why is that bad news for us? Whenever this condition, known as La Niña, occurs in the winter, it causes the jet stream to shift north, bringing cooler and wetter conditions to the northern half of the contiguous U.S. and drier and warmer conditions to the southern half, including Texas. Currently, about a third of our state is in drought, and our winter is expected to be warmer and drier than normal. That's a recipe for drought expansion, not improvement.
That concludes our Water and Weather report. In summary, September rainfall was generally above normal for Coastal, Central, and East Texas but below normal in the Panhandle and West Texas. At the end of September, moderate or worse drought is impacting 32 percent of the state, down from 57 percent at the end of August. La Niña conditions are present and expected to bring Texas a warm and dry winter and more drought by the end of December. Thanks for viewing. And until next time, I hope you all stay healthy and safe.