SUMMARY:
- Much of the state continues to be in drought.
- Warmer than normal and drier than normal conditions are predicted for the next three months.
- Six cats can keep you warm during historic cold slaps.
I wrote this article on February 20, 2020.
When I wrote last month’s column, I had no idea that I’d be shivering in the dark cold without power for 20 hours with my wife and six cats. And we were some of the lucky ones: many went days without power and water. As I write, we are still under a boil water notice in Austin due to cold-induced water plant failure and the loss of line pressure. Our neighborhood has two waterline breaks (and I could still hear exploding transformers this morning, so we may not yet be out of this).
Although it was bitter cold, we’ve had colder days in Texas. In Austin, the record of 2 degrees below 0 was set in 1949. For Dallas, it was 8 degrees below 0 set in 1899, a particularly epic winter. For El Paso, it was 8 degrees below 0 in 1962. For San Antonio, it was 0 degrees in 1949 while for Houston is was 5 degrees set in both 1930 and 1940 (National Weather Service). According to the Texas Almanac, the coldest temperature recorded in Texas was 23 degrees below 0 at Tulia (February 12, 1899) and Seminole (February 8, 1933). However, this recent cold snap was colder for longer than before. For Dallas, the average temperature for February 14 through February 16 was 10.8 degrees, besting the old three-day record of 11.7 degrees for December 22 through 24, 1983 (WFAA). The state climatologist said that only one week in history, in 1983, was colder for the state than this recent week of shivering delight.
Ironically, it was record high temperatures that set near-record low temperatures in motion. Something called a sudden stratospheric warming occurred in the atmosphere above the Arctic where temperatures about 4 miles above land surface increased 100 degrees in early January (from -110 degrees to a balmy -10 degrees). This, perhaps enhanced by an Arctic warmed by climate change, set into motion a weakening of the polar vortex, allowing Arctic air to march through the continents and down to Texas. But not only Texas was affected: snow also fell in Saudi Arabia and Jerusalem, dusting the camels (who looked about as pleased about it as our cats). Interestingly, the sudden stratospheric warming occurred in January, resulting in many to predict an Arctic Invasion of the continent some five weeks ahead of the event. Call it a bellweather of cold weather to come, something we’ll hopefully be following more closely in the future.
The recent rains (and ices and snows!) have topped off our 5,000-gallon rainwater tank. The tank is not connected to our central Austin home, but, as we assessed worse-case scenarios during the ERCOTastrophy, we talked about using it for flushing, washing, and, if needed, drinking (we still had a lot of wine, though!). Given its size and thermal mass, our rainwater tank wasn’t even close to freezing, so it was certainly there for use. While I think rainwater harvesting to meet all potable needs in urban settings is impractical for a variety of reasons, it could serve, with proper handling, as a good emergency supply. We never thought that we’d be contemplating drinking our harvested rainwater, so we plan to investigate having emergency filtration that, coupled with boiling (or UV treatment), would make it potable in the worst of scenarios. Afterall, the worst seems to be happening more and more frequently these days.
Figure 1: Snow accumulation for the lower 48 of the United States from September 30, 2020, to February 20, 2021 (source).
The past 30 days have been drier than previous months with parts of East Texas receiving 3 to 4 inches of precipitation over the past 30 days with much of the rest of the state receiving less than 1.5 inches of precipitation (Figure 2a). Parts of Big Bend and the Lower Rio Grande Valley received less than 0.1 inches of precipitation over the past 30 days (Figure 2a). Despite all the snow, much of Texas received less than normal precipitation with scattered parts of the western half of the state benefitting from above normal precipitation (Figure 2b). The majority of the state remains with less-than-normal precipitation over the past 90 days with the Lower Rio Grande Valley suffering from 25 to 50 percent less than normal (Figure 2c).
Figure 2a: Inches of precipitation that fell in Texas in the 30 days before February 20, 2021 (source). Note that cooler colors indicate lower values and warmer indicate higher values.
Figure 2b: Rainfall as a percent of normal for the 30 days before February 20, 2021 (source).
Figure 2c: Rainfall as a percent of normal for the 90 days before February 20, 2021 (source).
The amount of the state under drought conditions (D1–D4) decreased from 48.6 percent four weeks ago to 44.9 percent at present (Figure 3a) with drought fading on the Edwards Plateau but expanding and deepening in the Panhandle and parts of South Texas (Figure 3b). Exceptional Drought—focused in West and Far West Texas—decreased from 6.1 percent of the state four weeks ago to 5.2 percent at present (Figure 3a). In all, 72.8 percent of the state is abnormally dry or worse (D0–D4; Figure 3a), up from 68.6 percent four weeks ago.
Figure 3a: Drought conditions in Texas according to the U.S. Drought Monitor (as of February 16, 2021; source).
Figure 3b: Changes in the U.S. Drought Monitor for Texas between January 19, 2021, and February 16, 2021 (source).
The North American Drought Monitor for December continues to show a raging drought in much of the western United States with Exceptional Drought entrenched in the American Southwest (Figure 4a). Precipitation in most of the Rio Grande watershed in Colorado and New Mexico over the last 90 days is less than normal but with parts of southern Colorado receiving more than 1.5 times normal precipitation (Figure 4b). Conservation storage in Elephant Butte Reservoir increased slightly from 7.4 percent full on January 22 to 8.7 percent on February 20 (Figure 4c), at or near historic lows.
The Rio Conchos basin in Mexico, which confluences into the Rio Grande just above Presidio and is an important source of water to the lower part of the Rio Grande in Texas, is back into Severe to Extreme drought conditions (Figure 4a). Combined conservation storage in Amistad and Falcon reservoirs decreased over the past month from 47.5 percent on January 22 to 45.1 percent on February 20, about 18 percentage points below normal for this time of year (Figure 4d).
Figure 4a: The North American Drought Monitor for January 31, 2021 (source).
Figure 4b: Percent of normal precipitation for Colorado and New Mexico for the 90 days before February 20, 2021 (source). The red line is the Rio Grande Basin. I use this map to see check precipitation trends in the headwaters of the Rio Grande in southern Colorado, the main source of water to Elephant Butte Reservoir downstream.
Figure 4c: Reservoir storage in Elephant Butte Reservoir since 2019 with the median, min and max for measurements from 1990 through 2020 (source).
Figure 4d: Reservoir storage in Amistad and Falcon reservoirs since 2019 with the median, min and max for measurements from 1990 through 2020 (source).
A number of river/stream basins in the state have flows over the past seven days that are less than 25 percent of normal with several to half-a-dozen catchments in severe hydrologic drought with flows less than 5 percent of normal and one in extreme hydrologic drought (Figure 5a). Statewide reservoir storage is at 81.4 percent full as of February 20 (and trending downwards), down from 82.3 percent a month ago, and slightly below normal for this time of year (Figure 5b). Many reservoirs in east and northeast Texas remain less than 90 percent full (Figure 5c).
Figure 5a: Parts of the state with below-normal seven-day average streamflow as of February 20, 2021 (source).
Figure 5b: Statewide reservoir storage since 2019 compared to statistics (median, min and max) for statewide storage from 1990 through 2020 (source).
Figure 5c: Reservoir storage as February 20, 2021 in the major reservoirs of the state (source).
Sea-surface temperatures in the Central Pacific reversed their cooling trend this past month and warmed a quarter degree (Figure 6a). The Climate Prediction Center give a ~60 percent chance of neutral conditions developing in the spring (Figure 6b).
Figure 6a: Forecasts of sea-surface temperature anomalies for the Niño 3.4 Region as of January 19, 2021 (modified from source).
Figure 6b. Probabilistic forecasts of El Niño, La Niña and La Nada conditions (source).
The U.S. Seasonal Drought Outlook through May 31, 2021 projects drought persistence and development for the western half of Texas (Figure 7a). The three-month temperature outlook projects warmer-than-normal conditions statewide with greater warming to the southwest (Figure 7b) while the three-month precipitation slightly favors drier-than-normal conditions for the state with drier conditions in West and Far West Texas (Figure 7c).
Figure 7a: The U.S. Seasonal Drought Outlook for February 18, 2021, through May 31, 2021 (source).
Figure 7b: Three-month temperature outlook from February 18, 2021 (source).
Figure 7c: Three-month precipitation outlook from February 18, 2021 (source).