outlook+water: Drought decreases and storage increases, but the year is not starting off good

SUMMARY:

• Drought conditions (D1–D4) decreased to 44% of the state from 74% eight weeks ago; statewide reservoir storage increased to 74% full, about 7 percentage points below normal for this time of year.
  
• La Nada is still here, with a 70% chance of La Niña arriving before April.
• Drought is expected to remain and develop across nearly the entire state over the next three months.

I wrote this article on January 3, 2025.

 So, the drought situation is looking better over the past two months, with a decrease in drought conditions and an increase in state-wide reservoir storage. Feels good, right? And it is good because it could be worse with drought expanding and storage decreasing. However, we are in the season of decreasing drought and increasing storage, but Santa didn’t bring everything on our list. We got underwear instead of the latest PlayStation! 

The drouthiest parts of the state continue to be in drought with the expectation of continued and deepening drought conditions. Given that the Hill Country, West and Trans-Pecos Texas, and the parts of Mexico that feed the Rio Grande are still drier than Throckmorton County, 2025 could be a real challenging year for water supplies. This is not good with the Guadalupe, Colorado, Nueces, Rio Grande, and Edwards Aquifer in or flirting with new droughts of record.

In a bit of (maybe) good news, the possibility of a La Niña seems to fade with every passing month. There’s still a 70% chance of The Niña appearing over the next three months, but she looks to be a short one. The “maybe” here is that despite her later-than-expected arrival and weaker-than-expected strength, we are still getting the drier-than-normal and warmer-than-normal conditions expected with The Niña. Things could be worse, right?

The warmer-than-normal conditions are baked into Texas at this point. A post I made on the Hotter Than a Habanero blog noted that the current baseline “normal” annual average temperature (based on increasing temperatures) for the state is now warmer than the warmest years of the state-wide drought of record in the 1950s and the Dust Bowl (Figure 1). That ain’t good.

Figure 1: Average annual temperature in Texas from 1895 through 2023 (from the National Centers for Environmental Information).

In December, we got the Ye Olde Standard Texas Precipitation Pattern, with wetter conditions in the east and drier conditions in the west (Figure 2a). Although some parts of the state benefited from rain, almost the entire state saw less-than-normal rainfall (Figure 2b).

Figure 2a: Inches of precipitation that fell in Texas in December 2024 (modified from source). Note that cooler colors indicate lower values, and warmer indicate higher values.

Figure 2b: Rainfall as a percent of normal for December 2024 (modified from source).

The amount of the state under drought conditions (D1–D4) decreased from 74% eight weeks ago to 44% today (Figure 3a), with drouthier conditions developing across the southwestern half of the state and less drouthier conditions in the northeastern half of the entire state over the last month (Figure 3b). Extreme drought or worse decreased from 16.3% of the state eight weeks ago to 13.0% today, with exceptional drought increasing from 4.6% to 6.3% (Figure 3a). In all, 63% of the state is abnormally dry or worse (D0–D4; Figure 3a), down from 91% eight weeks ago.

The North American Drought Monitor, which runs a month behind current conditions, shows drought across the North American continent (Figure 4a). The Rio Grande Basin north of Elephant Butte Reservoir is in short- and long-term drought (Figure 4a). The Rio Conchos Basin in Mexico, which confluences with the Rio Grande just above Presidio and hosts the largest tributary to the Lower Rio Grande, remains in extreme to exceptional drought (Figure 4a). 

Conservation storage in Elephant Butte Reservoir—an important source of water for the El Paso area—increased from 5.8% eight weeks ago to 9.6% more recently (Figure 4b), still about 15 percentage points below a rather pitiful median storage. 

Combined conservation storage in the Amistad and Falcon reservoirs increased slightly to 20.7% full, up from 20.5% eight weeks ago. However, it is almost 40 percentage points below normal for this time of year and the lowest in at least the past 33 years for this time of year (Figure 4c).

Basins across the state continue to host flows over the past week below historical 25^th, 10^th, and 5^th percentiles (Figure 5a). Statewide reservoir storage is at 74.0% full, up about a million acre-feet from 70.6% four weeks ago but about 7 percentage points below normal for this time of year (Figure 5b). The reservoir marked in orange in the Dallas-Fort Worth area (the persimmon in a sea of blueberries) is New Terrell City Lake and has dropped from full in early March 2024 (Figure 5c). I couldn’t discern the cause, but I suspect it’s for maintenance on the reservoir and/or dam.

My (drumroll, please) “Hydrograph of the Month” is Lake Chapman due to lowish levels for this time of year (Figure 5d).

Sea-surface temperatures in the Central Pacific that, in part, define the status of the weather phenomenon known as the El Niño Southern Oscillation remain under neutral conditions, but sea-surface temps continue to drop (Figure 6a). Projections suggest a transition to La Niña conditions in December-February with a ~70% chance (Figure 6a, b). If there’s good news here, it’s that the coming La Niña looks to be a weak and short one.

The U.S. Seasonal Drought Outlook through March shows drought and drought development over the entire state except for much of the High Plains (Figure 7a). The three-month temperature outlook projects above-average temperatures for most of the state (Figure 7b), while the three-month precipitation outlook favors rainfall deficits for most of the state (Figure 7c).