outlook+water: La Niña persists, drought expands, and the next three months favor hot and dry

SUMMARY:

• Early projections suggest an active Atlantic hurricane season
• Those epic rains in the valley did nothing for the Rio Grande reservoirs
• Drought conditions (D1–D4) increased to 68% of the state from 49% of the state four weeks ago; statewide reservoir storage stayed the same at 76% full, about 8 percentage points below normal for this time of year.
• We remain in La Niña conditions with a 62% chance of a return of neutral conditions in the June-July-August season.
• Drought is expected to remain and expand over the next three months leaving only the easternmost part of the state drought-free.

I wrote this article on April 4, 2025.

Is it too early to talk about hurricanes? If you’re from Colorado, the answer is no. Colorado State University put out its Atlantic Tropical Storm projections last week, calling for 17 named storms with 9 of ‘em becoming hurricanes and 4 becoming major hurricanes. As support, they point to warmer-than-normal oceans (pretty much a given these days) and low chances (13%) of an El Niño forming (El Niños tend to suppress tropical storm formation due to shearing winds). The names for this year’s storms range from Andrea to Wendy with Chantal, Nestor, Olga, and Van in the mix (Figure 1).

We didn’t need a hurricane to break rainfall records in the Lower Rio Grande Valley last week. The details are complicated (via myRGC.com):

“…a disturbance in the upper levels of the atmosphere drove into western Mexico, tapping deep tropical moisture from the Pacific as it moved east. The disturbance then accessed more deep tropical moisture —probably from the western Caribbean but especially the Bay of Campeche — and met up with a stationary surface front, resulting in wind convergence that enhanced the atmospheric lift to spark thunderstorms…” 

Got that?

We got Ye Olde Standard Texas Precipitation Pattern in March with wetter conditions in the east and drier conditions in the west (Figure 2a). However, a sizable part of West and Far West Texas received less than 0.01 inches of rainfall (Figure 2a). Although some parts of the state benefited from rain, almost the entire state saw substantially less than normal rainfall (Figure 2b). The Lower Rio Grande Valley saw some epic rains of more than six times normal (Figure 2b) with more than 15 inches falling in the region (Figure 2a). The National Weather Service reported one of its gages receiving 13.78 inches, beating the previous record of 10.64 inches with Hurricane Hanna in 2020. Even more remarkable: these rainfalls were not due to a tropical system (and the moisture came from the Pacific).

The amount of the state under drought conditions (D1–D4) increased from 49% four weeks ago to 68% today (Figure 3a) with degradation over much of the state (Figure 3b). Extreme drought or worse increased from 17% of the state four weeks ago to 29% today with exceptional drought increasing from 6.3% four weeks ago to 14% today (Figure 3a). In all, 85% of the state is abnormally dry or worse (D0–D4; Figure 3a), up from 80% four weeks ago.

The North American Drought Monitor, which runs a month behind current conditions, shows drought across the North American continent but especially in the Southwest (Figure 4a). The Rio Grande Basin north of Elephant Butte Reservoir shows moderate to severe 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 Moderate to Extreme (Figure 4a).

Conservation storage in Elephant Butte Reservoir—an important source of water for the El Paso area—increased from 13% full four weeks ago to 14% more recently (Figure 4b), about 10 percentage points below a rather pitiful median storage of 25 percent full.

Combined conservation storage in the Amistad and Falcon reservoirs increased slightly to 21.5% full, up from 21.4% four weeks ago and 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 75.7% full, the same as it was four weeks ago, but about 8 percentage points below normal for this time of year (Figure 5b). The orange reservoir 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). The Lake is no longer used for water supply and appears to be undergoing long-term maintenance work.

My (drumroll please) Hydrograph of the Month is Falcon Reservoir due to its being upstream of the Lower Rio Grande Valley and showing absolutely no improvement from the rain bombs that fell downstream (Figure 5d).

Figure 5c: Reservoir storage as of April 4, 2025, in the major reservoirs of the state (modified from Texas Water Development Board).

Figure 6b. Probabilistic forecasts of El Niño, La Niña, and La Nada (neutral) conditions (graph from Climate Prediction Center and others).

The U.S. Seasonal Drought Outlook through May shows drought and drought development for the entire state except for the easternmost parts (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).

Figure 7a: The U.S. Seasonal Drought Outlook for April 1 through June 30, 2025 (source).

Figure 7b: Three-month temperature outlook for April-May-June 2025 (source).

Figure 7c: Three-month precipitation outlook for April-May-June 2025  (source).