outlook+water: Drought doubles (and is gonna get worse), La Niña looks to be a coin flip

SUMMARY:

• Drought conditions doubled to 74% of the state (D1–D4); statewide reservoir storage declined to 70.6% full, about 10 percentage points below normal for this time of year.
  
• La Nada is still here with a 60% chance of La Niña arriving in September-October-November.
• Drought is expected to remain and develop across nearly the entire state over the next three months.

I wrote this article on November 1, 2024.

 “Are you George Harrison?” I asked the young man dressed in a sharp suit while slinging a white Stratocaster and bag of the evening treats.

“Oh no,” he said. “Paul McCartney.”

It’s difficult to be frightened by someone who wrote “P.S. I Love You,” “Love Me Do,” and “Silly Love Songs.”

While All Hallow’s Eve at our house wasn’t all that scary, October was quite frightening meteorologically. This was the warmest October on record for the planet (Figure 1), the country, Texas, and many places across the state. At the moment, we are on track to have the warmest year on record, which would displace 2023 as the warmest. The year 2023 went out with a burn, so we’ll see.

It was also one of the driest Octobers on record (and I’m not talking about a lack of liquor). I happened to be at our house in Austin when seven or so drops of rain fell, the only rain to arrive during the month. Other than that, nothing (and our landscape shows it). Despite predictions of rain for Halloween, all we saw was a ghostly rendition of rain past, vapors that floated into the night. Sadly, long-term predictions don’t provide much hope for relief from temps and drought.

Figure 1: Global temperature anomalies in October (plot from Our World in Data).

October was scary, and not just because of All Hallow’s Eve. A sizable hunk of the state—almost half?—received little to no rain (Figure 2a). October is usually on the wet side, but not this one. Although some parts benefited from rain, almost the entire state saw less than 25% of normal (Figure 2b).

Figure 2a: Inches of precipitation that fell in Texas in October 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 September 2024 (modified from source).

The amount of the state under drought conditions (D1–D4) doubled from 34% four weeks ago to 74% today (Figure 3a), with dry conditions developing across almost the entire state (Figure 3b). Extreme drought, or worse, increased from 8.9% of the state four weeks ago to 16.3% today, with exceptional drought increasing from 3.4% to 4.6% (Figure 3a). In all, 91% of the state is abnormally dry or worse (D0–D4; Figure 3a), up from 74% four 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 water source for the El Paso area—increased from 5.7% four weeks ago to 5.8% more recently (Figure 4c), but it is still about 15 percentage points below a rather pitiful median storage.

Combined conservation storage in the Amistad and Falcon reservoirs decreased to 20.5% full from 20.8% four weeks ago and is almost 40 percentage points below normal for this time of year (since 1990) and the lowest in at least the past 33 years for this time of year (Figure 4d).

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 70.6% full, down about 790,000 acre-feet from 73.1% four weeks ago and about 10 percentage points below normal for this time of year since 1990 (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 (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, yet again, Canyon Lake due to a remarkable downward trend of record-low lake levels (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 September-November, but with a lower chance (60 %) than last month (81%; 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 January shows drought and drought development over nearly the entire state (Figure 7a). The three-month temperature outlook projects (surprise, surprise) above-average temperatures for the state (Figure 7b), while the three-month precipitation outlook favors rainfall deficits for much of the state (Figure 7c).