July 2024: Southwest Climate Outlook

The Southwest Climate Outlook is published by the Climate Assessment for the Southwest (CLIMAS), with support from University of Arizona Cooperative Extension, and the New Mexico State Climate office.

Questions/Contact: Stacie Reece, sreece@arizona.edu

June precipitation was above normal across much of Arizona and New Mexico, and much-above normal for areas of the Colorado Plateau and southern Rocky Mountains. The remnants of tropical storm Alberto delivered a surge of moisture to the region in late June, and a monsoonal circulation pattern happened to be in place, so the result was an early, running start for the summer rain season.

June temperatures were much-above average across nearly all of Arizona and New Mexico, and in some locations, it was the warmest June in the record.

Water year (October 2023 – June 2024) precipitation totals range from above normal for parts of southern Arizona, the Colorado Plateau, and northern New Mexico, to below normal for southern New Mexico and northwest Arizona.

Drought-conditions classifications have changed little over the last month in Arizona, but in New Mexico, some areas showed indications of improving conditions, with 15% of the state’s area emerging from drought or classification as abnormally dry over the past month, now classified as having no drought. Southern New Mexico remains the area hardest hit by current drought, with extreme drought conditions in the area of Carlsbad, NM, and also in the bootheel. Moderate to severe drought conditions extend from southern New Mexico into southeast Arizona.  About two thirds of Arizona is classified as abnormally dry or in moderate to severe drought. About 83% of New Mexico is classified as abnormally dry or worse.

NIDIS Improved and Expanded State Pages on Drought.Gov

Monsoon precipitation since June 15 has been above normal to much-above normal across much of New Mexico, and above normal for areas of central, southern, and northeastern Arizona. Seasonal totals exceeding 4 inches have been widespread in New Mexico, and some areas have estimated totals exceeding 8 inches. Areas where monsoon precipitation has been below normal include Carlsbad, NM; Show Low, AZ; and Phoenix, AZ—all locations where amounts have not exceeded 2 inches.

Lakes Mead and Powell have managed to hold on to last year’s storage increase that resulted from the above normal 2023 spring snowmelt—together they currently hold more water than they did one year ago. Other Arizona reservoirs on the Salt, Gila, Verde and Little Colorado rivers are storing above normal amounts of water, but less than one year ago. Reservoir storage in New Mexico is broadly below normal, and in most cases also less than one year ago.

 _{The map gives a representation of current storage for reservoirs in Arizona and New Mexico. Reservoir locations are numbered within the blue circles on the map, corresponding to the reservoirs listed in the table. The cup next to each reservoir shows the current storage (blue fill) as a percent of total capacity. Note that while the size of each cup varies with the size of the reservoir, these are representational and not to scale. Each cup also represents last year’s storage (dotted line) and the 1991–2020 reservoir average (red line). The table details more exactly the current capacity (listed as a percent of maximum storage). Current and maximum storage are given in thousands of acre-feet for each reservoir. One acre-foot is the volume of water sufficient to cover an acre of land to a depth of 1 foot (approximately 325,851 gallons). On average, 1 acre-foot of water is enough to meet the demands of four people for a year. The last column of the table lists an increase or decrease in storage since last month. A line indicates no change. These data are based on reservoir reports updated monthly by the  Natural Resources Conservation Service - National Water and Climate Center (USDA)  .} 

Pacific sea surface temperatures (SSTs) along the equator are showing warm anomalies (difference from average) in the west and cool anomalies in the east--a La Niña-like pattern, but lacking sufficient intensity or extent of cool anomalies to meet the criteria of a La Niña event.  

A similar pattern with anomalies of similar intensity is expected to persist though the August – October season.

SST anomalies averaged over the eastern (Nino 3) and coastal-eastern (Nino 1+2) ENSO monitoring regions have been negative for months, but in the central (Nino 4) and east-central, primary (Nino 3.4) monitoring region, the area-average SST has remained warmer than average. For a La Niña event to be considered possibly under way, the Nino 3.4 index will have to show anomalies cooler than -0.5°C below average for a month.

ENSO forecasts currently favor La Niña conditions over neutral ENSO conditions for seasons comprising September 2023 through February 2024, but only slightly—probabilities of ENSO neutral are generally greater than 40% in that window, and La Niña probability peaks around 50%. There is very little chance of an El Niño event developing this year, and there is a decent chance of a La Niña event, but also a good chance of no event at all and neutral conditions in the Pacific. In any case, the farthest-out seasonal prediction, for the March – May 2024 season, strongly favors neutral, suggesting that even if a La Niña event occurs, it is not expected to last long.  

The spread of forecasts from individual ENSO models shows all models either remaining in ENSO-neutral state or developing a weak-to-moderate La Niña state with peak SST anomalies between –0.5 °C and –1.5°C. Statistical forecast models tend to favor neutral ENSO, while dynamical forecast models tend to favor La Niña.

The August – October seasonal precipitation forecast very slightly favors below normal precipitation for Arizona and New Mexico, assigning that outcome a probability of 33-40%, leaving at least a 60% probability precipitation will be either near normal or above normal.

The August – October seasonal temperature forecast favors above normal temperatures for Arizona and New Mexico, assigning that outcome a probability of 50-70%, indicating a greater confidence in the temperature forecast as compared to the precipitation forecast.

Significant wildland fire potential in August is expected to be above normal for much of Arizona and New Mexico. In this year’s fire season Arizona has seen over 1,000 fires burn over 147,000 acres, while in New Mexico over 500 fires burned over 78,000 acres. By this time last year, a similar number of acres had burned in Arizona, but around 50,000 additional acres had burned in New Mexico.

Today is the day to make your August predictions!

Forecasts for August must be entered by TONIGHT at 11:59 PM. You can check the  Dashboard Page  to make sure you've submitted predictions for ALL FIVE Southwest cities. Sign up now to join the fun and track our iconic summer storm season!

But who's winning so far? Check  The Leaderboard  to see how the scores stack up!

Recorded 7/19/2024

Aired 7/23/2024 

Get ready for a big episode day as this month’s Southwest Climate Podcast hosts Zack Guido and Mike Crimmins kick off the monsoon season.  The crew cover the evolution of the current monsoon phases from onset to where we are today with stats and analysis.  And there is even a bit of a philosophical introspection on the data and sources (do you believe?).  Your hosts share what they have learned along the way - but stick around to the end to get their hot take on what is coming next.  

 Listen Here 

The Climate Assessment for the Southwest (CLIMAS) program was established in 1998 as part of the National Oceanic and Atmospheric Administration’s Climate Adaptation Partnerships (CAP) Program (formerly known as Regional Integrated Sciences and Assessments, or RISA). CLIMAS—housed at the University of Arizona’s Institute of the Environment—is a collaboration between the University of Arizona and New Mexico State University. The CLIMAS team is made up of experts from a variety of social, physical, and natural sciences who work with partners across the Southwest to develop sustainable answers to regional climate challenges.