The University of Arizona

Southwest Climate Outlook August 2016 - Climate Summary | CLIMAS


Southwest Climate Outlook August 2016 - Climate Summary

Thursday, August 18, 2016

Precipitation and Temperature: July precipitation totals were below average across most of Arizona and New Mexico in the past 30 days (Fig. 1a), due in part to an extended break in monsoon activity. July temperatures were above average across nearly the entire region (Fig. 1b), linked to global trends that saw record-warm temperatures in 2016 and to regional patterns of warmer and drier conditions that correspond to the aforementioned break in monsoon activity. August precipitation to date is average to above average for most of Arizona and portions of New Mexico (Fig. 2), partly linked to moisture associated with Tropical Storm Javier that resulted in heavy precipitation in parts of the Southwest. In August, temperatures have been mostly average to below average in Arizona and mostly above average in New Mexico (Fig. 3).

Monsoon: A strong start for the monsoon in late June was followed by an extended break in activity for much of July. The end of July saw another multi-day system that brought frequent storm activity to the region, particularly in southeastern Arizona, which has seen some of the heaviest monsoon activity this year (see Monsoon Tracker). Seasonal totals to date for New Mexico generally have been below average, although August rainfall has helped make up some of the precipitation deficit.

Drought & Water Supply: Long-term drought persists across the Southwest (Fig. 4), reflecting multiple years of drought conditions and accumulating precipitation deficits. In the Aug. 16 U.S. Drought Monitor, most of Arizona was designated as experiencing moderate drought (D1), while most of New Mexico was designated as abnormally dry (D0). This pattern is unlikely to reverse in the short term, especially with a weak La Niña event likely occurring this fall into winter, which could bring warmer and drier conditions to the Southwest. Water year precipitation to date is below average in much of the Southwest, particularly in Southern California, most of southern Arizona, and western New Mexico (Fig 5).

La Niña: Sea surface temperature anomalies and atmospheric patterns all indicate ENSO-neutral conditions. Uncertainty remains as to whether an actual La Niña event will occur, but current model consensus points toward the formation of a weak La Niña event between now and October that is expected to last through winter 2017 (see La Niña Tracker).

Wildfire: Cooler and wetter-than-average conditions linked to the lingering effect of El Niño tamped down early-season fire activity in April and May. Fire activity picked up in June and July, but precipitation from cold front, monsoon, and tropical storm activity, as well as increased relative humidity across the region, helped limit the risk of severe wildfire. As of August, wildland fires had burned approximately 220,000 acres in Arizona and 274,000 acres in New Mexico. Favorable weather conditions permitted fire managers to let a number of fires burn for beneficial use to reduce future wildfire risk.

Precipitation & Temperature Forecasts: The July 21 NOAA-Climate Prediction Center’s seasonal outlook for September calls for increased chances of above-average precipitation for most of Arizona and western New Mexico (Fig. 6) and increased chances of above-average temperatures across the western U.S. (Fig. 6). The three-month outlook for September through November calls for increased chances of above-average temperatures across the U.S.— and the Southwest in particular—while calling for equal chances of average, above-average, or below-average precipitation.