Southwest Climate Outlook December 2021

Date issued

Precipitation and Temperature: Nov precipitation was between record driest and near average in Arizona and New Mexico (Fig. 1a). Nov temperatures were between much above average and record warmest in Arizona and New Mexico (Fig. 1b). Sept-Nov precipitation was mostly average to below average in Arizona, and average to much below average in New Mexico (Fig. 2a). Sept-Nov temperatures were between above average and much above average in Arizona, and between much above average and record warmest in New Mexico: a pattern that extended across much of the western U.S. (Fig. 2b). Twelve-month precipitation totals show the influence of the monsoon in southern Arizona and New Mexico, as well below normal to record driest regions across most of the western U.S. (Fig. 3).

Drought: The U.S. Drought Monitor (USDM) showed minor improvements in drought categorizations in a few areas of the Southwest, but drought conditions are still found across the Southwest (Fig. 4), and the entire western U.S. The variable monsoon totals and La Niña this winter, continue to raise concerns about long-term and cumulative precipitation deficits.

Snowpack & Water Supply: Mid-December snow water equivalent (SWE) is highly variable in the Southwest, with most of the region recording below-average conditions (Fig. 5). Most of the reservoirs in Arizona and New Mexico are at or below the values recorded at this time last year. Most are also below their long-term average (see reservoir storage for Arizona and New Mexico). Water levels at Lakes Mead and Powell continue to drive the conversation about Colorado River water management and shortage declarations in response to those water levels. The Rio Grande in New Mexico and Elephant Butte Reservoir raise similar concerns in New Mexico, although there has been less national attention to date.

Hurricanes & Tropical Storms: The Eastern North Pacific saw activity across the bulk of the season, with 19 named storms but only two major hurricanes (Fig. 6). The accumulated cyclonic energy (ACE) was near normal through August, but Sept-Nov were quiet with five named storms, resulting in a seasonal ACE of approximately 75% of normal.

ENSO Tracker: ENSO has reached La Niña status according to most outlooks, based on observed and forecast SSTs, emergent atmospheric conditions, and coupling between the two that is indicative of La Niña (see ENSO-tracker for details).

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

Disclaimer. This packet contains official and non-official forecasts, as well as other information. While we make every effort to verify this information, please understand that we do not warrant the accuracy of any of these materials. The user assumes the entire risk related to the use of this data. CLIMAS, UA Cooperative Extension, and the State Climate Office at Arizona State University (ASU) disclaim any and all warranties, whether expressed or implied, including (without limitation) any implied warranties of merchantability or fitness for a particular purpose. In no event will CLIMAS, UA Cooperative Extension, and the State Climate Office at ASU or The University of Arizona be liable to you or to any third party for any direct, indirect, incidental, consequential, special or exemplary damages or lost profit resulting from any use or misuse of this data.