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After a warm and dry winter (detailed in past issues of the SW Climate Outlook), drought, fire, and poor air quality (dust and pollen) are growing concerns as spring turns to summer. In May, warm temperatures (Fig.1), including triple-digit highs (Fig. 2), are increasingly common, while average precipitation is among the lowest monthly totals for the region (Fig. 3), and additional precipitation is unlikely. At the same time, the winds are picking up due to seasonal transitional conditions (Fig. 4), further increasing fire risk (Figs. 6a-b) and impacting air quality and public safety (e.g. dust storms). (read more)

Precipitation and Temperature: The Southwest was characterized by below-average precipitation in April, ranging locally from record driest to near average (Fig. 1a). Temperatures were mostly above average for yet another month, with record-warm conditions along the eastern third of Arizona and the edge of western New Mexico, but also with a band of average to below-average temperatures on the eastern edge of New Mexico (Fig. 1b). (read more)

Oceanic and atmospheric conditions over the last month remained generally consistent with a La Niña event (Figs. 1-2), but given the rapid decline of these conditions and the imminent seasonal transition, it is only a matter of time before ENSO-neutral conditions return. The current ENSO forecasts reflect this steady weakening, with most indicating a likely transition to ENSO-neutral conditions over the spring, and others having already declared an end to this La Niña event. On April 10, the Japanese Meteorological Agency (JMA) identified ongoing La Niña conditions but called for a 90-percent chance that this event will end in spring. On April 10, the Australian Bureau of Meteorology maintained their ENSO Outlook at “inactive,” stating “there is little sign of El Niño or La Niña developing in the coming months.” On April 12, the NOAA Climate Prediction Center (CPC) continued its La Niña advisory but expected a transition to ENSO-neutral conditions by May and forecast a greater-than-50-percent chance of ENSO-neutral lasting through summer. On April 19, the International Research Institute (IRI) issued its ENSO Quick Look, which still identified weak La Niña conditions present but called for a rapid transition to ENSO-neutral conditions over spring (Fig. 3). The North American Multi-Model Ensemble (NMME) is consistently indicative of a return to ENSO-neutral conditions, but with greater uncertainty over what the latter half of 2018 might hold (Fig. 4). (read more)

Precipitation & Temperature: Precipitation varied considerably across the Southwest in February, but temperatures remained warm throughout the region. Precipitation amounts ranged from below average to much-above average, with the wetter areas concentrated in southern Arizona and southwestern New Mexico and the driest areas occurring in the Four Corners region and northeastern New Mexico (Fig. 1a). Temperatures ranged from average to above average in Arizona, and from above average to much-above average in New Mexico (Fig. 1b). (read more)

La Niña conditions continued for another month, with both atmospheric and oceanic conditions demonstrating a La Niña pattern (Figs. 1-2). Forecasts continue to suggest a weak-to-moderate La Niña event that has likely peaked and will gradually weaken this spring. (read more)