Oceanic and atmospheric conditions are still within the range of ENSO-neutral (Figs. 1-2), but rising sea-surface temperatures (SSTs) and shifting atmospheric conditions are reflected in recent forecasts, which call for an El Niño event forming by the end of 2018 and lasting through the winter. (read more)

The precipitation rankings for the months that encompass the monsoon period (see Fig. 3 on p. 2) smooth out the variability over space and time that is characteristic of this season. The cumulative totals for the monsoon for most of the major metropolitan areas in the region (Fig. 1) came in at or above average, with the exception of El Paso. (read more)

Precipitation and Temperature: Precipitation in September ranged from average to above average in New Mexico and from below average to much-above average in Arizona (Fig. 1a). September temperatures were warm throughout the region, ranging from much-above average to record warmest in Arizona and mostly above average to much-above average in New Mexico (Fig. 1b). (read more)

Monsoon precipitation varies considerably in space and time across the Southwest, as illustrated by monthly totals for various stations. (Fig. 1). Statewide patterns highlight widespread areas of both above- and below-average totals (see Fig. 4 on p. 5). The Fig. 2 plots of daily precipitation, temperature, and dewpoint temperature for the same stations as Fig. 1 capture the intermittent nature of monsoon precipitation as well as the persistent elevated dewpoint most locations experienced this summer. (read more)

With little change from last month, the Southwest remains in an ENSO holding pattern. Oceanic and atmospheric conditions are still within the range of ENSO-neutral (Figs. 1-2), but the forecasts point toward the likely emergence of an El Niño event this fall and lasting into the winter. (read more)

Precipitation and Temperature: Precipitation in August ranged from much-below average to average in New Mexico and from much-below average to above average in Arizona (Fig. 1a). August temperatures were mostly above average across Arizona and New Mexico, with swaths of much-above average and isolated locations of record-warmest conditions (Fig. 1b). (read more)

Monsoon precipitation totals vary considerably across the Southwest. Monthly totals for select locations reveal near or below-average amounts compared to long-term averages (Fig. 1). There are widespread regions with above-average totals as well (see p. 5), revealing the challenge of characterizing monsoon performance using single stations. (read more)

The Southwest remains in an ENSO holding pattern, with oceanic and atmospheric conditions still within the range of ENSO neutral over the last month (Figs. 1-2), and the forecasts and outlooks reflect that. (read more)

Precipitation and Temperature: Precipitation in July ranged from below average to much-above average in Arizona and New Mexico (Fig. 1a), illustrating the extent to which monsoon precipitation varies across the region. July temperatures were warmer than average in nearly all of Arizona and New Mexico (Fig. 1b), and since July 1, most of the daily temperature anomalies (deviations above or below the average temperature) have been warmer across the region (Fig. 2). (read more)

In 2008, the National Weather Service (NWS) changed the definition of the start of the Southwest monsoon from a variable date based on locally measured conditions to a fixed date of June 15 (and a fixed end date of Sept 30). Prior to 2008, the flexible start date reflected the seasonal progression of the monsoon, with a considerable temporal gradient across the region (Fig. 1). (read more)