ben's blog

The Southwest saw the first strong burst of widespread monsoon activity near the end of June.  Most of the first half of July was characterized by a distinct break in monsoon activity, as atmospheric circulation patterns and lack of available moisture limited opportunities for widespread storms to develop, especially at lower elevations.  As July progressed, there were increasingly favorable conditions for storms to develop and spread, culminating in an extended period of widespread activity during late July and early August. Tropical Storm Javier helped jumpstart activity in mid-August, just as the previously mentioned extended run was winding down, and provided a brief extension to storm activity via a surge of moisture from the Gulf of California. The remainder of the monsoon window will be a waiting game to see if favorable moisture and atmospheric circulation patterns develop, as well as the potential influence of eastern Pacific tropical storm activity that could supplement storm activity and provide additional moisture to fuel storm activity. (read more)

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). (read more)

All oceanic and atmospheric indicators of the El Niño-Southern Oscillation (ENSO) have returned to neutral conditions (Figs. 1-2). The development of a La Niña event in 2016 remains a distinct possibility, even while the timing and intensity remain relatively uncertain. (read more)

El Niño conditions continued their active decline (Figs. 1-2), and consensus is that they have reached ENSO-neutral status at the time of this writing. Forecast discussions focused on the decline of atmospheric and oceanic anomalies that characterize an El Niño event—convective activity, equatorial sea surface temperatures, and trade winds—and forecasters saw consistent evidence of a return to ENSO-neutral status across these indicators. Seasonal ENSO outlooks coalesced around La Niña conditions emerging by summer or fall 2016, with relatively high certainty that La Niña conditions would be in place sometime by mid-to-late 2016. (read more)

El Niño Recap & La Niña Outlook

This El Niño event was one of the strongest ever recorded (Fig. 5), and if past performance was any indication of what was expected for the Southwest, the region should have seen above-average precipitation over much of the cool season (winter and spring). The Southwest generally saw lower-than-expected precipitation totals that were much closer to average, or even below average in some cases.  There are several reasons why this event did not meet expectations. (read more)