SW Monsoon Tracker/Recap
The North American Monsoon was quiet for much of the Southwest through early July. The rest of July was active and numerous locations approached or set single-month precipitation records. August saw a widespread shutdown of monsoon activity across much of Arizona, which lasted for the rest of the official season. During the same period, New Mexico saw more consistent precipitation activity, including a last gasp in late September when a cluster of storms hit both central and far southern parts of the state. Weather stations in regional metropolitan areas recorded mostly average to above-average totals (Fig. 3 on p.2), with the larger anomalies in Tucson and El Paso attributed to near-record July precipitation. Conversely, Yuma and Albuquerque had been lagging behind their seasonal averages but received late-season boosts to their seasonal totals.
Precipitation rank maps reveal July was mostly above normal (top 33 percent) and much-above normal (top 10 percent) across nearly all of Arizona and much of western and northern New Mexico (Fig. 1). August flipped that script, with most of Arizona and western New Mexico recording below-normal or much-below-normal precipitation, and with a large pocket of dry conditions centered over the Four Corners region even while eastern New Mexico was much-above normal to record wettest (Fig. 2). September was a variation on that theme, with most of Arizona and southwestern New Mexico recording below-normal or much-below-normal precipitation while northwestern Arizona and northern and eastern New Mexico recorded above-normal to much-above-normal precipitation (Fig. 3).
The cumulative seasonal precipitation totals diminish the more extreme monthly variations (Fig. 4), with percent of total and days with rain revealing a high degree of spatial heterogeneity of precipitation totals and frequency across the region (Figs. 5-6 on p.4).