Nov 2017 SW Climate Outlook - Weak La Niña Events in the Southwest

Looking more closely at winter Dec-Feb (DJF) precipitation, most weak La Niña events (ENSO Index Value between -0.5 and -1.0) recorded below-average precipitation, although a few years (1968, 1985) are notable outliers (Figs. 5-6). Looking at the monthly breakdown of weak La Niña events reveals that while the DJF totals for Tucson, AZ and Las Cruces, NM are mostly below average (Figs. 7-8), there have been some individual months that recorded precipitation above the monthly average (represented by black lines on the plots). The most likely outcome is below-average precipitation totals for the winter season, but the way that these events unfold will have an impact on how residents of the Southwest perceive and experience this La Niña event.