December Precipitation & Temperature: December precipitation ranged from average to much-below average across most of Arizona and New Mexico, with record-dry conditions along the western edge of Arizona and in pockets of central and eastern New Mexico (Fig. 1a). December temperatures were above average to record warmest in both states (Fig. 1b), continuing the pattern observed during fall 2017. (read more)
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, moderate, and strong 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). (read more)
After a relatively late start, La Niña has ramped up over the past 30 days in terms of observed conditions and projected intensity, with sea-surface temperatures (SSTs) demonstrating a more consistent La Niña pattern (Figs. 1-2). Current forecasts and outlooks suggest a weak-to-moderate La Niña event lasting through the winter. (read more)
Precipitation & Temperature: November precipitation was below average across most of Arizona, with record-dry conditions in the western third of the state (Fig. 1a). In New Mexico, precipitation was average to much-below average, with small pockets of record-dry conditions in the central part of the state (Fig. 1a). November temperatures broke record highs across nearly all of Arizona and New Mexico (Fig. 1b). (read more)
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). (read more)
Most models now suggest that a weak La Niña event has emerged (Figs. 1-2) and is likely to last through this winter. On Nov. 8, the Australian Bureau of Meteorology called for a 50-percent chance of La Niña forming in 2017, noting that while sea-surface temperatures had cooled, the cooling had stalled, whereas atmospheric indicators had shifted slightly toward weak La Niña. (read more)
Precipitation & Temperature: October precipitation was below average to record driest in Arizona, with the driest conditions occurring in the southwestern corner of the state (Fig. 1a). In New Mexico, precipitation was average to above average in the eastern half of the state, and average to below average in the western half (Fig 1a). October temperatures were above average to much-above average across both Arizona and New Mexico (Fig. 1b) except for small regions in the north and in eastern New Mexico. (read more)
Oceanic and atmospheric indicators remain generally within the range of ENSO-neutral but have shifted more towards La Niña conditions in the past month (Figs. 1-2). Most seasonal outlooks and forecasts reflect these changes, and continue to call for the formation of a La Niña event as the most likely outcome by the end of fall and continuing into this winter. (read more)
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. (read more)
