CLIMAS: August Southwest Climate Outlook

 

Southwest Climate Outlook

August 2013

Vol 12 Issue 8

Climate Summary

Drought: Monsoon precipitation has brought some short-term drought relief to parts of Arizona and New Mexico, but drought remains widespread and intense.

Temperature: Record-setting heat in June has not carried into July and August in part because of widespread monsoon activity.

Precipitation: Rainfall has been largely above average since the beginning of the monsoon in both Arizona and New Mexico. 

ENSO: ENSO-neutral conditions are expected to persist through the upcoming fall and most likely through the winter.

Forecasts: Above-average temperatures are expected in upcoming seasons, while precipitation outlooks are a coin flip.

Summary Tweet: Wet monsoon in parts of SW improved drought. But more needed this winter and ENSO unlikely to help. More SW Climate http://bit.ly/12ptEkk (click to Tweet)

Climate Snapshot

The first half of the monsoon has not disappointed, delivering copious rain to many parts of the Southwest. Record amounts have fallen in parts of southeast Arizona and the consistent cloud cover and evaporation have helped keep temperatures near average after a record-setting, sizzling June. Characterizing the monsoon as good or bad, however, is challenging due to an inadequate number of monitoring stations to properly identify the high spatial variability. For the areas experiencing average or above-average rain, short-term drought conditions have improved. Recent updates of the U.S. Drought Monitor reflect this. In Arizona, for example, the area classified with at least severe drought decreased from about 73 to 56 percent between July 16 and August 13. In New Mexico, extreme and exceptional drought-the two most severe drought categories-decreased from about 86 to 66 percent during the same period. While improvements are evident, these numbers are still high, and New Mexico remains the most drought-stricken state in the U.S. Even if the monsoon remains active-precipitation forecasts for coming months are a coin flip-intense and widespread drought will remain a mainstay in the region through at least the early winter. Winter precipitation will therefore be critical for improving short- and long-term drought impacts, which include dwindling water supplies, particularly in New Mexico, where combined reservoir storage is at 16 percent of capacity. The Colorado River is also in need of a hefty dousing of precipitation. Water supply projections by the U.S. Bureau of Reclamation suggest high chances that Lake Mead’s water elevation will fall below 1,075 feet above sea level in 2015 or 2016, a threshold that would initiate the first water shortage declaration and affect some Arizona water users. The El Niño-Southern Oscillation (ENSO) provides the best glimpse of future precipitation. ENSO forecasts call for a neutral event; there is a slight tendency for neutral events to favor drier-than-average conditions in the Southwest. However, while La Niña events almost always deliver dry conditions to the region, neutral events are less definitive.

Read the SW Climate Outlook online
website

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Zack Guido

zguido@email.arizona.edu

CLIMAS

climas.arizona.edu

 

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