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Southwest Climate Outlook March 2016 - Last Gasp for El NIño? | CLIMAS


Southwest Climate Outlook March 2016 - Last Gasp for El NIño?

Thursday, March 17, 2016

Precipitation & Temperature: Over the past 30 days, precipitation totals were well below average for most of the southwestern U.S. (Fig. 1). Despite anticipation for above-average precipitation this winter due to the strong El Niño event, a ridge of high pressure diverted moisture around the Southwest for much of the last 60 days. The resulting precipitation patterns look more like La Niña than El Niño, as the coastal Northwest and northern California have recorded well above-average precipitation and the Southwest has been very warm and dry (see El Niño Tracker). Temperatures in February were well above average for most of the Southwest, setting numerous high-temperature records, especially in southern Arizona and coastal Southern California (Fig. 2).

Image Source - Advanced Hydrologic Prediction Service

Image Source - NOAA National Centers for Environmental Information

Drought: Long-term drought persists across much of the Southwest, and recent warm and dry conditions have done little to improve regional outlooks on short-term drought (Fig. 3). There was hope that a strong El Niño might reduce precipitation deficits, but multi-year droughts, such as those experienced during much of this century so far, will require more sustained above-average precipitation over multi-year periods to fully recover. 

Image Source - U.S. Drought Monitor

Snowpack & Water Supply: This winter, below-average precipitation and above-average temperatures have dropped snow water equivalent (SWE) percent of normal to well below average in Arizona and southern New Mexico, with values ranging between 0 and 25 percent of normal. Northern New Mexico and much of the Upper Colorado River Basin are faring somewhat better, with SWE values between 75 and 110 percent of normal (Fig. 4). It remains to be seen how the rest of winter and spring will play out in high elevation areas, and how this will affect reservoir storage in the region (See reservoir storage information).

Image Source - Western Regional Climate Center

El Niño Tracker: With winter winding down and little on the horizon to indicate a shift towards a wetter signal, this El Niño event is shaping up to be a bit of a disappointment compared to forecasts and media characterizations that dominated the run up to the actual event. Expectations for a strong El Niño had been high, beginning with the false start of this El Niño event in 2014–2015, and continuing with a general sense of the potential a strong El Niño event could have to mitigate ongoing drought conditions (see expanded El Niño Tracker).

Environmental Health & Safety: The Southwest has been awash in color as flowering plants exploded to life, fed by the increased precipitation during fall 2015 and kickstarted by above-average temperatures of the past month or so. As a result, pollen counts are up, and as dry conditions persist, we can expect increased dust and particulate matter as well.  Wildfire also looms on the horizon, as growth spurts in fine fuels last fall and dry conditions this winter and spring have combined to increase fire danger classifications across the Southwest (Fig. 5). 

Image Source - Wildland Fire Assessment System

Precipitation & Temperature Forecast: The March 17 NOAA-Climate Prediction Center three-month seasonal outlook calls for increased chances of above-average precipitation for most of the Southwest (Fig. 6, top), and increased chances of above-average temperatures across most of the western United States (Fig. 6, bottom).

Image Source - NOAA/NWS - Climate Prediction Center