Conditions Favor El Niño this Winter: Significant drought expected to lessen in parts of the Southwest and persist in others.

From October 2017 to September 2018, the Southwestern U.S. experienced below-normal to record-low precipitation.
Long-term precipitation deficits and record-high temperatures have contributed to very low streamflows and reservoir levels.
Conditions favor the development of El Niño this winter, but significant drought is expected to persist in most of Utah and Colorado.

WATER YEAR (OCTOBER 2017-SEPTEMBER 2018)

Extreme Drought Entrenched in the Four Corners. Weak El Niño Expected through Winter and Spring.

• Extreme drought remains entrenched in the Four Corners area of the Southwest.
• Recent above-normal precipitation has resulted in some drought improvement in eastern areas of Colorado and New Mexico.

Quarterly Climate Impacts and Outlook for the Western Region for June – August 2020.  Dated September 2020.

Summer temperatures were well above normal in California, Nevada, the Four Corners and Wyoming. Pacific Northwest and Montana temperatures were near normal or above normal with a few small pockets below normal. Large areas of the West observed a drier than normal summer with southeast California into Arizona being the driest. This is the second year in a row with “missing” monsoon rains.

Quarterly Climate Impacts and Outlook for the Western Region for September – November 2019.  Dated December 2019.

Autumn temperatures were well below normal across the northern tier of the region while near to above normal temperatures were observed across California and the Southwest.  Several areas of the West reported below normal autumn precipitation including northern California, eastern Utah, and western Colorado. Montana, northern Wyoming, northwestern Utah, and the Southwest reported above normal precipitation.

Quarterly Climate Impacts and Outlook for the Western Region for June – August 2019.  Dated September 2019.

Quarterly Climate Impacts and Outlook for the Western Region for March – May 2019.  Dated June 2019.

Spring temperatures were variable across the West.  The North Pacific storm track remained active through the spring season bringing above normal precipitation to much of the West.

Background: The 2017-2018 Drought in the Southwest

According to the U.S. Drought Monitor’s drought severity designations, “Abnormally Dry” conditions crept into the Southwest region in October 2017 and deepened into widespread “Moderate Drought” in November 2017. The region was in “Severe Drought” by January 2018; “Extreme Drought” by March 2018; and “Exceptional Drought” by May 2018. The “Exceptional Drought” lingered in the region until January 2019. In 2018, the region experienced more than 45 weeks in drought.

Quarterly Climate Impacts and Outlook for the Western Region for December 2018 – February 2019.  Dated March 2019.

Persistent stormy conditions helped to maintain near-to-below normal temperatures across much of the West this winter.  Abundant precipitation and moderate temperatures helped alleviate drought conditions in large areas of the West.

Long-term drought in the Southwest will continue to impact reservoirs and water supply

• Weak El Niño conditions developed in January; an “El Niño Advisory” is in effect as of 14 February 2019.
• ​Since October 2018, the region has experienced mostly wetter and cooler conditions than 1981-2010 normals (Fig 1).
• Extreme and Exceptional Drought in the Southwest has decreased in extent from 25% in October 2018 to 5% in February 2019 (Fig 2).
• Several years of above-average precipitation and run-off will be needed to alleviate the water supply deficits r

Quarterly Climate Impacts and Outlook for the Western Region for December 2019 – February 2020.  Dated March 2020.

Winter temperatures were above normal for much of the West. Near to below normal temperatures were observed in the Central Rockies states.  ​Scattered areas across the northern tier of the West reported above normal precipitation due to an active, poleward shifted storm track. In contrast, western Oregon and the Southwest observed near-to-below normal precipitation, due to persistent ridging during January and February.