During the past four weeks, persistently dry, warm weather contributed to an expansion and degradation of drought across the southern Plains and lower Mississippi Valley away from the immediate Gulf Coast, with many stations across the region recording top-5 driest Septembers on record. Short term abnormal dryness and areas of moderate drought also developed over parts of the middle Mississippi Valley. In contrast, excessive rainfall associated with an upper level low and a stalled frontal boundary inundated parts of the East. In particular, rainfall in excess of 20 inches across central and eastern South Carolina generated widespread catastrophic flooding. Rainfall also eased drought conditions across the Northeast, but pockets of moderate drought remain in southeastern New England and the Tri-State region. Abnormal heat dominated the western half of the CONUS, and while most regions remained status quo with respect to drought, areas of above average precipitation brought relief to parts of southern Arizona and New Mexico, southern Idaho, and Montana.

Strong El Nino conditions are ongoing across the equatorial Pacific, with robust atmospheric coupling. The latest CPC ENSO advisory indicates a 95 percent chance that El Nino conditions will persist through the winter months. Therefore, climate anomalies associated with El Nino events, which become increasingly prominent over the U.S. during the Fall and Winter months, played a significant role in this outlook. Through the end of January, widespread drought relief is anticipated across the central and southern Plains, lower Mississippi Valley, and the eastern U.S. In contrast, a drier ENSO climate signal over the middle Mississippi and Ohio Valleys makes substantial relief of the short term drought conditions less likely, although there is too much uncertainty to warrant additional drought expansion in this outlook. Based on the CPC seasonal forecasts, the greatest potential for drought development is across the northern tier of states, including the Great Lakes region and northern Plains. Drought persistence or intensification is forecast across the Northwest. For the Southwest, El Nino associated climate anomalies favor an enhancement of the early wet season. Therefore, drought improvement is favored across central and southern California. There is greater confidence for improvement across the coastal regions and valleys, whereas significant improvement across the Sierras relies on colder temperatures to support substantial snowfall. Further east, drought removal or improvement is forecast across the southern Great Basin and interior deserts. A pronounced dry signal during El Nino years favors drought development across Hawaii. Drought persistence with no further expansion is forecast across Puerto Rico, where the start of the dry season may be offset by a wet climate signal during El Nino years. Drought development is not anticipated across Alaska during the first part of the winter season.

Forecaster: Adam Allgood

Next Seasonal Outlook issued: November 19, 2015 at 8:30 AM EDT