Extended Outlook Calls for Above-Normal Temps Across Contiguous U.S.

Posted on 03/09/2017 10:21 AM

The National Weather Service's Climate Prediction Center (CPC) forecast for September through November calls for above-normal temps across the contiguous U.S. and Alaska. The greatest chance for above-normal temps are in the southwestern states (excess of 60%), the Gulf Coast region and from the eastern Great Lakes to the northern Atlantic Coast (in excess of 50%). The CPC says a broad area of "slightly enhanced probabilities" for above-normal temps (33% to 40%) is indicated from the far northern Rockies eastward to the Upper Mississippi Valley due to the early effects of a developing weak La Nina.

Regarding influences for the extended outlook, the CPC says the "predicted transition to La Nina conditions and the most likely impacts are considered for the seasonal outlooks primarily beginning in OND (October-November-December) 2016 through the winter into early spring, 2017."

The CPC calls for above-normal precip across Montana, North Dakota and northwest South Dakota. Below-normal precip is expected across portions of California and Nevada and well as much of the Southwest. Elsewhere, chances are equal for normal, below- or above-normal precip, which includes the entire Corn Belt, as well as the Central and Southern Plains.

CPC Outlooks for September-November:

90daytemp_aug2016
90dayprecip_aug2016


The outlook for September calls for equal chances of normal, below- or above-normal temps and precip across the Corn Belt and Plains.

In its text discussion for the September outlook, the CPC says there is a high amount of uncertainty surrounding the precip forecast.

CPC Outlooks for September:

30daytemp_aug2016
30dayprecip_aug2016


Below, we compare the Seasonal Drought Outlook to the current Drought Monitor:

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drought_monitor_aug182016


According to the Seasonal Drought Outlook, although development and intensification of drought becomes less likely as temps cool this fall, persistence is favored across the long-term drought areas of the Northeast. "Prospects for drought removal improve to the west across northern Ohio, northeast Indiana and lower Michigan where drought is more short-term in duration," it states. "Drought persistence is forecast across the interior Southeast and parts of Alabama, Georgia, Tennessee and the upstate of South Carolina are the most likely areas for development through the end of November. Improvement or removal of drought is favored across the Great Plains along with southeast Arizona and New Mexico. Persistence is forecast across the protracted drought areas of the West, while removal is favored along coastal Oregon where it becomes wetter earlier during the fall season."

The outlook states that during the past month, "insufficient rainfall coupled with above-normal temperatures contributed to an increase in short-term drought across parts of the central and eastern U.S. with drought intensifying across the Northeast. Improving drought conditions were limited to parts of the Southeast and middle Mississippi Valley."


 

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