El Nino expected to affect July climate | TSLN.com

El Nino expected to affect July climate

BROOKINGS, S. D. – The latest climate outlook for July 2015 continues to indicate wetter and cooler conditions for the central U.S. – including most of South Dakota.

According to the June 30 National Oceanic Atmospheric Administration's (NOAA) Climate Prediction Center update, average temperatures for July are more likely to lean cooler than the normal in a large area from New Mexico and Texas to the Great Lakes region. "All of South Dakota is included in this area on the updated forecast map," said Laura Edwards, SDSU Extension Climate Field Specialist.

Edwards added that the Pacific Northwest and southeastern states are tending towards temperatures that are warmer than normal in the month ahead.

The update projects a large area of the U.S. to be wetter than normal in July, with the highest probabilities in the states of Missouri, Illinois, Kentucky and Tennessee. This area also covers the southern two-thirds of South Dakota.

Drier conditions are favored in the Pacific Northwest and the Gulf Coast regions.

"The summer season can be challenging for precipitation, as oftentimes thunderstorms emerge and can produce copious amounts of rain in a localized area," Edwards said.

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This July forecast does weigh the first week or two of the month more heavily than the last two weeks where forecast skill can diminish quickly, Edwards explained.

For the month ahead, drought is not much of a concern as the forecast for cool and somewhat wet conditions continues. "There is a small area of moderate drought in the southeast part of South Dakota, but this area has greatly diminished in size since early May," Edwards said.

She added that it is unlikely any long term, excessive heat waves will impact the state in the month ahead as well. "So crops and gardens could do well in the coming weeks," she said.

A look back at June 2015

This cool and wet pattern over the central states is consistent with the typical summertime El Nino impacts. "The temperature outlook for July, in particular, has been very consistent in most of the climate models in the last few weeks," said Dennis Todey, South Dakota State Climatologist & SDSU Extension Climate Specialist. "Continuing cool conditions would be consistent with wetter conditions that exist over most of the area."

Overall June was wet in western South Dakota, and a mixed bag in the eastern counties. Localized thunderstorms brought heavy rains to McPherson and McCook Counties in particular. "Most areas of the Black Hills had two to three times their average June precipitation," Todey said.

For Edgemont, Oral and Rapid City, June 2015 was the wettest on record, according to preliminary data. Cottonwood, Hot Springs and many others ranked this June among the top five wettest on record.

At the same time, June was overall warmer than average in many of these same areas, Edwards explained, pointing to Lead, Roscoe and Pactola Dam, which all ranked June 2015 among the top 10 warmest on record (in about 50 years or more.) "Only a handful of stations in South Dakota were cooler than average, as most locations were just a degree or two above average for the month," she said. "The many days of cloud cover and increased humidity likely had an impact in maintaining warmer overnight temperatures, especially in the western counties."

–SDSU Extension