What will Summer 2015 Hold?

Posted: May 21, 2015, 4:53 pm by bmarmo

With Memorial Day Weekend upon us, many folks are starting to get into that summer mindset. And after all, meteorological summer does begin on June 1st. While early spring was relatively chilly, warm conditions have dominated the Eastern US for much of May. So, the question is, “how are things trending over the next few months?”

For those folks who read our long range products, you know we like to keep a close eye on important oscillations. Below is summary of the oscillations expected to have an impact on the overall pattern for the Summer of 2015.

Despite taking a lot longer than originally anticipated, El Niño conditions finally came to fruition this past March. In its simplest form, El Niño (the warm phase of ENSO) is the anomalous warming of ocean water across the Equatorial Pacific Ocean. With El Niño predicted to continue for the rest of this 2015, we can expect it to have an impact on this summer. Another oscillation we have been following is the Pacific Decadal Oscillation (PDO). While the PDO has two phases (“warm/positive” and “cold/negative”) like ENSO, it is different as it occurs on a time scale of decades. Also sea surface temperature anomalies associated with the PDO occur in the Northern Pacific Ocean (in contrast to the Tropical Pacific for El Niño). The PDO has been strongly positive of late, and is expected to remain that way for the foreseeable future. Overall, El Niño and a positive PDO correlate with slightly cooler than normal temperatures across the Northeast, Mid-Atlantic and Midwest with warmer than usual temperatures along the West Coast.

The upcoming summer might be hard to generalize as a whole, mainly because it looks like there could be a good deal of variation when it comes to temperatures, especially for the Northeast and Mid-Atlantic. 2014 actually serves as fairly good “analog” year along with 1957. Both of these analog years began warm and that’s just what we expect in June 2015.

Temperature anomalies for June of 1957. 1957 serves as a good analog for what we expect in early summer.

Despite the projected warm start, the East Coast will likely end up around normal overall, with the second half of the summer trending on the cooler side. Below average temperatures are expected in the Midwest, but on the other hand, the West Coast should see positive temperatures anomalies throughout the summer. As for precipitation, much of the Plains is anticipated to be relatively wet. In contrast, the Northeast, Mid-Atlantic and Pacific Northwest are forecast to be on the dry side. As of right now, the Midwest is forecast to see rainfall totals close to average. The temperature and precipitation forecast maps below are for June, July and August 2015.

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