The past three summers have been particularly hot. If the upper level jet stream ridge this summer sets up far enough to the West and is sharp enough, then the down stream trough would be strong enough to bring Atlanta a more run of the mill summer temperature-wise, and allow for periodic episodes of widespread thunderstorms. But this is a big IF that does not currently seem in the cards. So the early thinking on this summer is warmer and drier than average in Georgia.
A remarkably mild winter with just brief intense cold snaps was followed by a record warm March and a mostly warm April. But the atmosphere is expected to adjust to changes in the Pacific Ocean with conditions of the Pacific leaving the cooler than normal waters of La Nina the past three years behind and the return of EL NINO or warmer than normal central Pacific Ocean temperatures heading through summer and into next winter.
These changes are expected to place most of the jet stream atmospheric ridging of high pressure associated with prolonged extreme heat over the Great Plains and Rocky Mountains with troughing over the Great Lakes to Mid-Atlantic region during the coming summer providing lower than normal temperatures for the east-central regions.
The data of going from several years of La Nina to an El Nino shows a cool signal. In fact, if not for multi-decadal trends of warming and dry soil conditions in the Southeast the forecast might actually call for a cool summer.
The last time Atlanta had a “below normal” summer was way back in 2004! But it was just a tad below-normal. The last “near-normal” summer was 2008. The last “cooler than normal summer” was 2003 when there were just 7 days of 90 degree weather and none above 95!
But as of now my call for the summer is warmer than normal when averaged over the entire 3-month period but not quite as swealtering as the past two. Relative to normal, the hottest may be early and late. I project temperatures to average 1-2 degrees above normal averaged over the 90-day period of June, July and August. So not a cool summer, but some hope for less hot than last year. For comparison, last summer was 3.3F above-normal and rainfall was about half of average.
Drought looks to continue or expand in much of the state with the worse drought in South Georgia and rainfall for Atlanta at least a couple inches below average. There will be a fair share of days below 90 and some well short. But don’t get me wrong, there will be plenty of days between 90 and 100.
My forecast is based on analog years which come from matches to the winter, and the warm pattern of March and April, along with the solar cycle, state of the the PDO and AMO phase, and the transition from La Nina to El Nino and decadal trends. Climate models were also consulted.
Click on the maps to see what the analog years predict for this summer compared to the temperature departure from normal for the past two years.