Summer Outlook: It'll be hot in the nation's northern tier
Above-average temperatures are expected for the northern half of the nation this summer, according to an updated outlook released Friday by The Weather Company, an IBM Business.
The core of the heat in early summer will be centered from the Northwest through the Midwest, but will expand into the East later.
"The historically strong El Niño event is weakening rapidly and we should transition into La Niña conditions by late summer. Model guidance shows a rather dramatic reversal of the background tropical Pacific forcing signal that would favor a hot summer again, especially across the northern U.S. and especially late," said Dr. Todd Crawford, chief meteorologist.
In June, areas from the Pacific Northwest through the northern Plains are forecast to see temperatures the farthest above average.
The June forecast temperatures in the Northeast and parts of the West have been decreased from previous outlooks due to lingering impacts from El Niño and because of a recent blocking weather pattern that may persist. This same blocking weather pattern has kept below-average temperatures firmly entrenched in the Northeast and mid-Atlantic so far in May.
Keep in mind, these outlooks are overall trends for the entire month. An individual cold front or an upper ridge of high pressure can lead to a brief period of colder or warmer weather, respectively.
Summer Forecast: June-August
The trend of warmer-than-average temperatures overall during summer months the last several years is expected to continue.
"The last six summers have been the hottest six-year stretch in the last 120 years, barely eclipsing the very hot 1930s," Crawford said.
Well-above-average temperatures are expected this summer for the northern tier of states from the Pacific Northwest into the northern and central Plains, Great Lakes, mid-Atlantic and Northeast. The northern Plains and Upper Midwest are forecast to see temperatures the farthest above average.
The only area where cooler-than-average temperatures are expected this summer will be across much of Texas to Louisiana. Though temperatures there may only be near or slightly below average.
"We expect that the full La Niña forcing will not be in place by June, but will come roaring into play by July and, especially, August," Crawford said. "We expect a strongly 'back-loaded' summer with the heat continuing into September."
Typically, La Niña summers feature hotter temperatures from the central U.S. into the Northeast.
Crawford notes that during previous years where rapid changes from El Niño to La Niña occurred, the worst of the summer heat was focused from the northern Plains to the Great Lakes states.
Another factor to consider regarding temperatures this summer are sea-surface temperatures in the western North Atlantic, which are forecast to be warmer than any time over the past five years. That often results in warmer temperatures in the eastern U.S.
Overall, computer model guidance indicates widespread warmth with little hint of cooler-than-average temperatures across the nation.
The heat should be less significant across the southern states where temperatures should generally be around to slightly above average, except across much of Texas and Louisiana where temperatures are likely to end up near or slightly cooler than average.