Above-average temps, rain predicted for summer
Forecasting a “hot, humid” summer doesn’t exactly require a crystal ball, but some experts are anticipating this summer could be a bit more harsh than usual. Meteorologists are anticipating above-average temperatures and rainfall in parts of the eastern and southern U.S., with nearnormal conditions for parts of the Plains and Intermountain West.
The predictions come from the National Weather Service Climate Prediction Center, but they’re echoed by AccuWeather, a popular private forecasting company. Weather.com, meanwhile, is hewing toward a cooler than average start to the summer for the southern U.S., taking a more aggressive stance on the role that a burgeoning El Niño pattern will play.
Regardless of how the summer shapes up, a few staples of the summertime are a virtual guarantee large thunderstorm complexes, perhaps with damaging or destructive winds, will likely affect parts of the Plains, Midwest or even Mid-Atlantic, while the late summer will feature increased tropical concerns in vulnerable parts of the Southeast and along the Eastern Seaboard.
Overall, a few highlights stood out between the three outlooks:
■ Cooler weather is likely over the southern United States for June due to the position of key weather systems influenced by a budding El Niño
■ Chilly water temperatures off the Pacific Coast and soggy soils in California may delay the arrival of brutal heat for the West Coast
■ The Pacific Northwest is looking hotter and drier than normal
■ The Plains and perhaps Midwest will see the eventual emergence of aboveaverage temperatures
■ The jury is out for the Northeast and Mid-Atlantic, where the varying forecast enterprises have differing opinions
Perhaps the most official summer outlook is that of the National Weather Service Climate Prediction Center, which is painting above-average odds of elevated temperatures across the West, the South and the East Coast. The bull’s eye of the anomalous heat should, according to their outlooks, be centered over New Mexico, eastern Arizona and the Four Corners. The northern Plains and Upper Midwest should see temperatures near average during June, July and August.
While many might expect El Niño or La Niña to be a main driver in summer weather over the Lower 48, ENSO, or the El Niño Southern Oscillation, has its biggest impacts in the wintertime. For summer, that means less predictability.
“We’re actually expecting the transition for El Niño during the May through July season, so confidence increases [deeper into the summer],” said Johnna Infanti, a meteorologist at the Weather Prediction Center who produced the recent summer outlook. “It only plays a minor role, since the atmosphere
takes a while to catch up to the warming [waters] in the tropical Pacific” that are associated with El Niño.
There were some conjectures that meteorologists were able to draw knowing that an El Niño is looming, including the potential for drier weather in the Pacific Northwest and coastal Alaska.
Apropos to precipitation, the eastern U.S., and particularly the Ohio and Tennessee Valleys, look wetter than typical according to the Weather Service. Extra dry weather, meanwhile, should be found over the Desert Southwest - contributing to the heat also expected there.
AccuWeather agrees on increased East Coast heat and odds of a more typical summer over the Midwest and northern Plains. Where the outlooks differ is over the West Coast. AccuWeather hints at cooler than average conditions,
whereas the National Weather Service expects a toasty summer along the Pacific shoreline.
Regarding the East Coast, AccuWeather is forecasting more 90 degree days than average in places like Boston, New York, Philadelphia and Washington D.C.. That said, they don’t think it will be as hot as last summer, when Boston hit 90 degrees 21 times (compared to an average of 15 times), New York hit that temperature 25 times (compared to an average of 17 times), and Philadelphia did 4 dozen times (the average is 30 times per summer).
For the West Coast, AccuWeather states that summer’s hottest weather should be delayed, cutting back on temperatures. They blame cooler water temperatures in the eastern Pacific, coupled with waterlogged soils left from a winter of heavy rains. That, AccuWeather argues,
will make it tougher to heat the air above as quickly.
Those are similar factors to what the Weather Service looked at.
“We take a look at a number of different dynamical climate models, as well as the state of local drivers like soil moisture or local sea surface temperatures,” said Infanti.
Another place that AccuWeather’s and the Weather Service’s outlooks differ? The central states.
AccuWeather places a bull’s eye of warmth over the Plains, while the Weather Service is hesitant to swing either way.
“There’s a bit more uncertainty over the central U.S. because, in general, the climate models we use have better agreement toward the coast,” Infanti said. “There was a tendency toward mixed signals . . . for that little swath . . . over the [central U.S.]”
Weather.com is also in line with AccuWeather in forecasting a cool early summer for the western U.S. for similar reasons. Like AccuWeather, they also paint odds of anomalously warm weather over the Plains states.
Weather.com believes that the southern U.S. will see a cooler start to summer. The National Weather Service agrees that the start of summer will be cool, but believes the second half of summer will feature heat that will compensate. Weather.com seems to agree.
The reason? Weather.com is expecting a more rapid swing to El Niño, which Infanti at the Weather Service alluded to. That will induce ridging, or the development of a stagnant heat dome within a northward jog of the jet stream, over the northern U.S.; that should keep places like Seattle and Portland warm while squashing the cooler weather over the South. That should break down deeper into the summer.
Across the board, particularly from July onward, forecasters at all three organizations did pinpoint the Desert Southwest, particularly in New Mexico and eastern Arizona, as looking especially hot and dry from July onward. Infanti said a “strong signal” existed for dry weather, and dry air heats up faster, which reinforces hot temperatures.
There will also be a delayed start to the Southwest Monsoon, or the periodic afternoon thundershowers that hover over the desert, bringing much of the region’s annual rainfall.