The official start of summer is just days away on June 20, and blistering heat has already been swelling over the Plains. In the final days of spring, a season marked by wild weather swings for many, the hot weather is expected to shift eastward across the Midwest and into the interior Northeast.
Meanwhile, a pocket of unseasonably cool air near the Atlantic coast will hold its ground and suppress temperatures for some eastern United States locations for part of this week, leading to a more dramatic change come late this week.
“The weather pattern from this past weekend has been brought about by an atmospheric roadblock that limits the normal west to east movement of weather systems across the nation,” Senior Meteorologist Brett Anderson said.
“In this case, heat has been surging northward over the Plains, while a pocket of cool air has formed and dipped southward in the eastern third of the nation,” Anderson explained.
Temperatures over the weekend climbed 10-20 degrees Fahrenheit above average over parts of the northern Plains. Ninety-degree highs were recorded as far north as central North Dakota amid the hot spell, and forecasters say temperatures could even flirt with the century mark in a few locations.
Where cooler air invaded, temperatures failed to climb to 70 degrees in places like eastern North Carolina over the weekend. The high in Wilmington, North Carolina, on Saturday was 69, compared to a normal high of 87. And, the contrast was even more stark for areas farther to the north. The temperature barely topped 50 on Saturday at Saranac Lake, New York, where high temperatures tend to average in the lower 70s during the middle of June.
On Monday, the core of the chilly air had settled over southern Virginia and North Carolina. Record low maximum temperatures were set at several locations including Roanoke, Virginia, with a high of 63 breaking the old record of 64 set in 2007. A high of 63 was also observed for at Piedmont Triad International Airport, North Carolina, breaking the old record of 64 set in 1965.
“While the overall traffic jam will continue, it will weaken a bit, and weather systems will get squeezed as the week progresses. That will allow for some changes,” Anderson said.
Some eastward movement of weather systems will allow a storm over southern Canada to drag a front across the northern Plains and the Upper Midwest with the potential for severe weather Wednesday.
Highs are forecast to jump to near 90 in much of Minnesota and Iowa by midweek ahead of that front.
In the Midwest, highs will be in the 70s to near 80 at the start of the week before experiencing a shift to highs well into the 80s to the lower 90s in Chicago, Detroit, Indianapolis, Cleveland, Cincinnati, St. Louis and Milwaukee into the latter parts of this week.
Warmth will build rather quickly over the interior Northeast as well, where some of the most dramatic temperatures swings are anticipated. It was chilly enough for a frost to grip parts of the region, including north-central Pennsylvania, over the weekend.
It should feel more like the middle of July by the end of the week from West Virginia to Pennsylvania, New York state and much of New England. Highs will reach upward into the 80s to even near 90 in a few spots.