Heat to briefly surge into Northeast late this week
A back-and-forth pattern of cool versus hot and steamy versus less humid will set up into next weekend, but cooler air may win out over the next several weeks.
RealFeel® explains not only how it feels based on temperature, humidity and wind speed but also other factors such as sunshine intensity and shade. This is available on the free AccuWeather app.
After a couple of days of lower humidity and noticeably cooler air early this week, a bubble of heat will break off from a searing heat dome over the middle of the United States later this week, AccuWeather meteorologists say.
A couple of days of wonderful conditions are in store for those with outdoor plans or laborers.
The all-important dew point temperature will be slashed by 15-30 degrees Fahrenheit across the region from Sunday to Monday night. The dew point is the temperature the air must be cooled to in order for the air to become saturated. Typically, dew point temperatures in the 70s, like it was in many areas on Sunday, are considered to be quite humid. By Monday evening, dew point temperatures will dip to October-like levels, in the 40s and 50s in many areas.

In some of the northern Appalachians, the dew points can dip into the 30s. This means it will feel dry and the perspiration index will be way down compared to many days since the middle of June.
Along with the big slash in humidity will come a cut in temperatures, especially at night. The sun will tend to go to work during the day, but the air will regain its origin from central Canada at night. Temperatures will dip into the 60s in Washington, D.C., and into the 40s in some of the chilly spots over the Northeast's interior.
Over the next several days, a heat dome with highs in the 90s to low 100s will build over the middle of the Great Plains and the Mississippi Valley.

A piece of that heat dome will break off and lunge east later this week.
"The late-week scorcher heading into the East will be a quick whiplash," AccuWeather Senior Meteorologist Chad Merrill said. "The timing is in sync with the late-June surge in temperatures, but this one won’t last nearly as long."
Detroit will jump well into the 90s Thursday and Friday. Philadelphia will leap into the mid- and upper 90s Friday and Saturday with RealFeel temperatures in the lower 100s. Overnight temperatures won’t offer any relief, as they'll be in the mid-70s to lower 80s.
A backdoor cold front looks to squash the heat by Sunday.
"While the Mid-Atlantic and Northeast have been no stranger to high humidity this summer, the mid-90s have only made an appearance once this month in Philadelphia," Merril said. "Detroit has only reached 92 degrees this month. New York City will reach well into the 90s Friday and Saturday, following only three days with highs in the 90s earlier this month. So the short, hot and humid spell will be significant."

That two-day stretch of hot and humid conditions will occur as the jet stream moves prior to discharging more cool air, bringing lower humidity later in the month as a pattern favoring a lower number of hot and steamy days evolves.
Just like what ended the heat wave from late June, a strong backdoor cool front will drop for the upcoming weekend. By "backdoor," meteorologists mean the cool air will arrive from the northeast and north rather than the traditional west or northwest.

For next weekend, how far to the west and southwest the cooler air can travel is still uncertain. However, a southward plunge in the jet stream accompanying the cool push may give it much more south and west momentum than late June.
Temperatures may be slashed by 20-40 degrees in the wake of the backdoor front next weekend.
In the pattern for the next three to four weeks, as a rough guide, the number of days with near to below historical average temperatures and humidity levels may outweigh the hot and humid days by a margin of two out of three or perhaps three out of four days in the Northeast.

As each wave of cooler and less humid air collides with hot and humid air, rounds of thunderstorms are in store. Some of the storms will be severe.
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