As a push of cooler, less humid air approaches western Pennsylvania, northern West Virginia and western Maryland Thursday afternoon and evening, spotty heavy, gusty thunderstorms will form over the region.
While the storms will be hit-or-miss, a few communities can be hit hard with damaging wind gusts and flash flooding.
Late Thursday afternoon, a thunderstorm wind gust reached 68 mph in Westmoreland County, Pa., according to a report by AWOS.
The storms have the potential to cause travel delays and sporadic power outages along the I-70, I-79 and Route 22 corridors.
The risk of severe weather will diminish later Thursday night as the cooler, less humid air begins to filter in from Canada.
Highs will be near 80 degrees Friday and Saturday with nighttime lows in the 50s to near 60 degrees. The sky will be generally clear over the region during the period. However, patchy fog is possible during the early morning hours along the rivers.
During next week, warmth and humidity will return. However, there is also the chance of additional rounds of showers and thunderstorms.
A surge of warmth into the Northeast will create Boston's warmest day so far this year on Monday.
Summer warmth will dominate most of this week in Pittsburgh, creating the warmest days so far this year.
It will not feel like a typical early May week around Washington, D.C., and Baltimore this week with warmth dominating.
Early indications suggest that the first tropical system of 2015 could spin up off the southern Atlantic Coast of the United States later this week.
After a cooler-than-normal summer 2014, the Northeast can anticipate more 90-degree days. Meanwhile, drought conditions will expand in the West.
Severe snowstorm: 33.8" in Havre (24.8 inches of which fell in 24 hours).
New Orleans, LA (1978)
Persistent thunderstorms caused worst flooding in 30 years at New Orleans; lightning ignited an oil storage tank at Covent, LA.
Kanab, UT (1982)
Sinbad the Sailor, the horse President Reagan rode on the TV series Death Valley Days, was struck by lightning and killed in Kanab, UT.