While it doesn't look like we're going to see another stretch of 90-degree days this week, as some forecasts last week had suggested, we are in line for a string of days in the upper 80s to, perhaps
90 degrees, with plenty of humidity to justify keeping the AC on.
The problem is a slow-moving low-pressure system over the Northern Great Plains. The counter-clockwise circulation around that big low is drawing warm, humid air north from the Gulf of Mexico into the southeastern part of the nation. The heat and moisture are making the air very unstable, touching off showers and thunderstorms in the Mississippi and Ohio valleys.
Forecasters say Central Maryland can expect warm (upper 80s), showery weather right through Saturday as this system moves ever-so-slowly to the east. A few of the storms could be strong to severe.
The showers could persist into Saturday. But as the big low moves into eastern Canada, we'll begin to feel the backside of the circulation, with winds shifting to the northwest. With a little luck, that will drop afternoon highs into the mid-80s by Sunday, with drier air and sunnier skies.