A Taste of Autumn Arrives This Weekend, and So Is a Flooding Risk

The forecast for the Midwest and the interior Northeast is a double-edged sword. While relief from the heat is on the way, the atmospheric conditions will also support gusty thunderstorms and heavy rain capable of triggering flash flooding.

Cooler Air Moving Down from Canada

There is good news for millions of Americans tired of the heat. A surge of Canadian air will bring cooler temperatures this weekend to the Great Lakes, the central and northern Appalachians, and beyond. However, the change in the pattern will also spark drenching rain and the threat of severe weather.

The cooler and less humid conditions have already begun to spread to some areas of the Great Lakes and the Northeast. Highs in the upper 80s will swap out with readings that top out in the 70s to low 80s. Areas that see clear skies after the sun goes down could see overnight lows that dive as low as the 40s, bringing a true taste of fall to the northernmost areas of the U.S.

How far the jet stream dips will influence how far south the cooler and less humid air is able to infiltrate. A strong and rounded jet stream dip would send the cooler conditions offshore and into the Southeast. Conversely, a dip located farther inland would allow the warm and moist air to hang on throughout the populated Interstate 95 corridor.

What forecasters are certain about is that the break from the heat and humidity will be the main weather headline for the Great Lakes and the interior portions of the Northeast this weekend. The surge of cooler air will slowly push to the southeast as the weekend progresses. 

Downside of the Forecast

The downside of this forecast is that the cooler air aloft will clash with the warmer air hovering near the surface, supporting the formation of towering clouds and the resulting rain showers and gusty thunderstorms. The Great Lakes region will bear the brunt of the storms, predicted to experience small hail and the possibility of waterspouts.

The greatest concentration of storms on Friday through the weekend will ignite along the leading edge of the cool air. The threat of downpours and flash flooding will be the highest along the southern and mid-Atlantic coastline. Some of these storms could creep as far north as New England and as far south as the northeastern Gulf Coast.

A number of major metro areas will be under the gun for heavy rain and flash flooding at various times this weekend. This includes Philadelphia, Atlantic City, and Washington, D.C. The outer fringes of the storms could reach New York City and Boston to the north, and Charleston, Savannah, and Jacksonville to the south.

Many Americans will be headed out this weekend for outdoor fun as summer nears its end. Be sure to enable all smartphone weather notifications if you live in the eastern third of the nation so that you are not caught off guard by the stormy weather.

Weather changes fast, so help your community stay prepared. Share this story with friends, family, or your group chat, and keep your forecast in the now with Weather Forecast Now.