Fall vibes incoming: Major cooldown to sweep from Midwest to East Coast
A dramatic drop in temperature is expected for a large area of the eastern United States into this week, and in some areas, it will bring season's first frost and even wet snowflakes.
The same weather system that’s about to bring an end to summerlike temperatures in the Northeast could affect the formation of a tropical storm in the Caribbean next week. Here’s how.
A strong cold front moving from the central to the eastern United States will have millions of Americans reaching for fall apparel and hot beverages into the upcoming week as the coolest air so far this season rushes east, according to AccuWeather meteorologists.
The drop in temperature will be dramatic, especially compared to the near-record warmth that preceded the cooldown from the previous weekend into early last week. For some, the mercury will go from the 90s for high temperatures to the 30s for low temperatures in just a matter of days, a drop of up to 60 degrees.
Accompanying the cooler weather will be damp and unsettled conditions, with the potential for a select few to experience their first snowflakes of the season.
Outdoor activities ranging from pumpkin picking to leaf-peeping, as well as football and playoff baseball games, will be impacted by the colder weather early this week.
A dramatic swing in temperature into this week
October began with warmth more typical of the midsummer months rather than early autumn across the Midwest and in parts of the Northeast due to an unusually strong area of high pressure for this time of year.
"After a reprise of summer for much of the Great Lakes and Northeast over the last week, a flip forward to the middle of fall is in store," said AccuWeather Meteorologist Dean DeVore. "These much chillier conditions can also lock in for a while."
Temperatures that were 10 to 20 degrees above the historical average to start the month will end up 10 to 20 degrees below average by the start of this week.
Signs of the approaching cooler weather arrived across the Plains and Upper Midwest earlier last week. In Minneapolis, a new daily record high of 92 was established last Sunday, but then the mercury only topped out in the 60s on Wednesday and Thursday, and highs are forecast to remain in the 50s into this upcoming week.
In Chicago, a run of temperatures above 80 that dated back to the last day of September came to an end on Thursday, and it is forecast to be no higher than the 50s through midweek.
In Pittsburgh, October started out with five consecutive days of high temperatures of 80 or higher for the first time since 1950. On Monday, afternoon high temperatures in the Steel City are ranging roughly 25 degrees lower than that.
The big cities along I-95 from Washington to Boston will also experience their coolest weather so far this season this week. High temperatures that have been in the 70s and 80s to start the month will settle into the low to mid-60s in places such as Philadelphia and New York City.
The cooler weather will not be limited to just the northern part of the country, as Southerners will enjoy a much-needed break from the seemingly never-ending summertime heat that carried into the beginning of fall.
Temperatures that made it into the 80s and even lower 90s for some to start the month in places such as Charlotte, North Carolina; Jacksonville, Florida; Little Rock, Arkansas; and Nashville, Tennessee; will be replaced by much more comfortable readings in the 60s and 70s for afternoon highs. Accompanying the cooldown will also be a drop in humidity.
"This cooldown will be in stark contrast to the summerlike warmth that has preceded it across the South," said AccuWeather Senior Meteorologist Joe Lundberg.
Cooler days will also mean chillier nights, resulting in the season's first frost and freeze risk for millions by the end of the week.
On Friday, frost and freeze watches, warnings and advisories were issued by the National Weather Service along the Plains from the Dakotas and Missouri south to Kansas and Missouri, an important agricultural belt that experienced an end to the growing season this past weekend.
Additional frost and freeze warnings may be issued as the core of the cold air shifts eastward early this week. By midweek, temperatures could dip to near-freezing territory across interior Michigan, northern Ohio, northwestern Pennsylvania and upstate New York. In general, a smaller percentage of places will be threatened by a frost or freeze in the Northeast on Monday and Tuesday compared to the Plains on Saturday.
While these chillier conditions at night are fairly typical for early October in the north, areas in the South could have readings that challenge record-low temperatures. Charleston, South Carolina; Savannah, Georgia; and Tallahassee, Florida; are among the locales expected to dip into the 40s early Monday morning, the coldest readings since last spring.
Rain (and snow?) could impact activities
Those with outdoor plans early this week will not just want to don some clothing more appropriate for cooler weather but also grab some wet weather accessories. AccuWeather meteorologists expect some rain to accompany the transition to cooler weather and for showers to linger after it in some areas.
A continuation of dreary weather can be expected farther west, well after a cold front and associated moisture from what was Philippe went through. This will especially be the case downwind of the Great Lakes, where some lake-effect showers can develop—and not just of the rainy variety.
"In the Great Lakes, the colder air moving over the relatively warmer lakes will make for volatile conditions," said DeVore. "This can lead to lake-effect rain showers, waterspouts and even some graupel mixing in with the rain."
Graupel forms when temperatures higher in the atmosphere are cool enough for snowflakes to reach near the ground, but they end up becoming coated with a layer of ice.
Areas farther away from the warmer lakes may even get some wet snowflakes into Monday, as even colder air moves in higher in the atmosphere. While accumulating snow is not expected to be widespread, some higher-elevation locales such as the Adirondacks of upstate New York could receive their first flakes of the season.
Additionally, special marine warnings were issued on Saturday for locations across Lake Erie from Lorain Harbor, Ohio, to Buffalo, New York, cautioning of waterspouts that can overturn boats and create hazardous seas.
Those heading outdoors early this week for autumn activities such as visiting a pumpkin patch, taking in the changing fall colors or participating in fun runs or marathons will need to dress warmly, especially if the events take place in the morning hours.
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