Wet pattern to evolve ahead of mid-October cooldown in eastern US

Warmth and dryness will hold a while longer in much of the eastern United States, but there may be changes closer to the middle of the month.

Waves of cool air will continue to cause temperature fluctuations across parts of the North Central states into this weekend.

This back-and-forth battle will lead to patches of showers and locally heavy thunderstorms from the Plains to the Great Lakes and part of New England.

Meanwhile, many areas farther to the east and south will remain warm and dry into the start of this weekend.

An exception in the Deep South will be part of Florida, where a tropical system may brew nearby.

The lack of rain and unusually warm and sunny days has the soil abnormally dry and some locations in the East are teetering on drought conditions.

At some point later this weekend into early next week the dry flow of air will stop and the atmosphere will moisten up over much of the Eastern states, according to AccuWeather Lead Long-Range Meteorologist Paul Pastelok.

Cloud cover may hold temperatures back during the day, but may act as a natural blanket at night.

"Even though high temperatures may be no greater than the upper 70s to lower 80s, temperatures may not drop below 70 in some of the big East Coast cities next week," Pastelok said.

"This may lead to higher energy use, since some people will need to keep their air conditioners on at night, compared to opening their windows to let in cool air of late."

As the flow from the Gulf of Mexico and the Atlantic increases this weekend and into next week, the risk of rain will also ramp up.

Depending on whether or not a tropical system is involved, there could be a dose of heavy rain spreading northward from the Gulf of Mexico and eastward from the Midwest.

Toward the middle of the month, there are signs that presses of cool air from the northern Plains will make more eastward progress.

"It should feel significantly cooler during some days near and past the middle of October, compared to that of recent weeks," Pastelok said.

"However, you have to temper that with the fact that normal temperatures trend downward at a substantial rate from early October to late October."

For example, the normal high in New York City on Oct. 1 is near 70. By the end of October, the normal high is in the upper 50s.

"Temperatures may still be above average most days in the East and especially the Northeast during the middle and latter part of the month," Pastelok said. "We don't see any sign of a big blast of cold air sweeping from the northern Plains to the East like some people are looking for just yet."

Because of this, the potential for tropical storm development will continue in the Caribbean, Gulf of Mexico and the southwestern Atlantic through the end of October.