Eastern US: Where rain could foil outdoor plans into the weekend

Drenching rain is coming to some locations in need, while others will get a break from relentless storms into this weekend and beyond in the eastern United States.

Weather conditions over the eastern United States from Thursday through this weekend will be a tale of two regimes with dry and cool air across the north and humid air strewn with drenching downpours across the south, AccuWeather meteorologists say.

A weather division will develop following heavy, gusty and severe thunderstorms that swept large portions of the East at midweek and hold fast through the weekend.

A break from heat, storms in the Midwest, Northeast

Conditions from the Great Lakes to the Northeast will be great for most outdoor plans, and air conditioners will get a break beginning in some areas Thursday and the coastal areas of the Northeast by Thursday night. Many people can open the windows and let in fresh, cool air for a while.

In most cases, midday and afternoon temperatures will remain high enough for swimming. For those who exercise or work outdoors, conditions will be much more forgiving, with lower humidity than what is typical for the second half of July and lower temperatures than the past week.

As the core of the cool air takes root, high temperatures will be in the 70s F over the northern tier and in the mountains by this weekend. Chicago will have highs in the lower 80s. New York City and Cincinnati can expect highs in the mid-80s. Meanwhile, Washington, D.C., will have highs in the upper 80s to near 90, which is 10-15 degrees lower than peak highs from earlier this week when the mercury reached 104.

Correspondingly, by this weekend, lows will range from the 50s in the northern tier and over the mountains to a few degrees of 70 in New York City and the lower 70s in Washington, D.C. Lows will be in the low to mid-60s in Chicago and Cincinnati.

The weather from Thursday to the weekend will also be a welcome break for some areas across the northern tier that have been flooded with rain in recent weeks.

There will be some exceptions to the dry pattern. Portions of the northern Plains will experience some shower and thunderstorm activity on the western fringe of Canadian high pressure that will creep slowly eastward and reach portions of the western and northern Great Lakes region this weekend. However, that activity appears to be spotty.

Similarly, very spotty shower and thunderstorm activity may occur over parts of the central Appalachians and the northern tier of the Northeast this weekend. However, these showers would only affect a tiny fraction of the area for a few minutes out of the day. This means that for those still looking for relief from building drought concerns in recent weeks, whatever meaningful rain falls up until Thursday morning will be it, most likely until Monday at the earliest.

The zone from Virginia to Tennessee will be the dividing line between mainly rain-free conditions to the north and showery and thundery conditions to the south.

Days of downpours, thunder for the Southeast states

Within the long-lasting mosaic of showers and thunderstorms forecast to extend from the central Gulf Coast to the southern Appalachians and the southern Atlantic coast, some areas will receive drought-easing moisture from frequent downpours. Enough rain will fall to foil outdoor plans and perhaps even lead to flash flooding.

"A general 1-3 inches of rain is likely to fall from late this week through this weekend," AccuWeather Meteorologist Elizabeth Danco said, "But where those downpours persist, amounts may reach or exceed 6 inches during the period."

Parts of the Carolina coast, southern Louisiana, and the southern Appalachians are most likely to receive close to 6 inches of rain. However, small pockets of similar rain can occur throughout the Southeast.

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Some of the more intense downpours can bring rainfall rates of 1-2 inches per hour for a time, which is more than enough to lead to urban flooding problems.

The same pattern may persist well into next week for the Southeast.

The frequent downpours will help keep extreme heat at bay during the day, but they can make for extra sticky conditions at night, as humidity levels will remain elevated. Widespread highs will be in the 80s with a few spots reaching the low 90s when and where rain holds off for a few hours in the afternoon.

Due to the extent of clouds and frequent showers, high temperatures will generally be a few degrees below the historical average.

Humidity, showers and thunderstorms to expand northward next week

Next week, the protective influence of Canadian high pressure will slowly dissolve from the Midwest to the Northeast.

While this is not likely to open the floodgates in terms of southern moisture overspreading the region, it will bring an uptick in humidity levels, raise nighttime temperatures and create an environment more favorable for some showers and thunderstorms to erupt at least in a spotty to regional setting.

Even with that pattern, some areas may continue to miss out on daily rainfall well into next week.

Meanwhile, a tropical wave of low pressure will push across the Florida Peninsula early next week, where it will enhance downpours and thunderstorms.

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