Showers, thunderstorms to return to Midwest and Northeast this week

After millions in the Midwest and Northeast were able to enjoy a summer weekend without high humidity, an uptick in moisture this week will lead to showers and thunderstorms.

Following a comfortable and mostly rain-free weekend for the second half of July in the Midwest and Northeast, more humid air with the likelihood of showers and thunderstorms will return for the fourth week of July, AccuWeather meteorologists say.

An area of high pressure with origins in central Canada will continue to control the weather in the Northeast and much of the Midwest through early Monday. Most areas can expect low humidity, just a few clouds, and temperatures lower than the historical average for the date.

The break from thunderstorms is surely appreciated in areas such as northern New York and parts of Vermont and New Hampshire that were hit by multiple rounds of heavy rain and flooding.

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Through the week, the influence of the high pressure system will slowly fade, and more humid air will expand northward. Along with the uptick in moisture, there will be an increasing chance for showers and thunderstorms.

While the moisture does not guarantee that every location will receive some rain this week, the opportunity for downpours does exist.

This random nature of summertime rainfall is largely driven by the sun's heating, provided there is moisture available. The sun's heat causes towering clouds to form that begin to drop rain and produce lightning. Some places may pick up multiple downpours each day, while other areas may struggle to catch a few drops of rain by the end of this week.

It is possible that some of the storms in the pattern turn locally severe, bringing torrential downpours as well as isolated damaging wind gusts. AccuWeather meteorologists were highlighting an area from Maryland to North Carolina as a zone where such incidents may occur on Monday.

From Monday to Wednesday, a corridor across the central and northern Appalachians may have a higher chance of multiple downpours than the beaches in the Northeast and the shores of the Great Lakes. A split in the moisture over the Midwest could make parts of the Ohio Valley and upper Great Lakes wetter than areas from Chicago to Detroit. Because of the randomness of summer rainfall in the pattern that is likely to develop, the wet versus less-rainy areas may shift around from day to day.

During the latter part of the week, a storm from Canada will drop southeastward and into the Midwest before progressing into the Northeast, and a general increase of showers and thunderstorms is likely. This may evolve into a round of severe weather in some locations.

The recent rounds of intense heat and limited thunderstorm activity have caused abnormally dry to drought conditions to expand over parts of the East. Where a thorough soaking occurs this week and does not trigger flash flooding, it will be beneficial for an agricultural, gardening and reservoir standpoint.

While the air will turn more humid and the nights will trend warmer than this weekend as a result, extreme heat is not expected to build over the region. Rather, daytime and nighttime temperatures will tend to converge to near the historical average.

Highs this time of year typically range from the upper 70s over the northern tiers of the Midwest and Northeast to the mid-80s over the Ohio Valley and near 90 in cities such as St. Louis, Washington, D.C., and Norfolk, Virginia. The historical average for lows around this point in July ranges from the mid-50s over the northern tier to the low 70s in the major cities.

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