A much more active weather pattern is set to unfold across the Plains, Midwest, and parts of the Great Lakes beginning this weekend and continuing well into next week. The setup is being driven by a strengthening upper-level trough moving into the Plains, which will act as the catalyst for widespread thunderstorm development, heavy rainfall, and multiple rounds of severe weather.

The concern is not just isolated storms, but rather a prolonged period of unsettled weather capable of producing repeated heavy downpours, damaging winds, hail, and isolated tornadoes from Texas through the central Plains and into portions of the Midwest and western Great Lakes.

Why the Pattern Is So Active

A major driver behind this persistent storm pattern is the ongoing negative phase of the Arctic Oscillation (AO). When the AO trends negative, it often allows colder air masses and blocking patterns to linger farther south across North America. Instead of the jet stream flattening out into a stable summer-like pattern, it becomes more amplified and chaotic.

At the same time, El Niño conditions continue to strengthen in the Pacific. Normally, El Niño can enhance subtropical moisture and increase storm activity across parts of the southern and central United States. Right now, these two large-scale climate signals are essentially working against each other, creating a highly volatile atmospheric setup.

The result has been an unusually persistent stretch of rainy weather, repeated severe thunderstorm outbreaks, and temperature swings across much of the country.

Severe Weather Threat Increasing

As the trough pushes eastward, warm and humid air from the Gulf of Mexico will surge northward into the Plains and Midwest. This will provide ample fuel for thunderstorms to rapidly intensify.

The corridor from Texas through Oklahoma, Kansas, Missouri, Iowa, Illinois, Wisconsin, and into parts of Michigan appears particularly vulnerable to repeated severe weather episodes between Saturday and Tuesday.

Forecast concerns include:

• Damaging straight-line winds
• Large hail
• Localized tornadoes
• Flash flooding from repeated thunderstorms
• River and stream rises in flood-prone areas

Some locations may experience multiple rounds of storms over several consecutive days, significantly increasing rainfall totals.

Heavy Rainfall Concerns Continue

Beyond the severe weather threat itself, the flooding potential is becoming increasingly important. Widespread heavy rainfall is expected from portions of Texas and Oklahoma northeastward through the Mid-Mississippi Valley and into the Upper Midwest.

Given how saturated some soils already are, it will not take excessive rainfall rates to trigger flooding issues. Urban flooding, low-lying roadway flooding, and rises on creeks and streams are all possible throughout the period.

The repeated nature of the storms may ultimately become a bigger issue than any one individual severe weather event.

East Coast Finally Warms Up — But Not For Long

Meanwhile, the eastern United States will finally begin to break out of the stubborn cool pattern that has dominated much of the spring season. Temperatures will moderate noticeably heading into the weekend and early next week.

However, this does not appear to be the start of a sustained summer heat pattern.

The lingering blocking setup associated with the negative Arctic Oscillation continues to favor periodic “backdoor” cold fronts diving southward from eastern Canada into the Northeast and Mid-Atlantic. These fronts are notoriously difficult for forecast models to handle properly and often lead to temperatures being overestimated several days in advance.

In fact, some model guidance has repeatedly attempted to push widespread 90-degree heat into the East, only to later trend cooler once these backdoor fronts become better resolved. Forecast adjustments recently have leaned more toward lowering temperatures rather than increasing them.

Late-Season Snow Possible Again In The Rockies

Another fascinating aspect of this pattern is the potential for additional late-season snowfall along portions of the Front Range of the Rockies, including areas near Denver.

While it may seem unusual for mid-May, spring snow events are not uncommon when deep troughs continue to carve into the western and central United States. Cooler air wrapping into the backside of these systems could once again bring accumulating snow to higher elevations and even parts of the urban corridor.

What This Could Mean For Summer

There has been growing discussion recently surrounding the possibility of extreme summer heat developing across the United States this year. However, the current atmospheric signals do not strongly support a prolonged, widespread heat dome pattern developing anytime soon.

The ensemble guidance for the Arctic Oscillation continues to suggest the negative phase may linger well into the summer months — potentially even into August. If that occurs, it would likely continue supporting a more active and stormy jet stream pattern rather than allowing persistent heat to dominate large sections of the country.

As long as frequent troughs continue moving across the nation, showers and thunderstorms will remain common across the Plains and East, limiting the ability for long-duration extreme heat to establish itself.

Agriculture Already Feeling The Impact

The ongoing wet and cool pattern is already beginning to create agricultural concerns across portions of the Plains. Excessive rainfall, colder-than-normal temperatures, delayed planting, and repeated severe weather episodes are starting to affect crop conditions in some areas.

If the current pattern persists deeper into late spring and early summer, agricultural impacts could become more widespread across portions of the central United States.

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