The Wedge Is Coming: Why Wednesday Could Feel Completely Different Across the Region

If you step outside Monday afternoon, it may be difficult to believe what could be waiting for us just 48 hours later.

High temperatures Monday are expected to reach around 89° in Rowan County, 90° in Davie and Davidson counties, and 92° in Cabarrus County.

By Wednesday?

I’m forecasting highs of only around 68° to 72° across the region.

That is a temperature drop of roughly 20 degrees in just two days.

So what is causing such a dramatic change?

The answer is something meteorologists in the Carolinas know very well: cold-air damming, commonly called “the wedge.”

What Is The Wedge?

Cold-air damming occurs when an area of high pressure becomes positioned to our north and northeast and pushes cooler air southward along the eastern side of the Appalachian Mountains.

Because cooler air is denser and heavier than warmer air, that shallow layer of cool air can become trapped against the mountains.

Think of the Appalachians as a wall. The cool air moves southward but has difficulty moving west across the higher terrain, so it begins piling up along the eastern slopes.

That creates a wedge-shaped area of cooler air extending southward through portions of Virginia and the Carolinas.

And when the wedge settles into our part of North Carolina, the difference can be dramatic.

First, We Have To Get Through Monday

There won't be much that feels like fall Monday.

Highs should climb to around:

Rowan County: 89°
Davie County: 90°
Davidson County: 90°
Cabarrus County: 92°

Humidity will also remain noticeable.

Showers and thunderstorms become possible later Monday afternoon, with rain and storm chances increasing considerably Monday evening and Monday night.

Some thunderstorms could produce gusty winds and heavy downpours.

That activity is part of the transition toward the very different weather expected later in the week.

Tuesday Is The Transition Day

Tuesday is when you'll really begin noticing that something has changed.

Instead of temperatures near 90°, highs should only reach the upper 70s to lower 80s.

My current forecast has highs around:

Rowan County: 79°
Davie County: 79°
Davidson County: 80°
Cabarrus County: 82°

Showers and thunderstorms will remain possible, particularly as we move through the afternoon and evening.

But the bigger change will be taking place behind the scenes as cooler air begins pushing farther south.

Then Comes Wednesday

Wednesday may be one of those days when you walk outside and immediately notice the difference.

Instead of sunshine, heat and afternoon thunderstorms, we're looking at a much more classic wedge setup: clouds, cooler temperatures, northeast flow and periods of rain or showers.

Current forecast highs are:

Davie County: 68°
Rowan County: 69°
Davidson County: 70°
Cabarrus County: 72°

Compare that with Monday.

Davie could fall from 90° to 68°.

Rowan could go from 89° to 69°.

Davidson could drop from 90° to 70°.

Cabarrus could go from 92° to 72°.

That's roughly a 20-degree temperature drop across the region in about 48 hours.

Wednesday's Rain Is Different

There's another important difference in the forecast.

The rain chances Monday and Tuesday are tied more closely to showers and thunderstorms developing with daytime heating and the approaching front.

Wednesday is different.

Once the wedge becomes established, clouds and showers can occur during much more of the day. This isn't necessarily an afternoon thunderstorm setup.

Instead, Wednesday could feature periods of light rain or showers beneath a stubborn deck of clouds with temperatures struggling to climb.

In other words, don't look at Wednesday's rain chances and assume we're talking about another round of summertime afternoon thunderstorms.

It could feel much more like a cool, damp fall day.

Will The Cool Weather Stick Around?

At least for a little while.

Thursday currently looks mostly cloudy with highs only around 69° to 71° across the four-county region.

Overnight lows Wednesday night and Thursday night could fall well into the 50s, with some locations potentially reaching the lower 50s.

The wedge should eventually weaken, but temperatures are expected to remain below what we've been experiencing recently.

How Strong Will The Wedge Become?

That's one of the biggest things I'll be watching over the next couple of days.

Cold-air damming events can be tricky to forecast.

Small differences in the strength and position of high pressure to our north, the amount of cloud cover and precipitation, and the development of low pressure nearby can make several degrees of difference in afternoon temperatures.

That's especially important Wednesday and Thursday.

If the wedge becomes stronger than currently expected, temperatures could struggle even more.

If it is weaker or erodes more quickly, temperatures could end up a little warmer.

So while confidence is increasing that much cooler weather is coming, the exact temperatures will continue to be fine-tuned.

From Summer To Fall In 48 Hours

Monday may still feel like the middle of summer.

By Wednesday, you may be reaching for something you haven't needed very much lately — a jacket.

The transition won't happen quietly, either. Showers and thunderstorms Monday night and Tuesday will help usher in the change before cooler northeast winds, clouds and showers take over.

I'll continue watching the latest guidance and updating the forecast for Rowan, Davie, Davidson and Cabarrus counties as we get closer.

But right now, one thing is becoming increasingly clear:

Summer is about to get pushed out of the way — at least for a few days — by one of the Carolinas' most familiar cool-weather setups: the wedge.