How A Wedge Not In The Golf Bag Will Affect Weather At The Masters

The Masters golf tournament is as much a signal of Spring as flowers blooming on the majestic Georgia course. By the time you read this, some of the top golfers in the world will be on the course using their irons, drivers, and wedges. However, my meteorological lens has been paying attention to a different type of “wedge” that will affect the storied event this weekend.

Much of the Masters weekend will feature wet conditions with late Friday and Saturday being particularly rainy. So what’s going on? The graphic below shows a cold front and low pressure draped across the Southeast. Both of these features certainly would be enough to cause rainfall. However, another significant player is also on the map. High pressure ridging indicative of something called cold-air damming. The leading edge of cold, dense air “wedged” against the spine of the mountains will ooze southwestward as a back door wedge front, according to the National Weather Service. The “wedge” will continue to strengthen into Saturday. The wedge front and other associated weather forcing will drop temperatures into the upper 40s by Saturday with strong northeastery winds and rainfall.

These are certainly not the type of conditions you would expect at the Masters, but those of us around here know that the “wedge” can be a “thing” in early Spring. My colleague Professor John Knox, an atmospheric sciences professor at the University of Georgia, posted on his Facebook page, “….For frequent readers of my posts, this is The Wedge. Not a sand wedge. Not a pitching wedge. It’s The Wedge. By which meteorologists in this region mean, a shallow-in-the-vertical wedge of cold air associated with high pressure along the East Coast, e.g. in the mid-Atlantic.” Knox pointed out that Augusta National is pretty much the bullseye for impacts as the wedge bulldozes its way into Georgia.

On Thursday, I was actually looking at model runs and noticed an arc-like feature in the simulated radar imagery. At first I thought it was an outflow boundary. However, I quickly realized it was the “wedge” front. The map below is from a Thursday evening run of a high-resolution weather model called the HRRR. Do you see the “blob” of green arcing into South Carolina and eastern Georgia? That is a wedge of colder temperatures (essentially a density current) moving from northeast to southwest. Because colder air is denser, the wedge front can actually behave like a cold front and lift warmer air. This can initiate or enhance rainfall.

Cold-air damming or “the wedge” is a very well-understood phenomenon. For a great analysis of the science behind it, I strongly recommend this essay at iWEATHERNET.com. The NOAA Glossary of Meteorology formally defines cold-air damming as, “The phenomenon in which a low-level cold air mass is trapped topographically. Often, this cold air is entrenched on the east side of mountainous terrain….” Professor Knox and his former student Jared Rackley, now a meteorologist at the National Weather Service – Pittsburgh, published a 2016 study on the climatology of southern Appalachia cold air damming events. They found that the Southeast is affected by a “wedge” type event roughly 50 days annually. They also confirmed that these events are most likely from 15 October–15 April.

As we approach the weekend, I reflect on the last statement in an email Thursday from a colleague, Walker Ashley, at Northern Illinois University. He said, “I’d say enjoy the weather, but goodness, that’s quite the wedge inbound.”