Omega Block Produces Cool Conditions and Chance of Snow

Posted: May 2, 2023 10:50 am

Widespread cool temperatures have set up across the Midwest and the East Coast to start the month of May, blamed on what weather experts refer to as the “Omega Block.”

What is this weather pattern and what type of conditions can you expect with it in the coming days? Read on for all of the details.

Understanding the Omega Block

An Omega Block is the term used to describe a significant atmospheric traffic jam that happens across the jet stream. This pattern resembles the Greek letter Omega, giving it its unique name.

The pattern hinders the typical west to east track of weather systems while also delivering cooler air and unsettled conditions overall.

This Omega Block is forecast to linger over a large part of the continent for the next few days. The setup will usher in temperatures that are more typical of March than May. Some areas will also see heavy snow with frosts and freezes an issue for other locations.

Snow Predictions

The big story of this weather pattern will be the heavy and accumulating snow. The snow started falling across the Great Lakes over the weekend. The white stuff began to pick up as the work week started and is forecast to continue through Wednesday for some parts of the central Appalachians and the Upper Peninsula of Michigan.

The highest amount of snow will likely happen in the overnight hours after the sun goes down. You can expect a general 3 – 6 inches of new snow in northern Wisconsin.

Up to 2 feet of snow is a possibility in northern Michigan. While the warmer temperature this time of year will limit accumulation on the roads, motorists will still want to exercise caution.

The central Appalachians will see the snow linger into Wednesday. The higher terrains of Pennsylvania and southwestern New York are forecast to see up to 2 inches of snow.

The top elevations of West Virginia may record 6 – 12 inches of accumulation. This wet and heavy snow may bring down trees and create power outages.

The rest of the Midwest and the Northeast will escape the snow. However, residents are sure to be caught off guard by the unseasonably cold temperatures associated with the Omega Block.

The coldest day for the Midwest will be Tuesday while the temperatures will reach their lowest points on Wednesday and Thursday in the Northeast. You can expect daily high readings to trend about 10 – 15 degrees below normal for the first few days of May.

For instance, the mercury will hover in the 40s in Chicago and Detroit on Tuesday. New York City will struggle to climb out of the mid 50s through Thursday. The breezy conditions will bring the real feel readings down every further.

As is typical, the higher elevations of the central Appalachians will see some of the coldest temperatures in this part of the country with high temperatures in the upper 30s in store.

Frost and Freeze Odds

Areas that do not see any snow may still be under the gun for a late-season frost or freeze. Overnight lows could support the development of damaging frost, particularly in areas with clear skies overnight.

The odds of a frost are highest on Tuesday night for the Upper Midwest. The Ohio and Tennessee valleys will see this risk on Wednesday or Thursday night.

The chance of a frost or freeze hit the interior Northeast by Thursday night with the risk hanging on through Saturday night.

A frost or freeze is not an anomaly in early May. However, temperatures that trended warmer than the historical average this past winter and early spring have translated to early budding season for many plants and flowers.

This means that these buds are more susceptible to the dangers of a late-season cold snap.

Thunderstorm Activity a Possibility

The unsettled conditions will set the stage for the possibility of thunderstorm activity. These storms will form as the air in the upper levels of the atmosphere clash with the warmer readings closer to the ground. Possible impacts of these storms include small hail, frequent lightning strikes, and high winds.

The Midwest will see the worst of the storms on Tuesday. By Wednesday, the chance of storms will move closer to the Ohio Valley and the Appalachians. Forecasters warn that the Omega Block has the tendency to create highly unsettled conditions.

For example, residents should be prepared for storms to fire up suddenly and with little warning.

There is not going to be a significant amount of moisture associated with this weather pattern. This is good news for residents along the Mississippi River Valley and the Susquehanna River worried about high water levels in these waterways raising the risk of flooding.

Warmup on the Way

Those weary of the cold are in luck. The northern Plains should start to see a warming trend in action by the middle of the week. These warmer readings are forecast to reach the Northeast by Friday.

New England may need to wait until the weekend to experience the warmup. The upward trajectory in the mercury will happen as the Omega Block starts to break up, paving the way for a more typical west to east movement of weather patterns.

Dry conditions are also in the forecast for the Northeast over the weekend. This will be welcome news after last weekend brought heavy rain and raw weather to the region on the heels of two separate storm systems.

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