Wake low weather phenomena may have caused outages in SE Wisconsin

Over 63 thousand people were without power early Sunday morning after a squall line of rain/storms rolled through Saturday night into early Sunday. Could weather have been the cause? 

Yes, it is possible as a unique weather event unrolled.

Rain & storms started to enter from the west near 10 p.m. Saturday. 

A complex of rain & storms exited southeast Wisconsin between 3 a.m.-3:30 a.m. Sunday morning, and a wake low formed behind it. 

What is a wake low?

A wake low is a mesoscale (or small-scale) low-pressure area that develops behind a large line of rain & storms.

Rain/Storms moving east as a wake low formed behind it where it was dry. 

How does this form?

In order to get a large line of storms, warm/moist air must rise up into the atmosphere. As it rises, it cools and eventually, that air sinks back to the ground. As it sinks, it warms up and becomes lighter. This area of lighter air behind the storm complex then forms a small area of low pressure.

Vibrant green color in Waukesha and Racine counties show the strong winds from the wake low. 

The pressure difference between this new small area of low pressure behind the precipitation to the pressure in the squall line creates a tight pressure gradient that ultimately leads to strong gusty winds. Wake lows are often impossible to forecast and occur rather quickly.

What did we see?

Early Sunday morning, some areas experience 30-50mph wind gusts, and locally higher gusts were possible outside from observation sites. Viewers sent in pictures of damaged trees and outdoor objects moved due to these strong winds.

(Photo Credit: Lori Gall in New Berlin)

Since we have had such dry conditions leading to dry vegetation, strong winds could more easily snap tree limbs. Strong winds could also be the main cause of widespread power outages in our area.