4Warn Weather – High winds are possible tonight between 6 p.m. and 10 p.m. because of an unusual weather phenomenon called a “wake low.”
Late Monday (April 27) afternoon, a wake low formed over Northern Indiana and southwest Michigan.
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The National Weather Service in Grand Rapids issued multiple severe thunderstorm warnings for 60mph winds.
What’s unusual is that there weren’t thunderstorms, and in fact, the rain has already passed.
What is a wake low?
A wake low is one of those weather terms that sounds strange, but the idea is pretty simple.
It is a small area of low air pressure that can form behind a line of showers or thunderstorms, often near the back edge of a squall line or rain shield.
In other words, the rain might be ending, but the atmosphere is still busy.
When air pressure drops quickly behind the rain, air rushes toward the lower pressure, and that rush can create sudden, strong winds.
Wake lows can develop 30 to 50 miles behind a thunderstorm line, and wind gusts of 40 to 60+ mph can persist for 30 to 60 minutes in some cases.
Why wake lows are tricky
So, a wake low is sneaky.
It is not a tornado, and it may not look dramatic on radar by the time it reaches your neighborhood.
But it can still rattle windows, knock down small branches, and make driving harder.
In Michigan, especially on active spring days like today, the back side of the rain shield deserves attention, too.