There is a good weather visual on why the eastern half of the US has been so stormy in recent weeks. That visual also shows storminess could let up about two weeks from now.
We meteorologists show you surface low pressure systems. If we want to get technical, we also show you the pressure lines, called isobars, circling the center of the storm. The stronger storm systems have more pressure lines because of the larger air pressure change across the storm.
Here is the surface forecast for tomorrow, April 13, showing a storm system stretching from Canada to Michigan to the Gulf of Mexico.
But the real creator of storm systems is the jetstream. The jetstream is a compact, river-like area of strong winds up around 30,000 feet in the atmosphere. The strong winds in the jetstream act as a vacuum to suck the lower air near the ground up into the higher part of the atmosphere. The less air left at the surface causes a storm center to form.
The great visual on why we are so stormy right now shows you the strong winds in a vigorous jetstream traversing the US The stronger winds are shown in yellow, orange and red. The elliptical-shaped strong winds are called “jetstream cores.” The storm center will be positioned somewhere under the jetstream core.
There are two storm systems showing up as crossing over the Great Lakes and Michigan in the next 10 days. Bear in mind each storm system could have three periods of precipitation. One period of precipitation comes at the leading edge of the storm, when the warmer air starts to move in. The second round of precipitation comes as the heart of the storm system moves across Michigan. The final area of precipitation occurs on the back side of the storm. Notice I’ve been using the word “precipitation” instead of just saying rain. There is still enough cold air to produce snow showers on the back side of these storm systems.
Just stare at the jetstream forecast for several replays. You’ll see the individual segments of stronger jetstream winds with each storm system. The red colors are winds around 150 mph. Now you understand why those winds aloft would be strong drivers of severe weather at the ground.
Now notice the change in the jetstream’s strength when we get out around April 22. The bright yellow, orange and rad colors disappear. The winds in the jetstream diminish. It appears as though this stormy phase we’ve been in will let up in the last few days of April.
What you are seeing is a very common pattern. The upper-air will go through phases of storminess followed by a relaxing of the jetstream. A classic pattern we’ve found over the years is four storm systems, then a quieter period.
We may have a lot of storminess and precipitation to get through before the quieter period. Also, remember I’m saying precipitation. Yes, it looks like snow may not be done yet in Michigan.
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