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Traffic jam in the sky: How a cut-off low kept us cloudy all week

Why have we been so gloomy?

A persistent area of low pressure across central Tennessee has spun clouds and light drizzle across mid-Missouri over the past week. This is the SAME storm system that brought the loud round of thunderstorms LAST Friday morning.

So what's cause this storm to only move a few hundred miles over the past 5 days?

Well, there are a few reasons.

  1. A strong ridge of high pressure has developed over the New England coastline.
  2. The remnants of what was tropical storm Arthur
  3. The jet stream is well off to the north-- usually the driver for storm systems.

These 3 things have all cause this low to stay in place. The high pressure and tropical system have acted somewhat like a road block... keeping the system from progressing into the Atlantic Ocean. Now, typically this kind of back up can be solved by the jet stream guiding storms up and over these areas of high pressure, but in this case, our gloomy low pressure has been cut off from that too.

That's how it gets the name "cut-off low". It's literally been cut off from the main flow!

Where this storm "cuts off" is important too. The counter clockwise winds are acting to pull moisture from off the Atlantic Ocean which is feeding moisture for thick cloud cover across mid-Missouri.

A return to sunny skies?

How do we (eventually) get this low to hook back up to the jet stream and get on out? Well, it may seem a bit counter intuitive, but the storms we see this weekend will be the catalyst for getting that process going.

The low pressure system set to bring us thunderstorms this weekend will bend the jet stream far enough back to the south, that it will pull the stubborn cut-off low back into the main flow, allow a return to sunnier skies by next week!



Luke Victor

Luke Victor gives forecasts on ABC 17 News broadcasts and reports on weather stories on air and online, giving viewers and readers a deeper look at what causes different types of weather.


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