It may not be the brightest of weeks across the Upper Midwest but the clouds do have a silver lining. Since the state of Minnesota is once again in a drought, we enthusiastically welcome every drop we receive. This week has been gloomy and soggy and seems to have no end in sight. There are some bright spots in the forecast, but for the most part, our April showers will be making several comebacks. All this clouds cover and moisture owes it's life to the weather phenomenon known as "The Stationary Front".
In the winter we are very familiar with the cold front, as the cold bite from up north sweeps through the state. The same can be said for the warm front, when we get a surge of warm air moving through the area. When we have two air masses that come together but neither one is the dominant force, then the meeting point is a stationary front. This is the point where the two air masses butt heads with no particular air mass making any significant forward movement. Since warm air is less dense than cold air it tends to be pushed upwards and its this rising air that leads to constant clouds and precipitation.
This is certainly the weather story this week as a high pressure in Canada is sending in cold air from the northeast and a series of lows are sending in warm air from the south.
The stationary front is also a pathway for little impulses to travel. Imagine a stream with a little whirlpool moving along the current of the stream. Its not any different in the with the fluid dynamics of the atmosphere.
Those areas of low pressure, called "Shortwaves" in meteorology, create a little extra lift resulting in more intense periods of rain and storms. This happened on Tuesday with the storms to our south and snow to our north and this can happen again as we head into Thursday.
Occasionally, one of the air masses will be strong enough to overtake the other and move the stationary bound far enough away to put us in the clear for a while, as should be the case to start the weekend. Now you know why the rain comes and goes!
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