COLUMBIA, S.C. — Rain is no big deal in the Midlands but, it might be if you have had Friday plans recently. The last 7 weeks have featured measurable rain on Friday making for a pretty odd trend that surprisingly we can explain.
To dig into why we have seen this rain we have to look at the upper atmosphere. A persistent pattern around the Arctic produces low pressure which we call Rossby Waves.
These waves help direct the flow of the Jet Stream but also help determine the paths that low-pressure systems travel across the US. As it turns out, one of these waves takes about 5 to 7 days to travel from Alaska to the Central United States. This feature aids in the formation of our surface lows, and given that time frame we are seeing rain about once a week with this active pattern.
That is once again the case as a wave moves across the US we will be seeing a storm will be pushing across the country bringing us the chance of rain as we go into Saturday morning, just like we have seen for over the past month.
As we go into the Summer months, this type of setup becomes less common as large subtropical highs influence our hot and humid weather.