Return flow back in the forecast

July 11th, 2014 at 8:20 am by under Weather
Diagram of "Return Flow"

Diagram of “Return Flow”

We have certainly highlighted the unprecedented cool air for next week. But in front of that cool air will be an all-too-familiar  pattern for July. The return flow pattern. A couple of key things we look for here. High pressure will move along the east coast, that changes it’s circulatory function in a sense. Because of its position it will act like a pump. It will essentially pump warm humid Gulf air back into our region. In a sense it opens up the flow from the Gulf of Mexico to our area. This makes those dew points  rather tropical  as they will rise to the 70s and with the increased availability of moisture we will see showers and occasional thunderstorms develop with this unstable air mass.

This typical July-like pattern will over the course of a few days be replaced by a ‘lobe’ from that ‘vortex’ or circulation that is referred to as the Polar Vortex. This concept is often misunderstood, especially in the  national media as it is referred to simply as The Polar Vortex. This is scientifically inaccurate as the vortex or circulation itself moves very little. It has a semi permanent position near the Arctic Circle. That location does not vary and the vortex is never moving into a different location. However, sometimes we see a piece, chunk or scientifically called a ‘lobe’ break off this vortex and make its way to our region.  This is not a common feature during the summer months so it is certainly very unusual.

2 Responses to “Return flow back in the forecast”

  1. Mary says:

    Don’t like the warm humid Gulf air and will gladly welcome the lobe from that vortex! Thanks for the explanation on this unusual weather event. I am curious if or how air pollution affects our weather. Does it make storms stronger, lightning stronger or do storms track or follow it? I was near the steel plant in Butler once when it stormed and the lightning was unbelievably strange and the rain was like it was poured from buckets. Is there a certain pollutant known to maybe effect our weather more? Don’t know if this is in your field of study just curious.

  2. Greg Shoup says:

    Thanks Mary for your insightful comment. There has only been one definitive study that I know of which tries to conclude that pollution from China may be contributing on a global scale. It states that pollution may be changing the storm track. While this is certainly a possibility I would like to see more studies done like this and more documentation before all the climate scientists can come to a definitive conclusion. There is still a pretty tenacious debate between scientists in the public and private sector about this issue.
    I know that government scientists have come to the conclusion that man made pollution is have an effect on a global scale. The problem is no one really knows what and how that will ultimately effect our climate over the next one-thousand years. There has been quite a bit of conjecture but I would like to again see more conclusive studies before we close the book on this issue.