Return flow back in the forecastJuly 11th, 2014 at 8:20 am by Greg Shoup under Weather
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.