Sunday, July 28, 2013

Summer is headed back to the Mid-South!

An uncommon mid-latitude weather system has made for cooler weather in the Mid-South to end the week. While these systems are no stranger to the area, they certainly aren't as common in the middle of the summer. This system has brought northwest flow, or widespread northwest winds in the mid and upper levels, that help usher in (relatively) cool, dry air. As a result, we have seen near record low temperatures at night and quite comfortable high temperatures during the day. 

National weather map at 3pm Sunday, showing very comfortable temps for summertime all the way into the Deep South, while dewpoints (humidity values) are also well below normal (less than 60 as far south as the Lower OH Valley), thanks to surface wind from Canada circulating into the Ohio Valley.

850mb pressure pattern, wind, and temps. A strong area of low pressure resides over  the western Great Lakes, bringing northwest wind into the Ohio Valley  and northerly wind into the Mid-South.
 This pattern is atypical this time of year because a different type of pattern usually dominates the south. This includes a semi-permanent area of high pressure that sets up off of the east coast of the U.S., bringing long periods of southerly winds, streaming warm, humid air into the region. As the aforementioned mid-latitude low pressure system weakens and recedes to the north, our more typical Bermuda high-dominated weather will return and give us a real taste of summer in the Mid-South. There will also be chances for showers and thunderstorms toward mid-week due to lingering effects of the low pressure system to our north. By next weekend we could be pushing towards a heat wave. It certainly does not take long for summer to decide to return, enjoy the nicer weather while it is here!

By Monday evening, the low in the Great Lakes weakens and moves east, allowing  southerly flow over the Plains to re-establish and shift east into the Lower Mississippi Valley. Here comes summer again!

-William Churchill
MWN Social Media Intern 

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