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Heather’s Weather Whys: the X’s and O’s of summertime weather

Sometimes parts of the jet stream act like a defensive line, blocking any weather system that tries to move along.
Credit: WGRZ

This year’s NFL season may be up in the air, but we can still talk X’s and O’s. Although since we’re also talking weather, we’d better do it in terms of H’s (highs) and L’s (lows).

This time of year, the atmosphere can put up some pretty impressive defensive plays. Meteorologists refer to these plays as blocking patterns.

There’s a few different looks, but they all hold the potential for the same result: several days of nearly-stationary weather systems which can mean a really nice week for some and a really cruddy week for others.

Cutoff Low

As the name suggests, this is when a strong area of low pressure cuts off from the main flow of the jet stream. Without those fast upper level winds to carry it, that low sits and spins itself out wherever it lands. That means days of cool, cloudy and rainy weather.

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Blocking High

If you like hot, dry weather, this pattern is for you. This time of year especially, strong ridges of high pressure and the heat that comes with them can anchor in place. This happens fairly often in the central United States; this kind of pattern can result in some pretty intense heat waves and short term droughts.

RELATED: What is the heat index?

Omega Block

This is a fancy combination of the first two setups. An Omega block gets its name from the shape the jet stream takes as it winds around two stubborn lows and one robust high; it looks like the Greek letter omega. In this pattern, those under the regions of low pressure will experience cloudy, unsettled weather while those under the high get lots of sun and heat.

Rex Block

A true Rex block pattern isn’t too common around here, but they happen a little more frequently on the West Coast. In this case, an area of high pressure and an area of low pressure stack north to south, creating a funky figure-eight jet stream pattern. 

New episodes of Heather’s Weather Whys are posted to the WGRZ YouTube channel every Wednesday evening. 

If you have a weather question for Heather to answer, send it to her at heather.waldman@wgrz.com or connect with her on Facebook or Twitter.

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