As goes the jet stream (18,000-34,000 feet high or so-up to 9 miles in altitude), so goes the weather down here on earth.

Upper-level low pressure troughs (troffs) and high pressure ridges often dictate where the weather is wettest and coldest or driest and hottest.

In coming days it will be hotter in Iowa than Georgia as high pressure aloft creates an early season “Heat Dome” from the Southern Plains to the Midwest.

Normally the jet stream moves generally from West to East across the Northern Hemisphere with undulations North and South along the way.

But sometimes an atmospheric “block” will form, locking a pattern in place with little movement for a time.

And sometimes a “blocking pattern” can result in weather systems “retrograding” or moving “backwards” in reverse from East to West.

We are about to see a pattern do just this over the course of the next 1-10 days or so.

In this case it looks like the biggest impact will be on temperatures, but some impact on precip as well.

We get a “Rex Block” transitioning into an “Omega Block”. They are named after the shape of the jet stream pattern. They can form anywhere, the location varies all the time.

[ SEE more on blocking here. ]

Sometimes such a system can help a tropical low form in the Atlantic off the SE coast and move inland. As of now NO tropical system is expected but it’s happened in the past so bears watching. As of now a NON-tropical low is all that is expected by next weekend.

See for yourself what I am talking about:

IF NOT for the formation of the Omega Block pattern in the jet stream, we would have probably been looking at that extreme heat moving into our region, but if the equations are correct the heat wave will be held at bay for us as the upper low over the Atlantic backs up and moves into our area from the East.

Weather 101.

This map the dark colors show how abnormal the 500mb pattern becomes:

For more follow me on Twitter @MellishMeterWSB.

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