Raindrops Not 'Teardrop' Shaped And More You Didn't Know

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T​he weather pattern is flipping from what meteorologists call zonal to amplified in the week ahead, bringing with it some notable weather changes across the United States.

Here's a Meteorology 101 primer on these patterns: The jet stream had been in what's called zonal flow, which means it was flowing in a mostly flat west-to-east fashion across the country, but that's now changing.

The jet stream is switching to what's called amplified flow, meaning it's stretched out into a wavy north-to-south configuration, as seen below.

A​mplified weather patterns tend to be stormier and often have big temperature contrasts from one part of the country to another.

An East versus West temperature split is the most widespread aspect of this week's pattern change. The jet stream dropping southward into the West means temperatures will gradually turn colder than average across most of the region by Tuesday or Wednesday.

Meanwhile, parts of the central and eastern states will see temperatures threatening record highs at times through midweek. That's because the jet stream will be riding far to the north over the eastern half of the U.S., allowing plenty of southerly wind flow to transport unusually warm air for late October northward. Some spots across the Great Lakes could break 80 degrees.

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R​ain and snow will impact western and central states. The first precipitation impacts from this pattern change will be felt with the incoming jet stream disturbance over the Pacific Northwest on Sunday. Rain and mountain snow can be expected from Washington and Oregon to Northern California.

Some of that rain and mountain snow will then spread east through the Rockies, including parts of Utah, Colorado and Wyoming, and into the western High Plains by late Monday and Tuesday.

(​MAPS: Track Rain And Snow Day-To-Day)

Then, the central U.S. will see increasing chances of much-needed rainfall once the cold front associated with the southward-plunging jet stream reaches the region by midweek. The latest forecast for Wednesday below shows rain chances stretching across parts of the Midwest and Plains.

Rainfall may continue along this cold front in some areas through Halloween, which you can read more about at this link.

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Chris Dolce has been a senior meteorologist with weather.com for over 10 years after beginning his career with The Weather Channel in the early 2000s.