March 30, 2018

A Stagnant Weather Pattern Will Give Way to More Cool Weather for the Eastern U.S.

You didn't think winter would go down without a fight, did you? The stagnant weather pattern that's blanketed the United States this week is finally giving way and will be replaced by a pattern that will allow frequent shots of below-normal temperatures to dip across the eastern two-thirds of the United States over the next week.

The pattern we've seen in the upper levels of the atmosphere resembled an omega block, which occurs when a stationary ridge of high pressure over the middle of North America is bookended by low-pressure systems on the western and eastern sides of the continent. An omega block leads to warm, calm weather in the center of the United States and Canada with unsettled weather on either coast.

The blocking pattern we experienced last week kept moving—albeit very slowly. This sluggishness allowed persistent showers and thunderstorms to develop over the southern half of the country, where flash flooding and severe thunderstorms were a serious issue for several days, especially across Texas and Louisiana.

Some areas in Louisiana and Texas saw flash flooding from more than eight inches of rain from heavy rain thunderstorms training over the same spots for several days. Unfortunately, the most plentiful rainfall missed the areas hardest-hit by drought over the past few months. Areas that saw more than an inch of rain almost completely avoided parts of the country that are in some level of drought.

What can we expect over the next few days? Temperatures for most of us east of the Rockies will follow one of those classic, springtime up-down-up-down trends as storms and disturbances come and go. The Climate Prediction Center shows below-average temperatures for most of us east of the Rockies, while above-average temperatures and dry conditions continue for the western section of the country.

Snow should mostly be relegated to the Rockies and the northern states, where a fast-hitting winter storm could drop up to eight inches of snow in Minnesota and Wisconsin on Friday and Saturday. There's a quick chance of snow or a wintry mix from Sunday into Monday from the central Plains through the Mid-Atlantic, but it shouldn't amount to much if it snows at all. The sun angle is high enough this time of year that wintry precipitation won't stick around very long if it accumulates at all.

Our next chances at significant weather should emerge toward the middle and end of next week, when heavy rain and thunderstorms are possible along and east of the Mississippi River, and a potential heavy rain event could welcome the first weekend of April for parts of the West Coast.

[Model: Tropical Tidbits | Rain Map: Dennis Mersereau | Temp. Outlook: NOAA / CPC]
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I graduated from the University of South Alabama in 2014 with a degree in political science and a minor in meteorology. I ran Gawker's The Vane for two years and I've contributed to Mental Floss, Forbes, Popular Science, and the Washington Post's Capital Weather Gang. I also teamed up with Outdoor Life to write a book called The Extreme Weather Survival Manual, which came out in October 2015.

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