A volatile weather pattern is underway across the Contiguous U.S., resulting in a multi-day severe weather outbreak across the Great Plains. Soon after, the pattern flips into a colder phase, inducing unseasonably cold weather that will spread across the eastern two-thirds of the nation next week.
The progressive and active weather has introduced widespread severe weather and a tornado outbreak across the United States, which continues this weekend and early next week. Once the large-scale system matures and moves east, the significantly colder air mass in its wake will begin spreading across the Midwest by mid-week.
The cold pool will shut down severe weather activity while unseasonably cold weather advances across the Great Lakes and Ohio Valley towards the East Coast late next week. Much colder weather than usual will also spread across the Southeast U.S.
The cold will reach the Mid-Atlantic and Northeast U.S. by Friday and extend through Sunday.
Below is this weekend’s weather pattern across the Contiguous U.S., revealing two large upper-level troughs (lows) nationwide. While the cold from Canada over the Great Lakes drifts towards the Upper Midwest, the large Low currently over the West will trigger further cooling by mid-next week.
Notice a well-defined jet streak rounding the western trough, providing ample moisture and shear to support additional severe weather outbreaks across the Great Plains and Mississippi Valley over the next three days.
The following video provides an overview of the current weather, which gradually flips into a colder phase throughout the week. A significantly colder air mass will spread across much of the U.S. from mid- to late next week.
Let’s examine the details of the weather situation across the United States over the next 7-10 days.
Weather pattern flips: Ridge on the West and deep low on the East
The currently established pattern reveals two upper lows/troughs, with ridging to the south, a sort of Omega blocking. As the next week progresses, the eastern trough will gradually vanish while the western low matures, dominating a large part of North America.
Therefore, it establishes the dipole weather pattern: a significant low on the East and a gradually building upper ridge (blocking) on the West.
Typically, this means the potential for severe weather across the Great Plains diminishes due to the lack of upper-level support from the unfavorable wind orientation to support high moisture. However, the large trough will park over the Great Lakes and the Northeast U.S. after mid-next week, allowing a much colder air mass to spread towards the south and east.
This will also be supported by a surface low, which will form across the Midwest on Thursday and gradually move towards the Northeast U.S. through Saturday.
The 5-day temperature anomaly across the U.S. from mid-next week into the early days of the week after indicates a significant and persistent cold pool dominating the eastern two-thirds of the country.
Meanwhile, the Western U.S. gradually warms up under the building’s upper ridge and a blocking high.
Unseasonably cold weather spreads across the eastern two-thirds of the United States
The weather pattern flip starts by mid-week, when the upper low deepens from southern Canada onto the Great Lakes. This allows a significantly colder air mass to develop over the Dakotas and Minnesota, spreading south on early Wednesday.
During the day, cold pushes across Nebraska and Iowa into Kansas and Missouri, with 10-15 °C colder air mass than usual.
Cold from the higher levels also translates to the ground. A significantly cold day is forecast over the Midwest. Daytime temperatures on Wednesday will be about 20 to 30 °F below normal for the region.
However, it will be colder than usual across much of the central and eastern U.S., with the coldest weather across the Midwest, the Great Lakes, the Ohio Valley, and the Northeast U.S.
By Thursday, the core of the upper cold wave will advance further east, allowing temperatures to continue cooling down across the central Plains and Mississippi Valley, including the Tennessee Valley.
On Thursday, a large cold pool will dominate about two-thirds of the Contiguous U.S..
The cold at the surface has stopped advancing far south and is forecast to reach central Texas, Louisiana, Missisippi, and Alabama by Thursday afternoon. An afternoon that is about 10-20 °F colder than usual is expected.
While the coldest day is forecast across the Ohio and Tennessee Valleys, over the Great Lakes and Northeast U.S., 20 to 25 °F below normal temperatures are in sight.
Thursday morning will bring below-freezing temperatures across the northern and central Rockies, while the cold will be intense across the northern Plains, Midwest, and Upper Midwest.
Lowest temperatures will be just shy above freezing in many areas. Where winds are lacking, expect frost to happen, which would be damaging to the crops this late in the spring season.
The upper low matures on Friday, with its core over the Northeast U.S. Therefore, the colder temperatures in the upper and mid-levels are forecast across the Great Lakes, Ohio Valley, Mid-Atlantic, and Northeast U.S.
The chart below shows 10-15 °C colder than usual mid-level temperatures. Friday will also engulf much of the eastern two-thirds of the U.S. in significantly colder weather.
The 2m surface temperature anomaly chart indicates where the colder temperatures are forecast on Friday afternoon. Unseasonably cold weather, especially across the Ohio Valley.
However, the Midwest, Mississippi Valley, East Coast, and Southeast U.S., including the Florida panhandle, will also experience well-below-normal temperatures on Friday.
Expect Friday’s lows to freeze again across interior Colorado, Wyoming, Montana, and Idaho. On Friday morning, the mid-30s to low-40s are forecast across the north-central Plains, Midwest, the Great Lakes, Ohio, the Tennessee Valley, and the Southeast U.S.
Temperatures down to the low 40s are forecast as far south as Red River, northern Louisiana, southern Mississippi, Alabama, and Georgia, as well as the interior Carolinas and Virginia.
Conditions are then forecast to gradually improve over the weekend as the upper wave finally decays and moves east. And temperatures are forecast to return to normal under the strengthening blocking high from the west.
Wxcharts, WeatherBell, and Pivotalweather provided images used in this article.
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