The Parade of Unsettled Weather Will Continue Into the Weekend

There has been a pretty remarkable parade of intense storm systems this past week, Greg Carbin, the branch chief of forecast operations for the National Weather Service, said on Wednesday. And it isn’t over.

Days after severe weather swept from Florida to Maine, another rapidly strengthening system — potentially more intense than the last — will threaten the eastern half of the United States from Friday into Saturday.

Starting late last weekend, one storm walloped the Northeast with significant snow, while another hit the Northwest. Less than 48 hours later, that West Coast storm intensified as it moved across the Central U.S., producing widespread wind damage, deadly tornadoes and extensive flooding by the time it moved over the East Coast.

While that was unfolding, another storm brought blizzard conditions to the western mountains, caused avalanches in the Sierra and, like the one before it, was poised to bring more severe weather to the East within days.

Here are the hazards to expect, and when.

• Blizzard conditions are possible in the Midwest on Friday.

• Tornadic weather will return to the South on Thursday and Friday.

• Rain will fall along the East Coast, exacerbating current flooding.

• Unsettled weather also will continue to blast the West, with another storm there Friday and Saturday.

• Temperatures will plummet this weekend into next week for many locations across the United States.

It’s déjà vu

Like Tuesday’s storm, severe thunderstorms could create at least some risk of damaging winds and tornadoes Thursday night into Friday morning, stretching from central and east Texas into Mississippi. As the storm system strengthens Friday, the risk for severe storms will increase, with high winds and a few strong tornadoes also possible. Friday’s risk area stretches from Louisiana to the Carolinas, with an increased risk from Alabama to North Carolina.

Forecasters with the Weather Prediction Center said that, compared to Tuesday, much colder air will influence the precipitation on the northwest side of this storm, allowing for an impactful winter storm from the central Plains to the Great Lakes.

As the storm intensifies Friday, blowing snow and blizzard conditions are likely across the Midwest. The storm’s exact track will change which areas gets snow, especially in cities like Chicago.

Warmer, moist air will once again stream into the eastern side of the storm, allowing for rain in areas already hit hard by the previous two storms. It might bring a bit less rain than the previous system, but any measurable precipitation will exacerbate the ongoing flooding on rivers up and down the East Coast. It may not take much to produce or sustain major river flooding in some areas of New York, Connecticut and New Jersey, Mr. Carbin said.

A polar plunge

After the storm passes, a blast of bitterly cold air will push southward into the Central part of the country Friday into Saturday. Temperatures this weekend will dip 20 to 30 degrees below zero, the coldest air of the season so far for parts of northern Idaho, Montana and Wyoming.

“Many stations will flirt with daily low-temperature records and low-max temperature records,” Mr. Carbin said, adding that “high temperatures will be as much as 40 degrees below the normal.”

A stiff wind will make it feel even colder. Wind chill temperatures will be particularly dangerous, making it feel as cold as minus 60 across the northern Rockies and northern Plains, and 30 to 40 degrees below zero across the central Plains.

A few locations in Kansas and Nebraska may get close to all-time low max temps on Monday, but it’s going to be very close, Mr. Carbin said. Salina, Kan., is forecast to have a high of around 0 on Monday, getting very close to their all-time coldest high temperature on any day. The record coldest high daily temperature in Salina, Kan., was minus 4 on Jan. 3, 1919, according to Mr. Carbin.

The cold won’t stay bottled up north; freezing temperatures are expected to reach as far South as the Gulf of Mexico early next week, just in time for another storm system to form. With that frigid air in place, it could be cold enough for precipitation to fall as snow on or near the coast in the Northeast.

The blast of bitterly cold air will push southward through the Gulf Coast on Monday and Tuesday, with temperatures dropping below freezing in some locations. And if that weren’t enough, another storm system will impact the East from Monday into Tuesday — but there is a lot of uncertainty about where and what type of precipitation might fall.

“The challenge will be whether there is a weather system around to provide the moisture and lift needed for precipitation,” Mr. Carbin said.

The current weather pattern has recently been very well forecast five to seven days out, Mr. Carbin said. But that pattern is starting to break down somewhat, so systems now being forecast a week out have higher uncertainty than what forecasters saw with the ongoing pattern about a week ago.