The FOX Forecast Center expects a fairly disruptive storm that will impact millions of Americans, creating travel trouble and leading to power outages along the East Coast.
The expected impacts come as a trough of low pressure rolls out of the western U.S. on Friday, triggering the development of a surface low over the central Plains. This initial low will kick off the event with widespread rain and some snow in the Upper Midwest by Saturday, the FOX Forecast Center said.
Widespread heavy rainfall to spread through East
A broad area of moderate to heavy rain will likely develop starting Friday from the Gulf Coast to the Great Lakes and eastward toward the East Coast.
A Flood Watch is in effect from Sunday afternoon through Monday afternoon in the Eastern Adirondacks, central and northern Vermont, including the Champlain Valley.
Flash flooding will be a concern along the Gulf Coast to parts of the mid-Mississippi and lower Ohio valleys on Saturday, while the threat shifts eastward from the Florida Panhandle up to the mid-Atlantic and much of the Northeast on Sunday.
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This system's fast movement will help limit rain totals. However, significant moisture and sufficient instability should still support rainfall rates high enough to produce some flooding concerns, the FOX Forecast Center said.
Dangerously strong winds to whip up on Sunday, Monday
Gusty winds will likely develop over portions of the Rockies and Plains on Saturday due to the sharp difference in pressure between a wavy cold front and strong high pressure over the interior West. Gusts between 30 and 40 mph are expected in these areas.
Strong winds are then expected to develop along the mid-Atlantic and New England coasts late Sunday and into Monday, with 50-70 mph gusts possible near the coast.
These wind speeds could be high enough to create big travel problems at major airport hubs over the weekend, and power outages are possible across multiple states.
Snow expected in Great Lakes, interior Northeast
Some snow will be possible on the northwestern side of the low from the north-central Plains and Midwest into the Great Lakes on Friday and Saturday.
Because of limited leftover moisture behind the system and the cold air not arriving quickly enough, snow totals will be limited to 1-3 inches for most locations in the Northern Plains. Some snow may also fall after the system passes, mainly over the Great Lakes into the Appalachians, the FOX Forecast Center said.
As colder air rushes in behind the low on Sunday night, the rain is expected to switch over to snow across the interior of the Northeast.
Upstate New York, Pennsylvania, Vermont, New Hampshire and Maine could see snow accumulating Sunday evening and lingering through Monday morning. A general 1-3 inches of snow will likely fall with locally higher amounts in favored upslope areas and higher elevation areas. Significant impacts from the snow do not appear likely, the FOX Forecast Center said.
"The (Interstate) 95 corridor, it's a bust if you like snow. It's a pro if you like 60s, but it's going to come with rain," Merwin said. "Sunday, although it's going to be mild, you're going to be inside your house. Sunday night, we start to cool things off, but still above freezing for the 95 corridor."
Severe weather threat in the South
This storm will also bring the potential for severe weather in the South.
The FOX Forecast Center said a few severe storms may develop Friday night in parts of the Ark-La-Tex region and near the Ozarks as moisture streams off the Gulf of Mexico.
By Saturday, with enough moisture and strong wind shear – the change in wind speed and direction with height – in place, a more substantial threat of severe thunderstorms could materialize. Tornadoes, damaging winds and large hail will all be possible from East Texas to Louisiana, Arkansas, western Mississippi and West Tennessee.
"We're probably not going to see that traditional supercell development," Merwin stressed. "But when you get a line of thunderstorms, and you're tracking mainly a wind threat, sometimes we can have these quick spin-up tornadoes along that line. And those are sneaky. They happen fast."
It appears some severe weather threat will still exist as the overall system shifts farther east on Sunday, according to the FOX Forecast Center. Computer forecast models suggest the central and eastern Carolinas to the Delmarva Peninsula could be at risk for a few strong to severe storms.