"Potent" cold spell sweeping eastern U.S on Halloween
Halloween trick-or-treaters face the strongest push of cold air so far this season, with forecasters warning of potentially record-low minimum temperatures on Wednesday from the Southern Plains to the Midwest.
The big picture: Some 64.5 million people were under freeze warnings in the U.S., as a "potent cold front" that began sweeping in from Monday was bringing the threat of "freezing to sub-freezing overnight temperatures" from the Southern Plains to the Northeast, per the National Weather Service.
- Storms associated with the front were bringing the threat of snow squalls to cities including Minneapolis, Chicago and Milwaukee, with the weather service warning of hazardous travel conditions this week across the Upper Midwest through the Great Lakes due to this.
State of play: The NWS said temperatures would plunge particularly in the central and eastern U.S. as the front pushed through the Mid-Atlantic and much of the Southeast coast overnight, while the "Blustery COLD winds" were expected in parts of the Midwest.
- A strong Canadian high-pressure system that's set to center itself over the central U.S. Tuesday is set to bring colder-than-average temperatures that could see records smashed in some places, though the outbreak was expected to be more notable for its expansiveness rather than for the record lows.
What they're saying: "Temperatures will fall dramatically for much of the East over the next couple of days," the NWS noted in a Monday night forecast discussion.
- "Another shot of cold air will arrive over the Northern/Central Plains on the backside" of shortwave energy that's set to soak parts of the Upper Midwest, Great Lakes and interior Northeast through Wednesday morning, per the NWS.
- "Freeze Warnings are also in effect from northern Texas through Arkansas and up into much of the Tennessee/Ohio Valley through this Wednesday as high pressure remains overhead. This will mark an end to the growing season for many."
Meanwhile, the first atmospheric river event of the season is likely to begin on Wednesday over the Pacific Northwest as a low pressure system and associated moisture plume arrive in the region.
- "There will be flash flooding concerns associated with this AR, partly due to rain over snow pack in the higher elevations as well as runoff threats over saturated soils," according to the NWS.
- "Dry/gusty conditions over parts of southern California and the Southeast will continue to support an Elevated fire weather risk on Tuesday."
Of note: While the NWS notes the Baltimore-Washington, D.C., region faces the "coldest weather of the fall thus far is in store over the next couple of nights," temperatures will reach 70° again in the national capital by next weekend.
Editor's note: This article has been updated with new details throughout.