An Arctic eruption has caused temperatures to drop from the northwest through the large basin.
Temperatures will generally be 10-20 degrees below average, but the coldest places in Montana and North Dakota can be as much as 40 degrees below average.
THE NORTHWEST WEATHER TURGES MANY INTO LEGS
Wind cooling alarms have been issued across these regions, where wind cooling temperatures can drop as low as -30 to -40 degrees.
At these temperatures, frostbite can occur over a period of 20 minutes or less.
In the western United States, the series of storm systems continues off the Pacific Ocean.
Wednesday and Thursday, the heaviest rain falls over Southern California.
Lightning flood warnings have been issued from San Diego to Irvine.
Finally, in the southeast, strong storms are likely on Wednesday afternoon and evening.
Strong thunderstorms with harmful winds and frequent lightning are likely.
Isolated tornadoes are also possible.
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The highest risk areas for severe weather include parts of northern Mississippi and northern Alabama into southwestern Tennessee.