The former will dump significant snow from the Central Plains to the Mid-Atlantic coast on Tuesday evening. The deepest snow will pile up in Iowa. Some of the snow will be very heavy with snow speeds of up to 2 inches per hour, the Weather Prediction Center says.
“If these snow totals become reality, they would be very rare for Iowa,” wrote the National Weather Service in Des Moines.
“On average, a few daily snowfalls of a foot or more have historically only occurred every 15 to 20 years.”
When a foot or more of snow falls in Des Moines one day, it’s only the tenth time a foot or more has fallen since 1884. The last time they saw that much snow in one day was in 2004.
“Snow in the Midwest is not rare,” said CNN meteorologist Chad Myers, who predicted snow in the plains for years.
What makes this system rare is how much is expected to fall in one day. In Des Moines, more than a foot of snow is more likely to build up over two or three days.
“This storm with such a wide area of 12 to 18 inches can make road mining thin,” Myers said. “Be ready to be stuck for a few days.”
Outside of Iowa, snow in excess of four inches is expected from Kansas to Michigan.
Not only snow can cause problems. Ice can build up just south of the snow that stretches from Kansas to New Jersey. Ice can form up to a tenth of an inch with localized spots of up to a quarter of an inch.
“Travel can quickly become dangerous in parts of this region,” the forecast center said.
Rain falls in the southeast, where daily temperatures are above average. Severe storms can develop in the Mississippi River Valley, including eastern Arkansas and western Tennessee
The atmospheric river on the west coast can bring record snow
Another system is expected to travel through the region from Tuesday to Wednesday.
“The midweek system tuned for an atmospheric moisture surge has the potential to dump an extreme amount of precipitation, possibly flirting with snowfall duration records, in parts of Southern California and the western Great Basin,” said Jenn Varian, a meteorologist for weather services in Las Vegas.
The Sierra Nevada is expected to take the biggest hit from the moisture with this system, Varian said, but depending on storm heights, additional overflow could be possible.
The mountain peaks could see between 60 and 100 centimeters of snow Tuesday evening through Friday morning.
Northwestern California looks likely to have the most rain from Monday onwards. “Moisture plumes with AR (atmospheric river) events are always troublesome and may not know more details until the event begins to unfold,” said the San Francisco office of the National Weather Service.
Atmospheric rivers are long, narrow areas of the atmosphere – like rivers in the air – that carry water vapor, according to the National Oceanic and Atmospheric Administration
Predicted rain totals Tuesday through Thursday evenings range from 2.5 to 4.5 inches at the lower-lying locations. In comparison, the hills could see 6 to 8 inches of rainfall, perhaps even isolated amounts of 10 to 13 inches.
In anticipation of this midweek system, a large part of the region will have to deal with strong winds. High wind warnings and advisories are posted from Los Angeles to Phoenix, where winds will blow 45 to 55 mph today.
From Tuesday through Wednesday, gusts of wind can be as high as 60 mph across parts of California.