The first will shed significant snow from the Central Plains to the Mid-Atlantic coast by Tuesday night. The deepest snow will accumulate in Iowa. Part of the snow will be very heavy, with snowfall rates of up to 5 centimeters an hour, says the Weather Forecast Center.
“If these snow totals materialize, they will be very rare for Iowa,” wrote the National Weather Service in Des Moines.
“On average, single daily blizzards of 30 cm or more occur only historically every 15 to 20 years.”
If a foot of snow falls in Des Moines in one day, it will only be the tenth time that a foot or more has fallen since 1884. The last time they saw so much snow in one day was in 2004.
“Midwest snow is not uncommon,” said CNN meteorologist Chad Myers, who has spent years predicting snow on the plains.
What makes this system rare is how much it is expected to fall in a day. Des Moines is much more likely to see more than a foot of snow accumulated in two or three days.
“This storm with such a wide area of 12 to 18 inches can stretch road cleaning assets,” said Myers. “Be ready to be stuck for a few days.”
Outside Iowa, snow above 4 inches is expected from Kansas to Michigan.
It is not just the snow that can cause problems. Ice can accumulate south of the snow, which runs from Kansas to New Jersey. Up to a tenth of an inch of ice can be formed with dots located up to a quarter of an inch.
“Traveling can quickly become dangerous in parts of this region,” according to the forecasting center.
The rains will fall in the Southeast, where daily temperatures will be above average. Heavy storms can develop across the Mississippi River valley, including eastern Arkansas and western Tennessee
Atmospheric west coast river could bring record snow
Another system is planned to pass through the region from Tuesday to Wednesday.
“The midweek system in line with a wave of atmospheric moisture has the potential to pour an extreme amount of precipitation, potentially flirting with snowfall duration records, in portions of Southern California and western Great Basin” said Jenn Varian, a meteorologist from the meteorological service in Las Vegas.
Sierra Nevada is expected to receive the greatest impact from moisture with this system, Varian said, but additional overflow may be possible depending on the height of the storm.
Mountain ridges could see 60 to 100 inches of snow from Tuesday night to Friday morning.
Northwestern California, starting on Monday, is likely to see more rain. “Moisture plumes with AR (atmospheric river) events are always complicated and may not know any more details until the event starts to unfold,” said the San Francisco National Weather Service office.
Atmospheric rivers are long, narrow regions in the atmosphere – like rivers in the sky – that carry water vapor, according to the National Oceanic and Atmospheric Administration
Predicted rain totals Tuesday through Thursday at night range from 2.5 to 4.5 inches at the lowest altitude locations. In comparison, the hills could see 15 to 20 centimeters, perhaps even isolated amounts of 25 to 33 centimeters of rain.
Ahead of this system in the middle of the week, much of the region will face strong winds. Strong wind warnings and alerts are posted from Los Angeles to Phoenix, where winds will blow from 45 to 55 mph today.
From Tuesday to Wednesday, winds can reach 60 mph in parts of California.