The start of spring might be just around the corner, but Mother Nature doesn't seem to care whatsoever. Winter Storm Ulmer — which is affectionately referred to as "Bomb Cyclone" — is about to shake up the Rockies, central and northern Plains, and the Upper Midwest just before the weekend hits.

The storm is set to bring Hurricane-like conditions with strong wind gusts, heavy snow, and dangerously low air pressure, according to CNN. Colorado, Wyoming, Nebraska and South Dakota will take the brunt of it: As of Wednesday afternoon, these states have blizzard and winter storm warnings in effect and many schools and businesses are expected to be closed through Thursday. In fact, about half of the country (1.5 million square miles) have watches, warnings, or advisories in place.

So, when you should you start to hibernate? Like, yesterday. In danger of whiteout conditions and wind gusts up to 75 mph, the National Weather Service in Boulder, Colorado issued this message to locals: "Please cancel any travel plans Wednesday afternoon and evening especially east of I-25, and stay tuned for further updates!" According to CNN, Wyoming and South Dakota have closed state offices, and a 130-mile strech of westbound Interstate 80, from Ogallala, Nebraska to the state line with Wyoming, is currently closed.

The worst of the storm will happen late Wednesday but there's still plenty of wet, windy weather in the forecast for Thursday. In the morning, Ulmer will continue to hit the northern Plains with blizzard conditions and strong winds. There will also be a mix of rain and snow moving through the upper Mississippi Valley into Thursday night. After the snow stops, many states like Illinois, Tennessee, Arkansas, and Alabama and are at risk for severe rain and flooding.

But why is everyone calling it a "Bomb Cyclone?" If the pressure levels drop 24 millibars in less than 24 hours, it's considered bombogenesis. Since the start of the storm on Tuesday, the pressure has already dropped 27 millibars, which means the storm is in hurricane territory. And that's not the worst of it: The Weather Channel reports that the storm was already equivalent to a category 1 hurricane by Wednesday afternoon but it will likely reach category 2 status later on.

One positive: Because the storm is moving at such a rapid speed, snow won't have enough time to accumulate, which means states should expect no more than one foot of snow on the ground. A silver lining!