A potent “Bomb cyclone” will snarl more holiday travel this weekend

You may be hearing the term “bomb cyclone” as the storm headed toward Minnesota makes its way across the country. What does that mean?

When and area of low pressure is developing, we call that “cyclogenesis.”

If a storm is intensifying so quickly that the pressure drops 24 millibars or more in 24 hours, we call that “bombogenesis” aka a “bomb cyclone”. The storm headed our way dropped an incredible 43 millibars in 24 hours as it impacted the West Coast and produced wind gusts up to 106 mph, measured at Cape Blanco, Ore. While we will not see such high winds here in Minnesota, the storm will have significant impacts as it hits the state.

Thanksgiving

This is the quieter weather day, in between our two storms this week. Temperatures stay below average across Minnesota, with highs only in the 20s.

By Thursday afternoon, light snow starts to move in from the Southwest, and there is also a slight chance for light snow near Lake Superior.

The snow continues to spread across the state through Thursday evening, including likely starting late Thursday evening for the Twin Cities. By early into the overnight, most of the state will be seeing snow.

Storm Impacts Friday through Sunday

Besides being a strong storm system, the incoming weather is a complex forecast because Minnesota will be right on the temperature line where we are expecting combinations of snow, rain, and even ice. A temperature variation of only a couple degrees could completely vary how much snow versus rain falls.

Given that variable, here is what is currently most likely:

We are still watching for some ice across the state Friday. Fortunately, most of this looks light and often mixing with snow, so it is unlikely to be a major ice event, but the roads could get slick, especially in Western Minnesota.

Besides the ice, Friday is more likely to be mostly snow across the state as temperatures will be slightly cooler. Saturday will be just a few degrees warmer, ranging from the low to mid 30s across Minnesota, but that is just enough to allow for many areas to see rain mixing in.
Here is the potential dividing line of rain and snow for Saturday afternoon:

While the entire state will see accumulating snow, the greatest impacts will be to Northern Minnesota, where most of the precipitation stays snow versus any rain. Parts of the Arrowhead of Minnesota and Northwest Minnesota, including near the Moorhead area, could see some isolated totals near a foot of snow.

The same areas seeing the heaviest snow could also see wind gusts in excess of 40 mph on Saturday, leading to blowing snow and reduced visibility. Travel will likely be impacted.
By Saturday night, it gets cold enough that almost all of Minnesota will see more snow, before the snow tapers-off Sunday as the storm finally moves away.

Next Week

After Sunday, we have a stretch of weather that looks much quieter at least through mid week. Temperatures will stay a few degrees below average though, with highs in the 20s around the Twin Cities and some teens in Northern Minnesota.

Programming note

You can hear my live weather updates on MPR News at 7:48 a.m. Monday through Friday morning.