Bomb Cyclone To Pack Snow, High Winds, Blizzard

W​inter Storm Elliott is intensifying into a likely bomb cyclone as it tracks through the Plains, Midwest and Great Lakes with snow and strong winds, including blizzard conditions for some.

Elliott will also bring strong winds and a possible flash freeze to parts of the Midwest, East and South.

(​MORE: Brutally Cold Air Arrives With Elliott)​

H​ere’s a look at where the storm is now and what’s to come.

H​appening Now

Snow is falling right now from parts of the Great Lakes into the Lower Mississippi Valley. A separate area of snow, sleet and freezing rain is spreading through interior parts of the Northeast.

(​LIVE UPDATES: Elliott’s Impacts In The Plains, Midwest, Great Lakes)

The cold front’s passage is being accompanied by strong winds gusting to 50 mph (locally even higher) in the Plains. B​lowing snow is impacting travel even in areas where snow has ended because of the strong winds.

A major temperature drop is also spreading through the central states.

B​lizzard warnings have been issued for parts of the Northern Plains, upper Midwest and Great Lakes, as illustrated by the pink polygons in the map below. Those warnings include Buffalo, New York, Des Moines, Iowa, Grand Rapids, Michigan, and Pierre, South Dakota.

W​inter storm warnings and winter weather advisories are in effect for a much larger area that extends from the upper Midwest to the Great Lakes and mid-South. Among the cities included are Chicago, Cleveland, Detroit, Indianapolis, Milwaukee, Minneapolis-St. Paul, Nashville and Memphis.

T​ravel should be avoided in many of these areas since it could become difficult or impossible. That’s not just because of the snow, but also strong winds and extreme cold.

Below, we’ll step you through the timing, snowfall forecast, wind forecast, and other impacts from this storm, then we’ll provide perspective on bomb cyclones and how this storm lines up with other December and all-time Great Lakes storms.

F​orecast Timing

Friday

The storm will reach its peak intensity with high winds, snow and blizzard conditions in parts of the Great Lakes, from northern and eastern Wisconsin and far northeast Illinois to parts of Michigan, northern Indiana, northern Ohio, western Pennsylvania and western New York.

A​ny rain or rain changing to snow in the Northeast will be followed by bitterly cold air that could result a flash freeze, making for icy conditions in spots.

H​igh winds are also expected over much of the East as far south as Georgia and the Carolinas.

S​aturday

B​y Saturday, the storm will move away into eastern Canada, but strong winds will likely linger in much of the Great Lakes and upper Mississippi Valley. Those winds blowing over the Great Lakes could produce bands of heavy lake-effect snow that could last into Christmas Day in the eastern Great Lakes.

Also, lingering areas of blowing and drifting snow are expected outside the lake snowbelts in the Midwest where snow fell the previous few days.

H​ow Much Snow?

Plains, Midwest, Great Lakes

More than a foot of snow is likely in the western Great Lakes snowbelts, where winds blowing over the lakes will enhance snowfall downwind of lakes Superior and Michigan over the Upper Peninsula, western Lower Michigan and extreme northern Indiana.

U​p to 6 inches of snow could fall in parts of Wisconsin, northeast Illinois and much of the rest of Michigan outside the lake snowbelts.

Farther south, a widespread area from the Central Plains to the mid-Mississippi and Ohio valleys has a chance of at least a few inches of snow. And at least light snow totals might be enough to make roads slick as far south as parts of Missouri, northern Arkansas and Tennessee.

N​ortheast

T​otals over 6 inches are possible in the high country of the central Appalachians, Adirondacks, Green and White Mountains.

High W​ind Threat

High winds will be the most widespread impact from Elliott.

The strongest winds from this storm are expected Thursday night through Friday into early Saturday in the Midwest and along the East Coast from New England to Georgia Friday.

T​he National Weather Service has issued high wind warnings for parts of upstate New York and northern and eastern New England, including the Boston metro area.

T​hese winds will be capable of downing tree limbs and knocking out power, particularly where they combine with snow accumulations weighing down trees and power lines in the Midwest and East. Plan ahead now for the potential for power outages in cold weather if you live in these areas.

Even areas of lower snowfall totals may see dangerous reductions in visibility due to strong winds combined with snow and also drifting snow on roads, especially in outlying areas.

T​he winds will also lead to areas of coastal flooding.

M​inor to moderate coastal flooding is expected with Friday’s late morning or early afternoon high tide from the southern Delmarva Peninsula to parts of coastal New England, including Long Island and the Jersey Shore.

L​akeshore flooding is also expected along the eastern shores of Lakes Erie and Ontario in western and upstate New York Friday into Saturday night. In Buffalolake levels could exceed 3 feet above flood stage, according to the NWS, a level that’s been reached only three other times since the mid-1970s. That could inundate flood-prone areas near the lake such as the Old First Ward in South Buffalo.

O​ther Threats

There are two other things we could see with this storm that could be dangerous for your drive.

F​irst, as the arctic cold front sweeps through the Plains, Midwest and East, snow squalls could develop.

These are bursts of snow, but they’re brief, typically lasting less than an hour. The reason they’re dangerous is they can quickly lower visibility and coat roads in a thin film of snow, making them slippery.

M​ulti-vehicle accidents can and do occur within these snow squalls, particularly on major freeways with more traffic. Keep that in mind, even if your area of the Midwest and East does not have heavy accumulations of snow in the forecast. It could instead come down in these short-lived bursts.

S​econdly, there’s the potential for a flash freeze. T​his occurs when rain soaks pavement, then is followed quickly by an arctic cold front that ushers in subfreezing air.

That fast-arriving cold air would then turn any lingering water on untreated roads into patches of ice, making travel slippery and dangerous, particularly on bridges and overpasses.

T​his is certainly possible in parts of the Ohio Valley and East ahead of the cold front Thursday into Friday.

(​MAPS: 10-Day U.S. Forecast Highs/Lows)

B​omb Cyclone Perspective

We mentioned earlier that this winter storm could become a bomb cyclone.

A​s a rule of thumb, meteorologists refer to a strengthening low as “bombing out” or undergoing bombogenesis if its minimum surface pressure drops by at least 24 millibars in 24 hours or less, though that criteria also depends on a storm’s latitude.

Meteorologists frequently discuss pressure in terms of millibars, rather than inches of mercury.

The reason this all matters beyond just a geeky statistic is the lower the pressure in a storm, the more intense it is. And the greater difference in pressure over an area, the stronger the winds.

(​MORE: What Is A Bomb Cyclone?)

W​inter Storm Elliott has the potential to plunge to a pressure that could threaten December low-pressure records in the Great Lakesaccording to data compiled by NOAA Weather Prediction Center meteorologist David Roth.

F​or now, the latest ensemble model forecasts do not bring Elliott’s low to the level of what is considered the all-time low-pressure record – the so-called “Cleveland Superbomb” of late January 1978.

Nevertheless, this combination of wind, snow, cold, snow squalls and flash freezes will be a travel headache.

If you reside or have pre-Christmas travel plans in these areas, monitor the forecast closely and be prepared to make alternate travel arrangements. C​heck back with us at weather.com for important forecast updates.

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