Winter Storm Helena is expected to bring feet of snow to portions of the West early this week and then may turn its snowy and icy sights on parts of the South late this week into the weekend.
(INTERACTIVE: Helena Snowfall Tracker)
With the calendar now saying January, colder temperatures are taking hold of a large portion of the Lower 48 states, setting the stage for the wintry weather.
With
cold air in place from high pressure, upper-level energy will pivot
through the East. This could result in snow and/or ice for parts of the
South and East.For this reason, keep in mind the forecast you see on weather.com or on The Weather Channel or the Weather Underground app will likely change over the next few days, so be sure to check back often for the latest updates.
(MORE: How Winter Storms Are Named | Winter Storm Central)
In the meantime, the weather system responsible for this will pummel the West with heavy snow. Let's start there, then cover the potential Southern wintry threat.
Western Snow
Winter storm warnings are in effect for a sizable swath of the West, from the Siskiyous and Sierra of California to the high country of southern Wyoming and Colorado, including the entire Salt Lake Valley.
Winter Alerts
Here's our forecast timing in the West:
- Tuesday Night: Heavy snow will fall in the Siskiyous and Sierra of California, with snow also in parts of the Great Basin and Rockies of Colorado and southern Wyoming.
- Wednesday: Heavy snow will continue in the Sierra, with moderate to heavy snow also stretching east into the Great Basin and Rockies of Wyoming and Colorado. Snow will also be falling in the cities of Denver and Salt Lake City.
- Thursday: Snow will sag southward in the West, including the Sierra, central and southern Rockies and the Four Corners.
- Friday: Snow may linger in the Four Corners higher elevations and adjacent southern High Plains early before tapering off.
Adjacent low elevations of the Great Basin are likely to pick up at least 3 inches of snow.
(CITIES: Reno, Nevada | Boise, Idaho | Salt Lake City | Denver)
Snowfall Forecast
Southern Snow/Ice Ahead?
Jet stream energy responsible for the heavy snow in the West will then make its way to the South and East later this week, with cold air in place.If a decent surface low-pressure system forms in response to that energy, this could enhance the potential for wintry weather. Conversely, a more progressive and moisture-starved system with a weak surface low would decrease the odds.
Forecast guidance is beginning to narrow the uncertainty regarding the Southern wintry threat, both in timing and general location. It is becoming more probable at least some snow or ice will occur in parts of the Southeast late this week.
(MORE: Five Things To Know About Wintry Weather in the South)
An initial round of light snow could ripple from the central Plains to the Ohio Valley, Appalachians and possibly the Northeast Wednesday into early Friday.
Friday into Saturday is when the South has the potential to see snow or ice accumulations as upper-level energy and at least a weak surface low glide through the region.
Our most recent forecast maps in the South for Friday and Saturday are shown below, illustrating the areas that could see snow or mixed precipitation. Those locations would also be in play for possible accumulations.
(FORECASTS: Atlanta | Nashville | Raleigh)
Friday's Forecast
Saturday's Forecast
For now, there is no need to change any plans for later this week given the lingering uncertainty.
But, keep in mind, the potential exists for difficult winter driving conditions in parts of the South beginning Friday. Check back with us at weather.com for the latest updates on this potential wintry mess.
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