Winter Storm Jonas is just only beginning to take shape over the central United States, as the system will turn into a major snowstorm by later Friday into Saturday across parts of the East Coast. Heavy snow is likely to fall across more than 14 states, with dangerous blizzard conditions developing over parts of the Baltimore and Washington, D.C. metropolitan areas. In addition to the snow, Winter Storm Jonas will also feature strong winds, significant icing and coastal flooding.
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Locally heavy snow was developing over parts of the central Plains Wednesday night. The National Weather Service has posted winter storm warnings and winter weather advisories for parts of Nebraska, Kansas, Missouri, far northeastern Oklahoma and northwestern Arkansas.
This snow will gradually taper off during the day on Thursday, giving way to an area of low pressure that will develop over the Lower Mississippi Valley Thursday night. On the warm side of Winter Storm Jonas, scattered severe thunderstorms, including a few tornadoes, may impact parts of the Gulf Coast states and Florida through Friday.
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Across the East, winter storm watches are posted across the Tennessee Valley, lower Ohio Valley, central to southern Appalachians, much of the Middle Atlantic region and into parts of the Northeast. Most of those are valid Thursday night through Saturday. Memphis, Tennessee, Nashville, Tennessee, Paducah, Kentucky, Richmond, Virginia, Charlotte, North Carolina, and Philadelphia are among some of the cities in those winter storm watches.
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Some or all of the largest cities in the Northeast – Washington, D.C., Baltimore, Philadelphia, and New York – will be significantly impacted by this storm with heavy snow and strong winds, bringing travel to a grinding halt, between Friday afternoon and Sunday morning.
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While a high-impact snowstorm is likely, key uncertainties remain with the exact track of Winter Storm Jonas and how long it will last. All of those factors will dictate impacts at any particular location.
Let’s start with the impacts from Jonas, then we’ll detail the forecast timing.
Snow and Ice Impacts
- The exact storm track will dictate areas with the heaviest snow.
- At least 1 foot of snow most probable: Appalachians from eastern Kentucky into most of West Virginia, Virginia except southeast portion, Maryland, D.C., northern Delaware and extreme northwest North Carolina. Parts of these areas may see more than 20 inches of total snowfall.
- At least 6 inches of snow likely: I-95 corridor northward through New York City, as well as Long Island.
- Uncertainty still high: There remains considerable uncertainty regarding snow amounts on the northern edge of Jonas’ snow shield from south-central and east-central Pennsylvania to southern New England. These areas could see snowfall exceeding 6 inches, but confidence is not as high as areas just to the south.
- Ice: The highest probability of accumulating ice to the extent of not only leading to slick roads, but also some tree damage and power outages, extends from northeast Arkansas to southeast Missouri, Kentucky, southern West Virginia, southern Virginia, western and central North Carolina, and upstate South Carolina.
High Winds
- Strongest wind potential: Delmarva Peninsula, Chesapeake Bay, New Jersey and Long Island Saturday. Occasional gusts to 60 mph, coupled with the weight of wet, heavy snow in some of these areas, will likely lead to power outages, downed trees and limbs, and perhaps some structural damage.
- Additional strong gusts: Washington and Baltimore metropolitan areas, where blizzard conditions are possible; New England coast, particularly southeast New England, Cape Cod, Nantucket Island and Martha’s Vineyard; North Carolina’s Outer Banks.
Coastal Flooding
There remains some uncertainty regarding coastal flood impacts, as, once again, the exact track and forward speed of the low-pressure center will dictate wind direction, wind duration and the length of the wind flow over water, or fetch, all components to determining the amount of coastal surge flooding and battering waves atop the surge.
With a full moon this weekend, tides will already be running high, which could worsen coastal flooding impacts, as strong winds drive onshore during multiple tide cycles.
Areas of particular concern include:
- Delaware, including both Delaware Bay and the Atlantic beaches
- The western side of Chesapeake Bay, including tidewater inlets and the Norfolk/Newport News metropolitan area
- The Jersey shore, including the south shore of Raritan Bay
In these areas, major coastal flooding is possible for both Saturday morning and Saturday evening high tides, with potential beach erosion and even property damage.
Other areas with a chance of moderate coastal flooding include the west end of Long Island Sound, the south shore of Massachusetts, Cape Cod, Martha’s Vineyard and Nantucket Island.
For more on the threat of coastal flooding and strong winds, see our full article at this link.
Winter Storm Jonas: Timing
- Thursday/Thursday night: Light snow in the central and northern Plains. By Thursday night, the Plains snow diminishes, while a broad stripe of snow, sleet and/or freezing rain develops from eastern Oklahoma and Arkansas into Kentucky, the Appalachians and adjacent Piedmont of Virginia and North Carolina.
- Friday/Friday night: Rain changes to snow in the Tennessee Valley. A mess of snow, sleet or freezing rain continues in the lower Ohio Valley, Appalachians, North Carolina and Virginia. Snow spreads north up the Interstate 95 corridor mainly south of New York City. Winds intensify Friday night along the coast from the Carolinas to the Jersey Shore, and near Chesapeake Bay.
- Saturday/Saturday night: Heavy snow in the Appalachians and parts of the Mid-Atlantic states, with some sleet/freezing rain mixed in at times. Snow will spread into southern New England. Precipitation may change to snow as far south as parts of South Carolina. Rain changes to snow near the Mid-Atlantic coast. Strong, possibly damaging winds from the Delmarva Peninsula to Cape Cod.
- Sunday: Snow and strong winds diminish along the Mid-Atlantic Seaboard, but may linger much of the day in coastal New England.
(FORECAST: Louisville, Kentucky | Roanoke, Virginia | Greensboro, North Carolina)
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