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Whatever you want to call it, the storm hitting the East Coast this week is a freak of nature, says Kevin Myatt, weather columnist for The Roanoke Times.
For Southwest Virginia, the merging of two extreme weather systems likely will mean high winds, heavy rain and possibly a record October snowfall.
Anything is possible, Myatt says, but the storm is bringing more tricks than treats.
“Confidence is high that there will be major to historic East Coast storm system as Hurricane Sandy is absorbed into a polar trough dipping southward,” Myatt wrote on Friday, as storm trackers kept a watchful eye on these two systems.
“Details on where exactly it tracks and what effects it produces on particular locations remains uncertain. Landfall between Virginia’s Eastern Shore and the eastern end of Long Island, N.Y. seems most likely.”
Southwest Virginia can expect windy weather through Tuesday, and possibly longer, this week.
“Wind gusts of more than 40 mph are likely; wind gusts of more than 60 mph may be possible during at least some of that time frame, depending on the storm’s track,” Myatt said. “The closer the center tracks to us, the more wind there will be.”
The threat of snow, possibly even heavy snow, has increased some for Southwest Virginia, “as forecast models depict a farther south track that could pivot the core of colder air and waves of moisture into the region Monday and Tuesday,” Myatt said.
As is typical, the best chances of significant snow will be in higher elevations and west of Roanoke, including mountain communities like Galax, Carroll and Grayson.
“But the system is so dynamic, it is possible that snow will extend farther south and east and into lower elevations,” Myatt said.
The storm will heavily affect multiple Eastern U.S. states. Coastal flooding from high waves — exacerbated by high tides created by a full moon — is possible from North Carolina to Maine.
“Unlike a hurricane with a tight inner core, high winds with a strong extratropical low will extend hundreds of miles from the storm center. There will be torrential rain, too — probably well to our north and east,” Myatt said.
Southwest Virginians should be prepared for possible power outages this week.
“Even 40 mph wind gusts may be enough to cause damage to trees, and blow limbs into power lines, due to remaining leaves on the trees and possible leftover weakened or loosened limbs from the June 29 derecho and other summer storms,” Myatt said. Wind gusts of 60 mph and/or heavy wet snow would cause much more numerous and widespread power outages.
“The fall colors are absolutely gorgeous in spots. Enjoy them Friday and Saturday before they blow away.”
It might be a good idea to find the snow shovels and test the snow blower this weekend — just in case, Myatt said. “You may not need them for another two months (or four, if it’s like last winter), but then again...”
“Since the wind is just about a given, rain is unlikely to be a huge factor here, and snow is by far the number one topic of interest” among his blog readers, Myatt said.
Two forecast models have led the way in suggesting snowfall — and maybe piles of it — may occur in Southwest Virginia on Monday and Tuesday. “This is because these models track the low west-northwest over the Delmarva Peninsula toward southern Pennsylvania at just the right angle to allow it to swirl both Arctic air and thick moisture around its west and southwest sides into our region,” Myatt said. “This is not the usual way we get snow in our region, but of course, this is not a typical storm system, this is a once-in-a-lifetime atmospheric setup.”
He says there are some reasons to be skeptical of the bigger snowfall amounts predicted.
Westerly winds over the mountains go downslope into much of our region, and this can dry out low-level moisture.
The ground is very warm, coming out of summer and a week of 70s to low 80s last week.
“I’ve said before that warm ground is a very overrated factor in not expecting snow to stick, but this is a little different than even last Feb. 19, with a day in the 60s and a mild winter leading into a 5- to 9-inch snowfall.”
Myatt said it will take very heavy snow and surface temperatures falling to very near freezing, if not below, to overcome a high melt rate. Even then, it would probably slowly melt from underneath, so the total on the ground would be less than the total that falls.
He also wonders what effect the warmth of a tropical storm will have when injected into a cold front.
“The warm core of the storm actually cuts off snow totals to the northeast — almost edging into our neck of the woods, and driving the heaviest core of snow west of Interstate 77. Because of how this storm is expected to wrap up, it may indeed occur that somewhere to the south has heavy snow while someone north has rain.
“Heck, it might snow at Raleigh while it’s raining in Pennsylvania.”
Myatt said there is at least one precedent for this kind of topsy-turvy rain/snow division — the Appalachian Storm of 1950, which became so wrapped up over the Ohio Valley it was driving a cold front north through Pennsylvania while pushing a warm front southwest through Michigan. Southwest Virginia got 6-10 inches in that event, while eastern Kentucky, western West Virginia and southern Ohio had snow in feet.
“That storm, like this one, was a surface low pulled northwest from the coast into a polar trough. But it didn’t have a hurricane feeding into it.”
Myatt said the storm track could end up too far north for it to rotate much moisture into our region for snow. “The storm track might even go too far south and cross through central Virginia, and more and more of our area from northeast to southwest would get a windy rainstorm.”
The Bottom Line
“I think we’re going to see our first snowflakes this week,” Myatt said.
Even if the storm tracks farther north, “the circulation around it will probably be enough for some upslope snow showers to creep over the mountains, maybe even later in the week than the Monday-Tuesday timeframe.”
A system coming off the ocean with tropical moisture “is going to have a lot it can fling at us, and if it’s cold enough, as many models show, there is a chance it could be a huge, paralyzing dump of slushy white for at least part, if not all, of our region.”
So, to put it simply:
Big East Coast storm? Just about certain.
Big snow for us? Maybe.