UPDATE 10:15 AM, 10/29: After Sandy’s left hook, winds will roar late Monday/Tuesday in SW Virginia; leaves, rain and some snow will fly
UPDATE 10:15 AM: At left is a new satellite photo of Hurricane Sandy — still considered a hurricane, with 85 mph winds, though it is a hybrid storm with both tropical and extratropical elements. Sandy has begun to make her “left hook” and has started moving north-northwest. Expect a faster northwest movement for Sandy later today as she is caught in the jet stream trough and becomes more extratropical than tropical. That distinction will matter little to residents along the coastal areas from Cape Cod to Cape Hatteras getting battered by her waves, especially in the New York-New Jersey area likely to take the brunt. In fact, the growing extratropical nature of Sandy means her strong winds are just spreading out wider. For Southwest Virginia — expect this to just be like a breezy, January day in late October until Sandy gets closer to the coast, and the contrast between her intensely low (likely record-breaking for that region) central pressure and high pressure to our west grows. That’s when stronger winds will pick up — 20-40 sustained with 50-60 gusts still appears to be about right for this evening through early Tuesday. As for snow … areas that have already seen snow may see some off and on through the day, mostly light, and mostly not sticking, except maybe at the higher elevations generally above 2,500 feet or so. Whether there is more widespread significant snow to the east or lower elevations of current winter weather warnings and advisories clustered along the West Virginia border and west of I-77 depends a lot on how much moisture Sandy’s circulation can rotate in to our region over the mountains overnight and Tuesday. Most forecast models keep it pretty light, with the heavy stuff being squeezed out to the west. Still, do not be surprised to see perhaps some heavier bursts of snow and some white on grassy areas in the New River Valley and Blue Ridge areas tonight and early Tuesday, and wet snowflakes may even make it into the Roanoke Valley at times. END UPDATE
UPDATE 6:15 AM: Winter weather advisories have been added this morning for elevations above 2,500 feet in Bland, Giles and Craig counties, with 2-5 inches of snow projected along the higher ridges. A cold, increasingly windy day and night are ahead, with mostly light rain gradually become mixed with or changing to snow farther east and at somewhat lower elevations. Winds may gust as high as 60 mph by evening as well. Expect some sporadic power outages and scattered tree damage with those winds. END UPDATE
We can stop talking about Sandy in future tense now, in terms of U.S impact. Hurricane Sandy — a hybrid storm with a warm-core center, so still a hurricane — has already sent storm surge piling over the Outer Banks of North Carolina and into Virginia Beach, with 50 mph winds gusts reported already in parts of New Jersey and coastal storm surge all the way south to Florida and north to Long Island — even though it’s nearly 300 east-southeast of Cape Hatteras. It’s projected to move a little east of north for a short time , then get jerked suddenly northwest by the digging polar trough, making landfall early Tuesday on the coast of New Jersey as an extremely intense extratropical low-pressure system (not tropical, so not a hurricane — but folks getting hammered by it won’t care). Where exactly it lands and what it’s called are really meteorological semantics at this point … its impact will be felt over most of the Eastern U.S., as its storm-force wind field (39 mph+) is 1,000 miles wide. This is going to be large-scale disaster for a huge area, with many large metropolitan areas affected. Southwest Virginia is a tiny piece of a big mosaic, but we will have significant affects as well.
As Sandy moves inland and slowly moves westward into Pennyslvania, our winds will pick up in response to the pressure gradient between the extremely deep low pressure in the storm and high pressure to the west. Expect winds to gradually increase through the day Monday, reaching 20-40 mph sustained with gusts of 50- 60 mph at times by Monday evening and Tuesday. Winds of this speed and duration WILL result in some downed trees and scattered power outages across Southwest Virginia. Be prepared.
Snow has already begun in the highest elevations near the southwest tip of the state on this Sunday evening — not directly related to Sandy, but indicative of the cold air moving in — the polar trough that will eventually lift Sandy inland. Snow, and lots of it, will bury much of central and eastern West Virginia, especially at high elevations, where 1-2 feet or locally more will fall. Several inches may also occur above 3,000 feet west of Interstate 77 and northward along the ridges just east of the Virginia-West Virginia line, with some snow into lower elevations as well. (NWS-Blacksburg snowfall projection map on page linked here, scrolling down.) Farther east, the depth of cold air and availability of moisture swirling around the backside of the low will be marginal, as much of it will be squeezed out over West Virginia’s high terrain. Still, periods of rain and/or snow may occur Monday night and Tuesday in the New River Valley, along the Blue Ridge and even into the Roanoke Valley and points east, with a greater possibility of snow the higher up you are and farther west you are relative to Roanoke. It does not appear at this time there will be continuous enough heavy precipitation for widespread snow accumulation, as air temperatures near the surface will be marginal (likely a little above freezing in many locations) and ground temperatures are warm. But we’ll keep an eye our to see if more intense bands of precipitation that projected develop that could keep snow going for a longer period of time in any other areas.
The official rain area has been slowly lifted northward, and I don’t think heavy rain will be an important impact for our region, as the bulk of Sandy’s moisture streams well to our east and north. Some showers are already being pulled through tonight, related to the cold front moving in from the west and caught in Sandy’s broad rotation.
With a storm this intense and unprecedented, some surprises somewhere are just about inevitable. We’ll watch closely for any of those that might develop that would affect our region.