UPDATE 1:30 PM: The flood watch has been expanded northward to Roanoke and the New River Valley. Another 1-3 inches of rain may fall through mid-morning Wednesday as a second area of low pressure ripples northeastward along the stalled front. END UPDATE
UPDATE 9 AM
Flood watch issued for counties along/south of Wytheville-Floyd-Martinsville line. A flood watch signifies potential for gradual rising of streams and some rivers to flood stage — as opposed to rapid flooding with torrential rain that would warrant a flash flood watch — with totals of 4-6 inches possible in some locations.
New rain totals through 9 AM across NWS-Blacksburg area linked here. Widespread 1-2 inches in evidence, with some amounts exceeding 3 inches.
By mid-evening Monday, rainfall amounts of 0.25 to 0.75 inches were common in the Roanoke and New River valleys northward, with some 1-inch-plus amounts already near the North Carolina line. And of course it has continued to rain for more than 3 hours after that as I am typing this shortly after midnight, and will continue to rain in the early morning hours. I’ll post some new numbers sometime in the morning. With much of the region in moderate drought, a soaker of mostly light to moderate rain (a few periods of heavy rain here and there) is ideal. It won’t necessarily end the drought, especially in parts of Southside Virginia that ran a foot or more deficits in 2012, but it will ease it quite a bit. There may be a lull in the rain during the day Tuesday, as one ripple of low pressure moves to the east and a second approaches from the southwest. But the second low riding up the stalled frontal boundary is expected to bring another round of moderate rain with similar amounts Tuesday evening. It will be colder Tuesday, hovering around 40 in the Roanoke and New River valleys, as some of the modified Arctic air eases into Virginia, aided by the backside rotation of the low moving off the East Coast. It is possible that some higher elevations west of Interstate 77 or along the Virginia-West Virginia line will get some icing by Tuesday evening, but a widespread wintry weather situation is not expected in Virginia.
There is still a tricky southern stream disturbance to monitor for Friday. Most forecast guidance has the system staying mostly south of Virginia, but it wouldn’t take much of a bump in the path northward for it to bring a light to medium snowfall to our region. Confidence continues to grow in a major Arctic outbreak pouring southward out of Canada next week. We’ll try to hone in on more details of both of these events once we get past the rain.