Ice storm warning is up -- will it verify?Posted Jan31, 2008 at 08:38 AMA big chunk of Southwest Virginia is now under an ice storm warning late tonight through midday Friday, including Roanoke County and every adjacent county, plus the New River Valley and everything north and west. Click here for the latest on warnings and advisories from the National Weather Service in Blacksburg. Everything about this storm system is more powerful than similar borderline ice situations we've had in the past year, particularly Feb. 13 and Dec. 16 of last year. The damming of cold, dry air ahead of the storm is stronger, which gives more opportunity for ice to develop, but so is the flow of warm, moist air aloft. That flow of warm air will eventually overcome the cold, but the longer it can keep from doing so, the more ice threat we will have. The weather service is thinking a quarter to a half inch of ice is quite possible over most of the area, hence the ice storm warning. That much ice would result in scattered power outages and some tree damage, locally very troublesome in areas that get the worst ice, but not an areawide paralyzing ice storm like many of you remember from 1994. The Roanoke Valley is always the big question. I will reiterate my thinking that the potential for the floor of the Roanoke Valley, all the way to downtown, to get some ice out of this situation is greater than in the 33-degree escapes Roanoke city had twice last year. The opportunity for evaporational cooling on the front end -- initial precipitation evaporating in cold, dry air at the surface, thereby lowering the temperature -- is much greater. I wouldn't be surprised to see an hour or two of sleet mixed in at the front end, either, which could lay down a cold surface layer. Higher elevations and the fringe areas of the Roanoke Valley are highly likely to see ice, and quite possibly the quarter-inch required to verify the ice storm warning. The trouble will come if the cold air holds in more stubbornly than expected on Friday. That is how this potentially significant ice storm could become a major one. For now, it looks like the falling rain itself will pull some warmer air toward the surface Friday morning, and an advancing warm front will get us above freezing before this can get extremely bad. |
About this blog
Kevin Myatt works on the copy desk for The Roanoke Times and is its principal weather geek, writing a weekly weather column and advising the newsroom on weather topics. He helps guide students on a storm chasing trip to the central U.S. each May and was an editor for "Hurricanes and the Middle Atlantic States." .....Advertisement.....
|
...Advertisement...
...Advertisement...
Comments
[January 31, 2008 12:35 PM]
Brian SweeneyI notice the NWS has already dropped the maximum possible ice accumulation from 1/2 inch to 1/4 inch. Is this due to less precip, harder rain bringing down warmer temps or a combo?
[January 31, 2008 4:06 PM]
Kevin MyattLooks like the weather service -- for Roanoke area -- has dropped it to 1/4 inch tonight with up to 1/10 inch on Friday morning ... so totalling up to about .35 inch. Maybe a later onset owing to extremely dry air the moisture is falling into. I thought the half-inch was a little high anyway, probably more likely in the typical high elevation areas that usually get slammed harder by ice.