UPDATE 12:40 AM, 1/2: I’m simply going to add a link to the Weather Journal column with my 5 picks for top weather events of the year in The Roanoke Times readership area — based on intensity of impact, breadth of impact, unusual nature of the event, meteorological records, newsworthiness, etc. Frankly, though, there was an obvious pick for No. 1 (June 29 derecho) and everything else is arguable below that. Weatherwise, expect a few more showers — maybe even some snowflakes — overnight into Wednesday morning. The next few days appear to be pretty placid, with near-normal temperatures (40s highs, 20s lows) and only a couple of weak disturbances that may trigger a few sprinkles or flurries, Thursday and perhaps over the weekend. We’ll look ahead more in depth in the next blog post sometime Wednesday evening. END UPDATE
Happy New Year, Weather Journal fans! It certainly was a wild 2012. The National Weather Service in Blacksburg has released a list of what its meteorologists voted as the top five weather events in its forecast area for 2012. I’ll have my own list in Wednesday’s newspaper (and I’ll link it here) of the top five events in The Roanoke Times readership area, a much smaller area than the Blacksburg forecast area.
December finished with a 44.7-degree average for Roanoke — the 6th warmest December in the past 101 years, eight-tenths of a degree warmer than last December, and only two-tenths of a degree cooler than November — putting the year at 59.5 degrees. I’m checking with the National Weather Service about where this ranks the year as a whole — this online listing suggests it would be the warmest year on record, but I have another chart provided by the weather service office that shows 1930 as having a 59.6 average. Either way, a very warm year.
The radar has showed splotches of precipitation moving across Southwest Virginia all day on Monday, but very little has reached the surface. Dry air east of the Virginia-West Virginia border and I-77 corridor has been hard to penetrate by the weak overrunning flow of moisture from the west and southwest. Some will eventually get through, as the air slowly saturates, but amounts look to be rather meager. Because there is so much dry air, evaporational cooling may be sufficient for some sleet or snow, but enough milder air is filtering northward, without much of anything to fight it with cold air from the northeast, that most of the precipitation will probably be rain. I say “probably” because we’ve had a couple of precipitation events in the last week that didn’t work as expected due to subtle changes in the atmosphere’s thermal profile. There may be another chance of some frozen precipitation late Tuesday as cold air filters in on the backside, but again, it just appears like amounts will be very light, less than a tenth of an inch of liquid for most, maybe a quarter-inch west of I-77.
We do have a milder pattern taking over for a while over the weekend and next week, as extremely cold air near Hudson Bay will remain wrapped up, for now, by a rapidly spinning area of low pressure. Whether the pattern changes to allow this cold air to surge southward later this month or early in February may be the single biggest determinant in how winter 2012-13 will end up being characterized. Locally, we’re actually off to a milder start in December than our second warmest winter on record a year ago, but nationally, there is more snow cover, and there are far more signs of Arctic air stirring to our north than this time last year. We’ll watch the push and pull of mild and cold the next several days to see if this ends up being a mild repeat or is overtaken by an Arctic surge.