First off, Easter: You’ll need a jacket or even a light coat if you attend sunrise services, with lows in the 30s to low 40s over most of the area. A frost advisory is out mostly west of the Blue Ridge. But it will warm up quickly by afternoon, so short-sleeves will be in order, with highs mostly in the upper 60s to mid 70s.
Sunday marks the anniversay of the EF-2 tornado that tore through Pulaski and the EF-1 tornado minutes later that hit nearby Draper. The National Weather Service has a good summary of that event linked here. Also, here’s a look back at the Weather Journal blog that day, the next-morning story in The Roanoke Times and a story 2 days later, both by Amy Matzke-Fawcett, and a follow-up analysis on the tornadoes I wrote. Historically, Southwest Virginia usually experiences its worst tornadoes when a very bad outbreak in states to our west bleeds over into our region, like last year’s April 27 tornadoes. But the April 8 tornadoes in the Pulaski area were much different in that they were the only ones reported in the entire United States that day. A unique situation involving a stalled boundary between a cool-air wedge to the north and warm, humid air to the south set up the Pulaski-Draper tornadoes of 2011. (The Roanoke Times covered Pulaski’s remembrance of the tornadoes Saturday at Calfee Park — I will link here when it becomes available.)
Fast-forward a year, and it’s an entirely different weather situation for Southwest Virginia. We’ve talked a bit about some cooler weather this week. Tuesday through Thursday, in particular, will likely be a few degrees below normal (65-66 highs/44-45 lows are Roanoke norms those days, 62/37 for Blacksburg) following some reinforcements of the Canadian air that has taken hold of our weather. There will be a few more frost/freeze threats in the coming week, though a “hard freeze” does not appear to be likely. But perhaps the most important feature of the next week or so of weather may be how dry it is. The air coming in off the Canadian prairies is largely devoid of moisture — we’ve seen some dew points in the teens and 20s the last couple of days. Also, the dominant northwest wind flow we’ll see most of this week will prevent Gulf of Mexico moisture from making inroads into our region — a very different event than what occurred in much of April 2011, when we were swamped with sticky, Gulf air. One result of this dry air will be wide ranges between low and high temperatures, approaching 40 degrees on some days between 30s lows and 60s/70s highs. Dry air both warms and cools quickly. Some of the reinforcing cold fronts may be able to squeeze out a bare minimum of sprinkles through lift ahead of the fronts or upslope northwest winds behind the fronts (snow showers in higher elevations west of I-81 stil a possibility at midweek), but total amounts of these are likely to be less than a tenth of an inch, certainly no more than a quarter-inch, through Friday. With any breezes blowing at all, the dry air and increasingly dry surface fuels like leaves and grass will be susceptible to the spread of fires much of this week — Sunday afternoon is of particular concern, and much of Northern Virginia, which has gotten much less rain recently than Southwest Virginia, is under a red flag warning or fire weather watch for Sunday. For now, overall drought is not especially bad anywhere in the state — “abnormally dry” conditions exist for northern and southeastern parts of the state — but that could grow if we get many more weeks as dry as this one. As we move past this week’s cool, dry interlude, high pressure may gradually become repositioned just east of our area, allowing for a stronger flow of warm and moist air from the Gulf of Mexico. Nothing specific yet, but we’ll keep an eye on that for possible wetter weather after this coming week.