Thanks largely to last week’s statewide rain/snow storm, Virginia is now considered entirely free of drought according to the U.S. Drought Monitor.
Something missing from March so far in the United States is tornadoes. There has only one confirmed tornado — in Georgia on March 4. January and February were active in the Deep South and Gulf Coast region, but March has started slowly. Last March produced the extreme March 2-3 tornado outbreak in the Ohio Valley, but conditions curtailed much of the rest of the year, with 2012 being an unusually low year for tornadoes nationally. The reasons for 2012 being a low year for tornadoes were largely related to the extreme warmth early in the spring season shutting down a lot of the contrasting air masses tornadoes form along, and the presence of extreme heat and dry weather in later seasons squelching tornado development. 2013 is a little different. There continue to be vigorous low-pressure systems, but so far in March, they have not quite drawn instability, shear and deep moisture together in a way for a tornado outbreak. My suspicion is that the tornado season will pick up a little later this spring, when warmer air and Gulf moisture tangle a little more regularly with colder air masses sinking in from the north.
Speaking of tornadoes, Weather Journal alum Kathryn Prociv has a post today on tornadoes in the mountains on USTornadoes.com. The Pulaski and Glade Spring tornadoes of 2011 are among those featured.
There are many St. Patrick’s Day-related activities scheduled for Saturday. The good news is that it will likely be the warmest day of the next week, and maybe the warmest day so far this month. Westerly wind flow will start pushing in some milder air the next couple of days, enhanced by downslope compression and warming as it moves over the Appalachians, pushing us into the 50s to low 60s on Friday and more widespread 60s on Saturday. 70 is not out of the realm of possibility for Roanoke and points south and east, if there happens to be more sun than clouds. The bad news, though, is that a bit more moisture coming in with that mild air and a low pressure system moving through the Ohio Valley may be able to squeeze out a few showers Saturday. It doesn’t look like a washout-type rain, but some light showers will be possible, so some umbrellas at outdoor events may be a good idea. Late Saturday, a new cold front pushes through, and it appears a wedge of cooler air may develop banked against our mountains Sunday and Monday. With moisture overrunning this cooler air mass, we may see more frequent and abundant showers than we do Saturday. At this time, it appears the wedged air mass will be colder than normal with highs in the 40s across much of Southwest Virginia, but not cold enough for frozen precipitation. I’m a bit leery of this, though, especially in 3,000+ elevations and north of I-64, where it’s possible it could get just cold enough late Sunday night and early Monday for some sleet or wet snow to reach the surface. Were it just a month earlier, there would be a more widespread threat of mixed precipitation, but the higher sun angle and longer days are far enough along now to have more effect on our near-surface temperatures. Even with that being so, it appears a cold front will renew colder than normal temperatures by mid to late next week, and long-term models continue to suggest normal to below-normal temperatures to be the rule through near the month’s end.