So far in 2025, Virginia has not experienced much severe weather, even as states to our west are having repeated outbreaks, including on this Wednesday.
Wait a minute. Virginia has had two ice storms that broke trees and power lines, flooding that inundated homes in our Southwest counties, and multiple windy cold fronts that have blown down power lines and spread fires and even pulled in dust from thousands of miles — what do you mean Virginia hasn’t had much severe weather so far in 2025?
It all comes down to what the word “severe” really means.
By the dictionary, “severe” simply means “intense.”
Applied to weather, lots of things can be severe in a generic sense — a severe ice storm, a severe heat wave, severe drought, severe flooding.
But when meteorologists use the word “severe,” they are almost always referring to a narrowly defined class of thunderstorm impacts, the kinds of effects that if observed or detected by radar, can lead to a severe thunderstorm warning being issued.
Upcoming weather
Virginia continues to miss most of the rain it needs to ease developing dryness while others several hundred miles west will get way too much rain. The lower and middle Mississippi River Valley is expecting 6-12 inches of rain over the next four days, starting with rounds of severe thunderstorms and tornadoes on this Wednesday. This will translate to periods of mostly light showers for Virginia through the weekend as storm systems are stubborn to move eastward, with Sunday perhaps turning into a fairly rainy day, though amounts are expected to be mostly under an inch. Colder weather looks to make an encore by the second week of April — expect some frosty mornings and maybe even some mountain snow showers.
After a surge of warmth that may push 90 for some on Friday and Saturday, colder weather looks to make an encore by the second week of April – expect some frosty mornings and maybe even some mountain snow showers.
All about wind and hail
Specifically, severe thunderstorm effects include winds gusting 58 mph or stronger, hail 1 inch in diameter or greater, and tornadoes.
Nothing else makes a thunderstorm “severe.”
Torrential rain can’t make a storm “severe” no matter how bad the flooding might become. (There are other kinds of warnings that cover flooding.)
Frequent or vivid lightning can’t make a storm “severe.” (Don’t wait for a severe warning to get off the lake or inside a car or a structure if lightning is approaching.)
Wind gusts that are only 57 mph or hail 0.9 inch in diameter also don’t make a storm severe, though practically speaking, those can do similar damage to winds a mile per hour faster or hail a tenth of an inch larger.
Much of the winds we get with strong cold fronts or inland tropical effects don’t gust above 58 mph, but blow down plenty of limbs and cause scattered to numerous power outages, owing partly to their duration. A whole lot of smaller hail, piling up in snow-like drifts, can cause its own intense impacts, but that occurs very infrequently in our region and technically wouldn’t be considered a severe thunderstorm unless at least some of the hail is an inch or more in diameter.
So, when a severe thunderstorm warning is issued, it means that National Weather Service forecasters have determined by radar or surface reports that a thunderstorm is likely to contain winds gusting 58 mph or greater and/or hail 1 inch or larger in diameter.
If radar indicates tight circulation that might be a tornado or the precursor to one, or there are ground reports from people of a tornado being sighted or damage consistent with a tornado, a tornado warning is issued, possibly overlapping or superseding an existing severe thunderstorm warning. (For the most part we’re going to let tornadoes be a separate subject for another day and not delve into them too deeply with this column today. Check out this Cardinal Weather column from last spring, linked here, about why Virginia sometimes has tornadoes, but isn’t really a “tornado alley.”)
It’s important to know what exactly is meant, and not meant, by “severe” when you hear or see that term in weather reports.
How do storms get to be severe?
Four factors determine how intense a thunderstorm will become.
· Moisture. If there is very little moisture, there won’t be a thunderstorm. Storms become more likely the more humid it is. There are variations in how wetter and drier layers can be stacked in the atmosphere that don’t make this a direct relationship in such a way that the more moisture there is where you can feel it, the stronger or more severe a storm will be, definitely. But, very generally speaking, a day of 60s or 70s dew points that soaks your shirt in sweat will have a better chance of storming, and storming harder, than a more comfortable day with lower dew points.
· Instability. Warmer air near the surface rises into colder air aloft. The steeper the contrast, the more rapidly moist updrafts will lift in the atmosphere, increasing the chances for lightning, heavy rain, gusty downdrafts and hail as updrafts reach regions of ice crystal formation then collapse rapidly. Sometimes there is a layer of warmer air aloft that “caps” the rising updrafts and prevents storms from developing. But that can also be like a lid on a boiling pot that will blow off suddenly and violently with powerful storms building rapidly if the updrafts are powerful enough to erode the cap and break through.
· Lift. Atmospheric boundaries like frontal systems can give updrafts an extra boost that can overcome some factors they might not be able to overcome through instability alone. Mountainous terrain plays a role with lift in our region.
· Shear. Winds change in direction and speed with height. Very generally speaking, the more change there is in direction and speed moving upward, the more potential there is for storms to rotate, separating updrafts from downdrafts and making them last longer and continue to re-intensify, sometimes for hours. Rotating storms have a greater propensity to produce very large hail (the golfball- and baseball-sized stuff caused by hail being carried upward by repeated updrafts until it is too heavy and falls to the ground), recurring strong downdrafts of wind, and of course, tornadoes.
Severe thunderstorms don’t always have all four of these factors in spades.
Summer “pop-up” thunderstorms with very little shear, called “pulse storms,” build upward and collapse quickly, but that downfall can produce a mighty outflow of damaging winds gusting well above the necessary 58 mph and sometimes splatter some hail near an inch in diameter. There may only be a 10-minute window when severe effects can occur, but it can be a memorable tempest for anyone underneath the downdraft.
Squall lines and storm clusters occur with moderate levels of shear not sufficient for individual rotating storms, but as we well know from the June 29, 2012, derecho and other damaging wind squall lines since, they are fully capable of producing severe effects over considerable distances.
The fully rotating, discrete storms called “supercells” are king when it comes to producing severe thunderstorm effects, including tornadoes. While full-fledged supercells lasting more than a couple hours are somewhat infrequent in our region, transient supercell-like rotating structures forming within more clustered storms do occur more often.
That gets us to the more localized, short-term nature of severe thunderstorm impacts.
Severe for thee but not for me
One of the most difficult aspects of severe thunderstorms, both in forecasting and assessing impacts, is that most of the time, their impacts are confined to narrow corridors rather than widespread swaths.
While infrequently there can be something like the aforementioned 2012 derecho with a wall of outflow wind that affects a widespread area, the more common occurrence is sporadic or localized damaging wind, big hail in a small section of a storm, or a tornado path usually less than a quarter-mile wide (often a hundred yards or less) and seldom longer than a couple or three miles in length.
The temptation for those of us not affected by much more than some rain or modest gusts after days of hearing about a potential severe storms outbreak is to label it a “bust.” But, quite often, somebody within an hour’s drive, sometimes even a couple blocks away, may have had a tree blown onto their house or have a car or shingles dented by big hail — or something even worse.
There are indeed times when forecasted severe potential fails to fully come to fruition because a factor or two is a little off, and no one in the region gets bad storms. We’ve seen a couple episodes like that so far this spring.
But let’s all remember not to use what happened in our backyard as the sole judge of how bad a stormy day or night might have been for everyone around us.
Journalist Kevin Myatt has been writing about weather for 20 years. His weekly column, appearing on Wednesdays, is sponsored by Oakey’s, a family-run, locally-owned funeral home with locations throughout the Roanoke Valley. Sign up for his weekly newsletter: