In the middle of September a year ago, it appeared a low-pressure system off the coast of the Carolinas would become Tropical Storm Helene and head northwest inland toward Virginia. But that system never developed enough to be named, and “Helene” was saved for another storm on a later day.
Little did we know then that, just two weeks later, “Helene” would become deeply imprinted on our meteorological memory for perpetuity.
Cardinal News this week is featuring series of articles examining what is still ongoing recovery from the inland impacts of Hurricane Helene a year ago. We started Tuesday with a look at the agricultural recovery from Helene, and on this Wednesday continued with recovery in the town of Damascus, with additional articles planned Thursday and Friday.
This week’s weather: A slow-moving trough of low pressure is bringing about periods of showers and thunderstorms, peaking on Thursday and diminishing, as it appears now, on Friday . With the potential for the low to slow down further or even “cut off” from the jet stream and become stalled, plus two potential tropical systems forming in the Atlantic, it is possible that rain could linger into or redevelop during the weekend. Considering our widespread dryness going into this week, much of this rain is needed, with widespread 1-2 inches expected. But as last year’s impacts from Helene showed, a previously dry fall season can turn too soggy too fast with tropical involvement and/or slow-moving upper-level lows. For now, this looks like a showery period intermittently over the next several days, with perhaps some widespread general rain on Thursday, and uncertainties about the frequency and intensity of rain over the weekend into early next week.
Not the center of the tempest, but close enough
Southwest and Southside Virginia were a ring or two outside the bull’s-eye of Hurricane Helene’s inland impacts, which were truly catastrophic in the mountains of western North Carolina, altering landscapes and leveling forests with an onslaught of rain and wind that was beyond the darkest imaginations of many who experienced it.
But even at that, it was a generational disaster for places like Damascus and Grayson County, perhaps at the edge of that inner circle, where road networks were broken apart by rushing water, power knocked out for several days, and far too many homes and buildings damaged by flooding or wind.
Helene had significant impact across the entire region covered by Cardinal News. Water pouring out of the mountains of North Carolina and southern Virginia swelled the New River on its geography-defying northward run, lifting it to levels only exceeded by a similar hurricane-charged flooding episode in August 1940. Winds gusted to 50 mph, sometimes even more, over most of our region, and there were a spate of tornado warnings with intensely spinning storm cells in the tropical system’s outlying bands, and five confirmed tornadoes, four in Pittsylvania County and one in Bedford County.
Counting a stalling frontal system, the indirectly related “predecessor rain event,” Helene’s direct impacts from its inland track after its Florida Big Bend landfall, and its remnants drifting back over with a slow-moving upper-level low, the inclement weather effects continued from Sept. 23 to Oct. 2, with the most intense impacts on Sept. 26 and 27 as Helene’s old circulation center traversed northwestward just southwest of our commonwealth. That brought widespread 2-6 inches of rain across much of our region, with locally over a foot in the hardest hit areas, plus the aforementioned widespread wind gusts and sporadic tornadoes.
The upper-level low bearing Helene’s remnants brought a spate of more tornado warnings in Southside on Sept. 29 and localized flash flooding on Sept. 30-Oct. 2 to parts of Central and Southside Virginia that had largely escaped it previously.
Damage in Virginia alone has been estimated at over $4 billion, rivaling or even somewhat exceeding the monetary damage in Virginia from Hurricane Isabel in September 2003 that heavily affected most of the state except, ironically, the part most affected by Helene. In all, from its landfall on the Apalachee Bay to its broad impacts in the Appalachians, Helene is blamed for nearly $80 billion in damage and more than 200 deaths, two of those in Virginia. The National Weather Service has put together an interactive “story map” on Helene’s impacts on the Southern Appalachians, linked here.
Let’s examine a few meteorological lessons we can take moving forward from Helene.
Upper-level lows capturing hurricanes are bad news
The Helene catastrophe wasn’t just about the remnants of a hurricane moving inland.
A cut-off upper-level low — that is, one entirely removed from the jet stream flow, and therefore nearly stalled — hanging back over the Mississippi River was a key player in the atmospheric setup that made Helene so horrific.
The strong wind flow around the upper-level low kept the strong winds going longer around Helene’s circulation center, those winds eventually spreading out to a larger area as they only gradually weakened. Higher elevations in particular took some enormous blasts of wind, especially on southeast-facing slopes, with swaths of forests flattened in several patches of western North Carolina, even into the border counties and higher elevations of the southwest corner of Virginia.
But the upper-level low also turned Helene at an odd angle, lifting northwestward where it would normally track northeastward. This kept its counterclockwise flow blowing perpendicular into the southwest-to-northeast angled Appalachians for much longer, enhancing wind damage. The upslope lift of dense tropical moisture also lasted longer, intensifying a flooding situation already nearing epic proporations from days of prior rain and the initial leading tropical rain bands of Helene.
Helene was similar in this way to what became known as “Superstorm Sandy” in October 2012 or Hurricane Hazel back in September 1954, powerful hurricanes that gained an extended and enhanced inland lifetime as they became absorbed into upper-level low-pressure systems.
This combination should always give us pause when we see the potential for an upper-level low and a tropical system to connect. (Thankfully, this week’s slow-moving trough will likely be east of our region before it might link up with a tropical system in the Atlantic, but we’ll keep an eye on it.)
Winds far away from core can be deadly
Two fatalities in Virginia were directly attributed to Helene. Neither of those deaths occurred in the storm’s flooding, and neither occurred in the localities closest to the storm’s core impacts in western North Carolina.
One was in Tazewell County, one in Craig County, both attributed to wind blowing objects — a tree in one case, a farm outbuilding in another — onto people.
Neither wind fatality occurred amid the absolutely strongest gusts that Helene brought to Virginia, which likely reached near hurricane force in the highest elevations near the North Carolina border. These fatalities, and a lot of tree and power line damage, occurred in the 30 to 50 mph gusts that were common across most of our region on Friday, Sept. 27.
The counterclockwise circulation of tropical systems approaching us from the south throws a curve ball — strong winds with easterly trajectories.
We get gusts as strong as we saw in Helene half a dozen times a winter behind Arctic cold fronts. There are often scattered power outages and some trees blown down here and there with each of these but not usually on the scale that Helene wrought.
Two factors help intensify tropical system gust impacts compared to winter cold front gusts. One is that because almost all of those cold fronts bring west or northwest winds, and most strong squall line wind gusts are also from those directions, trees become naturally braced against far more common westerly wind trajectories, and they get pruned over the years of many limbs that would blow off with westerly wind gusts. Strong easterly wind trajectories push differently against trees and limbs than what is more typical and tend to cause more trees and limbs to fall at similar wind speeds.
Secondly, tropical systems often occur in late summer to mid fall when trees still have significant foliage on them, each leaf acting as a small sail to capture wind and pull on the limbs a little more, enhancing damage compared to the bare limbs of winter when even strong winds frequently whistle right through them.
Anytime winds gust over 30 mph for several hours, there is potential for wind damage and power outages, and we should not minimize our caution with such winds just because a tropical system is no longer officially a hurricane.
Northeast quadrant tornadoes
Overall, we might have caught a break with the tornado potential from Helene.
On Friday, Sept. 27, the National Weather Service at Blacksburg issued 21 tornado warnings, following a few more issued the night before, and preceding several more issued two days later, the vast majority of these near and east of the Blue Ridge.
Most of these warnings were issued when Doppler radar detected tight low-level rotation in squall bands or discrete cells hundreds of miles from the storm rotation center in the northeast quadrant of the storm. This is where east winds at the surface and southeast winds just above the surface in a slowly weakening tropical system’s rotation undercut south to west winds aloft, allowing updrafts to spiral upward and potentially induce low-level spin that can spawn tornadoes.
With Helene’s odd northwest turn, the northeast quadrant parked over our region for about 18 hours on Thursday, Sept. 26, and Friday, Sept. 27.
In all of that, only five tornadoes were confirmed, all EF-0 and EF-1 strength, the weakest two levels on the 0 to 5 Enhanced Fujita Scale. One of those at Dry Fork in Pittsylvania damaged about 30 buildings, including 20 homes, destroying one mobile home. Three other tornadoes in Pittsylvania County and one in Bedford County caused less damage.
Quite likely, there were other tornado touchdowns or short paths that eluded reporting and post-storm surveys, occurring in rural areas away from homes, or patches of fallen trees twisted down amid other non-tornado wind damage. But the National Weather Service can’t always wait for a ground confirmation to issue a warning when tight low-level rotation is detected — precious minutes between warnings and deadly storm effects can be lost.
Hurricane Ivan’s remnants in 2004 provide the standard for high-end tornado potential from tropical systems, with nearly 40 reported statewide, including a long-track EF-2 that damaged scores of homes and caused millions of dollars of damage through Henry County. If a few more of Helene’s spin-ups had reached the surface in populated areas, this could have been a far worse segment of the disaster for our region and state.
Inland tropical systems are something we have to deal with regularly
For our neighbors in North Carolina, it was only nine months after Helene when the next historic episode of tropical downpours brought death and destruction to a different part of the state.
Tropical Storm Chantal dumped over a foot of rain on parts of North Carolina west and northwest of Raleigh-Durham in early July. At least six people were killed in central North Carolina flash flooding.
A corner of that flooding episode crossed into southern Halifax County in our region, where 6 to 10 inches of rain in a short time raised creeks and rivers over roadways.
While unique in many ways, Helene was hardly the first, and certainly won’t be the last, tropical system to have destructive impacts on our region.
In this space, we have recounted the 1940 flooding disaster that remains the high-water mark on the New River even after Helene, and the narrowly focused extreme cataclysm of Hurricane Camille’s remnants over Nelson County and adjacent areas in August 1969. Later this fall, in early November, we will reach the 40th anniversary of the regional flooding disaster influenced by the remnants of Hurricane Juan, the deadliest and most destructive weather event in the history of the Roanoke Valley.
This history of recurring major tropical system effects, enhanced by our region’s steep terrain, makes this perhaps the top weather preparedness need for our region, the most likely next widespread weather disaster.
Combined with hotter oceans fueling deeper moisture transport northward and potentially stronger hurricanes, plus northern latitude warmth that may sometimes more readily force upper-level lows southward to intercept these systems, there may be another Helene out there in the not-too-distant future, if not for our region then for someone not far away.
Parts of our region are still recovering and rebuilding from Helene, but we should keep its lessons in mind for the next inevitable tangle with tropical trouble.
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: