When we think of how hurricanes affect our Southwest and Southside Virginia region, stickiness and sogginess come to mind.
Helene’s devastating impact last fall is fresh on our minds, and then there’s historic catastrophes like Camille and the 1940 hurricane that we have looked back on in this space, and many others.
But there is another side to passing hurricanes.
Hurricane Erin is running by off the East Coast on this Wednesday, close enough to stir some big surf and overwash flooding into the Outer Banks of North Carolina, with higher seas also expected along Virginia’s oceanfront.
It is not close enough to do anything too noticeable for our weather — but there are some indirect effects.
The counterclockwise rotation around Erin will turn a relatively cool northeast breeze into our region the next couple of days, dropping high temperatures that briefly recovered to the lower 90s in some locations over the weekend back into the 70s and lower 80s the rest of this week into the weekend. The northeast breezes may carry enough moisture off the ocean to lift against the mountains for a few showers, or at least some foggy drizzle at times.
But Erin is also a part of a much broader atmospheric pattern shift that is poised to bring down a much cooler, crisper air mass from Canada, with low dew points and unseasonably cool night and day temperatures next week to close out August.
There is a bit of a chicken-and-egg thing going on here. The broader change in the atmospheric pattern, with strong high pressure in the West and a deep dip in the jet stream over the East, pushing a strong cold front through by early next week, is a big part of the reason why Erin has been gently shoved away and fortuitously missed making a landfall in the continental U.S.
But Erin, with its rotation helping spin down cooler air, and its transport of tropical air and evaporative energy from hot oceans northward into cooler latitudes, is also a contributor to the developing fall appetizer on the way next week.
Hurricanes help autumn happen
In a broad sense, hurricanes are part of the process that helps turn summer to autumn each year.
Atlantic hurricane season peaks from mid-August to mid-October, just as the sun angle begins to edge lower over the Northern Hemisphere and the jet stream flow begins its descent southward from the northern latitudes, blobs of cool air near the North Pole starting to lop off summer’s warmth at the middle latitudes.
Hurricanes feed on the evaporative heat of warm ocean waters and transport that heat northward, spending much of the built-up energy in wind and rain, but dispersing a sizable chunk of tropical heat northward into cooler latitudes. And as that occurs, cooler air masses are also dislodged southward in balance, often behind the hurricanes where counterclockwise wind flow gives that cooler air to the north an extra tug southward.
It is very common for our region to get cool, genuinely autumnlike air masses — by later in the season, sometimes even Arctic air pushes capable of spraying snowflakes across the mountains — behind departing tropical systems, especially those that pass some distance east of us.
That is happening next week, it strongly appears, at least enough that we can call it a fall preview.
August poised to chill out again
August started with an unusually cool period.
The first eight days of August failed to reach 80 degrees at Roanoke, the longest sub-80 streak ever in August going back to the start of records in 1912. The first week of August was the coolest on record at Danville, based on average temperature, and the second coolest on record at Roanoke and Lynchburg.
Even with some temperatures that reached 90 over the weekend, the first 18 days of August are still among the top dozen or so coolest such periods on record at those locations, which each have more than a century of weather data.
August started cooler than normal across our region, and it has only bounced back to near to slightly above normal temperature at mid-month. Because the early cool averages were driven more by lower daytime highs in cloudy dampness, not especially chilly overnight lows on clear, calm nights, August has not ranked as highly for coolness in the mountainous western areas of our region. Those areas have some historic periods with more prolonged 40s and lower 50s lows than what we saw in early August.
It is possible, however, that this late August cool spell may have more in the way of cool overnight lows, with much drier air filtering in, possibly allowing some 40s to near 50 lows across parts of our region if we get a clear, calm night or two.
In any event, next week looks likely to bring several days of below-normal temperatures, which will be a fitting bookend to the early month cloudy coolness.
Those two cool periods should be enough to mathematically offset the sorta-hot mid-month, putting this August in play to be among the five or 10 coolest Augusts on record at several locations in our region.
Does it seem like déjà vu?
If talk of cool August low temperatures seems familiar, just look back to a year ago this week.
On Aug. 21, 2024, many locations in our region dropped into the 40s and lower 50s, the coolest August morning lows several spots had seen in the past 20 years. Burke’s Garden dropped to 38 a year ago Thursday morning.
Temperatures bounced back as high as the mid 90s a week later in our region, and of course September brought on the tropical downpours associated with Hurricane Helene, so that all serves as a cautionary tale about putting too much stock in a late August temperature dropoff being an “early fall.”
There are some ducks on the big pond between here and Africa that could yet develop into major tropical systems, though the developing weather pattern may deflect those away, also.
This cooler setup does look like it has staying power for several days. So while autumn may not be ready to reign just yet, what was once a particularly sticky summer looks like it’s on the ropes.
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:
