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Fans of summer are starting to feel like fans of winter did a few months ago.
Yet another low-pressure system wobbling loose from the jet stream and going nowhere fast is dominating our weather this week, spinning a continuous stream of moisture from the Atlantic Ocean and the Gulf of Mexico inland across Virginia and against our higher terrain while also suppressing daytime temperatures below seasonal norms.
This latest system that is becoming a “cutoff low” is causing a soggy week in Southwest and Southside Virginia, more so in some spots than others. Locations along the Blue Ridge south of Roanoke collected 3 to 7 inches of rain on Monday night and early Tuesday alone.
We are already in our third day of intermittent rain as you read this on Wednesday evening, with perhaps two, three, four – maybe more – days of this to go. In time, the low may unwind enough that we see more showery weather rather than organized bands of rain, but until something pushes it away, we are stuck with it.
Rain is not entirely unwelcome, as most of Virginia north of the Roanoke/Staunton River entered this rain in light to moderate drought, and many areas even to the south were starting to get a little dry despite ample May 29 rain with a different stubborn low-pressure system.
This rain may wash a lot of the yellow and beige off last week’s U.S. Drought Monitor map. But it may end up being too much in some spots, especially along the Blue Ridge south of Roanoke, where flash flood watches were issued as early as Monday. Click here for the latest watches and warnings from National Weather Service offices in Blacksburg; Wakefield; Sterling; Morristown, Tenn.; Charleston, W.Va.; and Raleigh, N.C., covering various areas in and near the Cardinal News coverage area.
This is called a cutoff low because the system becomes removed, or cut off, from the main flow of the jet stream. Centered to the west and southwest of our region, its counterclockwise rotation produces weather that isn’t fit for wearing cutoffs, with cloudy, cool days (though a bit humid this time) relative to the season and frequent rain.
There are some technical differences between entirely cutoff lows and partially cutoff closed lows and closed lows that are stalled or trapped by high pressure blocks, and we have seen variations of all of these repeatedly over the past month, with differing placements leading to a late May soaker in our region’s southern and western areas, streamers of smoke from Canadian wildfires and some cool, dry air also from Canada that brought on downright chilly mornings in much of our area earlier this month.
All of these are the result of persistent troughing in the eastern U.S., as upper-level flow dips far to the south with high pressure to the west and north much of May and June.
The jet stream has deposited this present low-pressure system over the Southeast U.S. and then will pull north away from it, leaving it to sit and spin, trapped south of high pressure over southeast Canada, continuing unseasonably warm and dry conditions that have fed wildfires up that way.
And the trough has kept summer from springing in our region.
Climate stations at Roanoke, Lynchburg and Danville still haven’t hit 90 degrees despite being many weeks past the dates for their average first 90-degree days and are starting to get into truly historic territory for the latest date on which a first 90-degree reading has been recorded.
In over 100 years of records, the first 90-degree high of the season has occurred as late as July only five times at Lynchburg, three times at Roanoke and just once at Danville. There is very good reason now to expect this one will be the next to wait until July to hit 90 at these locations, with the effects of this rainy low-pressure system hanging on at least to early next week, followed by reinforcement of the eastern U.S. trough and no indication of any kind of evenly modest hot high pressure moving in by the end of June.
For fans of summer sun and temperatures warm enough to splash around in the pool or lake, this past weekend provided a glimmer of hope with some sunny 80s, but it was quickly washed out this week by the latest cutoff low.
Just as an Arctic surge at Christmas did not in any way signal the weather for the remainder of our almost non-existent winter, it is quite possible that what we have been experiencing in May and June will not be a template for the rest of summer.
May and June in 2020 were also dominated by multiple cutoff lows and rainy periods with below-normal temperatures – but then July broke out with a lengthy stretch of hot weather, setting Roanoke’s record for longest streak of 90-degree days at 29.
But, last week, we discussed how summers during El Niño tend to not be among the hottest for our region and how high pressure blocking at northern latitudes sometimes traps cooler, wetter troughs to the south. There has also been some study surrounding how global climate change, particularly the more rapid warming of the Arctic, may be increasing the frequency of blocking patterns and trapped systems.
So, at this point we can’t say with much certainty whether summer as a whole in our region will trend toward how it started or flip to something hotter and drier, but we do know it’s off to a slow start with heat and that developing wetness this week may ease regional drought conditions that could amplify heat waves later.
The lean right now is toward a summer that doesn’t sizzle much in our backyard.
We did have enough heat and humidity present ahead of a cold front on Friday for a rather robust round of scattered thunderstorms, with the worst effects in parts of Southside.
In Danville, a window was blown out at Sovah Health-Danville, and a tree was blown onto a house. There were numerous reports of trees and power lines blown down in Henry and Pittsylvania counties plus the cities of Martinsville and Danville. A few thousand utility customers lost power for a while.
Thunderstorms at the start of Monday’s rain, this time lifting north-northeastward, produced some scattered wind damage reports in similar areas, from Patrick County east to Pittsylvania County and then north into the central part of the state.
To file away in the back of our minds for now, Tropical Storm Bret has formed and is steaming across the Caribbean the next several days, possibly reaching low-end hurricane status.
Beyond that we don’t have a solid bead on what it will do afterward, whether it will survive possible interaction with Hispaniola, or whether it will be a future threat to the United States or affect our region.
So let’s just be aware of it now and keep an eye on what it might do for next week and beyond.
Journalist Kevin Myatt has been writing about weather for 19 years. His weekly column is sponsored by Oakey’s, a family-run, locally-owned funeral home with locations throughout the Roanoke Valley.