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Three weeks ago in this space, we went over the seven things inland Virginians need to know about hurricane season.
It would seem Hurricane Idalia would fall squarely under item No. 2 in that list, “Atlantic coast is closer, but Gulf of Mexico storms can be worse for us.” There was even this specific admonition: “Anytime a hurricane is hitting somewhere between New Orleans and Tampa, our region should be on the lookout for significant impacts one to three days later – not always, but often.”
Idalia did indeed make landfall, right in the middle of that zone – in the Big Bend region of Florida, where the panhandle meets the peninsula – on Wednesday. But the “not always” clause in the above statement has been invoked for the Cardinal News coverage area.
Click here for the latest on Hurricane Idalia’s impacts in Florida and the Southeast.
In fact, the main effect for our region of what will be Tropical Storm Idalia as it sweeps along the coast of the Carolinas falls more under No. 6 on the Aug. 9 list: “Hurricanes help autumn happen.”
Idalia is helping bring in early autumn-like weather for a couple of days, with some breezy northeast winds and highs mostly in the 70s and lows in the 40s and 50s across our region on Thursday and Friday. A band or two of light rain showers might make its way into Southside counties on Thursday, but the prevailing pattern will force Idalia’s track to bend more east than north as it tracks over the Southeast, taking the heavier rain and wind well southeast of our region.
The cooler, drier air was due here anyway in the wake of a couple of early week cold fronts and high pressure pushing it down from Canada. But the backside of Idalia’s counterclockwise circulation will give it an extra tug, driving it in just a little deeper than it would have otherwise, with a little more breeziness to add to the fall preview ambience.
To be clear, this isn’t fall setting in for good.
The persistent heat dome over the central U.S. looks like it will again expand eastward next week, and our temperatures will again push toward 90 or even somewhat higher in lower elevations.
September usually has a few 90-degree days in the Roanoke Valley and areas east of the Blue Ridge, so that is not unusual. We’ll see down the road if the heat dome will be especially stubborn and expansive enough to give us unusual hot weather for September, or if its continued anchoring west of us will keep bringing in heat-disrupting cold fronts that should be getting cooler and cooler as the days shorten and sun angle lowers through the month ahead.
But this will be a brief foretaste of fall, timed to end August and begin September.
Perhaps this is a fitting ending to a meteorological summer (June 1 to August 31, when summer climatic data is calculated) that has kept finding ways to shorten and weaken the extreme heat in Southwest and Southside Virginia even as it has sizzled so many other parts of the nation.
Waterlogged Woolwine
On Sunday night, as rich moisture overran a cold front that had stalled to our south, slow-moving thunderstorms and bands of rain developed. The result was a splotchy patchwork for rainfall amounts varying from less than a tenth of an inch to 2 or 3 inches within only a few miles, influenced by both subtle atmospheric boundaries and geographic factors.
In one area of northern Patrick County, rainfall amounts were much greater than even that, as heavy downpours became nearly stalled for several hours. Radar estimates indicated as much as nearly 13 inches may have fallen in a couple of small localized areas, with a gauge near Woolwine measuring 10.62 inches. Numerous roads were closed, some damaged, and the Ararat River quickly rose above flood stage downstream into North Carolina.
Woolwine’s location, with Bull Mountain to the south and Rocky Knob to the west, plays a significant role in increasing and enhancing upslope flow on multiple sides when winds take on easterly or southeasterly trajectories.
While the early week rain was not connected to Hurricane Idalia, it did involve some moisture of tropical origin, and warm-rain processes that squeezed out heavy downpours efficiently. Warm-rain processes involve droplets of water coalescing in updrafts of extremely dense moisture, as opposed to cold-rain processes that condense first as ice crystals in below-freezing areas of clouds. Most of our precipitation, even in warmer months, is the result of condensation and ice crystal formation in colder layers of the atmosphere, but late summer to mid-autumn is often a time we see warm-rain processes at work on occasion at this latitude.
Last week we discussed how drought could become a concern in weeks ahead given likely high-pressure-dominated weather patterns. That is still true over most of the region even with the early week rain, as the vast majority of locations did not collect large amounts at all.
Again, it all goes back to how stubborn and expansive the heat dome remains in September.
Friday’s heat partly fizzles
The temperature didn’t really start rising much at Roanoke until noon last Friday (Aug. 25) – and it still made it to 94 degrees.
That is a testament to a day that would, quite likely, have easily been a 97- to 100-degree day in the Star City and other locations to the south and east if it had not been for a morning band of thunderstorms that disrupted what had been discussed (even in this space a week ago) as having great potential to be the hottest day of 2023.
It did not storm everywhere. But a bowing band of storms dived south-southeastward out of West Virginia across much of our region west of the Blue Ridge on Friday morning. The storm line weakened moving east along the Blue Ridge and eventually as it moved southward through the New River Valley toward the North Carolina line.
Regardless, debris clouds, outflow winds and remnant showers stymied morning heating just about everywhere in Southwest and Southside Virginia for several hours. Most locations in lower elevations made the lower 90s anyway, with a few mid 90s, but it wasn’t quite the 95-100 day that looked likely beforehand. It recovered into some steamy 80s in most of the areas west of the Blue Ridge that did get morning storms.
It was emblematic of a summer in which northwest flow around heat-dome high pressure parked to our west has brought down cold fronts, disturbances and storm clusters to keep extreme heat in check across our region.
Friday was apparently not the hottest day of 2023 anywhere in our region, and, with signs of hot weather ahead in early to mid-September, it also might not have been the hottest day for the remainder of the year at some or many locations in our region. We may yet have a couple of similarly hot days even as we gradually trend toward cooler weather in weeks ahead.
Journalist Kevin Myatt has been writing about weather for 20 years. His weekly column is sponsored by Oakey’s, a family-run, locally-owned funeral home with locations throughout the Roanoke Valley.
