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We are with summer now about where we were with winter going into March.
Summer hasn’t been as absentee up to this point in our region as winter was, but, aside from a few hot and/or sticky days here and there, it has been decidedly mild compared to many recent summers and lots of other places we continue to see in the news. In the Southwest and Southside Viginia area covered by Cardinal News, seemingly running against the grain of a summer that just produced a runaway warmest July on record globally, this summer has had the coolest average temperature through mid-August of any in the past 6 to 20 years at many stations across our region.
But just as we were wondering if the cold and snow we were seeing hit other parts of the country west of us would finally make it here in March, we are now in a similar place of wondering if we will yet have a period of extreme heat like many in the central and western U.S. have experienced. (The cold did finally come, but the snow was puny back in March.)
By the weekend and into next week, there are strong indications that a heat ridge will intensify over the central U.S. and expand eastward over us, perhaps with more intensity and possibly duration than we have seen at any point this summer.
After a couple more days of relatively cool mornings and warm afternoons that aren’t terribly humid, heat and humidity will build over the weekend and into next week. Most days will reach the 90s in the sub-2,000 foot elevations of our region starting Saturday or Sunday and continuing until at least the middle of next week.
While some forecast models have, at times, spit out 100-plus temperatures for our region next week, it is likely this is a bit overstated and, as we get closer in time, a run of 90s with some mid to upper 90s will be more the reality. The tendency this summer has been that greater humidity values and/or some upper-level disturbances sliding in from the northwest somewhat limit hot spells with more clouds and scattered thunderstorms than are modeled several days out.
There has been one official 100-degree report in Cardinal News territory this summer — reported on July 29 at the John H. Kerr Dam in Mecklenburg County, which means it occurred on July 28, as weather is reported on an 8 a.m to 8 a.m. EDT cycle at co-op stations.
The last, best chance for some more triple-digit reports, there and perhaps at other locations, may well be the early to middle part of next week. We have had some extremely hot periods with triple-digit temperatures in September before, but these usually occur following summers with prolonged heat, which in our particular region, this one hasn’t been.
August 1983 heat wave
The potential of a late August heat wave near the end of what had been a fairly mild summer raises the prospect of what happened 40 years ago.
The three-day run of heat from Aug. 20 to 22, 1983, remains the hottest three-day average high temperature on record in over a century of records at Roanoke (104.3) and Blacksburg (98.3, tied with July 20-22, 1926) and is among the top few three-day stretches at many locations across our region. Nothing rivaling its intensity and coverage would occur across Southwest and Southside Virginia for 29 years, until the late June-early July heat wave surrounding the 2012 derecho.
Danville, Roanoke and Farmville each peaked at 105 degrees during that heat wave, a mark that has only been reached once since at Danville (1989), twice at Farmville (106 on two days in 2012) and never since at Roanoke (104 in 2012 was closest). Roanoke’s high temperatures were 104, 105 and 104 on consecutive days Aug. 20-22 in 1983. Danville was close to that, with 104, 103, 105.
Appomattox reached as high as 103 in three days of 100-plus temperatures 40 years ago, Lynchburg 102 in two days of 100-plus temperatures and Martinsville 101 in two days over the century mark.
Blacksburg topped out at 99, the hottest it had been there since a 100-degree day 31 years early, and it hasn’t been above 97 in four decades since. Abingdon hit 99 — it would reach 100 there five years later in 1988, and then never as hot as either of those 1980s spikes until the 2012 heat wave.
In Lynchburg, the 1983 heat caused a propane tank explosion that damaged 12 apartment units. Many people were taken to area hospitals with heat exhaustion and some heat strokes, and of course, high school football coaches and band directors had to make decisions about August practices that didn’t threaten students’ health.
Somewhat similar to what is happening over the next few days, the 1983 heat spike occurred as a central U.S. high-pressure “heat dome” built both northward and eastward, the core of it gradually sliding eastward until it was just southwest of our region. This is often an optimal spot for extreme high temperatures in Southwest and Southside temperatures as westerly wind vectors over the mountains cause air to compress, heat and dry blowing downslope, augmenting the heat in most areas east of the spine of the Appalachians.
The 1983 heat wave broke suddenly with a backdoor cold front sliding in from the north and northeast, triggering severe thunderstorms with wind damage and an abnormally high number of reports of people being hit by lightning in the region. Three days after many locations had punched 100, temperatures fell short of 80 at most stations across our region.
There are some signs that a rather deep push of cool air, more from the northwest than the northeast, very keeping with this summer’s trends, will follow next week’s heat spike and bring it to an abrupt ending. The timing and intensity of that is in question this far out, but it does appear at this point that whatever heat builds in the waning days of August and meteorological summer won’t run continuously into September.
Last week, back on Monday, Aug. 7, there was a day when Southwest and Southside Virginia were placed in the middle of a moderate risk of severe thunderstorms by the Storm Prediction Center … and then nothing much happened.
Drier air filtered into our region, while the stronger storm dynamics went north with several storm reports over northern Virginia and a cold front pressed into more heat and moisture southward over the Carolinas. Essentially, the worst storms split around our region.
The moderate risk may well have verified over the larger region it covered, but was considered a major bust in the parts of Virginia covered by Cardinal News.
We’ve covered severe weather risk levels and overall thunderstorm development in prior Cardinal Weather columns, linked in this sentence. Getting the four ingredients — moisture, lift, instability and shear — in the right amounts and vectors is always a difficult call, as the prior day’s storm development and movement move the atmospheric furniture around for the next day.
Monday of this week sort of turned out similar, as waves of showers in the daytime hours sapped much of the instability that would have built up for afternoon thunderstorms.
However, late in the evening, the dynamics were sufficient for rotating storms right across the state line from Bristol prompting tornado warnings. A brief EF-1 tornado was confirmed in northwest North Carolina.
Eye on tropics
Last week we covered seven things to keep in mind about hurricane season for inland Virginia.
There is no obvious tropical threat on our horizon, just a couple of areas of disturbed weather that could become tropical systems in a few days far out in the Atlantic. And, possibly, some chance a system could develop in the western Gulf of Mexico underneath the heat dome next week.
We are at that time of year when, in just a few days, the whole scene could change with respect to tropical systems. And that in turn can affect our expectations with temperatures, thunderstorms and rainfall.
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.