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It felt like fall at times early this week with refreshingly cool, dry air for June. Don’t get used to it.
Searing heat for mid-June is on its way, with widespread 90s likely in the lower elevations of Southwest and Southside Virginia by Friday, and then after pulling back a few degrees over the Father’s Day weekend, a resurgence of heat that could last much of next week. Normal high temperatures for mid-June, based on the 30 years prior to 2020, generally run in the lower to mid 80s at the lower elevations of our region and 70s elsewhere.
Conveniently, this week’s hot spike will be timed well as a reminder to enter the Cardinal Weather heat prediction contest, which has a deadline of midnight Friday for you to pick the hottest projected temperatures for two sites from a list of 16 in Cardinal News’ main coverage area between June 15 and August 31. So Friday’s temperatures won’t count in the contest — and will likely be beaten out later in the season anyway, probably as early as next week. (Keep reading to the bottom of this article for my hottest temperature picks and for more information on how you can enter.)
A map accompanying a social media statement on the coming heat wave issued earlier this week by the National Weather Service shows the greatest probability of excessive temperatures next week occurring in the Ohio Valley and Great Lakes region.
Seeing this geographic orientation of a potential heat wave raises my attention more than any other for possible extreme impact on our own region.
Our region’s worst heat waves, historically, have tended to occur as the hottest air relative to normal spreads to our west and northwest — ironically, the same general direction we look for colder air masses to arrive from during the winter.
What tends to happen is that high pressure, at the surface and aloft, builds northward toward the Great Lakes and Canada, while also spreading eastward to encompass Virginia and much of the East.
This evolution tends to be drier than when heat builds at us only from the south, when the hotter air is often infused with considerable Gulf of Mexico and/or western Atlantic moisture. That brings on more clouds and scattered to numerous showers and thunderstorms, especially in the afternoons, commonly keeping actual air temperatures from being as hot as they would be in a drier atmosphere, though it may feel stickier.
Also, when the hot air bull’s-eye is more south of us, our region tends to be near the boundary with cooler air to the north, resulting in a greater chance of heat-breaking thunderstorms, and sometimes, intrusions of that cooler air southward to quell the heat at least for a couple days. Hot air building west and northwest of us already means the cooler boundary is a significant distance north of our region.
Time and time again, in our most searing heat waves, the strongest center of “heat dome” high pressure parks just to our southwest, generally over the Tennessee Valley, with secondary centers of high pressure to our west and northwest.
This results in another important feature for the hottest weather in Virginia: downslope wind flow. As wind, spun clockwise by the high to our southwest, blows lightly in a westerly or even northwesterly trajectory from the Ohio Valley, it compresses, dries out and heats crossing the Appalachians. This can add a few more degrees to daily high temperatures, especially in locations just east of mountain ridges, such as the Roanoke Valley and areas east of the Blue Ridge in Central and Southside Virginia.
It’s a bit early yet to discern exactly the structure of next week’s atmospheric features leading to what is expected to be a significant hot spell and quite possibly a full-on heat wave. By late next week, the heat dome may actually spread back to the west as far as the Rocky Mountains, its backside flow triggering the stormy “monsoon season” in the Desert Southwest, and possibly at some point later in June backing westward far enough to get us back in cooler northwest flow. But that’s unsettled and fuzzy on the horizon.
It does appear very likely our region will be underneath high pressure for multiple days next week and possibly beyond with little in the way of organized showers or storms — a few pop-up cells can never be ruled out when it’s that hot, especially over the mountains — and daily sunshine that could push temperatures well into the 90s in our region’s lower elevations and possibly even topping 90 in somewhat higher elevations.
Whether this could possibly lead to what would be Danville’s and/or Lynchburg’s first 100-degree temperatures in a dozen years, and only Roanoke’s second such triple-digit incursion since the 2012 heat wave that included the infamous derecho, is still unclear.
Also unclear is what this means for the rest of summer, expected widely to be the hottest or nearly the hottest on record for North America and the Northern Hemisphere with a 12-month streak of record hottest months globally in a warming climate, extremely warm sea surface temperatures on many of the world’s oceans, and the lingering effects of extra warmth pumped into the atmosphere from the dwindling El Niño (warm equatorial Pacific sea surface temperatures).
Climatologist Judah Cohen compares the current movement of heat-dome high-pressure systems around the Northern Hemisphere to a game of musical chairs that will ultimately come to a stop later this summer, essentially stalling the heat domes over large regions for extended periods of time.
Whether we are inside, at the fringe, or entirely outside these final heat-dome positions will determine whether this is a sizzling, stormy, or somewhat soft summer.
Last chance to enter heat prediction contest
This Friday, June 14, at midnight is the deadline for entries in the Cardinal Weather heat prediction contest, the winner of which receives a $25 gift card and enduring fame in Cardinal News as a master meteorological prognosticator.
For you to enter, pick any TWO of the locations in the italic paragraph below, guess what you think the hottest temperature will be for those two places between June 15 and Aug. 31, and email it to me at weather@cardinalnews.org along with your locality of residence. More than one person can enter on the same email, so get the whole family involved!
The winner will be whoever misses by the fewest degrees on the two combined guesses. If there is a tie, whoever sent it in first gets the gift card (though all get the recognition here in a September edition of the Cardinal Weather column).
You can click here on the article two weeks ago introducing the contest for a historic range of the summer’s hottest temperatures on the 16 sites listed, to give you a general idea of the range of how you might guess (though going a little outside the historic bounds is certainly allowed and could be correct, for all we know now).
To have skin in the game, I like to pick my own hottest predicted temperatures this summer for all the locations to be chosen from in this year’s contest. I considered a wide range of climate and weather pattern factors, including a tendency for summers in transition between El Niño and La Niña (probable, not certain) to have relatively short runs of extreme heat in our region, as we discussed in this space a couple months ago.
My main impetus, however, for going hot on this year’s predicted highest temperatures across the region is the rather unscientific concept that, after a dozen years of really having no sustained extreme high temperatures, we’re just due. I’m not saying next week’s heat wave will be it — these picks are, after all, for the hottest temperature between June 15 and Aug. 31, not necessarily next week.
Kevin’s highest temperature picks: Abingdon, 99; Appomattox, 101; Blacksburg, 98; Burke’s Garden, 93; Clintwood, 94; Covington, 99; Danville, 103; Galax, 95; John H. Kerr Dam, 105; Lexington, 100; Lynchburg, 101; Martinsville, 101; Roanoke, 102; South Boston, 103; Wise, 93; Wytheville, 96.
In 15 years of running a reader snowfall prediction contest for The Roanoke Times and for Cardinal News and a heat prediction contest in some of those years, I find my predictions usually are about the bottom of the top third — that is, about a third of the entries do better than mine, and about two-thirds do worse. So let’s see if you can beat me for whatever two sites you pick.
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.
