See also: The curious case of the May-October split of extreme heat in 1941
Wind flow, unlike trade and immigration, isn’t beholden to national borders.
This week’s skies over the southeastern quarter of the U.S. feature plumes of obscuring particles from both central and western Canada and northern Africa.
Overall, this is a fairly typical week of early June weather in Virginia — some warm 80s highs the next couple of days with increasing chances of showers and storms into the late week and weekend. But there is more happening than meets what we can see and feel at the surface.
Virginia skies early this week have intermittently been painted with a milky film as a layer of smoke originating from scores of wildfires in Canada has been transported southeastward by predominant northwest winds aloft.
The results here have mostly been aesthetic, as most of the smoke has been too high for the breathing issues experienced in parts of the Midwest, though the southwest corner of Virginia did see some lower smoke over the weekend. The plume was centered more south of Virginia on Monday and Tuesday before an expected move northward on Wednesday, when there may again be some chance of lower smoke for compromised air quality.
While the smoky skies are expected to start clearing up after a hazy Wednesday with changes in the atmospheric flow, a plume of dust from the Sahara Desert of northern Africa is working its way westward across the Atlantic Ocean.
This dust is expected to overtake Florida and much of the Gulf Coast the latter part of this week into the weekend, and some of it could make it as far north as Virginia.
Saharan dust carried westward is almost an annual occurrence, often more than once during the warmer months, though it varies in intensity and duration from year to year. One thing thick Saharan dust does is reduce the potential for hurricanes to form in the open Atlantic and track westward toward the U.S.
More commonly, much like smoke aloft, it results in brilliant red sunrises and sunsets and a milky haze during the day. Brought lower in the atmosphere, Saharan dust can create a gritty brown haze. That has happened here in Virginia at times over the years.
If the dust or smoke is transported to or along the surface, breathing issues and other poor air quality effects develop.
An approaching cold front from the west and a low developing along the coast of the Carolinas that could possibly take on some tropical characteristics may inhibit the arrival of Saharan dust this far north.
Yes, we just said Saharan dust inhibits hurricanes, but (1) the system along the coast of Carolinas will be north of most of the plume and (2) it is very unlikely to develop into anything beyond a tropical or subtropical depression or maybe a weak tropical storm, and quite likely will just be a weak area of low pressure along the coast.
The shift between a northwest flow bringing down Canadian smoke and an easterly flow transporting African dust around high pressure over the Atlantic to the north is emblematic of the back-and-forth bounce we’ve seen much of this spring, which we discussed briefly in last week’s Cardinal Weather column.
We have often seen a pattern with the jet stream dipping well to our west and warm, dry high pressure over us, then a quick cold frontal passage with some showers and storms, followed by a deep southward dip from Canada bringing cooler and drier (and recently smokier) air to us. This alternation has kept us from having any runaway heat so far this year and has also limited chances for prolonged rain or severe storms, excluding a day or two here and there.
When the smoke and dust of distant forecsasting clears, there is no guarantee this continues for the entirety of summer, but it should keep up out of major heat waves for the time being.
Which reminds me: Have you entered the Cardinal Weather summer heat prediction contest? Details in last week’s weather column linked here.
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:
