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Lots of folks will be headed to the beach this Memorial Day weekend. So will a pesky coastal low.
That will likely spell windy, squally weather at many beaches from Delmarva to Georgia, including Virginia and the Carolinas. And it may spread a fair amount of Memorial Day weekend rain into Southwest and Southside Virginia as well.
The low that is expected to track northward near or just off the coast will be a surface reflection of an upper-level low that will wobble around to our west for a few days, partially removed from the main flow of the jet stream.
There is at least some chance the coastal low may develop some characteristics of a tropical system, feeding off the energy of evaporation from warm sea surface temperatures, particularly those of the Gulf Stream about 100 miles off the Southeast U.S. coast.
This is not the typical atmospheric setup for a more robust, purely tropical system like a strong tropical storm or hurricane, which usually forms with high pressure aloft rather than an upper-level low. But a broader circulating hybrid subtropical low that draws part of its energy from the warm ocean, rather than entirely from atmospheric dynamics, is at least possible.
Either way, it will likely lead to some heavy rain squalls and gusty winds for some or many locations along the coast. Be mindful of this if you have weekend plans anywhere on the Southeast or Mid-Atlantic U.S. coastline, with the Carolinas and eastern Virginia perhaps most likely to be affected.
It may not be a constant wind-blown washout from Friday to Monday at any specific shoreline but there will probably be some periods of time within that stretch that aren’t good beach weather in many places. Pay attention to local forecasts for the particular region to which you are headed.
Those going to the lakes in Virginia or just hanging at the house for (or working through) what amounts to the cultural kickoff weekend of summer will likely not be spared the effects of the coastal low. It appears likely that by Saturday and Sunday, extending into Memorial Day itself, the low will spread substantial moisture inland on easterly to southeasterly winds with its counterclockwise spin.
Besides tapping the Gulf Stream’s warm ocean waters, wind flow from the east to southeast also glides uphill all the way from the shore westward across the state, hitting a sharp rise with the Blue Ridge and subsequent Appalachian ridges. This will cause moisture to be lifted, cooled and condensed, enhancing rainfall.
The track, intensity and full nature of this coastal low is not set in stone yet. It is not known yet if this storm will be mere nuisance or truly naughty.
One thing the Memorial Day weekend atmospheric setup will do is continue this month’s deviation from what has previously been a runaway warm year, with a few days of below-normal temperatures, perhaps struggling to make 70 for high temperatures when mid 70s to near 80 are more typical. See a couple sections below for more information on that.
Canada smoke
You may have noticed some red sunrises or sunsets this week, or, especially on Monday, even some blue-gray hazy mountains and smoky smell in the air.
This was the result of smoke from wildfires in the Canadian province of Alberta.
An intense early-season “heat dome” high-pressure system has been parked over western Canada much of this month, extending into the northwest U.S., with extremely high temperatures for so early in the season. Rampant wildfires have broken out in the heat and dryness in Alberta.
Clockwise rotation around the western North America hot high pressure system has brought a northwest-to-southeast flow across much of the eastern U.S., and, in addition to somewhat cooler air that we often see in mid to late May, that has also transported the smoke from Alberta our direction.
Smoke from western North America wildfires is actually not an uncommon visitor to our region. Neither is dust from the Sahara desert in certain other atmospheric setups.
The smoky haze is all the more remarkable for what has not been happening as much in our skies in recent years.
Visibility-choking and lung-burning surface ozone haze that often turned summer skies gray or white in our region during the late 20th century has been on a sharp decline for several years with changes in fuel composition standards for automobiles and shifts in energy generation processes, primarily the closing or conversion of coal-fired power plants within and west of our region.
Early extreme heat and rampant wildfires in a region so far north generally follow concerns about what is expected in an overall warming global climate.
Alberta was getting a reprieve early this week with an increase of showers and reduction in temperatures. But hot weather and dryness may return in the near future with continued wildfires.
Slightly cool May
Prior to this month, 2023 was on a blazing pace in Southwest and Southside Virginia, with temperatures running anywhere from 1 to 10 degrees above normal each month, especially January and February that were 6 to 10 degrees above normal. Even belated cold spells in March and April couldn’t keep these months from registering warmer than normal overall in our region.
May has followed a different course with near- to slightly below normal temperatures common. Several days of somewhat cooler than normal weather are expected to finish the month underneath the stubborn upper-level low wobbling around the central and eastern U.S.
2023 has not yet been knocked entirely off a pace that could continue to challenge for the warmest year on record at multiple sites in our region, but the runaway warmth of prior months has been stymied quite a bit by a May speed bump.
We could be beginning to see some El Niño-like influence on the atmospheric patterns. The stripe of warm water is already there in the equatorial Pacific even though it hasn’t lasted long enough yet to be considered an official El Niño.
We often see both periods of warmer and cooler weather during the course of an El Niño, but it’s more difficult to park a high-pressure system over the southeast U.S. for long-lingering warmth relative to normal than it is during its cool-water opposite La Niña that finally ended after three years in late winter/early spring.
May temperatures that have entirely stayed below 90 and trended more to 70s for highs with some nights in the 40s for lows contrast sharply with a year ago, when an early heat spike pushed temperatures well above 90 in most of our lower-elevation areas. Roanoke hit 96 and Lynchburg 94 on May 20 last year.
This leaves us on the lip of summer with a still record to near-record warm first five months of 2023. How hot will summer get? We’ll plan to dive into that next week and offer the opportunity for you to take some guesses as well.
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.