We have reached the part of the seasonal weather timeline where you may need a coat in the morning but be fine in shorts and short sleeves by the afternoon.
The last couple of afternoons and the remainder of this week comprise, finally, that stretch of sunny warmth many of you not inclined to winter (or just tired of this particularly icy winter) have longed for since before Thanksgiving. Many locations in Cardinal News’ Southwest and Southside Virginia coverage area have reached or exceeded 70 degrees since Tuesday and will again Thursday and Friday.
We’ll pay for it with weekend rain and thunderstorms, as a powerhouse low-pressure system tracks across the Upper Midwest and drags a cold front across the central and eastern U.S.
There will be potential for heavy rain and possibly some severe thunderstorms as that front pushes into the warm, moist air ahead of it. And we’ll have some gusty winds and somewhat colder temperatures behind the front early next week, before a quick warmup ahead of what will likely be another strong low and cold front a few days later.
It’s a rather familiar rhythm as late winter gives way to early spring.
Overall, it sounds a lot like what happened last week, a storm system that produced a couple of oddities beyond the rain, thunder, hail and wind that also occurred.
Car-spotting sprinkles
Last week’s strong low-pressure system pulled in a layer of blowing dust from west Texas that made it all the way to Virginia. This was visible by late on the afternoon of Wednesday, March 5, as a tan shroud obscuring the mountains and weakening sunlight somewhat.
Some of that dust became suspended in the atmosphere as a weak low-pressure system brought some showers of rain — and some icy graupel bits — by Friday night and early Saturday. The rain was not very heavy, and there was enough cold, dry air aloft that evaporational cooling allowed for some of it to reach the surface as graupel or sleet, even though surface temperatures were mostly in the 40s and 50s.
But the sprinkly rain and the sparse icy bits carried down some of that dirt suspended aloft, and, the rain not being heavy enough to wash it off, that spotted up a lot of vehicles over a wide area, not just in Virginia but many surrounding states.
We often talk about our regional weather in terms of air masses from other distant places, such as Arctic air masses or a Pacific cold front. But sometimes we get pollutant particles blowing in from other regions in sufficient quantities to be noticeable.
At different periods in recent years, our region has seen wildfire smoke from Canada and even dust from the Sahara Desert in Africa.
This time around, it was dirt from west Texas, and some of that is still on my car’s exterior.
Those bubbly dark clouds
Before the dust blew in late Wednesday, the first wave of rain and storms blew out by midday.
Just after that rain, clusters of dark boiling clouds hung eerily in clusters overhead.
These were mammatus clouds.
The origin of the word is the same as “mammal” and “mammary,” so I’ll leave it to your imagination why hanging bulbous clouds have gained that moniker.
But the clouds themselves weren’t imaginary. They form when the turbulent air motion in storms leads to strong downdrafts that carry moisture downward, cooling and condensing it into ice crystals, hanging in rounded pouch-like structures.
Mammatus clouds are not all that unusual, but a display like those that appeared over parts of our region last Wednesday is not common.
The sight of them may at least bring to mind funnels and tornadoes, but while they can be indicative of storms with strong updrafts and downdrafts that might spawn tornadoes, they are not directly related to tornadic activity, and often seem to occur after a line of storms has passed.
Depending on sun angles and the time of day, mammatus clouds can appear ominously dark as these did, or be cottony white, or painted orange and pink by a sinking late-day sun.
As our spring and summer get more rumbly, see if you can spot some mammatus clouds before or after thunderstorms roll through.
And how about that bloody moon?
This hasn’t happened yet, but is set for the early morning hours of Friday with a total lunar eclipse.
This is not to be confused with a solar eclipse, when the moon moves in front of the sun and blocks its light. Virginia experienced an 80-90% solar eclipse last April 8 (and my family and I had the privilege of seeing full totality in Arkansas, recalled in the link here).
The moon will begin moving into Earth’s shadow around midnight Thursday, and between 2:30 and 3:30 a.m., it will be fully in the shadow. The moon often appears to have a red glow as it goes deeper into the shadow.
For to-the-second details for your specific location, Time and Date is a good resource. Also, check out the NASA web site for a more in-depth explainer of lunar eclipses.
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:
