Kevin Myatt is The Roanoke Times' weather columnist.

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You might see a few wet snowflakes this morning, maybe even enough to put down a slushy coating here and there.

Any flakes you see are going against the grain.

With each passing day, it gets more and more difficult to snow. That's pretty intuitive. It's the normal advance of seasons.

In our region, we occasionally see significant snowfall in mid to late March, much more infrequently in April, and very rarely at only the highest elevations in May.

At the surface, the increasing sun angle and lengthening minutes of sunshine with each passing day mean more solar radiation is absorbed by the surface. This in turn leads to more warmth in the ground and more heating of the layer of air nearest the surface.

Conditions for snow can be perfect high in the atmosphere, but the snowflakes can hit warmer air near the surface and melt into raindrops on the way down.

Or, even if snow makes it to the surface, it can have a hard time accumulating on ground surfaces that have absorbed warmth from previous days' sunshine -- in this case, including two recent days of 80-degree weather and several days of 60s and 70s.

Snow can occur in late winter and spring if there are atmospheric mechanisms that can deliver enough cold air both aloft and at the surface to overcome the warming effects of the seasonal sunshine.

If snow falls today, it will be because high pressure in Canada was just strong enough to push enough Arctic air into the region as moisture from the Gulf of Mexico moves into it.

If snow falls heavily enough, a process called dynamic cooling may occur, as cold air high in the atmosphere is steadily pulled to the surface by falling precipitation.

Evaporational cooling may also play a role. As precipitation falls into drier air nearer the surface, each evaporating raindrop or snowflake uses a little heat, causing the air to cool.

If you see a few inches of snow in the morning as opposed to a scattered, slushy dusting, you'll know that dynamic and evaporational cooling have won the day.

Every so often, a storm system develops that easily overcomes March. An extreme case in point: 16 years ago today.

A massive Arctic air mass drove all the way to the Gulf of Mexico. Powerful storm energy came together from three separate branches of the jet stream. The result was the famous superstorm of March 12-13, 1993, that dumped 1 to 3 feet on all of Virginia's western half.

That kind of situation, or even something somewhat resembling it, is rare this time of year. More often, we experience borderline situations like this morning, when a degree or two could mean the difference between another cold rain and enough snow to turn things white for a while.

Any snow that falls this morning will be short-lived, another hallmark of the season. Slightly milder air moving in over the next several hours is expected to raise temperatures above freezing and turn any snow into rain.

There might be another opportunity for a system to try to work against the seasonal grain in the early to middle part of next week. That storm system will have to work a little harder if it is to bring snow to Southwest Virginia. The odds are against it, and growing longer by the day.

Weather Journal appears on Monday, Wednesday and Friday.