Kevin Myatt is The Roanoke Times' weather columnist.

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There's no better way to celebrate the beginning of meteorological spring and the end of a winter without widespread snowfall than trying to outguess a complicated winter storm that has at least some chance of ending Roanoke's snow dearth.

Meteorologists don't wait for the vernal equinox to start spring they start it about three weeks earlier, declaring March 1 the start of spring, for statistical convenience.

As the calendar flips from Feb. 28 to March 1 overnight Saturday into early Sunday, a complex storm system is likely to be affecting Southwest Virginia, and much of the southern and eastern United States.

It's so complex that there may not be a really good idea of what it's going to do until it's already under way, but here's a short and dirty version of what may happen.

While there are many moving parts to the developing storm, the centerpiece is a strong upper-level low that will be moving east-southeastward across the South.

This powerful swirl of cold winds aloft will, first, pull up Gulf of Mexico moisture ahead of it Saturday. Widespread rain is expected across the area Saturday as a result. With rain also expected today with a cold frontal passage, it looks at least as if there will be some drought help this weekend.

The first question is how quickly cold air will leak in from the north during the day Saturday. As cold air spreads southward, the rain will begin to change to sleet and snow. Higher elevations and locations north and northwest of Roanoke have the best chance of seeing significant snow Saturday, mainly overnight.

But the bigger question is what will happen to the upper-level low itself.

The low is likely to contain so much wind energy that it will eventually close off, or spin so rapidly that it becomes a swirling entity largely disconnected from the steering winds aloft.

This would slow the system down dramatically, and possibly trigger a strong surface low pressure system somewhere over the Southeast.

Various scenarios exist at that point.

The surface low might be fairly weak and get bumped out to sea, while the upper-level low spins aimlessly over the Southeast. If that happens, we might get only brushed with light rain or snow Sunday while somewhere to our south, such as Alabama, Georgia or the Carolinas, gets buried by heavy wet snow.

Conceivably, Roanoke could see the first round of snow affect areas to the north while the second batch Sunday goes south. Star City snow fans would find that a particularly cruel twist at the end of a long and disappointing winter, but it would be an appropriate ending.

But another possibility is that the upper-level low and surface low will ride together up the East Coast, the upper-level low somewhat inland.

Depending on the exact track of the systems, this development would create the possibility of widespread, and possibly heavy, snow.

Long term, it appears likely that milder weather is still on the way, and this coming cold shot for a few days is only a blip. So I think it is likely that this is the very last chance at a true winter storm in 2008-09.

It certainly looks like this very odd winter may be headed for an interesting conclusion, whether that ending is a big snow or yet another big miss.