Another Friday, another iffy forecast

It would be easy for meteorologists if arctic air was in place across the Carolinas, and a big low pressure system was moving out of the Gulf of Mexico toward the region.

That would mean a big winter storm.

But as was the case last Friday, a storm system expected to affect the region this Friday won't have all the ingredients needed to produce a sure-fire, lock-cinch wintry forecast.

Last Friday, the powerful low pressure system was lacking cold air. It got cold enough, briefly, for a few bursts of snow. But for the most part, that was a serious rain-maker.

This week, arctic air will be in place. The questions surround the storm's path and the amount of precipitation.

The cold air arrived early Tuesday and won't really leave this week, although it will become slightly modified across the Southeast. By Thursday, high temperatures might be in the range of 45 to 48 degrees in Charlotte.

The low pressure system hasn't formed yet. It will develop off a larger storm in the Pacific, then will follow a path into the western United States, across the Midwest, and then eventually into the Southeast or Mid-Atlantic.

The computer models have been evolving over the last 24 hours, and that probably will continue to happen for another 24 to 48 hours.  Monday at this time, the Friday event looked like nothing for the Carolinas. It appeared as if low pressure would track along the Ohio Valley and bring some major snowfall to places like Ohio, Pennsylvania, New York, and New England.

But some of the computer models have begun forecasting the low will dive a bit, into the Southeast.

Precipitation amounts still look light, but with arctic air in place when something starts falling from the clouds Friday morning, it wouldn't take much to cause problems.

Temperatures could be in the upper 20s and low 30s when something -- snow, sleet or rain -- begins falling. If it's rain, the precipitation will freeze on surfaces (especially bridges, overpasses, tree limbs and wires). That's the working definition of freezing rain.

Right now, there is nothing pointing toward a major freezing rain event for the Charlotte area. But there is enough input from computer models to show a few hours of light freezing rain, and that would be enough to bring some big business to auto body shops.

Farther to the north -- let's say, along the I-40 corridor -- the precipitation would be more likely to start as snow before changing over to sleet or freezing rain. Some of the computer models show Hickory and Statesville remaining below freezing for much, if not all, of Friday.

There's a long way to go yet.  If the models shift the storm back to the north, we could be looking at a bit of sleet or freezing drizzle Friday, but nothing else.

As WCNC-TV chief meteorologist Brad Panovich notes, "This one bears watching."