A Maryland State Highway Administration plow truck was prepared with salt, but the D.C. area was only getting rain. (Robert Thomson/The Washington Post)

Maryland highway workers were ready at 3 a.m. for what could have been freezing rain in the Washington area — only it wasn’t. If this becomes a common experience for the crews during the winter of 2013-14, it will just be typical.

Our area’s temperature often hovers right on the line between rain and disaster for drivers. The highway departments in both Virginia and Maryland can wind up dealing with a variety of different conditions — rain, freezing rain, sleet and snow — across the entire state, and sometimes within just a few miles as terrain and temperatures shift.

Melinda B. Peters, the Maryland state highway administrator, said Tuesday that the agency may begin planning for a storm a week ahead of time, depending on forecasts. Crews can be deployed in advance to treat roads with brine to prevent ice and snow from bonding with the surfaces and making them more difficult to plow and to drive.

The problem is the stuff washes off if the precipitation starts as rain — and it seems like most of the D.C. region’s winter storms start as rain. Despite advances in forecasting, it’s difficult to know exactly what to be prepared for.

That’s an experience shared by drivers about to launch their Thanksgiving holiday trips. We expect this storm to be mostly rain close to home, perhaps with a tail end of snow on Wednesday. But many drivers are making ambitious long-range trips to visit friends and family. And those trips may take them into the mountains of Virginia, Maryland, Pennsylvania, western New York and Massachusetts, where they’re more likely to encounter snow and ice.

Bob Marbourg of WTOP radio, who is the dean of D.C. area traffic reporters, said he applies a rule from aviation to driving in bad weather: “If you don’t know when not to go, then you should be careful about making the decision to go.” In other words, if weather conditions leave you really unsure when to leave and what route to take, let one of your options be staying safe and warm at home.

The snow crews also would love it if you kept that option alive. Marbourg and I attended the Maryland State Highway Administration’s annual winter preview on Tuesday morning. Peters and other highway officials reviewed the road-clearing strategies and showed off their trucks and plows, but a fundamental message was that as conditions worsen, you’re best off leaving the roads to them for a while.

I asked Peters for her best advice on traveling Tuesday and Wednesday through Maryland. “Patience,” she said. Drivers have spread out their getaway travels, but Tuesday and Wednesday evenings are likely to be very difficult, and would be even without the heavy rain that the Capital Weather Gang predicts for Tuesday night and the possible finisher of snow showers on Wednesday afternoon and evening. Delaying till Thanksgiving morning is looking better and better for those making relatively short trips.