A repeat of last week's white Christmas in North Texas is possible late Thursday night, but only slightly.Forecasters at the National Weather Service say there is a 20 percent chance of snow after midnight Thursday and a slight chance of snow and rain Friday morning.A powerful upper-level low pressure system on Wednesday was moving into Texas from the Baja Peninsula, said Jesse Moore, meteorologist for the weather service office in Fort Worth."We are going to see a gradual increase of moisture across the region tomorrow," Moore said Wednesday evening. "And, as the upper-level system moves in, it should create at least some light precipitation."He said temperatures, expected to be in the low 30s, might be just cold enough to produce snow.But, Moore noted, the low-pressure system will lose much of its power by the time it reaches North Texas, which is why there is only a slight chance of a Christmas Day repeat.West Texas, meanwhile, is in a better position to get snow late Wednesday night and especially after daybreak Thursday, according to the forecast."As the system moves eastward, there is a good chance for snow, like in the Midland-Odessa area," Moore said. "Four to 8 inches are possible in the Permian Basin. They'll have most of the moisture and the upper-level system."Moore said better chances of snow Thursday, about 30 percent, might be south of a line from Cisco to Waco and farther east to Athens."We'll be getting the fringe of it as it moves farther east," he said.Forecasters will have a better idea about the chances for snow after they see the low pressure system's actual track on Thursday, Moore said.The high temperatures Thursday and Friday are expected to be in the low 40s, but they will be about 10 degrees warmer Saturday and Sunday. There also is a slight chance for rain, about 20 percent, Friday night and Saturday, according to the weather service.