Weather systems headed east off the Pacific Ocean will help clear the air this week, but they won't bring the precipitation needed to build mountain snowpack, weather forecasters say.
"These don't look like any big system like we'd like to see right now," meteorologist Brian Nieuwenhuis said Saturday. "In terms of rainfall, they're not that significant — 10th of an inch in Medford."
Rain is forecast for most of the day Tuesday and for late Wednesday afternoon and evening. Then a drying trend is expected to return until the next system arrives next weekend, Nieuwenhuis said.
Snow levels on Tuesday will drop to 5,000 or 6,000 feet, meaning Mount Ashland may get a couple of inches of snow, he said. Levels will drop further, to about 4,000 feet, on Wednesday, but probably not low enough to affect driving conditions on mountain passes.
What the system will do, however, is help clear the air in Medford, which has been listed as unhealthy for sensitive groups for the past four days. Saturday's air quality index with the Oregon Department of Environmental Quality listed Medford's air as moderate.
"It has a double impact," Nieuwenhuis said. "Rain will help pull things out of the air, and the fact the system is coming through sort of scours out the valley."
A high pressure system and inversion has gripped the Rogue Valley since the last big storm hit on Dec. 6, leaving Medford with the driest calendar year on record in 2013.
Nieuwenhuis said that same high pressure system is driving cold air from the north down into the Midwest and South, where temperatures were expected to reach 15 and 30 degrees below Saturday.