Visbilities are between 0 & 5 miles across the forecast area, a result of dense fog and also poor air quality. A dense fog advisory is in place for areas west of the Cascades through 10 o’clock this morning. Also in place is an air stagnation advisory. An approaching front today though, will help to mix up surface air and improve the polluted air that is trapped near the surface. For this reason, the air stagnation advisory will expire into this afternoon.
Rain showers will move in at the Coast around 4 o’clock this afternoon. As the front moves inland, isolated activity is anticipated for West Side Valleys beginning around 5 & 6 o’clock this evening. Because the ground and surface air is so cold, isolated pockets of freezing rain are likely.
Freezing rain is precipitation that falls as rain, and freezes just before hitting the ground, or freezes on contact. So when you factor in the cold temperatures that have been in place, the ingredients are definitely there for frozen precipitation. High temperatures though will determine whether showers will bring rain or freezing rain. Highs are expected to be in the mid 30′s, above the freezing mark ..which may help us out in most locations.
Regardless of weather rain or freezing rain falls, it will refreeze in the overnight hours because temperatures will be near or below freezing, adding to existing snow and ice on the roads. This will make for slick roads for the morning commute — drive carefully as you are heading out tomorrow. More scattered showers are anticipated for the Cascades, but Siskiyou County should stay dry and very scarce showers are expected around midnight for the Basin. This may also be in the form of freezing rain.
By Friday, a new air mass moves in and showers will come to an end. This new air mass will help improve our temperatures. Highs will be in the 40′s for the first time in over a week for West Side Valleys. Keep in mind 40′s are average temperatures for this time of year — although they are cool, they will likely feel much warmer considering the recent cold spell.
Dry conditions will stick around for the weekend, but with the storm track just to the North some cloud cover will remain in place for the Valley, mountains & Coast.
Meteorologist Alyssa Caroprese