Weather forecasters expected warmer air and precipitation to move through the Treasure Valley overnight and knock out some of the deep freeze, which it did. But the rain never changed to snow before it hit the valley floor, where it instantly turned to ice.
The ice attached to everything. Thats why the Idaho Transportation Department closed a 70-mile stretch of Interstate 84 between Boise and Glenns Ferry Thursday morning during rush hour. It's also why several school districts, including Nampa and Caldwell, don't have classes today.
The National Weather Service measured 0.2 inches of ice at the Boise Airport at 7 a.m. That ice is expected to stick around at least for several hours, so residents should expect slippery and dangerous driving conditions through the morning and possibly beyond.
It is much warmer Thursday morning than it has been in recent days. The overnight low in Boise was 17 degrees, and by 7:30 a.m. it was 23. The low temperature Wednesday morning was 1 degree, and that was the first day since last Friday that the low stayed above 0, according to the National Weather Service.
Its been 13 straight days since temperatures in Boise have topped 32 degrees, and that might not happen today. The estimated high for the Boise area Thursday is 31 degrees. If it does get that warm, the ice covering roads should turn to slush this afternoon, officials say.
The rain did bring at least one benefit: It helped scrub some of the pollution out of the air across the valley. But did not totally knock out the inversion. The inversion is expected to end over the weekend when another storm system moves through, bringing snow along with it.
The rain is expected to stop by midmorning Thursday, so expect a foggy and cloudy afternoon. Friday is expected to be cloudy and damp, with a high temperature in Boise of about 34 degrees. Rain is expected on Saturday, with a high of 39, with snow to follow on Sunday, with a high of 35.
The more seasonal temperatures (highs in the 30s, lows in the 20s) are a welcome relief for many Treasure Valley residents, who have endured three weeks of frigid temperatures. All but two days in January have been below normal and not just a little. Average daily temperatures have been 10 to 24 degrees below normal.