Photo by David Rauzi
Shoveling snow off sidewalks along Grangeville's Main Street in December, 2016.
As of Tuesday, January 17, 2017
We are expecting a period of freezing rain for north central Idaho as moisture moves into the area tonight into the day Wednesday. Our focus is on the start of the event when temperatures will be coldest given how impactful any amount of freezing rain can be. Eventually rain will take over as temperatures warm Wednesday into Thursday. See below for some forecast details for your area.
DETAILS AND TIMING
• Idaho & Clearwater County, ID
o Moisture looks to begin around midnight tonight for Orofino, Elk River, and Pierce. Places like Grangeville may start later due to south winds drying the lowest levels of the atmosphere.
o Given cold valley temperatures, there is high confidence in a period of freezing rain for the canyons, such as Orofino, Kamiah, and others in the Clearwater drainage. Those on the Prairie itself and Weippe bench could also see freezing rain, but it will likely be more short-lived. At first, ice may stick to power lines & trees in valleys, but it's expected that warmer (above freezing) air will move in by Wednesday late morning into the afternoon, stopping rain from accumulating on trees etc. However, ground surfaces will remain cold, and freezing rain could be a big issue on roads well into the day Wednesday.
o Rain soaking into snow on roofs will add weight to structures.
o Rain ponding on roads where snow hinders drainage is another potential issue.
o By Thursday night into Friday morning, the atmosphere dries out and temperatures cool as a cooler air mass moves in.
UPDATE, Tuesday, Jan. 17 – Rain, snow and travel difficulties.
The National Weather Service office in Missoula is forecasting a weather system will bring wet and warmer weather to central Idaho and western Montana starting this evening (Tuesday, Jan. 17) and likely peaking in intensity Wednesday, Jan. 18.
For valleys, especially in North Central Idaho, the combination of rain, freezing rain, and sleet with potential ponding of water will likely cause hazardous travel conditions.
Due to the rain expected in Idaho and Clearwater counties, snow loading may stress roof structures. Snow levels will be rising and wet heavy snow and possibly rain is expected over mountain passes.
Motorists are advised to drive carefully during the next two days, as mixed winter precipitation will make travel more difficult.
Overall for Idaho County:
- Precipitation will move into the area Wednesday morning, Jan. 18, starting off as snow, followed by a period of freezing rain in the valleys, and finally to all rain by the afternoon.
- A refreeze on roads is possible after sunset Wednesday due to cold subsurface temperatures. Hazardous driving conditions will be possible through Wednesday evening.
- Another concern will be weight loading of snow due to the rainfall, causing strain on structures
For the Camas Prairie, Grangeville and vicinity:
- Snow accumulations of two to five inches are forecast above 4,000 feet.
For the Dixie, Elk City areas, and U.S. Highway 12 area from Lowell to Lolo Pass:
- Ice accumulations are forecasted of less than a tenth of an inch.