ideal black ice conditions? (Seattle, Pasco: power lines, home, safety)

[neal93]

What are ideal black ice conditions? Temperature, etc.? Am nervous about the possible commute between Pasco & Hermiston...

[j_k_k]

Originally Posted by neal93

What are ideal black ice conditions? Temperature, etc.? Am nervous about the possible commute between Pasco & Hermiston...

Look at the humidity and general moisture content in the air. Normally it's low here year round, which is why we don't get as much black ice. When there is a lot of water vapor in the air, there is more to freeze onto frozen surfaces. This is why in Seattle and Portland, when the temp hits 31, the roads can become hockey rinks.

[neal93]

Originally Posted by j_k_k

Look at the humidity and general moisture content in the air. Normally it's low here year round, which is why we don't get as much black ice. When there is a lot of water vapor in the air, there is more to freeze onto frozen surfaces. This is why in Seattle and Portland, when the temp hits 31, the roads can become hockey rinks.

31 degrees is a good cut-off point to watch out for?

[j_k_k]

Originally Posted by neal93

31 degrees is a good cut-off point to watch out for?

Well, water freezes at 32 F, roughly, depending on altitude. Therefore, it is unlikely to expect ice when the temperature is above freezing. But the fact of the matter is that in winter, in this region, nearly all mornings are below freezing. There could be ice any day, depending on moisture. And it is highly likely that we will have a cold snap at some point with sustained daytime highs in the teens or even lower. Lowest temperature I remember in my twelve years here was -15 F, with several feet of snow. Daytime highs during that cold snap were 5-10 F.

However, you should also consider that bridge decks and shadowed areas are generally colder than those underlaid by land and struck by direct sunlight, respectively. Travel at daybreak or dusk generally means longer shadows. So it might be 34 out, but it's quite possible there could be ice in a shadowed area or bridge deck.

[M3 Mitch]

Black ice is likely when the road surface is colder than the air, and there is plenty of moisture in the air. FWIW, the BMW outside temp has an alarm at 3C, I think that's 38F, below this temperature you start getting icing conditions.

I personally try to stay off the interstates and stay on backroads when it's slick around here. Too many distracted nittnoids on the super-slab for my taste.

FWIW, its usually dry enough around here that you seldom see any ice on the roads.

If you want to do something, first there are add-on outside thermometers you can put on your car, some of the simplest ones go on the outside rear-view mirror, and you can spring for a set of dedicated snow tires if you want. Consumer Reports November issue has some tire ratings. I personally prefer non-studded snow tires, Michelin has some good ones.

Don't wig out though, ice on the road is not the biggest threat to your safety when you are behind the wheel around here.

Down home in the South, *that's* where you get ice. Have a few days in the 20's temperature wise, get the trees and the road surface chilled down to the mid 20's - then it suddenly warms up and starts a drizzling rain. I have seen ice an inch thick on the road there. BTW there is no practical way to do anything about this besides just stay home - there will be yahoos, particularly in 4WD pickups, roaming around but they will find the ditch soon enough...

Besides, you need to stay home and fire up the wood stove when the pine trees shed limbs and take out the power lines...

If you do hit ice, if you are more or less alone on the road, so long as you don't make any rough control inputs, you can coast down to a more appropriate speed provided you have the room. If you are on the Interstate when the nut jobs all around start to spin, you will have to be very very good (and at least luckier than average) to avoid bending some tin.

[Alohikea]

Be careful over Jump Off Joe and the bridge. It can get ugly over Joe fast.