With the cold air moving in by mid week and slick travel a possibility in west Michigan it is time for a refresher coarse in driving. It still amazes me that people drive on the freeway during a snow event as if there isn’t any snow at all.
Icing of the road is very dangerous to travel. Even a small amount of ice on the road can lead to accidents. The temperature and the amount of precipitation determine how much ice will be on the roads. You have probably heard that ice freezes on the bridges and overpasses first. Why is this? Ice will freeze first on surfaces that drop to freezing or below.
Bridges and overpasses are cooled on TWO sides while road surfaces connected to the ground are only cooled on ONE side. When temperatures drop below freezing, there is a lag time in the soil dropping to freezing. A road connected to the ground will stay above freezing even after the air temperature drops to freezing (especially if temperatures had been above freezing the previous few days). Either temperatures have to fall well below freezing or the air temperature needs to be below freezing for a significant amount of time before a road surface connected to the ground will freeze. A bridge or overpass has air on BOTH sides of it. There is no relatively warm surface to keep the bridge or overpass above freezing when the air temperature drops below freezing. The bridge or overpass losses heat very quickly to the air as the air cools. The lag time between the temperature of the bridge or overpass and the surrounding air is very short. Once the air temperature drops below freezing, the bridge drops below freezing. If precipitation is occurring or there is standing water on the bridge or overpass, it will freeze quickly once the air temperature drops below freezing. A road connected to the surface may stay above freezing even after temperatures drop into the 20’s. This is especially true for roads in the southern U.S. Temperatures may be in the 50’s or higher for several days before colder weather moves in. It may take several hours for the soil temperatures to cool below freezing once the air temperature drops below freezing because of all the heat the earth’s surface has stored during the warm period.
When forecasting it is important to have an idea of how much frozen precipitation will accumulate on the roads. If the surface is below freezing, frozen precipitation will accumulate on all roads. If the temperature is below freezing and the surface is above freezing, it is bridges and overpasses that will ice over while surface roads will remain wet. Once the surface reaches freezing, ice will accumulate on all road surfaces. If precipitation is falling as sleet or snow, road surfaces will begin to cool since the melting process absorbs latent heat. If the wintry precipitation is heavy enough, it CAN accumulate on road surfaces that are above freezing. Once the precipitation stops, the snow or sleet quickly turns to slush and melts. Freezing rain or drizzle will only freeze on surfaces at or below freezing. Any amounts of ice, whether just on the bridges or overpasses or on all roads is dangerous. Some motorists make the mistake of thinking the bridges and overpasses will be safe to drive on because the rest of the surface roads are not frozen.
Wow, there are 50-degree readings at this hour downstate.
With 7 days of December 2019 now in the record book Grand Rapids has a mean temperature of 32.0° that is a departure of -0.8°. The highest so far this month is 40° and the lowest so far is 21° As is typical in December there has been very little sunshine. So far there has been 3.6” of snow fall with the most on the ground being 3” At this time here at my house it is of course cloudy and 36° and at this time there is just left-over snow piles on the ground but there is snow on… Read more »
What – December is currently below normal for temps? Who would have thought with all the warm weather hype on here!
You forgot the fact we are also below normal for snow fall as well. Who would have thought with all the delusional snow hype on here!
https://forecast.weather.gov/product.php?site=grr&product=cli&issuedby=grr
Check this out! Great conditions!
https://www.nubsnob.com/livecam/
Who is worse this year the Lions or the Red Wings?
Red wings Tigers lions Pistons they all stink ..INDY
Next weekend will be an awesome weekend for outdoor winter sports especially in snow country! Get outside and enjoy this great winter weather people!
News flash***** the average high temp this time of year is around 36 degrees! This is nothing like last December! In fact by the end of this month we will end up with another below normal temp month! We are entrenched in a long term below normal temp pattern with no change in sight! Mark it down!!
For December 8 the average H/L at Grand Rapids is 37/26. It was actually a little colder then average on this date last year with a H/L of 30/16. I am not sure how the month will end up it is still too early to say one way or the other as a lot still can change.
Slim
+10000 berry is warmcastin again…lol…INDY
Wrong again. Nothing warm about the past month and a half, just like last year. 8 days into December, ground is bare for 7 of them, just like last year. It is hilarious that you think I like warm weather when that is the farthest thing from the truth. Give me cool and dry year around!
Almost a third of the way through December already and the ground is still bare, just like last year. Looks like a quick 2 or 3 day cool shot, then right back near 40 next weekend meaning any snow we get will once again melt away.
This is what Bill mentions on his blog:
Weds. will likely hold between 15 and 20…then mid 20s on Thursday…temps. will moderate back to 35-40 for next Saturday.
Get ready for the arctic air and snow!!!!!!!!!!!!!!!!!!!!!!