WEST MICHIGAN — The rain falling on top of the snowpack is creating areas of dense fog late this afternoon and into this evening. The reason the fog is forming: the already moist air flowing over us from the southwest is cooling to its dewpoint temperature as it encounters the snow we have on the ground. Expect visibilities of two miles or less from Grand Rapids southward. To the north of GR, visibility could drop to near zero at times. In fact, it already has in some cases. Here is a look at visibilities in miles as of 4 PM this afternoon:
It looks like the fog will lift after 11pm this evening as the rain comes to an end and the winds pick up out of the northwest. The wind will carry drier air into the area, and mix the shallow layer of fog out. Until then, however, drivers can expect wet roads and poor visibility. Be sure to allow extra distance between you and the car in front of you, and reduce your speed.
One more thing to watch for: Low temperatures will drop to or slightly below the freezing mark overnight. This combined with the residual moisture from the rain, fog, and snow melt could create some black ice on untreated surfaces tomorrow morning. Sidewalks and secondary roads will be the most problematic. Therefore, drivers may also want to allow some extra time to get to work on Monday morning.