Roanoke Times
Copyright (c) 1995, Landmark Communications, Inc.
DATE: SATURDAY, December 18, 1993 TAG: 9312180199
SECTION: VIRGINIA PAGE: B-3 EDITION: METRO
SOURCE: ED SHAMY
DATELINE: LENGTH: Medium
A thick fog had settled overnight into tree branches and down to the straw-yellow grass. A film of ice had to be scraped from car windshields and windows; commuters crept to work with their headlights blazing.
Several localities reported accidents because of the fog and ice, the most serious in Blacksburg. Rebecca J. Elliott, 67, of Blacksburg lost control of her vehicle, and the car left Glade Road and hit a tree, according to police. Elliott, who was wearing her seatbelt, was listed in stable condition in the intensive care unit at Montgomery Regional Hospital on Friday night.
The fog persisted much of the morning in the Roanoke and New River valleys and along the James and the Maury rivers.
What happened?
It was all coming together while you were snoozing. Here's how the National Weather Service described the conditions that contributed to the eerie, cold-weather fog:
Cold air slinked in from the north and settled low in the mountain valleys.
Warm air rolled in from the southwest, hit our mountains like a ski ramp and - as warm air is apt to do - rose.
The wind died to near zero.
The warm air trapped the cold air close to the ground, pressing it against the surface of the rivers. But the river water - usually in the 30s this time of year - was warmer than the air atop it, and the surface water evaporated and condensed.
With no wind to disperse the moisture, the fog mushroomed and filled the bubbles of cold air trapped in the valleys.
The moisture that drifted onto your car froze there.
And the high-altitude warm air spent its day nibbling into the cold below, trying to work its way down toward the ground to warm our damp bones. That took the better part of the day, which is why the haze thinned as the day wore on but never did disappear.
by CNB