Wintry weather possible through Monday night

Little total liquid has registered in Mecklenburg county rain gauges from the current storm system. That's because much of it has been of the frozen variety since surface temperatures have been at or below freezing all Sunday night. Radar indicates that the county has seen anywhere from a third to two-thirds of an inch of precipitation this Monday morning.

While surface temperatures are near freezing the air aloft is significantly warmer, with temperatures near 40º at 5000 feet overhead this morning. Thus any frozen precipitation falling through that warm air melts and then refreezes either just before or just after it hits the cold ground. That's how sleet and freezing rain form, making roads, driveways, and sidewalks slippery.

This type of storm system resembles what's known as a "Miller B" winter storm. This graphic (from WeatherWorks) illustrates:

In this setup a low pressure center approaches across the Ohio valley, then gives way to a new storm which strengthens off the East Coast. The white shading is snow, orange is mixed wintry precipitation, and green represents plain old rain.

The rest of today - Monday - will be cloudy and cool, with surface temperatures slowly climbing into the mid- and upper 30s accompanied by liquid rain. Some of the ice will melt, but as the coastal low takes over colder air along with "wraparound" moisture will bring more wintry precipitation after sunset. Overnight, skies will clear and temperatures will drop into the low 20s, so whatever moisture is left on ground surfaces will refreeze.

Tuesday then looks clear and cold, with a cold northwest breeze and a high temperature only in the mid-30s. The cold air will stick around the rest of the work week, dropping morning lows into the teens. Keep  that winter clothing handy!