It has been 22 years since this area was glazed by one of the biggest ice storms to strike the United States.

The Rochester/Genesee Valley ice storm commenced on March 3, 1991.

It resulted from low pressure tracking into from the south into eastern New York.  This allowed warm air to flow into the upper levels of the atmosphere over Rochester, while northeast winds at the surface drew subfreezing air into the area.

Snowflakes which fell from the clouds melted into raindrops upon reaching the warmer layer above the surface, only to freeze upon reaching the ground where temperatures were below 32 degrees.

The storm was extraordinary.

It produced a 50 miles wide band of freezing rain aligned along the Genesee River Valley.  While Syracuse to the east experienced rain, Buffalo to the west had mainly sleet and snow.  But Rochester endured 17 hours of continuous freezing rain resulting in an ice accretion of more than one inch.

A winter storm warning is in effect for Monroe and Wayne Counties for Friday until Saturday morning.

Snow is expected to start small early Friday, becoming heavier throughout the afternoon and into the night.

By Saturday morning, there could be anywhere between eight to 12 inches of snow north of the Thruway and four to eight inches south of the Thruway.

Travel is expected to be especially difficult on Friday night.

The City of Rochester says crews and plowing contractors will be working around the clock.

In case of power outages, RG&E and NYSEG say they have emergency planners ready but still advise having battery powered flashlights on hand.