...WINTER WEATHER ADVISORY NOW IN EFFECT UNTIL 9 PM EST THIS EVENING... * WHAT...Freezing rain. The ice will result in very slippery conditions on sidewalks, roads and bridges. A light glaze of ice is expected. * WHERE...Portions of northern Virginia along and near the Blue Ridge and north-central Maryland. * WHEN...Until 9 PM EST this evening. PRECAUTIONARY/PREPAREDNESS ACTIONS... A Winter Weather Advisory means that periods of freezing rain will cause travel difficulties. Be prepared for slippery roads. Slow down and use caution while driving. The latest road conditions for the state you are calling from can be obtained by calling 5 1 1. The Winter Weather Advisory covers Frederick, Carroll, northwest Montgomery and northwest Howard Counties in Maryland, and Loudon County, Virginia. By the National Weather Service, Sterling, Va.