* WHAT...For the first Small Craft Advisory, northwest winds 10 to 15 kt with gusts up to 20 kt. For the second Small Craft Advisory, northwest winds around 10 kt with gusts up to 20 kt expected. * WHERE...Tidal Potomac from Key Bridge to Indian Head MD and Patapsco River including Baltimore Harbor. * WHEN...For the first Small Craft Advisory, until 8 PM EDT this evening. For the second Small Craft Advisory, from 8 AM to 6 PM EDT Thursday. * IMPACTS...Conditions will be hazardous to small craft. Inexperienced mariners, especially those operating smaller vessels, should avoid navigating in hazardous conditions.