* WHAT. South winds 10 to 15 kt with gusts up to 20 kt expected. * WHERE. Chesapeake Bay and adjoining estuaries north of Smith Point VA, and Tidal Potomac from Cobb Island MD to Smith Point VA. * WHEN. From 3 PM this afternoon to 6 AM EDT Thursday. * IMPACTS. Conditions will be hazardous to small craft.

* WHAT. South winds 10 to 20 kt with gusts to 25 kt. * WHERE. Tidal Potomac River from Indian Head MD to Smith Point VA, and Chesapeake Bay and adjoining estuaries north of Smith Point VA. * WHEN. Until 6 AM EDT Thursday. * IMPACTS. Conditions will be hazardous to small craft.

The Metropolitan Washington Council of Governments and District Department of Environment has issued a Code ORANGE Air Quality Alert Thursday for the District of Columbia. A Code Orange Air Quality Alert means that air pollution concentrations within the region may become unhealthy for sensitive groups. Sensitive groups include children, people suffering from asthma, heart disease or other lung diseases and the elderly. The effects of air pollution can be minimized by avoiding strenuous activity or exercise outdoors. For more information on ground-level ozone and fine particles visit the web site https://www.mwcog.org/environment/air/forecast/.

The Virginia Department of Environmental Quality has issued a Code ORANGE Air Quality Alert Thursday for Northern Virginia. A Code Orange Air Quality Alert means that air pollution concentrations within the region may become unhealthy for sensitive groups. Sensitive groups include children, people suffering from asthma, heart disease or other lung diseases and the elderly. The effects of air pollution can be minimized by avoiding strenuous activity or exercise outdoors. For more information on ground-level ozone and fine particles visit the web site Virginia DEQ air quality web site at www.deq.virginia.gov.

* WHAT. South winds around 10 kt with gusts up to 20 kt. * WHERE. Tidal Potomac from Key Bridge to Indian Head MD. * WHEN. Until 10 PM EDT this evening. * IMPACTS. Conditions will be hazardous to small craft.

* WHAT. South winds 10 to 20 kt with gusts up to 25 kt. * WHERE. Tidal Potomac River from Indian Head MD to Smith Point VA, and Chesapeake Bay and adjoining estuaries north of Smith Point VA. * WHEN. Until 6 AM EDT Thursday. * IMPACTS. Conditions will be hazardous to small craft.

* WHAT. Heat index values around 100 to 105 expected. * WHERE. Portions of central, northern and southern Maryland, The District of Columbia, and central and northern Virginia. * WHEN. From noon to 8 PM EDT Thursday. * IMPACTS. Hot temperatures and high humidity may cause heat illnesses to occur. * ADDITIONAL DETAILS. The combination of air temperatures in the 90s and high humidity will result in the potential for increased heat-related illnesses, especially those partaking in outdoor Independence Day activities.

* WHAT. Up to one half foot of inundation above ground level expected in low lying areas due to tidal flooding. * WHERE. Shoreline in Anne Arundel County. * WHEN. From 1 AM to 8 AM EDT Thursday, especially around the time of high tide. * IMPACTS. At 2.8 feet, flooding of some of the parking area near Dock Street in Annapolis may occur, with water surrounding the Alex Haley Memorial. * ADDITIONAL DETAILS. Tides one to one and a half feet above normal. High tide at Annapolis U.S. Naval Academy is at 5:00 AM early Thursday.