SMWLWX The National Weather Service in Sterling Virginia has issued a * Special Marine Warning for. Tidal Potomac from Indian Head to Cobb Island MD. * Until 600 PM EDT. * At 353 PM EDT, a strong thunderstorm was located 19 nm southwest of Aquia Creek, moving east at 25 knots. HAZARD. Wind gusts 34 knots or greater. SOURCE. Radar indicated. IMPACT. Boaters in small craft could be thrown overboard by suddenly higher winds and waves capsizing their vessel. * Locations impacted include. Potomac Creek, Widewater, Maryland Point, Nanjemoy Creek, Port Tobacco River, Swan Point, Mathias Point, U.S. 301 Nice Memorial Bridge, Popes Creek, Brent Point, Quantico, Westmoreland State Park, Fairview Beach, Cobb Island, and Dahlgren.

For the following areas. Tidal Potomac from Indian Head to Cobb Island MD. At 415 PM EDT, a strong thunderstorm was located 11 nm southwest of Potomac Creek, moving east at 25 knots. HAZARD. Wind gusts 34 knots or greater. SOURCE. Radar indicated. IMPACT. Boaters in small craft could be thrown overboard by suddenly higher winds and waves capsizing their vessel. Locations impacted include. Potomac Creek, Widewater, Maryland Point, Nanjemoy Creek, Port Tobacco River, Swan Point, Mathias Point, U.S. 301 Nice Memorial Bridge, Popes Creek, Brent Point, Quantico, Westmoreland State Park, Fairview Beach, Cobb Island, and Dahlgren.

* WHAT. Heat index values up to 107 expected. * WHERE. In Maryland, Cecil, St. Marys, Calvert and Southeast Harford Counties. In Virginia, Orange, Culpeper, King George and Southern Fauquier Counties. * WHEN. From noon to 8 PM EDT Friday. * 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.

* WHAT. For the first Heat Advisory, heat index values up to 100. For the second Heat Advisory, heat index values up to 106 expected. * WHERE. Portions of central, northern and southern Maryland, The District of Columbia and central and northern Virginia. * WHEN. For the first Heat Advisory, until 8 PM EDT this evening. For the second Heat Advisory, from noon to 8 PM EDT Friday. * 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 today.

* WHAT. Heat index values up to 107 expected. * WHERE. Portions of central, north central and northern Maryland, central, northern, northwest and western Virginia and panhandle West Virginia. * WHEN. From noon to 8 PM EDT Friday. * 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.

* WHAT. Heat index values up to 108 expected. * WHERE. In Maryland, Cecil, St. Marys, Calvert and Southeast Harford Counties. In Virginia, Orange, Culpeper, King George and Southern Fauquier Counties. * WHEN. From noon to 8 PM EDT Friday. * 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.

* WHAT. For the first Heat Advisory, heat index values up to 100. For the second Heat Advisory, heat index values up to 109 expected. * WHERE. Portions of central, northern and southern Maryland, The District of Columbia and central and northern Virginia. * WHEN. For the first Heat Advisory, until 8 PM EDT this evening. For the second Heat Advisory, from noon to 8 PM EDT Friday. * 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 today.

For the following areas. Tidal Potomac from Indian Head to Cobb Island MD. At 424 PM EDT, a strong thunderstorm was located 10 nm southwest of Potomac Creek, moving east at 25 knots. HAZARD. Wind gusts 34 knots or greater. SOURCE. Observed wind of 35 knots at Fredericksburg/Shannon Airport. IMPACT. Boaters in small craft could be thrown overboard by suddenly higher winds and waves capsizing their vessel. Locations impacted include. Potomac Creek, Widewater, Maryland Point, Nanjemoy Creek, Port Tobacco River, Swan Point, Mathias Point, U.S. 301 Nice Memorial Bridge, Popes Creek, Brent Point, Quantico, Westmoreland State Park, Fairview Beach, Cobb Island, and Dahlgren.

The areas affected include. Tidal Potomac from Indian Head to Cobb Island MD. Tidal Potomac from Key Bridge to Indian Head MD. At 357 PM EDT, Doppler radar indicated developing thunderstorms, capable of producing winds of 20 to 30 knots and lightning strikes. These developing thunderstorms were located along a line extending from 16 nm west of Key Bridge to 12 nm northwest of Mason Neck State Park to 6 nm west of Quantico, moving east at 15 knots.

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.