* 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.

At 616 PM EDT, Doppler radar was tracking strong thunderstorms along a line extending from near Callao to near Morattico to near Shacklefords. Movement was east at 25 mph. HAZARD. Wind gusts up to 40 mph and heavy rain. SOURCE. Radar indicated. IMPACT. Gusty winds could knock down tree limbs and blow around unsecured objects. Reduced visibility and minor flooding possible. Strong thunderstorms will be near. Urbanna, Callao, Robley, Saluda, and Glenns around 620 PM EDT. Lancaster, Lewisetta, and Heathsville around 625 PM EDT. Kilmarnock and Wicomico Church around 635 PM EDT. White Stone and Hartfield around 640 PM EDT. Fair Port around 645 PM EDT. Blakes around 650 PM EDT. Other locations impacted by these storms include Byrdton, Lottsburg, Moon, Laban, Avalon, Brook Vale, Bertrand, Grafton, Reedville, and Belle Isle State Park.

* 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.

* WHAT. Heat index values of 105 to 109 expected. * WHERE. Portions of southeast Maryland, northeast North Carolina, the eastern Virginia Piedmont, and central and southeast Virginia. * WHEN. From 11 AM to 8 PM EDT Friday. * IMPACTS. Hot temperatures and high humidity may cause heat illnesses.

* WHAT. South winds 10 to 15 kt with gusts up to 20 kt expected. * WHERE. Chesapeake Bay from North Beach to Drum Point MD, Tidal Potomac from Cobb Island MD to Smith Point VA and Choptank River to Cambridge MD and the Little Choptank River. * WHEN. Until 8 PM EDT this evening. * 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.