SMWLWX The National Weather Service in Sterling Virginia has issued a * Special Marine Warning for. Tidal Potomac from Key Bridge to Indian Head MD. * Until 630 PM EDT. * At 458 PM EDT, a strong thunderstorm was located 16 nm west of Key Bridge, moving southeast at 20 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. Fort Washington, Tidal Basin, Reagan National Airport, Woodrow Wilson Bridge, Key Bridge, Fort Hunt, National Harbor, and Alexandria.

For the following areas. Tidal Potomac from Key Bridge to Indian Head MD. At 524 PM EDT, a severe thunderstorm was located 7 nm west of Key Bridge, moving southeast at 20 knots. HAZARD. Wind gusts in excess of 48 knots. SOURCE. Observed wind. IMPACT. Boaters could easily be thrown overboard by suddenly higher wind and waves capsizing their vessel. Boats could suffer significant damage in high winds. Locations impacted include. Fort Washington, Tidal Basin, Reagan National Airport, Woodrow Wilson Bridge, Key Bridge, Fort Hunt, National Harbor, and Alexandria.

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 645 PM EDT. * At 519 PM EDT, a strong thunderstorm was located 20 nm west 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, Leesylvania State Park, Smallwood State Park, Quantico, Mathias Point, U.S. 301 Nice Memorial Bridge, Mason Neck State Park, Indian Head, Occoquan Bay, Popes Creek, and Brent Point.

For the following areas. Tidal Potomac from Key Bridge to Indian Head MD. At 559 PM EDT, a strong thunderstorm was located over National Harbor, moving southeast at 20 knots. HAZARD. Wind gusts 34 knots or greater. SOURCE. Observed wind. IMPACT. Boaters in small craft could be thrown overboard by suddenly higher winds and waves capsizing their vessel. Locations impacted include. Fort Washington, Tidal Basin, Reagan National Airport, Woodrow Wilson Bridge, Key Bridge, Fort Hunt, National Harbor, and Alexandria.

* WHAT. During the Excessive Heat Warnings, dangerously hot conditions with heat index values around 105 to 108 expected. * WHERE. In Maryland, Washington County. In Virginia, Shenandoah, Frederick VA, Page, Warren and Clarke Counties. In West Virginia, Morgan, Berkeley and Jefferson Counties. * WHEN. For the first Excessive Heat Warning, until 8 PM EDT this evening. For the second Excessive Heat Warning, from 11 AM to 8 PM EDT Tuesday. * IMPACTS. Extreme heat and humidity will significantly increase the potential for heat related illnesses, particularly for those working or participating in outdoor activities. * ADDITIONAL DETAILS. Very warm and humid conditions will persist into the overnight hours, adding heat stress to those without air conditioning. Ensure to stay hydrated and find ways to stay cool.

* WHAT. During the Excessive Heat Warnings, dangerously hot conditions with heat index values around 110 expected. * WHERE. Portions of central, northeast, northern and southern Maryland, The District of Columbia and central and northern Virginia. * WHEN. For the first Excessive Heat Warning, until 8 PM EDT this evening. For the second Excessive Heat Warning, from 11 AM to 8 PM EDT Tuesday. * IMPACTS. Extreme heat and humidity will significantly increase the potential for heat related illnesses, particularly for those working or participating in outdoor activities. * ADDITIONAL DETAILS. Very warm and humid conditions will persist into the overnight hours, adding heat stress to those without air conditioning. Ensure to stay hydrated and find ways to stay cool.

* WHAT. During the Heat Advisories, hot conditions with heat index values around 105 expected. * WHERE. Portions of central and north central Maryland and central, northern and northwest Virginia. * WHEN. For the first Heat Advisory, until 8 PM EDT this evening. For the second Heat Advisory, from 11 AM to 8 PM EDT Tuesday. * IMPACTS. Hot temperatures and high humidity may cause heat illnesses to occur. * ADDITIONAL DETAILS. Very warm and humid conditions will persist into the overnight hours, adding heat stress to those without air conditioning. Ensure to stay hydrated and find ways to stay cool.

* WHAT. For the Excessive Heat Warning, dangerously hot conditions with heat index values up to 107. For the Heat Advisory, heat index values up to 103 expected. * WHERE. Adams, Cumberland, Dauphin, Franklin, Lancaster, Lebanon, Perry, and York Counties. * WHEN. For the Excessive Heat Warning, until 8 PM EDT Tuesday. For the Heat Advisory, from 8 PM Tuesday to 8 PM EDT Wednesday. * IMPACTS. Heat related illnesses increase significantly during extreme heat and high humidity events.

The Maryland Department of the Environment has issued a Code ORANGE Air Quality Alert Monday for the Maryland suburban DC region. 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 mde.maryland.gov/programs/air/AirQualityMonitoring/Pages/index.aspx.

The Maryland Department of the Environment has issued a Code ORANGE Air Quality Alert Monday for the Baltimore City Metro and Annapolis region. 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 mde.maryland.gov/programs/air/AirQualityMonitoring/Pages/index.aspx.

The affected areas were. Tidal Potomac from Key Bridge to Indian Head MD. The thunderstorm has weakened and no longer poses a significant threat to boaters.

SMWLWX The National Weather Service in Sterling Virginia has issued a * Special Marine Warning for. Chesapeake Bay from Pooles Island to Sandy Point MD. Chesapeake Bay from Sandy Point to North Beach MD. Chester River to Queenstown MD. Eastern Bay. * Until 700 PM EDT. * At 604 PM EDT, a strong thunderstorm was located over Naval Academy, moving east at 15 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. Parsons Island, Pinehurst, Kent Narrows Bridge, Magothy River, Chester River, Gibson Island, Greenbury Point, Love Point, Naval Academy, Highland Beach, Sandy Point State Park, Baltimore Light, Severn River, Matapeake, Chesapeake Bay Bridge, and Annapolis.

For the following areas. Tidal Potomac from Indian Head to Cobb Island MD. At 600 PM EDT, a strong thunderstorm was located 8 nm west of Aquia Creek, moving east at 20 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, Mathias Point, U.S. 301 Nice Memorial Bridge, Maryland Point, Nanjemoy Creek, Port Tobacco River, Popes Creek, and Brent Point.

SVRLWX The National Weather Service in Sterling Virginia has issued a * Severe Thunderstorm Warning for. Southern Stafford County in northern Virginia. Northeastern Orange County in central Virginia. The City of Fredericksburg in central Virginia. South central Fauquier County in northern Virginia. Southeastern Culpeper County in northern Virginia. Northeastern Spotsylvania County in central Virginia. * Until 630 PM EDT. * At 540 PM EDT, a severe thunderstorm was located 13 miles northwest of Fredericksburg, moving east at 25 mph. HAZARD. 60 mph wind gusts. SOURCE. Emergency management in Culpeper County reported numerous trees down from this storm. IMPACT. Damaging winds will cause some trees and large branches to fall. This could injure those outdoors, as well as damage homes and vehicles. Roadways may become blocked by downed trees. Localized power outages are possible. Unsecured light objects may become projectiles. * Locations impacted include. Fredericksburg, Potomac Creek, Aquia Creek, Massaponax, Spotsylvania, Falmouth, Passapatanzy, Stones Corner, Locust Grove, Flat Run, Ramoth, Dunavant, White Oak, Lake Of The Woods, Cookstown, Goldvein, Leeland, Parker, Spring Valley, and Gold Dale.

At 552 PM EDT, a severe thunderstorm was located 8 miles west of Fredericksburg, moving southeast at 25 mph. HAZARD. 60 mph wind gusts. SOURCE. Emergency management. IMPACT. Damaging winds will cause some trees and large branches to fall. This could injure those outdoors, as well as damage homes and vehicles. Roadways may become blocked by downed trees. Localized power outages are possible. Unsecured light objects may become projectiles. Locations impacted include. Fredericksburg, Potomac Creek, Aquia Creek, Massaponax, Spotsylvania, Falmouth, Passapatanzy, Stones Corner, Flat Run, Ramoth, Dunavant, White Oak, Lake Of The Woods, Cookstown, Goldvein, Leeland, Parker, Spring Valley, Brooke, and Chancellorsville.