Light winds and plenty of low level moisture allowed areas of dense fog to form before dawn. The fog dissipated shortly after sunrise.
Every event with a place to put it; 16 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.
Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS LWX wrote it up.
Light winds and plenty of low level moisture allowed areas of dense fog to form before dawn. The fog dissipated shortly after sunrise.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Baltimore/Washington wrote its last area forecast discussion before the first event at May 16, 7:45 PM EST, 6 hours 15 minutes earlier.
Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 845 PM EDT Sun May 16 2021 .SYNOPSIS... An upper level ridge will gradually build over the region tonight through the end of the week resulting in generally dry weather and above normal temperatures. && .NEAR TERM /THROUGH TONIGHT/... 8:45 PM UPDATE: Changed a few minor details to the forecast overnight tonight. Firstly, have bumped lows down a tick to match more recent guidance, but only a degree or two here and there. Dew points have been running higher than the previous forecast, so have bumped those up a bit in the overnight as well. Mid-level subsidence behind exiting shortwave will lead to areas of low clouds/fog late tonight especially west of the Blue Ridge where it rained most of the morning. && .SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... Height rises will dominate this period leading to decreased chances of precip. Southwestern areas have the best chance of seeing any showers on Monday, with further drying expected into Tuesday as the subsidence inversion strengthens associated with building upper level ridge. A weak impulse of shortwave energy will slide through Tuesday around the periphery of the building ridge. This could lead to a shower or storm over the higher elevations, but chances are very low. The building upper ridge will result in significant warming, starting Tuesday then continuing through the rest of the week. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... Model guidance is in fairly good agreement regarding the large scale pattern across the CONUS during the long term period, but some small differences still remain. By Wednesday, a weakening upper level low will be in the process of shearing out as it lifts northward over the center of the CONUS. Meanwhile, a potent trough will be in the process of dropping southward along the West Coast. A ridge will be in place across eastern portions of the CONUS, and that ridge will only amplify/strengthen further toward the end of the week as the trough over the West Coast/Rockies digs further south. With ridging aloft and high pressure in place at the surface, a prolonged period of quiet weather conditions is expected. The main weather feature of note will be the heat. Temperatures will run well above normal, with highs in the 80s, to potentially even the lower 90s toward the end of the week. Although temperatures will feel summer-like, it won't be quite as humid as summer, with dewpoints mainly in the upper 50s to around 60. This combination of large scale subsidence in association with the upper ridge and marginal low level moisture will act to prohibit the development of afternoon showers and thunderstorms most days. Most of the forecast uncertainty lies with respect to where the upper level ridge will reside this weekend. If it were to weaken and/or retrograde a bit toward the west, that would open up the opportunity for disturbances moving along the northern periphery of the ridge to descend into the area within northwesterly flow aloft. If this were to occur, it could lead to opportunities for a few popup afternoon showers and storms and slightly cooler temperatures. Otherwise, the stretch of hot and dry weather conditions would continue into next weekend. && .AVIATION /01Z MONDAY THROUGH FRIDAY/... Areas of low clouds/fog are expected tonight, which will likely lead to restrictions, especially at MRB, CHO, and IAD. BWI, MTN, and DCA may also see some fog too, but kept the density lower in the recent TAFs, and certainty is lower as to how far east fog makes it. Though, with the abundance of rain in north-centrl MD today, seems that BWI may have a better shot now as well. VFR conditions and light winds are generally expected through the rest of the week. However, could see some fog around Monday night. && .MARINE... Fair weather conditions with winds below SCA conditions are expected through the end of the week as high pressure builds in over the area. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...None. MD...None. VA...None. WV...None. MARINE...None. && SYNOPSIS...LFR NEAR TERM...LFR/CJL SHORT TERM...LFR LONG TERM...KJP AVIATION...LFR/CJL/KJP MARINE...LFR/CJL/KJP
Hazardous Weather Outlook National Weather Service Baltimore MD/Washington DC 252 AM EDT Mon May 17 2021 ANZ530>543-DCZ001-MDZ008-011-013-014-016>018-504-506-508- VAZ052>057-180700- Chesapeake Bay north of Pooles Island MD- Chesapeake Bay from Pooles Island to Sandy Point MD- Chesapeake Bay from Sandy Point to North Beach MD- Chesapeake Bay from North Beach to Drum Point MD- Chesapeake Bay from Drum Point MD to Smith Point VA- Tidal Potomac from Key Bridge to Indian Head MD- Tidal Potomac from Indian Head to Cobb Island MD- Tidal Potomac from Cobb Island MD to Smith Point VA- Patapsco River including Baltimore Harbor- Chester River to Queenstown MD-Eastern Bay- Choptank River to Cambridge MD and the Little Choptank River- Patuxent River to Broomes Island MD- Tangier Sound and the inland waters surrounding Bloodsworth Island-District of Columbia-Cecil-Southern Baltimore- Prince Georges-Anne Arundel-Charles-St. Marys-Calvert- Central and Southeast Montgomery-Central and Southeast Howard- Southeast Harford-Prince William/Manassas/Manassas Park-Fairfax- Arlington/Falls Church/Alexandria-Stafford-Spotsylvania- King George- 252 AM EDT Mon May 17 2021 This Hazardous Weather Outlook is for the Maryland portion of the Chesapeake Bay, Tidal Potomac River, and I-95 corridor through central Maryland, northern Virginia, and District of Columbia. .DAY ONE...Today and Tonight A Dense Fog Advisory is in effect for portions of the area until 9 AM. .DAYS TWO THROUGH SEVEN...Tuesday through Sunday No hazardous weather is expected at this time. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected at this time. MDZ003>006-503-505-507-VAZ025>031-036>040-050-051-501-502-505>508- WVZ050>053-055-180700- Washington-Frederick MD-Carroll-Northern Baltimore- Northwest Montgomery-Northwest Howard-Northwest Harford-Augusta- Rockingham-Shenandoah-Frederick VA-Page-Warren-Clarke-Nelson- Albemarle-Greene-Madison-Rappahannock-Orange-Culpeper- Northern Fauquier-Southern Fauquier-Western Loudoun- Eastern Loudoun-Northern Virginia Blue Ridge- Central Virginia Blue Ridge-Hampshire-Morgan-Berkeley-Jefferson- Hardy- 252 AM EDT Mon May 17 2021 This Hazardous Weather Outlook is for portions of eastern West Virginia, northern and central Virginia, and central and western Maryland. .DAY ONE...Today and Tonight A Dense Fog Advisory is in effect for portions of the area until 9 AM. .DAYS TWO THROUGH SEVEN...Tuesday through Sunday No hazardous weather is expected at this time. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected at this time. MDZ001-501-502-VAZ503-504-WVZ501>506-180700- Garrett-Extreme Western Allegany-Central and Eastern Allegany- Western Highland-Eastern Highland-Western Grant-Eastern Grant- Western Mineral-Eastern Mineral-Western Pendleton- Eastern Pendleton- 252 AM EDT Mon May 17 2021 This Hazardous Weather Outlook is for the Allegheny Front counties in western Maryland, eastern West Virginia, and Highland County Virginia. .DAY ONE...Today and Tonight A Dense Fog Advisory is in effect for portions of the area until 9 AM. .DAYS TWO THROUGH SEVEN...Tuesday through Sunday No hazardous weather is expected at this time. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected at this time.
The national radar mosaic for the moment the first event began.
17 dense fog. Local standard time, as filed.
Light winds and plenty of low level moisture allowed areas of dense fog to form before dawn. The fog dissipated shortly after sunrise.
Light winds and plenty of low level moisture allowed areas of dense fog to form before dawn. The fog dissipated shortly after sunrise.
Light winds and plenty of low level moisture allowed areas of dense fog to form before dawn. The fog dissipated shortly after sunrise.
Light winds and plenty of low level moisture allowed areas of dense fog to form before dawn. The fog dissipated shortly after sunrise.
Light winds and plenty of low level moisture allowed areas of dense fog to form before dawn. The fog dissipated shortly after sunrise.
Light winds and plenty of low level moisture allowed areas of dense fog to form before dawn. The fog dissipated shortly after sunrise.
Light winds and plenty of low level moisture allowed areas of dense fog to form before dawn. The fog dissipated shortly after sunrise.
Light winds and plenty of low level moisture allowed areas of dense fog to form before dawn. The fog dissipated shortly after sunrise.
Light winds and plenty of low level moisture allowed areas of dense fog to form before dawn. The fog dissipated shortly after sunrise.
Light winds and plenty of low level moisture allowed areas of dense fog to form before dawn. The fog dissipated shortly after sunrise.
Light winds and plenty of low level moisture allowed areas of dense fog to form before dawn. The fog dissipated shortly after sunrise.
Light winds and plenty of low level moisture allowed areas of dense fog to form before dawn. The fog dissipated shortly after sunrise.
Light winds and plenty of low level moisture allowed areas of dense fog to form before dawn. The fog dissipated shortly after sunrise.
Light winds and plenty of low level moisture allowed areas of dense fog to form before dawn. The fog dissipated shortly after sunrise.
Light winds and plenty of low level moisture allowed areas of dense fog to form before dawn. The fog dissipated shortly after sunrise.
Light winds and plenty of low level moisture allowed areas of dense fog to form before dawn. The fog dissipated shortly after sunrise.
Light winds and plenty of low level moisture allowed areas of dense fog to form before dawn. The fog dissipated shortly after sunrise.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Virginia in 2021Every state in 2021This day in weather historyWarnings in Virginia, May 2021
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 963077, 963078, 963079, 963080, 963081, 963082, 963083, 963084, 963085, 963086, 963087, 963088, 963089, 963090, 963091, 963092, 963093.