Light winds and clearing skies with plentiful low level moisture resulted in areas of dense fog late at night. The fog dissipated shortly after sunrise.
Every event with a place to put it; 9 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 clearing skies with plentiful low level moisture resulted in areas of dense fog late at night. 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 Apr 10, 2:55 AM EST, 5 minutes earlier.
Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 355 AM EDT Sat Apr 10 2021 .SYNOPSIS... Unsettled conditions persist through the weekend as an area of low pressure moves into the Great Lakes region. A stationary front will linger north of the region Saturday as a secondary warm front moves northward late Saturday into Sunday. Then, cold front will cross the region through Sunday evening. Weak high pressure is expected to return for Monday and Tuesday before another weak low quickly slides by Wednesday. && .NEAR TERM /THROUGH TONIGHT/... The stationary front lingers across the central portion of the region and will continue to lift northward through the morning hours. As a result, lots of low clouds, areas of fog, and patchy drizzle is expected to persist during this time. Some slight improvements are expected late this morning into the afternoon as a southerly wind ensues. While clouds will linger, temperatures will run on the mild side given the WAA; in the low to mid 70s for most, with mid 60s across the higher terrain and valley areas. While conditions are expected to remain mostly dry throughout the afternoon hours, a warm front is slated to move northward Saturday night into early Sunday morning. As a result, showers and embedded thunderstorms are expected to develop from south to north and can be heavy at times through Sunday morning. && .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... The warm front will continue to progress northeastward early Sunday morning where remnant showers and embedded thunderstorms are possible to persist across northeastern MD by daybreak. Then there appears to be a lull in the action during the mid morning and early afternoon hours on Sunday. Some of the hires guidance indicates some mid level drying which may result in some peaks of sunshine during this time. Given the warm air mass in place, any additional sunshine will further aide in generating instability; further fueling the potential for any severe thunderstorms. Generally speaking, temperatures on Sunday will be a few degrees warmer than Saturday; in the mid-upper 70s mainly east of the Blue Ridge with some areas possibly rising into the low 80s; dependent on how much sunshine breaks through the cloud deck. Guidance continues to hint at a line of storms forming east of the Blue Ridge Sunday afternoon and moving east across the area with the front. While the potential for the development of severe storms is there, especially in terms of instability, the wind field aloft looks marginal at best. Also, the forcing isn't all that impressive as the parent low pressure system becomes cut off as it tracks into the Great Lakes. After the thunderstorms push through Sunday afternoon into the evening, precipitation should quickly come to an end across the region. Lows Sunday night will run cooler, but still above average, bottoming out in the upper 40s to low 50s. && .LONG TERM /TUESDAY THROUGH FRIDAY/... A weak cold front will cross the area late Tue night or early Wed with minimal impacts. A series of closed 500 mb lows across the Great Lks will send pulses of shortwave energy across the area during the second half of next week maintaining unsettled conditions and risk of spotty daytime showers mainly across northern areas. Otherwise, weak sfc high pressure will maintain a weak NW flow with mainly fair weather conditions. && .AVIATION /07Z SATURDAY THROUGH WEDNESDAY/... IFR and LIFR CIG/VSBYs will continue through the early morning hours Saturday in areas of patchy fog/drizzle. Some improvements are expected for the afternoon as VFR conditions are expected to return briefly by Saturday afternoon across the terminals. However a warm front will lift northward overnight Saturday into Sunday resulting in the development of showers and thunderstorms which may be heavy for a brief period; therefore reducing CIG/VSBYs once again into Sunday morning. VFR conditions are possible for a few hours late Sunday morning through early Sunday afternoon before a cold front crosses the region, bringing another round of showers and thunderstorms. Conditions clear rapidly Sunday evening as VFR conditions return and persist into Monday. A weak cold front will cross the area early on Tue with minimal impacts. && .MARINE... Generally weak wind field on Saturday will result in sub-SCA conditions over the waters. On Sunday, wind fields do pick up over land, but the warm air temperatures on top of the still chilly waters (50s) would cast doubt on a more widespread SCA event. The best chances would be closer to the shorelines. However, there will be a chance for thunderstorms Sunday afternoon, which could bring down some gusty winds and necessitate Special Marine Warnings. Possible SCA conditions next Thu in NNW flow. Otherwise, light flow below 10 kt most of the time.&& .TIDES/COASTAL FLOODING... Tidal anomalies remain elevated through the weekend, especially at the normal sensitive sites. This is due to a continued southerly flow across the region. While not very strong, the southerly flow may result in periods of minor coastal flooding at times of high tide. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...None. MD...None. VA...None. WV...None. MARINE...None. && SYNOPSIS...MSS NEAR TERM...MSS SHORT TERM...MSS LONG TERM...LFR AVIATION...MSS/LFR MARINE...MSS/LFR TIDES/COASTAL FLOODING...Staff
Hazardous Weather Outlook National Weather Service Baltimore MD/Washington DC 806 PM EDT Fri Apr 9 2021 ANZ530>543-DCZ001-MDZ008-011-013-014-016>018-504-506-508- VAZ052>057-110015- 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- 806 PM EDT Fri Apr 9 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...Tonight Areas of dense fog are possible late tonight. .DAYS TWO THROUGH SEVEN...Saturday through Thursday 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>053-055-110015- 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- 806 PM EDT Fri Apr 9 2021 This Hazardous Weather Outlook is for portions of eastern West Virginia, northern and central Virginia, and central and western Maryland. .DAY ONE...Tonight Areas of dense fog are possible late tonight. .DAYS TWO THROUGH SEVEN...Saturday through Thursday 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>506-110015- Garrett-Extreme Western Allegany-Central and Eastern Allegany- Western Highland-Eastern Highland-Western Grant-Eastern Grant- Western Mineral-Eastern Mineral-Western Pendleton- Eastern Pendleton- 806 PM EDT Fri Apr 9 2021 This Hazardous Weather Outlook is for the Allegheny Front counties in western Maryland, eastern West Virginia, and Highland County Virginia. .DAY ONE...Tonight Areas of dense fog are possible late tonight. .DAYS TWO THROUGH SEVEN...Saturday through Thursday 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.
9 dense fog. Local standard time, as filed.
Light winds and clearing skies with plentiful low level moisture resulted in areas of dense fog late at night. The fog dissipated shortly after sunrise.
Light winds and clearing skies with plentiful low level moisture resulted in areas of dense fog late at night. The fog dissipated shortly after sunrise.
Light winds and clearing skies with plentiful low level moisture resulted in areas of dense fog late at night. The fog dissipated shortly after sunrise.
Light winds and clearing skies with plentiful low level moisture resulted in areas of dense fog late at night. The fog dissipated shortly after sunrise.
Light winds and clearing skies with plentiful low level moisture resulted in areas of dense fog late at night. The fog dissipated shortly after sunrise.
Light winds and clearing skies with plentiful low level moisture resulted in areas of dense fog late at night. The fog dissipated shortly after sunrise.
Light winds and clearing skies with plentiful low level moisture resulted in areas of dense fog late at night. The fog dissipated shortly after sunrise.
Light winds and clearing skies with plentiful low level moisture resulted in areas of dense fog late at night. The fog dissipated shortly after sunrise.
Light winds and clearing skies with plentiful low level moisture resulted in areas of dense fog late at night. 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, April 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: 955458, 955460, 955461, 955463, 955464, 955465, 955466, 955467, 955468.