A combination of clear skies, abundant low level moisture, and light winds led to the formation of fog, some of which became dense with visibility less than a quarter of a mile.
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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.
A combination of clear skies, abundant low level moisture, and light winds led to the formation of fog, some of which became dense with visibility less than a quarter of a mile.
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 Sep 19, 9:24 PM EST, 3 hours 11 minutes earlier.
Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 1024 PM EDT Wed Sep 19 2018 .SYNOPSIS... High pressure will build over the region through Thursday before migrating over the western Atlantic on Friday. A cold front will approach from the northwest toward the end of the week before stalling near or over the region through the weekend. && .NEAR TERM /THROUGH TONIGHT/... A secondary cold front is decaying over the Mid-Atlantic as of early Wednesday evening. Surface high pressure is building over the region in its place. Any convective activity has waned. Patchy fog seems likely tonight given light winds, a mainly clear sky and wet ground, especially west of I-95. Some fog may be locally dense. && .SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY NIGHT/... 1020PM UPDATE: made some tweaks to PoPs in the vicinity of the central Shenandoah Valley for Thursday afternoon and evening as it looks like some trapped moisture combined with weakly convergent return flow should set of a few isolated to widely scattered showers and thunderstorms. Otherwise, high pressure will begin shifting to the east Thursday, with light easterly or southeasterly return flow. Low pressure will pass north of the Great Lakes on Friday, continuing its path northeastward to close out the work week. The associated frontal boundary will approach our region from the northwest late Friday and into Friday night. Current progression of the front by model guidance keeps precipitation mostly northwest of the CWA through the day on Friday, with coverage increasing Friday night. As such, have pushed back the timing and have low end chance POPs Friday afternoon for only our far northwestern zones (eastern WV/western MD). There is a severe risk mainly north of the PA border where better forcing/shear will be, and this risk should decrease with southward extent towards our area as more favorable parameters eject towards New England. Rain chances increase further east Friday night as the front sags southward. Temperatures Thursday through Friday will run in the low to mid 80s for highs and lows generally in the 60s, with near 70 degree readings Friday night ahead of the front. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... A cold front will be moving southward across the area on Saturday. Showers and perhaps a few thunderstorms will be possible near the boundary. It does appear the surface boundary will move south of the area before stalling during the latter part of the weekend, which will put the forecast area on the stable side of the boundary. However, the frontal zone aloft will likely remain near or perhaps even north of the area. At the same time, surface high pressure will be building over New England, resulting in a cold air damming pattern. Assuming the frontal zone aloft remains nearby, moist ascent over the surface wedge will result in plentiful clouds and the potential for light to moderate rain at times. Temperatures (especially highs) will likely fall below normal...and there's potential highs don't get out of the 60s for some areas by Sunday and Monday. It is worth noting that there is some potential the frontal zone gets far enough south at some point to preclude appreciable rain chances, but if the pattern over the past several months indicates anything, that won't be the case. The frontal zone will be lifting north early next week as low pressure moves through the upper Great Lakes. If/when we break out of the surface wedge, it will result in a slight warming trend. However, moist southwest flow ahead of a broad trough moving into the Plains will continue to result in clouds and chances for showers and some thunderstorms. The next cold front remains well to our northwest through Wednesday, with its passage occurring after the end of the forecast period. Given the multiple days of rain and precipitable water rebounding to 1.5-2.0 inches by Tuesday and Wednesday, some hydro concerns are not out of the question. && .AVIATION /03Z THURSDAY THROUGH MONDAY/... Patchy fog is likely west of I-95 tonight, could be locally dense especially INVOF MRB/CHO. Low clouds also developing off the New Jersey coast will advect southwest towards terminals east of I-95 by tomorrow morning, and could bring CIGs down to near IFR. Conditions should improve by mid morning. Otherwise, mainly VFR conditions expected at all terminals through Thursday night as high pressure moves overhead. A cold front will approach the terminals late Friday and Friday night, increasing rain chances. At this time, MRB would serve to see the highest chance of restrictions with the remaining terminals likely holding off until Saturday morning. Northerly breezes today will subside tonight, veering southeasterly on Thursday at less than 10 knots, then turning southerly and increasing on Friday ahead of the front. There will be a chance of showers and perhaps a thunderstorm as a cold front drops into the area through the weekend. The frontal zone will remain nearby (perhaps focused over central VA), and showers may reduce visibility at times through the period. Ceilings may eventually drop below VFR levels as well in possible cool air wedge as high pressure builds to the north. && .MARINE... Winds have diminished. Sub SCA conditions should prevail through Thursday night. SCA conditions may return on Friday as southerly flow increases ahead of a cold front approaching from the Great Lakes and Pennsylvania. The cold front will drop across the waters on Saturday, then stall nearby through early next week. This front will bring a wind shift to the north, then eventually easterly. Winds may be the strongest Monday as high pressure builds into New England. Showers will be possible through the period, with the highest chance of thunderstorms (though still low) on Saturday. && .TIDES/COASTAL FLOODING... Onshore flow will cause tidal anomalies to increase over the next couple days, possibly persisting through the weekend. This will likely lead to a renewed threat for coastal flooding, especially given increasing astronomical tides. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...None. MD...None. VA...None. WV...None. MARINE...None. && SYNOPSIS...BKF NEAR TERM...BKF/DHOF SHORT TERM...BKF/DHOF LONG TERM...ADS AVIATION...ADS/BKF/DHOF MARINE...ADS/BKF/DHOF TIDES/COASTAL FLOODING...DHOF
Hazardous Weather Outlook National Weather Service Baltimore MD/Washington DC 730 PM EDT Wed Sep 19 2018 ANZ530>543-DCZ001-MDZ011-013-014-016>018-508-VAZ052>057-202330- 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-Southern Baltimore-Prince Georges- Anne Arundel-Charles-St. Marys-Calvert-Southeast Harford- Prince William/Manassas/Manassas Park-Fairfax- Arlington/Falls Church/Alexandria-Stafford-Spotsylvania- King George- 730 PM EDT Wed Sep 19 2018 This Hazardous Weather Outlook is for the Maryland portion of the Chesapeake Bay, Tidal Potomac River, and adjacent counties in central Maryland and northern Virginia as well as the District of Columbia. .DAY ONE...Tonight No hazardous weather is expected at this time. .DAYS TWO THROUGH SEVEN...Thursday through Tuesday No hazardous weather is expected at this time. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected at this time. MDZ003>006-501>507-VAZ025>031-036>040-050-051-501>508-WVZ050>053- 055-501>506-202330- Washington-Frederick MD-Carroll-Northern Baltimore- Extreme Western Allegany-Central and Eastern Allegany- Northwest Montgomery-Central and Southeast Montgomery- Northwest Howard-Central and Southeast Howard-Northwest Harford- Augusta-Rockingham-Shenandoah-Frederick VA-Page-Warren-Clarke- Nelson-Albemarle-Greene-Madison-Rappahannock-Orange-Culpeper- Northern Fauquier-Southern Fauquier-Western Highland- Eastern Highland-Western Loudoun-Eastern Loudoun- Northern Virginia Blue Ridge-Central Virginia Blue Ridge- Hampshire-Morgan-Berkeley-Jefferson-Hardy-Western Grant- Eastern Grant-Western Mineral-Eastern Mineral-Western Pendleton- Eastern Pendleton- 730 PM EDT Wed Sep 19 2018 This Hazardous Weather Outlook is for eastern West Virginia, northern and central Virginia, and central and western Maryland with the exception of Garrett County. .DAY ONE...Tonight Patchy dense fog is possible late tonight. Please refer to the latest River Flood Warnings for the latest on main stem river flooding along the Shenandoah River. .DAYS TWO THROUGH SEVEN...Thursday through Tuesday No hazardous weather is expected at this time. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected at this time. DHOF
The national radar mosaic for the moment the first event began.
13 dense fog. Local standard time, as filed.
Observations from around the area indicate visibility fell to a quarter of a mile or less in dense fog.
Observations from around the area indicate visibility fell to a quarter of a mile or less in dense fog.
Observations from around the area indicate visibility fell to a quarter of a mile or less in dense fog.
Observations from around the area indicate visibility fell to a quarter of a mile or less in dense fog.
Observations from around the area indicate visibility fell to a quarter of a mile or less in dense fog.
Observations from around the area indicate visibility fell to a quarter of a mile or less in dense fog.
Observations from around the area indicate visibility fell to a quarter of a mile or less in dense fog.
Observations from around the area indicate visibility fell to a quarter of a mile or less in dense fog.
Observations from around the area indicate visibility fell to a quarter of a mile or less in dense fog.
Observations from around the area indicate visibility fell to a quarter of a mile or less in dense fog.
Observations from around the area indicate visibility fell to a quarter of a mile or less in dense fog.
Observations from around the area indicate visibility fell to a quarter of a mile or less in dense fog.
Observations from around the area indicate visibility fell to a quarter of a mile or less in dense fog.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Virginia in 2018Every state in 2018This day in weather historyWarnings in Virginia, September 2018
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: 784457, 784458, 784459, 784460, 784461, 784462, 784463, 784464, 784465, 784466, 784467, 784468, 784469.