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.
Every event with a place to put it; 19 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.
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 28, 8:08 PM EST, 4 hours 7 minutes earlier.
Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 908 PM EDT Fri Sep 28 2018 .SYNOPSIS... High pressure will build over the region this weekend and dominate the weather pattern into early next week. A weak cold front will approach from the Great Lakes toward the middle portion of next week. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... High pressure centered over the Ohio Valley this evening will continue pressing eastward into our area overnight. Light winds and mostly clear skies will prevail as a result. The 00z IAD upper air sounding sampled a much drier atmosphere compared to 24 hours ago, registering a precipitable water value of only 0.62" and a plethora of dry air above 850mb. Patchy fog expected tonight for our climatologically favored locations, but guidance not favoring widespread coverage as scattered low level clouds do build back over the area after midnight. The best coverage will be found across the Shenandoah Valley and the Potomac/Virginia Highlands. Flood Warnings continue across the CWA this evening as many rivers and streams are hovering near or above flood stage as a result of the recent rainfall. See the Hydrology section below for more details. Seasonable temperatures forecast tonight, ranging in the 50s to near 60 degrees area wide. Current forecast is on track with no major changes/updates needed. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY NIGHT/... Dry weather conditions expected throughout the weekend as surface high pressure will be centered to our north on Saturday, and then will slowly shift east and offshore into Sunday night while remaining in control. In the meantime, ridging aloft will build over the SE CONUS, which will then expand into the Mid- Atlantic region into Sunday. Light winds during the overnight hours may allow for patchy fog to develop Saturday and Sunday night. Temperatures during this time will near to above normal with high temperatures generally in the 60s to mid 70s and lows in the 50s and 60s. && .LONG TERM /MONDAY THROUGH FRIDAY/... An upper level 500mb high pressure system will build over the southeastern United States on Monday and strengthen through the end of next week. High pressure continues to be in place over the region on Monday. Winds will be light out of the south with skies remain mostly clear. The southerly flow will create warm air advection leading to a slow rise of daytime temperatures up into the mid to upper 70s. Tuesday into Wednesday, a shortwave trough will move near the area Tuesday. A surface low associated with this disturbance will move to the north of our region. A weak frontal boundary associated with this surface low will move through our region late Tuesday into Wednesday. Considering temperatures will be hovering in the 70s this would lead me to believe that the precipitation that forms from this boundary will be more stratiform then convective. Both the 12Z GFS and the 00Z Euro agree the precipitation will likely start Tuesday afternoon and shift out of the region early Wednesday morning. It seems from the models that this will be a drier frontal boundary which is indicated by the low Precipitable water values around a inch and half and the weak southerly flow. The frontal boundary should be completely through our region late Wednesday afternoon. Daytime temperatures should continue to warm through Wednesday. On Thursday, weak high pressure will build behind the frontal boundary but then a warm front looks to approach from the west. The boundary seems to be weaker and the models are in agreement that little to no precipitation is expected at this time on Thursday. Day time temperatures will continue to rise and be above normal in the 80s. && .AVIATION /01Z SATURDAY THROUGH WEDNESDAY/... High pressure will continue settling over the terminals tonight, resulting in predominately calm winds and VFR conditions. Patchy fog may impact mainly CHO with MVFR/IFR VIS, as all other terminals will likely see little to no impact as scattered clouds AOA FL050 return after midnight. VFR conditions will prevail Saturday and Sunday under high pressure, except for the chance for some patchy morning fog, mainly at CHO/MRB. On Monday, skies should remain mostly clear with light winds out of the south. VFR conditions expected. Tuesday, a weak boundary will approach from the west. Skies will become mostly cloudy with light southerly winds. Precipitation should be more stratified then convective. Some SubVFR conditions will be possible. && .MARINE... As high pressure continues to approach the waters from the west, light winds and sub SCA conditions are forecast to persist through the weekend. Atmospheric profiles are suggesting that winds will remain generally light throughout the weekend, while mixing may allow winds to gust into the teens, but it doesn't seem to reach criteria, and if it reaches it, it shouldn't last long enough to issue a Small Craft Advisory. On Monday, winds will be light out of the south with mostly clear skies. No small craft advisories expected at this time. Tuesday, a weak boundary will approach from the west. Rain will be possible with light winds out of the south. Small craft advisories may be needed. && .HYDROLOGY... Here we go again...minor to moderate flooding is relatively widespread across the area, with more than a dozen of our forecast points either in flood or expected to be. Several other larger streams for which we do not provide specific forecasts are still above their flood stages as well. The flooding will take time to work all the way through the river system, with the mainstem Potomac probably remaining above flood stage most of the weekend. That freshwater will ultimately get into the tidal zone near DC -- see the Coastal Flood section of the AFD for details on that. Thankfully, we now remain dry until at least the middle of next week, so there is no additional flood threat other than that for which warnings are already in effect. && .TIDES/COASTAL FLOODING... Light northwest flow behind a departing low pressure system should allow anomalies to gradually decrease through the weekend. The exception will be in locations that are susceptible to increased freshwater effects, mainly GTND2 on the Potomac, where moderate coastal flooding is forecast. Based on the latest forecast information and in light of the water coming down river, have replaced the Coastal Flood Watch for DC with a Warning. The primary impact Saturday afternoon through Sunday morning will be at Georgetown, although Southwest Waterfront will be hovering near the moderate threshold during each high tide. Coastal Flood Advisories are also in effect for Alexandria/Anne Arundel tonight. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...Coastal Flood Warning until 8 PM EDT Sunday for DCZ001. MD...Coastal Flood Advisory until midnight EDT tonight for MDZ014. VA...Coastal Flood Advisory until 2 AM EDT Saturday for VAZ054. WV...None. MARINE...None. && SYNOPSIS...IMR/BKF NEAR TERM...BKF SHORT TERM...IMR LONG TERM...JMG AVIATION...MM/BKF/CJL/JMG MARINE...IMR/BKF/JMG HYDROLOGY...JE TIDES/COASTAL FLOODING...MM/CJL/HTS
Hazardous Weather Outlook National Weather Service Baltimore MD/Washington DC 451 PM EDT Fri Sep 28 2018 ANZ530>543-DCZ001-MDZ011-013-014-016>018-508-VAZ052>057-292100- 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- 451 PM EDT Fri Sep 28 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 A Coastal Flood Warning is in effect for the District of Columbia tonight. Please consult River Flood Warnings for the latest information on main stem river flooding. .DAYS TWO THROUGH SEVEN...Saturday through Thursday The Coastal Flood Warning remains in effect for the District of Columbia through Sunday evening. Main stem river flooding may persist into the first part of the weekend, particularly on the Potomac River basin. .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>506-292100- 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- 451 PM EDT Fri Sep 28 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 Please consult River Flood Warnings for the latest information on main stem river flooding. .DAYS TWO THROUGH SEVEN...Saturday through Thursday Main stem river flooding may persist into the first part of the weekend, particularly on the Potomac River basin. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected at this time.
The national radar mosaic for the moment the first event began.
19 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.
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: 784492, 784493, 784494, 784495, 784496, 784497, 784498, 784499, 784500, 784488, 784489, 784490, 784491, 784487, 784482, 784483, 784484, 784485, 784486.