Alert archive / Maryland / Severe Thunderstorm Warnings in 2017
Severe Thunderstorm Warning 221, NWS Baltimore/Washington
NWS Baltimore/Washington issued this severe thunderstorm warning at Aug 12, 2017, 7:19 PM EDT for 4 counties in Maryland. It was in force for 41 min. No storm report in the archive falls inside the area while it was in force.
The area
The counties it named.
The facts
- Issued
- Aug 12, 2017, 7:19 PM EDT (23:19 UTC)
- Expired
- Aug 12, 2017, 8:00 PM EDT
- In force
- 41 min
- Issued by
- NWS Baltimore/Washington
- Area
- Storm-based polygon
- Hail
- 1.0 in
- Wind
- 60.0 mph
Counties Anne Arundel County, MD, Baltimore County, MD, City of Baltimore, MD, Howard County, MD
The radar
The Sterling radar (KLWX), 76 km from the middle of the area, began a volume at 23:19 UTC, the scan nearest the moment this went out.
Open the radar archive at this moment
The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.
The watch it was issued in
The SPC watch in force over the same counties when this warning went out.
| Issued | Product | Office | Lasted |
|---|---|---|---|
| Aug 12, 4:11 PM EDT | Severe Thunderstorm Watch | SPC | 7 hr |
The nearest sounding before it
Washington/Dulle, VA (KIAD), launched 12:00Z, 11.3 hours before the alert went out and 70 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.
- Mixed-layer CAPE
- 248 J/kg
- Mixed-layer CIN
- -78 J/kg
- Mixed-layer LCL
- 772 m above ground
- 0-6 km bulk shear
- 42 kt
- 0-1 km storm-relative helicity
- 12 m²/s²
- 0-3 km storm-relative helicity
- 78 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
What forecasters said that day
The local office's own words before this severe thunderstorm warning went out, 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 this severe thunderstorm warning went out at Aug 12, 2:52 PM EDT, 4 hours 27 minutes earlier.
Area forecast discussion, Aug 12, 2:52 PM EDT, 4 hours 27 minutes before
Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 252 PM EDT Sat Aug 12 2017 .SYNOPSIS...A cold front will move through the area this evening and become stationary across the Carolinas early in the week. Weak high pressure builds over the area Sunday and holds through mid week. && .NEAR TERM /THROUGH TONIGHT/...Cdfnt is currently moving through wrn PA and the OH river as seen on moisture discontinuity on 24-hr microphysics GOES-16 RGB. Air mass over the area ahead of front has destabilized after morning low clouds and fog with MLCAPE around 1000 J/kg. 0-6 km shear is respectable with around 45 kt, but appears limiting factor for severe storms is strongest forcing will remain north of the Mason-Dixon line. Nevertheless, expect nrms-widespread showers and sct thunderstorms as the front comes through later this evening with best chance of showers between 5PM-9PM. Activity will end from west to east after 8PM but linger through at least midnight in the southeast over srn St. Marys county. Definitely not expecting a repeat of last night. Some low clouds are possible over upslope areas overnight, otherwise lots of high clouds overnight. && .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...Weak high pressure will build over the area Sun and hold through the middle of the week. Low clouds and a few showers will be possible Sun night into Mon as sfc flow turns onshore but it will remain too stable for t-storms. && .LONG TERM /TUESDAY THROUGH SATURDAY/... Upper shortwave/surface reflection should depart to the east of the area Tuesday, leading to a drying trend through the middle of next week as high pressure builds. Decent model agreement through mid week, which includes a stark warming trend by Thursday. Models then diverge on timing/orientation of the next upper level wave and surface front that would in theory bring the next chance of organized precip. && .AVIATION /18Z SATURDAY THROUGH THURSDAY/...A brief t-storm is possible through 01Z tonight. Cdfnt then crosses the area with winds shifting and clouds scattering out. Mainly VFR Tue-Wed. Patchy fog possible Tue night in areas that receive rain if dry advection isn't strong enough prior to nightfall. NW flow AOB 10 kts. && .MARINE...Gusty showers and t-storms possible over the waters this evening. SMWs may be required. Cdfnt crosses the waters late this evening. Generally light winds expected mid-week as high pressure moves over the waters. && .TIDES/COASTAL FLOODING...Minor coastal flooding possible at Straits Point early this evening. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...None. MD...Coastal Flood Advisory until 8 PM EDT this evening for MDZ017. VA...None. WV...None. MARINE...None. && SYNOPSIS...LFR NEAR TERM...LFR SHORT TERM...LFR LONG TERM...DFH AVIATION...LFR/DFH MARINE...LFR/DFH TIDES/COASTAL FLOODING...LFR
Hazardous weather outlook, Aug 12, 6:53 PM EDT, 26 minutes before
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Local storm report, Aug 12, 6:13 PM EDT, 1 hour 6 minutes before
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</html>Local storm report, Aug 12, 6:59 PM EDT, 20 minutes before
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</html>Local storm report, Aug 12, 7:07 PM EDT, 12 minutes before
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</html>The office that day
Everything else NWS Baltimore/Washington issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 11, 8:11 PM EDT | Flash Flood Warning | LWX | Fauquier | 3 hr |
| Aug 11, 8:47 PM EDT | Flash Flood Warning | LWX | Fairfax, Prince William, City of Manassas Park | 3 hr |
| Aug 11, 9:51 PM EDT | Special Marine Warning | LWX | 114 min | |
| Aug 11, 9:52 PM EDT | Small Craft Advisory | LWX | 4 hr | |
| Aug 11, 10:18 PM EDT | Areal Flood Warning | LWX | Fairfax, Prince William, City of Manassas, City of Manassas Park | 6 hr |
| Aug 11, 11:24 PM EDT | Special Marine Warning | LWX | 96 min | |
| Aug 11, 11:40 PM EDT | Special Marine Warning | LWX | 65 min | |
| Aug 12, 12:57 AM EDT | Special Marine Warning | LWX | 63 min | |
| Aug 12, 4:27 AM EDT | Areal Flood Warning | LWX | Prince William, City of Manassas, City of Manassas Park | 5 hr |
| Aug 12, 6:58 AM EDT | Special Marine Warning | LWX | 92 min | |
| Aug 12, 9:25 AM EDT | Areal Flood Warning | LWX | Prince William, City of Manassas, City of Manassas Park | 6 hr |
| Aug 12, 5:58 PM EDT | Severe Thunderstorm Warning | LWX | Loudoun | 47 min |
| Aug 12, 6:25 PM EDT | Special Marine Warning | LWX | 2 hr | |
| Aug 12, 6:30 PM EDT | Severe Thunderstorm Warning | LWX | Loudoun | 17 min |
| Aug 12, 6:34 PM EDT | Special Marine Warning | LWX | 116 min | |
| Aug 12, 7:32 PM EDT | Severe Thunderstorm Warning | LWX | Arlington, Fairfax, City of Alexandria, City of Falls Church | 43 min |
| Aug 12, 7:43 PM EDT | Special Marine Warning | LWX | 2 hr | |
| Aug 11, 9:18 PM EDT | Flash Flood Warning | LWX | Prince George's | 3 hr |
| Aug 11, 10:48 PM EDT | Flash Flood Warning | LWX | Calvert, Charles, Prince George's, Saint Mary's | 3 hr |
| Aug 11, 11:55 PM EDT | Areal Flood Warning | LWX | Prince George's | 6 hr |
| Aug 12, 1:45 PM EDT | Severe Thunderstorm Warning | LWX | Allegany, Washington | 28 min |
| Aug 12, 2:51 PM EDT | Coastal Flood Advisory | LWX | Saint Mary's | 5 hr |
| Aug 12, 3:26 PM EDT | Severe Thunderstorm Warning | LWX | Allegany, Washington | 39 min |
| Aug 12, 3:50 PM EDT | Severe Thunderstorm Warning | LWX | Washington | 40 min |
| Aug 12, 5:00 PM EDT | Severe Thunderstorm Warning | LWX | Frederick, Washington | 45 min |
| Aug 12, 5:56 PM EDT | Severe Thunderstorm Warning | LWX | Carroll, Frederick, Howard, Montgomery | 49 min |
| Aug 12, 7:56 PM EDT | Severe Thunderstorm Warning | LWX | Anne Arundel | 49 min |
Nearby
Severe Thunderstorm Warnings in Maryland, 2017Every severe thunderstorm warning in 2017
Sources
The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.