Alert archive / Maryland / Severe Thunderstorm Warnings in 2020

Severe Thunderstorm Warning 41, NWS Baltimore/Washington

April 9, 2020Anne Arundel County, Prince George's County, Maryland

NWS Baltimore/Washington issued this severe thunderstorm warning at Apr 9, 2020, 12:13 PM EDT for Anne Arundel County, Prince George's County, Maryland. It was in force for 47 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
Apr 9, 2020, 12:13 PM EDT (16:13 UTC)
Expired
Apr 9, 2020, 1:00 PM EDT
In force
47 min
Issued by
NWS Baltimore/Washington
Area
Storm-based polygon
Hail
0.75 in
Wind
60.0 mph

Counties Anne Arundel County, MD, Prince George's County, MD

The radar

The Sterling radar (KLWX), 68 km from the middle of the area, began a volume at 16:14 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.

IssuedProductOfficeLasted
Apr 9, 12:01 PM EDTSevere Thunderstorm WatchSPC4 hr

The nearest sounding before it

Washington/Dulle, VA (KIAD), launched 12:00Z, 4.2 hours before the alert went out and 60 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.

Skew-T log-pSkew-T log-p diagram, Washington/Dulle, VA at 12:00Z on 2020-04-09Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 20 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Washington/Dulle, VA at 12:00Z on 2020-04-09The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 394 square meters per square second.1939587897117Sfc1 km3 km6 km9 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.
Mixed-layer CAPE
20 J/kg
Mixed-layer CIN
-589 J/kg
Mixed-layer LCL
1002 m above ground
0-6 km bulk shear
47 kt
0-1 km storm-relative helicity
394 m²/s²
0-3 km storm-relative helicity
416 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

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 Apr 9, 12:09 PM EDT, 4 minutes earlier.

Area forecast discussion, Apr 9, 12:09 PM EDT, 4 minutes before
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Hazardous weather outlook, Apr 9, 12:06 PM EDT, 7 minutes before
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      <div class="status" id="status">Temporary Notice</div>
      <h1 id="headline">This service is currently unavailable.</h1>
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In the hours before

Local storm report, Apr 9, 8:06 AM EDT, 4 hours 7 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
806 AM EDT THU APR 09 2020

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0725 AM     MARINE TSTM WIND 2 SE COBB ISLAND        38.24N  76.83W
04/09/2020  M39 MPH          ANZ537             MD   BUOY

&&

EVENT NUMBER LWX2000943

DH
Local storm report, Apr 9, 8:09 AM EDT, 4 hours 4 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
809 AM EDT THU APR 09 2020

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0800 AM     MARINE TSTM WIND 7 SSE SAINT GEORGE ISLA 38.01N  76.45W
04/09/2020  M39 MPH          ANZ537             MD   BUOY

&&

EVENT NUMBER LWX2000944

DH
Local storm report, Apr 9, 8:21 AM EDT, 3 hours 52 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
821 AM EDT THU APR 09 2020

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0818 AM     MARINE TSTM WIND POINT LOOKOUT           38.04N  76.32W
04/09/2020  M40 MPH          ANZ537             MD   BUOY

&&

EVENT NUMBER LWX2000945

DH
Local storm report, Apr 9, 8:49 AM EDT, 3 hours 24 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
849 AM EDT THU APR 09 2020

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0847 AM     MARINE TSTM WIND 8 E SMITH ISLAND        37.97N  75.88W
04/09/2020  M40 MPH          ANZ543             MD   BUOY

&&

EVENT NUMBER LWX2000946

DH
Special weather statement, Apr 9, 10:57 AM EDT, 1 hour 16 minutes before
Special Weather Statement
National Weather Service Baltimore MD/Washington DC
1057 AM EDT Thu Apr 9 2020

MDZ003-501-502-VAZ027-028-503-504-WVZ050>053-055-501>506-091615-
Washington-Extreme Western Allegany-Central and Eastern Allegany-
Shenandoah-Frederick VA-Western Highland-Eastern Highland-
Hampshire-Morgan-Berkeley-Jefferson-Hardy-Western Grant-
Eastern Grant-Western Mineral-Eastern Mineral-Western Pendleton-
Eastern Pendleton-
Including the cities of Hagerstown, Frostburg, Cumberland,
Strasburg, Woodstock, Mount Jackson, New Market, Winchester,
Hightown, Monterey, Romney, Paw Paw, Martinsburg, Charles Town,
Shepherdstown, Moorefield, Bayard, Mount Storm, Petersburg,
Elk Garden, Antioch, Keyser, New Creek, Ridgeville, Russelldale,
Headsville, Fort Ashby, Riverton, Brandywine, Franklin, Oak Flat,
Ruddle, and Sugar Grove
1057 AM EDT Thu Apr 9 2020

...SUDDEN ONSET OF GUSTY WINDS...

As of 10:57 AM...a strong cold front accompanied by showers was
located from just east of Cumberland Maryland to Franklin West
Virginia. This front is moving east at about 50 MPH.

A sudden onset of westerly wind gusts in excess of 50 MPH are
expected. This includes eastern West Virginia, western Maryland
and Highland County in western Virginia.

Winds of this magnitude are capable of damaging tents, blowing
around unsecured outdoor objects, and knocking down branches,
trees and power lines resulting in power outages.

The onset of strong winds should reach a line from Hagerstown
Maryland to Martinsburg West Virginia to Moorefield West Virginia
to Monterey Virginia by about 11:30 AM, and then the Catoctins of
northern Maryland to Winchester Virginia to Shenandoah Mountain by
noon. Should showers or thunderstorms along this front intensify
and wind gusts in excess of 58 MPH become imminent, Severe
Thunderstorm Warnings would be issued.

DHOF
Special weather statement, Apr 9, 11:19 AM EDT, 54 minutes before
Special Weather Statement
National Weather Service Baltimore MD/Washington DC
1119 AM EDT Thu Apr 9 2020

DCZ001-MDZ004-005-503>505-VAZ025-026-029>031-038>040-051>054-501-
502-505>508-092130-
District of Columbia-Frederick MD-Carroll-Northwest Montgomery-
Central and Southeast Montgomery-Northwest Howard-Augusta-
Rockingham-Page-Warren-Clarke-Greene-Madison-Rappahannock-
Culpeper-Prince William/Manassas/Manassas Park-Fairfax-
Arlington/Falls Church/Alexandria-Northern Fauquier-
Southern Fauquier-Western Loudoun-Eastern Loudoun-
Northern Virginia Blue Ridge-Central Virginia Blue Ridge-
Including the cities of Washington, Frederick, Ballenger Creek,
Eldersburg, Westminster, Germantown, Damascus, Bethesda,
Rockville, Gaithersburg, Silver Spring, Lisbon, Staunton,
Waynesboro, Stuarts Draft, Harrisonburg, Luray, Shenandoah,
Stanley, Front Royal, Berryville, Stanardsville, Madison,
Culpeper, Dale City, Manassas, Woodbridge, Lake Ridge, Montclair,
Reston, Herndon, Annandale, Centreville, Chantilly, McLean,
Franconia, Arlington, Alexandria, Falls Church, Warrenton,
Turnbull, Purcellville, Leesburg, Ashburn, Sterling, Big Meadows,
and Wintergreen
1119 AM EDT Thu Apr 9 2020

...SUDDEN ONSET OF GUSTY WINDS...

As of 11:15 AM...a strong cold front accompanied by showers and
developing thunderstorms was located from just west of Hagerstown
Maryland to just west of Martinsburg West Virginia to near
Shenandoah Mountain. This front is moving east at about 50 MPH.

A sudden onset of westerly wind gusts in excess of 50 MPH is
expected. This includes north-central Maryland, northern Virginia,
the northern and central Virginia Blue Ridge and the central
Shenandoah Valley.

Winds of this magnitude are capable of damaging tents, blowing
around unsecured outdoor objects, and knocking down branches,
trees and power lines resulting in power outages.

The onset of strong winds should reach a line from Frederick Maryland
to Harrisonburg Virginia by noon, and then approach the Interstate
95 corridor between noon and 1:00 PM. Should showers or
thunderstorms along this front intensify and wind gusts in excess
of 58 MPH become imminent, Severe Thunderstorm Warnings would be
issued.

DHOF

The office that day

Everything else NWS Baltimore/Washington issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Apr 8, 8:13 PM EDTWind AdvisoryLWXAlbemarle, Amherst, Arlington, Augusta, Clarke, Fairfax and 21 more23 hr
Apr 9, 2:42 AM EDTSevere Thunderstorm WarningLWXHighland63 min
Apr 9, 3:14 AM EDTSevere Thunderstorm WarningLWXAugusta, City of Staunton, City of Waynesboro61 min
Apr 9, 5:33 AM EDTSpecial Marine WarningLWX51 min
Apr 9, 7:58 AM EDTSpecial Marine WarningLWX66 min
Apr 9, 11:44 AM EDTSevere Thunderstorm WarningLWXClarke, Frederick, Loudoun, City of Winchester46 min
Apr 9, 12:00 PM EDTSpecial Marine WarningLWX90 min
Apr 9, 12:06 PM EDTSpecial Marine WarningLWX114 min
Apr 9, 12:43 PM EDTSpecial Marine WarningLWX52 min
Apr 9, 12:58 PM EDTSpecial Marine WarningLWX37 min
Apr 9, 7:37 PM EDTGale WarningLWX26 hr
Apr 9, 7:37 PM EDTSmall Craft AdvisoryLWX46 hr
Apr 9, 7:38 PM EDTWind AdvisoryLWXAlbemarle, Amherst, Arlington, Augusta, Clarke, Fairfax and 20 more22 hr
Apr 9, 7:47 PM EDTFreeze WatchLWXAlbemarle, Amherst, Augusta, Clarke, Culpeper, Fauquier and 16 more19 hr
Apr 9, 3:19 AM EDTCoastal Flood AdvisoryLWXAnne Arundel9 hr
Apr 9, 11:51 AM EDTSevere Thunderstorm WarningLWXBaltimore, Carroll, Frederick, Howard, Montgomery39 min
Apr 9, 12:24 PM EDTSevere Thunderstorm WarningLWXBaltimore, Harford, City of Baltimore66 min
Apr 9, 1:16 PM EDTSevere Thunderstorm WarningLWXBaltimore, Carroll, Harford, City of Baltimore18 min
Apr 9, 2:52 AM EDTSevere Thunderstorm WarningLWXGrant, Hardy38 min

Nearby

Severe Thunderstorm Warnings in Maryland, 2020Every severe thunderstorm warning in 2020

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.