Alert archive / Maryland / Severe Thunderstorm Warnings in 2020

Severe Thunderstorm Warning 321, NWS Baltimore/Washington

August 1, 2020Washington County, Maryland

NWS Baltimore/Washington issued this severe thunderstorm warning at Aug 1, 2020, 9:07 PM EDT for Washington County, Maryland. It was in force for 38 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 1, 2020, 9:07 PM EDT (01:07 UTC)
Expired: Aug 1, 2020, 9:45 PM EDT
In force: 38 min
Issued by: NWS Baltimore/Washington
Area: Storm-based polygon
Hail: 1.0 in
Wind: 60.0 mph

County Washington County, MD

The radar

The Sterling radar (KLWX), 75 km from the middle of the area, began a volume at 01:11 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 nearest sounding before it

Washington/Dulle, VA (KIAD), launched 00:00Z, 1.1 hours before the alert went out and 81 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-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

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: 878 J/kg
Mixed-layer CIN: -13 J/kg
Mixed-layer LCL: 1054 m above ground
0-6 km bulk shear: 31 kt
0-1 km storm-relative helicity: 73 m²/s²
0-3 km storm-relative helicity: 146 m²/s²
Significant tornado parameter: 0.3
Supercell composite: 2.7

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.

In the hours before

Local storm report, Aug 1, 8:51 PM EDT, 16 minutes before

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Local storm report, Aug 1, 8:53 PM EDT, 14 minutes before

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Local storm report, Aug 1, 8:57 PM EDT, 10 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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        The site you requested is temporarily down for maintenance or an unexpected outage.
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      <p id="message2">
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Local storm report, Aug 1, 9:06 PM EDT, 1 minute before

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<body>
  <main class="wrap">
    <section class="card" role="status" aria-live="polite">
      <div class="status" id="status">Temporary Notice</div>
      <h1 id="headline">This service is currently unavailable.</h1>
      <p id="message1">
        The site you requested is temporarily down for maintenance or an unexpected outage.
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      <p id="message2">
        Please try again in a few minutes.
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      <p class="small" id="detail">
        If you are an administrator, restore upstream service and remove the redirect/fallback rule when normal operations resume.
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The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 1, 8:37 PM EDT	Small Craft Advisory	LWX		4 hr
Aug 2, 2:19 PM EDT	Small Craft Advisory	LWX		27 hr
Aug 2, 3:28 PM EDT	Flash Flood Watch	LWX	Albemarle, Amherst, Arlington, Augusta, Clarke, Culpeper and 26 more	45 hr
Aug 2, 4:56 PM EDT	Tropical Storm Watch	LWX	Arlington, Fairfax, King George, Stafford, City of Alexandria, City of Fairfax and 1 more	18 hr
Aug 2, 5:11 PM EDT	Special Marine Warning	LWX		94 min
Aug 2, 5:19 PM EDT	Coastal Flood Watch	LWX	Arlington, Fairfax, King George, Stafford, City of Alexandria, City of Fairfax and 1 more	24 hr
Aug 1, 8:29 PM EDT	Severe Thunderstorm Warning	LWX	Washington	46 min
Aug 1, 9:40 PM EDT	Areal Flood Warning	LWX	Washington	6 hr
Aug 1, 9:54 PM EDT	Severe Thunderstorm Warning	LWX	Washington	31 min
Aug 2, 3:13 AM EDT	Coastal Flood Advisory	LWX	Anne Arundel	6 hr
Aug 1, 8:56 PM EDT	Areal Flood Warning	LWX	Morgan	103 min

Nearby

Severe Thunderstorm Warnings in Maryland, 2020 Every 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.