Alert archive / Virginia / Areal Flood Warnings in 2021

Areal Flood Warning 151, NWS Baltimore/Washington

September 16, 20214 counties in Virginia

NWS Baltimore/Washington issued this areal flood warning at Sep 16, 2021, 4:31 PM EDT for 4 counties in Virginia. It was in force for 3 hr. No storm report in the archive falls inside the area while it was in force.

The area

The counties it named.

The facts

Issued: Sep 16, 2021, 4:31 PM EDT (20:31 UTC)
Expired: Sep 16, 2021, 7:50 PM EDT
In force: 3 hr
Issued by: NWS Baltimore/Washington
Area: Storm-based polygon
Flood severity: None

Counties City of Manassas, VA, City of Manassas Park, VA, Fairfax County, VA, Prince William County, VA

The radar

The Sterling radar (KLWX), 24 km from the middle of the area, began a volume at 20:31 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 12:00Z, 8.5 hours before the alert went out and 20 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: 153 J/kg
Mixed-layer CIN: -184 J/kg
Mixed-layer LCL: 830 m above ground
0-6 km bulk shear: 12 kt
0-1 km storm-relative helicity: 43 m²/s²
0-3 km storm-relative helicity: 114 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 areal flood 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 areal flood warning went out at Sep 16, 3:50 PM EDT, 41 minutes earlier.

Area forecast discussion, Sep 16, 3:50 PM EDT, 41 minutes before

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Hazardous weather outlook, Sep 16, 4:07 PM EDT, 24 minutes before

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In the hours before

Local storm report, Sep 16, 3:48 PM EDT, 43 minutes before

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Local storm report, Sep 16, 4:18 PM EDT, 13 minutes before

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Local storm report, Sep 16, 4:21 PM EDT, 10 minutes before

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Local storm report, Sep 16, 4:24 PM EDT, 7 minutes before

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Local storm report, Sep 16, 4:26 PM EDT, 5 minutes before

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Local storm report, Sep 16, 4:29 PM EDT, 2 minutes before

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      <p id="message2">
        Please try again in a few minutes.
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        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
Sep 15, 9:40 PM EDT	Special Marine Warning	LWX		95 min
Sep 16, 2:44 PM EDT	Flash Flood Watch	LWX	Arlington, Fairfax, Loudoun, City of Alexandria, City of Fairfax, City of Falls Church	6 hr
Sep 16, 3:21 PM EDT	Areal Flood Warning	LWX	Arlington, Fairfax, City of Alexandria, City of Fairfax, City of Falls Church	6 hr
Sep 16, 3:50 PM EDT	Flash Flood Warning Considerable damage threat	LWX	Arlington, Fairfax, City of Alexandria, City of Falls Church	3 hr
Sep 16, 5:31 PM EDT	Flash Flood Warning Considerable damage threat	LWX	Fairfax, City of Alexandria	67 min
Sep 16, 7:47 PM EDT	Small Craft Advisory	LWX		21 hr
Sep 15, 8:24 PM EDT	Areal Flood Warning	LWX	Frederick, Washington	2 hr
Sep 15, 9:38 PM EDT	Severe Thunderstorm Warning	LWX	Baltimore, Cecil, Harford	52 min
Sep 16, 5:36 PM EDT	Areal Flood Warning	LWX	Carroll, Frederick, Howard, Montgomery	6 hr
Sep 16, 6:00 PM EDT	Areal Flood Warning	LWX	Baltimore, City of Baltimore	4 hr
Sep 16, 7:07 PM EDT	Areal Flood Warning	LWX	Carroll, Frederick	6 hr

Nearby

Areal Flood Warnings in Virginia, 2021 Every areal flood warning in 2021

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.