Alert archive / Maryland / Flash Flood Warnings in 2011

Flash Flood Warning 159, NWS Baltimore/Washington

September 9, 2011Baltimore County, Maryland

NWS Baltimore/Washington issued this flash flood warning at Sep 9, 2011, 5:36 AM EDT for Baltimore County, Maryland. 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 9, 2011, 5:36 AM EDT (09:36 UTC)
Expired: Sep 9, 2011, 8:30 AM EDT
In force: 3 hr
Issued by: NWS Baltimore/Washington
Area: Storm-based polygon
Flood severity: None

County Baltimore County, MD

The radar

The Sterling radar (KLWX), 91 km from the middle of the area, began a volume at 09:39 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, 9.6 hours before the alert went out and 87 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: 864 J/kg
Mixed-layer CIN: 0 J/kg
Mixed-layer LCL: 475 m above ground
0-6 km bulk shear: 30 kt
0-1 km storm-relative helicity: 81 m²/s²
0-3 km storm-relative helicity: 123 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 2.8

Open this sounding in Storm Lab

What forecasters said that day

The local office's own words before this flash 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 flash flood warning went out at Sep 9, 4:04 AM EDT, 1 hour 32 minutes earlier.

Area forecast discussion, Sep 9, 4:04 AM EDT, 1 hour 32 minutes before

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Hazardous weather outlook, Sep 9, 5:13 AM EDT, 23 minutes before

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In the hours before

Local storm report, Sep 9, 3:16 AM EDT, 2 hours 20 minutes before

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Local storm report, Sep 9, 3:26 AM EDT, 2 hours 10 minutes before

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Special weather statement, Sep 9, 3:47 AM EDT, 1 hour 49 minutes before

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Local storm report, Sep 9, 4:35 AM EDT, 1 hour 1 minute before

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Local storm report, Sep 9, 4:37 AM EDT, 59 minutes before

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Local storm report, Sep 9, 4:52 AM EDT, 44 minutes before

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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 8, 8:32 PM EDT	Flash Flood Warning	LWX	Arlington, City of Falls Church	4 hr
Sep 8, 9:50 PM EDT	Areal Flood Warning	LWX	Arlington, Fairfax, Loudoun, Prince William, City of Fairfax, City of Falls Church and 2 more	4 hr
Sep 8, 10:16 PM EDT	Special Marine Warning	LWX		39 min
Sep 8, 10:59 PM EDT	Areal Flood Warning	LWX	Arlington, Fairfax, Prince William, Spotsylvania, Stafford, City of Alexandria and 2 more	10 hr
Sep 9, 12:12 AM EDT	Coastal Flood Warning	LWX	Arlington, Fairfax, City of Alexandria, City of Fairfax, City of Falls Church	9 hr
Sep 9, 1:47 AM EDT	Areal Flood Warning	LWX	Fairfax, Loudoun, Prince William, City of Fairfax, City of Manassas, City of Manassas Park	8 hr
Sep 9, 2:28 AM EDT	Areal Flood Warning	LWX	King George	2 hr
Sep 9, 3:47 AM EDT	Special Weather Statement	LWX	Baltimore, City of Baltimore	88 min

Nearby

Flash Flood Warnings in Maryland, 2011 Every flash flood warning in 2011

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.