Alert archive / Maryland / Flash Flood Warnings in 2008

Flash Flood Warning 20, NWS Baltimore/Washington

September 6, 2008Harford County, Maryland

NWS Baltimore/Washington issued this flash flood warning at Sep 6, 2008, 4:38 PM EDT for Harford County, Maryland. It was in force for 4 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 6, 2008, 4:38 PM EDT (20:38 UTC)
Expired: Sep 6, 2008, 9:02 PM EDT
In force: 4 hr
Issued by: NWS Baltimore/Washington
Area: Storm-based polygon
Flood severity: None

County Harford County, MD

The radar

The Dover AFB radar (KDOX), 108 km from the middle of the area, began a volume at 20:38 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, 8.6 hours before the alert went out and 115 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: 439 J/kg
Mixed-layer CIN: -1 J/kg
Mixed-layer LCL: 477 m above ground
0-6 km bulk shear: 23 kt
0-1 km storm-relative helicity: 111 m²/s²
0-3 km storm-relative helicity: 91 m²/s²
Significant tornado parameter: 0.1
Supercell composite: 1.0

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 6, 3:19 PM EDT, 1 hour 19 minutes earlier.

Area forecast discussion, Sep 6, 3:19 PM EDT, 1 hour 19 minutes before

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Hazardous weather outlook, Sep 6, 11:22 AM EDT, 5 hours 16 minutes before

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In the hours before

Local storm report, Sep 6, 2:42 PM EDT, 1 hour 56 minutes before

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Local storm report, Sep 6, 2:46 PM EDT, 1 hour 52 minutes before

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Local storm report, Sep 6, 2:47 PM EDT, 1 hour 51 minutes before

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Local storm report, Sep 6, 2:52 PM EDT, 1 hour 46 minutes before

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Local storm report, Sep 6, 3:37 PM EDT, 1 hour 1 minute before

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Local storm report, Sep 6, 4:36 PM EDT, 2 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 6, 8:38 AM EDT	Flash Flood Warning	LWX	Albemarle, Nelson, City of Charlottesville	6 hr
Sep 6, 11:20 AM EDT	Flash Flood Warning	LWX	Arlington, Fairfax, Orange, Prince William, Spotsylvania, Stafford and 2 more	6 hr
Sep 6, 11:53 AM EDT	Flash Flood Warning	LWX	Culpeper	3 hr
Sep 6, 12:20 PM EDT	Flash Flood Warning	LWX	Loudoun	6 hr
Sep 6, 12:38 PM EDT	Flash Flood Warning	LWX	Madison	4 hr
Sep 6, 5:13 PM EDT	Areal Flood Warning	LWX	Arlington, Fairfax, Prince William, Stafford, City of Alexandria, City of Fairfax and 3 more	4 hr
Sep 6, 6:10 PM EDT	Areal Flood Warning	LWX	Loudoun	3 hr
Sep 6, 1:58 PM EDT	Flash Flood Warning	LWX	Frederick	5 hr
Sep 6, 3:12 PM EDT	Flash Flood Warning	LWX	Carroll	5 hr

Nearby

Flash Flood Warnings in Maryland, 2008 Every flash flood warning in 2008

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.