Alert archive / Maryland / Flash Flood Warnings in 2009

Flash Flood Warning 41, NWS Baltimore/Washington

August 28, 2009Harford County, Maryland

NWS Baltimore/Washington issued this flash flood warning at Aug 28, 2009, 1:29 PM EDT for Harford County, Maryland. It was in force for 103 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 28, 2009, 1:29 PM EDT (17:29 UTC)
Expired: Aug 28, 2009, 3:12 PM EDT
In force: 103 min
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 17:33 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

Wallops Is Stn, VA (KWAL), launched 12:00Z, 5.5 hours before the alert went out and 195 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: 2064 J/kg
Mixed-layer CIN: -19 J/kg
Mixed-layer LCL: 762 m above ground
0-6 km bulk shear: 15 kt
0-1 km storm-relative helicity: 21 m²/s²
0-3 km storm-relative helicity: 38 m²/s²
Significant tornado parameter: 0.0
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 Aug 28, 11:18 AM EDT, 2 hours 11 minutes earlier.

Area forecast discussion, Aug 28, 11:18 AM EDT, 2 hours 11 minutes before

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Hazardous weather outlook, Aug 28, 11:23 AM EDT, 2 hours 6 minutes before

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In the hours before

Special weather statement, Aug 28, 9:17 AM EDT, 4 hours 12 minutes before

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Special weather statement, Aug 28, 11:55 AM EDT, 1 hour 34 minutes before

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Special weather statement, Aug 28, 12:03 PM EDT, 1 hour 26 minutes before

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Special weather statement, Aug 28, 12:07 PM EDT, 1 hour 22 minutes before

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Special weather statement, Aug 28, 1:04 PM EDT, 25 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
Aug 28, 12:43 AM EDT	Special Marine Warning	LWX		92 min
Aug 28, 1:49 AM EDT	Special Marine Warning	LWX		86 min
Aug 28, 2:22 AM EDT	Special Marine Warning	LWX		113 min
Aug 28, 5:50 AM EDT	Flash Flood Watch	LWX	Arlington, Fairfax, City of Alexandria, City of Fairfax, City of Falls Church	22 hr
Aug 28, 11:59 AM EDT	Special Marine Warning	LWX		91 min
Aug 28, 1:10 PM EDT	Special Marine Warning	LWX		95 min
Aug 28, 3:57 PM EDT	Small Craft Advisory	LWX		12 hr
Aug 28, 12:12 AM EDT	Flash Flood Warning	LWX	Carroll	4 hr
Aug 28, 12:29 AM EDT	Flash Flood Warning	LWX	Baltimore	4 hr
Aug 28, 1:01 AM EDT	Flash Flood Warning	LWX	Harford	4 hr
Aug 28, 5:00 AM EDT	Flash Flood Warning	LWX	Harford	77 min
Aug 28, 12:13 PM EDT	Severe Thunderstorm Warning	LWX	Prince George's	47 min
Aug 28, 1:47 PM EDT	Flash Flood Warning	LWX	Carroll, Frederick, Howard, Montgomery	103 min

Nearby

Flash Flood Warnings in Maryland, 2009 Every flash flood warning in 2009

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.