Alert archive / Maryland / Flash Flood Warnings in 2009

Flash Flood Warning 40, NWS Baltimore/Washington

August 28, 2009Harford County, Maryland

NWS Baltimore/Washington issued this flash flood warning at Aug 28, 2009, 5:00 AM EDT for Harford County, Maryland. It was in force for 77 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, 5:00 AM EDT (09:00 UTC)
Expired: Aug 28, 2009, 6:17 AM EDT
In force: 77 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 09:00 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, 9.0 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: 454 J/kg
Mixed-layer CIN: -24 J/kg
Mixed-layer LCL: 1571 m above ground
0-6 km bulk shear: 17 kt
0-1 km storm-relative helicity: 20 m²/s²
0-3 km storm-relative helicity: 35 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 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, 4:03 AM EDT, 57 minutes earlier.

Area forecast discussion, Aug 28, 4:03 AM EDT, 57 minutes before

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Hazardous weather outlook, Aug 27, 9:58 PM EDT, 7 hours 2 minutes before

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
958 PM EDT THU AUG 27 2009

ANZ530>543-DCZ001-MDZ006-007-011-013-014-016>018-VAZ052>057-
281000-
CHESAPEAKE BAY NORTH OF POOLES ISLAND MD-
CHESAPEAKE BAY FROM POOLES ISLAND TO SANDY POINT MD-
CHESAPEAKE BAY FROM SANDY POINT TO NORTH BEACH MD-
CHESAPEAKE BAY FROM NORTH BEACH TO DRUM POINT MD-
CHESAPEAKE BAY FROM DRUM POINT MD TO SMITH POINT VA-
TIDAL POTOMAC FROM KEY BRIDGE TO INDIAN HEAD MD-
TIDAL POTOMAC FROM INDIAN HEAD TO COBB ISLAND MD-
TIDAL POTOMAC FROM COBB ISLAND MD TO SMITH POINT VA-
PATAPSCO RIVER INCLUDING BALTIMORE HARBOR-
CHESTER RIVER TO QUEENSTOWN MD-EASTERN BAY-
CHOPTANK RIVER TO CAMBRIDGE MD AND THE LITTLE CHOPTANK RIVER-
PATUXENT RIVER TO BROOMES ISLAND MD-
TANGIER SOUND AND THE INLAND WATERS SURROUNDING BLOODSWORTH
ISLAND-DISTRICT OF COLUMBIA-NORTHERN BALTIMORE-HARFORD-
SOUTHERN BALTIMORE-PRINCE GEORGES-ANNE ARUNDEL-CHARLES-ST. MARYS-
CALVERT-PRINCE WILLIAM/MANASSAS/MANASSAS PARK-FAIRFAX-
ARLINGTON/FALLS CHURCH/ALEXANDRIA-STAFFORD-SPOTSYLVANIA-
KING GEORGE-
958 PM EDT THU AUG 27 2009

THIS HAZARDOUS WEATHER OUTLOOK IS FOR THE MARYLAND PORTION OF THE
CHESAPEAKE BAY...TIDAL POTOMAC RIVER...AND ADJACENT COUNTIES IN
CENTRAL MARYLAND AND NORTHERN VIRGINIA AS WELL AS THE DISTRICT OF
COLUMBIA.

.DAY ONE...TONIGHT

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY

AN UPPER LEVEL DISTURBANCE ALONG THE GULF COAST WILL MOVE TO THE
NORTH...CROSSING THE AREA FRIDAY AFTERNOON AND EVENING. WITH
PLENTY OF MOISTURE AVAILABLE...PERIODS OF MODERATE TO HEAVY RAIN
WILL BE POSSIBLE.

TROPICAL STORM DANNY IS FORECAST TO TRACK NORTH-NORTHEAST OFF THE
MID ATLANTIC COAST LATE FRIDAY NIGHT INTO SATURDAY. WHILE THE
LATEST NATIONAL HURRICANE CENTER FORECAST KEEPS DANNY OFFSHORE...
COASTAL RESIDENTS SHOULD MONITOR LATER FORECASTS FOR TRACK
UPDATES.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL NOT BE NEEDED THROUGH TONIGHT.

MDZ003>005-009-010-501-502-VAZ021-025>031-036>042-050-051-
WVZ050>055-501>504-281000-
WASHINGTON-FREDERICK MD-CARROLL-MONTGOMERY-HOWARD-
EXTREME WESTERN ALLEGANY-CENTRAL AND EASTERN ALLEGANY-HIGHLAND-
AUGUSTA-ROCKINGHAM-SHENANDOAH-FREDERICK VA-PAGE-WARREN-CLARKE-
NELSON-ALBEMARLE-GREENE-MADISON-RAPPAHANNOCK-FAUQUIER-LOUDOUN-
ORANGE-CULPEPER-HAMPSHIRE-MORGAN-BERKELEY-JEFFERSON-PENDLETON-
HARDY-WESTERN GRANT-EASTERN GRANT-WESTERN MINERAL-EASTERN MINERAL-
958 PM EDT THU AUG 27 2009

THIS HAZARDOUS WEATHER OUTLOOK IS FOR EASTERN WEST VIRGINIA...
NORTHERN AND CENTRAL VIRGINIA...AND CENTRAL AND WESTERN MARYLAND
WITH THE EXCEPTION OF GARRETT COUNTY.

.DAY ONE...TONIGHT

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY

AN UPPER LEVEL DISTURBANCE ALONG THE GULF COAST WILL MOVE TO THE
NORTH...CROSSING THE AREA FRIDAY AFTERNOON AND EVENING. WITH
PLENTY OF MOISTURE AVAILABLE...PERIODS OF MODERATE TO HEAVY RAIN
WILL BE POSSIBLE.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL NOT BE NEEDED THROUGH TONIGHT.

In the hours before

Special weather statement, Aug 28, 1:52 AM EDT, 3 hours 8 minutes before

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Special weather statement, Aug 28, 2:11 AM EDT, 2 hours 49 minutes before

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Local storm report, Aug 28, 2:38 AM EDT, 2 hours 22 minutes before

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Special weather statement, Aug 28, 2:59 AM EDT, 2 hours 1 minute before

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Local storm report, Aug 28, 4:46 AM EDT, 14 minutes before

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Local storm report, Aug 28, 4:54 AM EDT, 6 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, 12:13 PM EDT	Severe Thunderstorm Warning	LWX	Prince George's	47 min
Aug 28, 1:29 PM EDT	Flash Flood Warning	LWX	Harford	103 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.