Alert archive / Virginia / Flash Flood Watches in 2017

Flash Flood Watch 3, NWS Baltimore/Washington

June 19, 201717 counties in Virginia; 9 counties in Maryland

NWS Baltimore/Washington issued this flash flood watch at Jun 19, 2017, 4:09 AM EDT for 17 counties in Virginia; 9 counties in Maryland. It took effect at Jun 19, 2017, 1:09 PM EDT. It was in force for 5 hr.

The area

The counties it named.

The facts

Issued: Jun 19, 2017, 4:09 AM EDT (08:09 UTC)
In effect from: Jun 19, 2017, 1:09 PM EDT
Expired: Jun 19, 2017, 5:43 PM EDT
In force: 5 hr
Issued by: NWS Baltimore/Washington
Flood severity: None

All 26 counties

Anne Arundel County, MD, Baltimore County, MD, Carroll County, MD, City of Baltimore, MD, Frederick County, MD, Harford County, MD, Howard County, MD, Montgomery County, MD, Prince George's County, MD, Arlington County, VA, City of Alexandria, VA, City of Charlottesville, VA, City of Fairfax, VA, City of Falls Church, VA, City of Fredericksburg, VA, Culpeper County, VA, Fairfax County, VA, Fauquier County, VA, Greene County, VA, Loudoun County, VA, Madison County, VA, Nelson County, VA, Orange County, VA, Rappahannock County, VA, Spotsylvania County, VA, Stafford County, VA

The radar

The Sterling radar (KLWX), 21 km from the middle of the area, began a volume at 08:12 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, 8.2 hours before the alert went out and 19 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: 1336 J/kg
Mixed-layer CIN: -29 J/kg
Mixed-layer LCL: 1366 m above ground
0-6 km bulk shear: 7 kt
0-1 km storm-relative helicity: 115 m²/s²
0-3 km storm-relative helicity: 124 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 watch 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 watch went out at Jun 19, 4:00 AM EDT, 9 minutes earlier.

Area forecast discussion, Jun 19, 4:00 AM EDT, 9 minutes before

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Hazardous weather outlook, Jun 18, 10:56 PM EDT, 5 hours 13 minutes before

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In the hours before

Local storm report, Jun 18, 10:10 PM EDT, 5 hours 59 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
Jun 19, 12:59 PM EDT	Severe Thunderstorm Warning	LWX	Loudoun	46 min
Jun 19, 1:10 PM EDT	Flash Flood Warning	LWX	Nelson	5 hr
Jun 19, 1:49 PM EDT	Severe Thunderstorm Warning	LWX	Albemarle, Nelson	29 min
Jun 19, 1:54 PM EDT	Severe Thunderstorm Warning	LWX	Albemarle, Greene, Madison, Page, Rockingham	51 min
Jun 19, 2:00 PM EDT	Severe Thunderstorm Warning	LWX	Clarke, Fauquier, Frederick, Loudoun, Warren	25 min
Jun 19, 2:07 PM EDT	Severe Thunderstorm Warning	LWX	Loudoun	38 min
Jun 19, 2:17 PM EDT	Severe Thunderstorm Warning	LWX	Culpeper, Fauquier, Madison, Rappahannock	43 min
Jun 19, 2:18 PM EDT	Areal Flood Warning	LWX	Albemarle, Greene, Madison, Page, Rockingham	4 hr
Jun 19, 2:29 PM EDT	Special Marine Warning	LWX		91 min
Jun 19, 2:37 PM EDT	Flash Flood Warning	LWX	Albemarle	3 hr
Jun 19, 2:44 PM EDT	Flash Flood Warning	LWX	Albemarle, Greene, Madison	3 hr
Jun 19, 2:45 PM EDT	Severe Thunderstorm Warning	LWX	Culpeper, Fairfax, Fauquier, Loudoun, Prince William, Rappahannock and 3 more	45 min
Jun 19, 2:50 PM EDT	Special Marine Warning	LWX		115 min
Jun 19, 2:57 PM EDT	Special Marine Warning	LWX		2 hr
Jun 19, 3:00 PM EDT	Severe Thunderstorm Warning	LWX	Loudoun	45 min
Jun 19, 3:19 PM EDT	Severe Thunderstorm Warning	LWX	Arlington, Fairfax, Loudoun, City of Alexandria, City of Fairfax, City of Falls Church	41 min
Jun 19, 3:28 PM EDT	Special Marine Warning	LWX		92 min
Jun 19, 4:08 PM EDT	Special Marine Warning	LWX		2 hr
Jun 19, 4:13 PM EDT	Special Marine Warning	LWX		2 hr
Jun 19, 4:55 PM EDT	Special Marine Warning	LWX		65 min
Jun 19, 5:16 PM EDT	Special Marine Warning	LWX		89 min
Jun 19, 5:58 PM EDT	Special Marine Warning	LWX		92 min
Jun 19, 6:27 PM EDT	Special Marine Warning	LWX		2 hr
Jun 19, 6:45 PM EDT	Special Marine Warning	LWX		2 hr
Jun 19, 12:50 PM EDT	Severe Thunderstorm Warning	LWX	Frederick, Washington	40 min
Jun 19, 1:41 PM EDT	Severe Thunderstorm Warning	LWX	Carroll, Frederick, Washington	49 min
Jun 19, 4:00 PM EDT	Severe Thunderstorm Warning	LWX	Anne Arundel, Howard, Prince George's, City of Baltimore	45 min
Jun 19, 4:49 PM EDT	Severe Thunderstorm Warning	LWX	Calvert, Charles, Saint Mary's	41 min

Nearby

Flash Flood Watches in Virginia, 2017 Flash Flood Watches in Maryland, 2017 Every flash flood watch in 2017

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.