Alert archive / Virginia / Flash Flood Warnings in 2012

Flash Flood Warning 49, NWS Baltimore/Washington

August 9, 2012Frederick County, Virginia

NWS Baltimore/Washington issued this flash flood warning at Aug 9, 2012, 6:01 PM EDT for Frederick County, Virginia. It was in force for 2 hr. 1 report came from inside the area while it was in force.

The area

The outline as issued, with what was reported inside it.

The facts

Issued: Aug 9, 2012, 6:01 PM EDT (22:01 UTC)
Expired: Aug 9, 2012, 8:06 PM EDT
In force: 2 hr
Issued by: NWS Baltimore/Washington
Area: Storm-based polygon
Flood severity: None

County Frederick County, VA

The radar

The Sterling radar (KLWX), 65 km from the middle of the area, began a volume at 22:02 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.

What was reported inside it

Time	Report	Where	Remark
Aug 9, 6:30 PM EDT	FLASH FLOOD	1 Ese Cedar Grove, VA	HIGH WATER

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The nearest sounding before it

Washington/Dulle, VA (KIAD), launched 12:00Z, 10.0 hours before the alert went out and 72 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: 648 J/kg
Mixed-layer CIN: -133 J/kg
Mixed-layer LCL: 1287 m above ground
0-6 km bulk shear: 9 kt
0-1 km storm-relative helicity: 7 m²/s²
0-3 km storm-relative helicity: 28 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

190 
WGUS51 KLWX 092201
FFWLWX
VAC069-100100-
/O.NEW.KLWX.FF.W.0049.120809T2201Z-120810T0100Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
601 PM EDT THU AUG 9 2012

THE NATIONAL WEATHER SERVICE IN STERLING VIRGINIA HAS ISSUED A

* FLASH FLOOD WARNING FOR...
  EAST CENTRAL FREDERICK COUNTY IN NORTHWEST VIRGINIA...

* UNTIL 900 PM EDT

* AT 557 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED
  VERY HEAVY RAIN CAPABLE OF PRODUCING FLASH FLOODING. ADDITIONAL    
  RAINFALL AMOUNTS AROUND 2 INCHES CAN BE EXPECTED.


MOST FLASH FLOOD DEATHS OCCUR IN AUTOMOBILES. NEVER DRIVE YOUR
VEHICLE INTO AREAS WHERE WATER COVERS THE ROAD. FLOODWATER USUALLY IS
DEEPER THAN IT APPEARS. JUST ONE FOOT OF FLOWING WATER IS POWERFUL
ENOUGH TO SWEEP VEHICLES OFF THE ROAD. MAKE THE SMART CHOICE WHEN
FLOODED ROADS ARE ENCOUNTERED...TURN AROUND...DONT DROWN.

LAT...LON 3930 7810 3930 7809 3927 7804 3920 7813
      3922 7824 3936 7818

$$


BJL

1 follow-up statement

054 
WGUS71 KLWX 100006
FFSLWX

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
806 PM EDT THU AUG 9 2012

VAC069-100016-
/O.CAN.KLWX.FF.W.0049.000000T0000Z-120810T0100Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
FREDERICK VA-
806 PM EDT THU AUG 9 2012

...THE FLASH FLOOD WARNING HAS BEEN CANCELLED FOR EAST CENTRAL
FREDERICK COUNTY...

RAIN HAS MOVED OUT OF THE WARNED AREA...THEREFORE THE FLASH FLOOD
WARNING HAS BEEN CANCELLED.

LAT...LON 3930 7810 3930 7809 3927 7804 3920 7813
      3922 7824 3936 7818

$$

KONARIK

The office that day

Everything else NWS Baltimore/Washington issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Aug 9, 1:34 AM EDT	Small Craft Advisory	LWX		28 hr
Aug 9, 6:11 AM EDT	Special Marine Warning	LWX		19 min
Aug 9, 12:45 PM EDT	Special Marine Warning	LWX		60 min
Aug 9, 1:07 PM EDT	Special Weather Statement	LWX	Greene	38 min
Aug 9, 1:08 PM EDT	Special Marine Warning	LWX		43 min
Aug 9, 1:41 PM EDT	Special Marine Warning	LWX		15 min
Aug 9, 3:02 PM EDT	Small Craft Advisory	LWX		29 hr
Aug 9, 3:49 PM EDT	Severe Thunderstorm Warning	LWX	Frederick	41 min
Aug 9, 4:23 PM EDT	Special Weather Statement	LWX	Frederick, City of Winchester	52 min
Aug 9, 4:27 PM EDT	Severe Thunderstorm Warning	LWX	Frederick	48 min
Aug 9, 5:23 PM EDT	Special Weather Statement	LWX	City of Winchester	52 min
Aug 9, 5:36 PM EDT	Special Weather Statement	LWX	Frederick	39 min
Aug 9, 6:16 PM EDT	Special Weather Statement	LWX	Frederick, City of Winchester	44 min
Aug 9, 6:46 PM EDT	Special Weather Statement	LWX	Loudoun	44 min
Aug 9, 6:47 PM EDT	Special Weather Statement	LWX	Loudoun	43 min
Aug 9, 7:19 PM EDT	Severe Thunderstorm Warning	LWX	Loudoun	41 min

Nearby

Flash Flood Warnings in Virginia, 2012 Every flash flood warning in 2012

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.