Alert archive / Virginia / Flash Flood Warnings in 1997

Flash Flood Warning 4, NWS Baltimore/Washington

June 18, 1997Clarke County, Virginia

NWS Baltimore/Washington issued this flash flood warning at Jun 18, 1997, 5:26 PM EDT for Clarke County, Virginia. It was in force for 59 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: Jun 18, 1997, 5:26 PM EDT (21:26 UTC)
Expired: Jun 18, 1997, 6:25 PM EDT
In force: 59 min
Issued by: NWS Baltimore/Washington
Area: Whole counties

County Clarke County, VA

The radar

The Sterling radar (KLWX), 47 km from the middle of the area, began a volume at 21:29 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, 9.4 hours before the alert went out and 55 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: 392 J/kg
Mixed-layer CIN: -95 J/kg
Mixed-layer LCL: 671 m above ground
0-6 km bulk shear: 40 kt
0-1 km storm-relative helicity: 156 m²/s²
0-3 km storm-relative helicity: 219 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 2.4

Open this sounding in Storm Lab

The text

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

000 
TTAA00 KWBC 182124
FFWWBC
VAC043-069-171-182225-

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE STERLING VA
526 PM EDT WED JUN 18 1997

THE NATIONAL WEATHER SERVICE IN STERLING VA HAS ISSUED A
FLASH FLOOD WARNING EFFECTIVE UNTIL 625 PM EDT
FOR PEOPLE IN THE FOLLOWING LOCATIONS...

IN NORTHWESTERN VIRGINIA

   ...SHENANDOAH COUNTY
   ...FREDERICK COUNTY IN VIRGINIA
   ...CLARKE COUNTY
 
AT 520 PM NATIUNAL WEATHER SERVICE DOPPER RADAR SHOWED AN AREA OF
INTENSIFYING THUNDERSTORMS OVER SHENANDOAH...CLARKE...AND
FREDERICK COUNTIES. THESE STORMS ARE PRODUCING HEAVY RAIN AS THEY
MOVE NORTHEAST AT 25 MPH.

THESE STORMS WILL CONTINUE TO MOVE SLOWLY NORTHEAST THROUGH THE
THREE COUNTIES BY 625 PM.

BE PREPARED FOR RAINFALL IN EXCESS OF TWO INCHES AN HOUR...RAPID
RISES IN SMALL STREAMS...AND PONDING OF WATER ON ROADS AND IN LOW
PLACES.
 
IF FLASH FLOODING IS OBSERVED...ACT QUICKLY.  MOVE TO ESCAPE FLOOD
WATERS.  DO NOT STAY IN AREAS SUBJECT TO FLOODING WHEN WATER BEGINS
RISING.

BGS

The office that day

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

Issued	Product	Office	Counties	Lasted
Jun 18, 4:29 PM EDT	Tornado Warning	LWX	Frederick, Shenandoah	31 min
Jun 18, 4:41 PM EDT	Severe Thunderstorm Warning	LWX	Warren	49 min
Jun 18, 4:47 PM EDT	Tornado Warning	LWX	Clarke	33 min
Jun 18, 5:01 PM EDT	Severe Thunderstorm Warning	LWX	Loudoun	59 min
Jun 18, 5:06 PM EDT	Severe Thunderstorm Warning	LWX	Fauquier	49 min
Jun 18, 5:15 PM EDT	Tornado Warning	LWX	Loudoun	30 min
Jun 18, 5:26 PM EDT	Flash Flood Warning	LWX	Frederick, Shenandoah	59 min
Jun 18, 5:33 PM EDT	Tornado Warning	LWX	Loudoun	47 min
Jun 18, 5:50 PM EDT	Flash Flood Warning	LWX	Loudoun	2 hr
Jun 18, 6:02 PM EDT	Severe Thunderstorm Warning	LWX	Fairfax	33 min
Jun 18, 6:10 PM EDT	Severe Thunderstorm Warning	LWX	Frederick	60 min
Jun 18, 6:34 PM EDT	Severe Thunderstorm Warning	LWX	Fairfax	31 min
Jun 18, 6:46 PM EDT	Tornado Warning	LWX	Fauquier, Prince William	49 min
Jun 18, 6:52 PM EDT	Severe Thunderstorm Warning	LWX	Arlington, City of Falls Church	48 min
Jun 18, 7:31 PM EDT	Severe Thunderstorm Warning	LWX	King George	59 min
Jun 18, 7:37 PM EDT	Severe Thunderstorm Warning	LWX	Fairfax, City of Fairfax	63 min

Nearby

Flash Flood Warnings in Virginia, 1997 Every flash flood warning in 1997

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.