Alert archive / Virginia / Severe Thunderstorm Warnings in 2000

Severe Thunderstorm Warning 13, NWS Baltimore/Washington

April 21, 2000Prince William County, Virginia

NWS Baltimore/Washington issued this severe thunderstorm warning at Apr 21, 2000, 2:10 PM EDT for Prince William County, Virginia. It was in force for 50 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: Apr 21, 2000, 2:10 PM EDT (18:10 UTC)
Expired: Apr 21, 2000, 3:00 PM EDT
In force: 50 min
Issued by: NWS Baltimore/Washington
Area: Whole counties

County Prince William County, VA

The radar

The Sterling radar (KLWX), 30 km from the middle of the area, began a volume at 18:14 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 watch it was issued in

The SPC watch in force over the same counties when this warning went out.

Issued	Product	Office	Lasted
Apr 21, 12:00 PM EDT	Severe Thunderstorm Watch	SPC	5 hr

The nearest sounding before it

Washington/Dulle, VA (KIAD), launched 12:00Z, 6.2 hours before the alert went out and 28 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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 626 m above ground
0-6 km bulk shear: 52 kt
0-1 km storm-relative helicity: 230 m²/s²
0-3 km storm-relative helicity: 254 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.

073 
WUUS51 KLWX 211811
SVRWBC
MDC017-033-VAC153-211900-

BULLETIN - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE BALTIMORE-WASHINGTON
210 PM EDT FRI APR 21 2000

THE NATIONAL WEATHER SERVICE IN STERLING VIRGINIA HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  PRINCE GEORGES COUNTY IN CENTRAL MARYLAND
  PRINCE WILLIAM COUNTY IN NORTHERN VIRGINIA
  CHARLES COUNTY IN SOUTHERN MARYLAND

* UNTIL 300 PM EDT

* AT 210 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
  SEVERE THUNDERSTORM  5 MILES WEST OF THOMASON PARK...OR ABOUT 7
  MILES WEST OF QUANTICO...MOVING NORTHEAST AT 30 MPH.

* THE SEVERE THUNDERSTORM WILL BE NEAR...
   THOMASON PARK AT 216 PM EDT
   TRIANGLE AT 218 PM EDT
   DUMFRIES...MONTCLAIR AT 220 PM EDT
   CHERRY HILL...GEORGETOWN VILLAGE AT 224 PM EDT
   MARUMSCO WOODS...MARUMSCO HILLS AT 228 PM EDT

IF YOU ARE CAUGHT OUTSIDE...SEEK SHELTER IN A STRONG BUILDING.
DAMAGING WIND...LARGE HAIL...VERY HEAVY RAIN...AND DEADLY LIGHTNING
ARE ALL POSSIBLE IN SEVERE THUNDERSTORMS. STAY INSIDE AWAY FROM
WINDOWS UNTIL THE STORM HAS PASSED.

AS THE STORM APPROACHES MOVE TO A PLACE OF SAFETY. TUNE INTO NOAA
WEATHER RADIO OR YOUR LOCAL RADIO OR TV STATION FOR THE LATEST
WEATHER INFORMATION.

A SEVERE THUNDERSTORM WATCH REMAINS IN EFFECT UNTIL 500 PM EDT FRIDAY
AFTERNOON FOR AND NORTHWESTERN MARYLAND AND NORTHERN VIRGINIA AND THE
PANHANDLE OF WEST VIRGINIA.

.END/ JM

What forecasters said that day

The local office's own words before this severe thunderstorm 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 severe thunderstorm warning went out at Apr 21, 10:40 AM EDT, 3 hours 30 minutes earlier.

Area forecast discussion, Apr 21, 10:40 AM EDT, 3 hours 30 minutes before

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE/WASHINGTON
1040 AM EDT THU APR 20 2000

PREV FCST HAS GUD HANDLE ON AFTN WX SITN. MANY FAVORABLE FACTORS WL BE
PRESENT TO SUPPORT TSTMS AND PSBL SVR TSTMS.

A VORT MX ROTATING ARND OH VLLY CUTOFF LOW WL MOV OUT OF ERN TN
VLLY AND INTO THE WRN FA BY 18Z. CLRG HAS BN OCCURRING OVR WRN PTNS
OF FA THIS AM CONSISTENT W/DRY SLOT PROGGED BY LAST FEW MDL RUNS.
AT 300 MB...MLDS DID NOT CAPTURE PSN OF 95 KT JET. MDLS HAD JET
CNTRD TOO FAR W OF ITS ACTUAL 12Z PSN OVR GA. SO...FAIRLY STG JET WL BE
MOVG INTO FA THIS AFTN AND RGN WL BE UNDER LF QUAD.

AS UPR LOW HEADS EWD...ATMOS WL CONT TO DESTABILIZE. MODIFIED AM SDNG
GIVES LI OF -5 DEG C. IN ADDITION...SDNG HAD GUD VEERING IN LOW LVLS
AND SRH WAS 221 M/SEC2.

SFC DWPTS WERE IN 50S TO LOWER 60S THIS AM AND 850 MB PLOT SHOWED
PLENTY OF RH.

SFC LOW HAS FORMED NR CHO THIS AM. PRESENCE OF LOW MAY KEEP NRN FA
IN THE CLDS THIS AFTN WHICH WUD INHIBIT INSTAB SOMEWHAT. IN SRN FA
HOWEVER...LOW WL INCR UVV/S.

THINK BEST CHC FOR SVR WX WL BE IN SW ZONES DUE TO CLRG...SFC LOW
AND PROXIMITY OF UPR DYNAMICS. HOWEVER...EXPECT ENTR FA TO HV
TSTMS THIS AF]TN.

LOW WL BE STACKED OVHD TONIGHT AND LINGER ON SAT WHICH WL PROLONG
THE PCPN.

.LWX...SCA MD PTN CHES BAY AND POTOMAC.

ARTHUR

The office that day

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

Issued	Product	Office	Counties	Lasted
Apr 21, 1:32 PM EDT	Severe Thunderstorm Warning	LWX	Culpeper, Fauquier, Spotsylvania, Stafford	43 min
Apr 21, 2:21 PM EDT	Severe Thunderstorm Warning	LWX	Spotsylvania, City of Fredericksburg	24 min

Nearby

Severe Thunderstorm Warnings in Virginia, 2000 Every severe thunderstorm warning in 2000

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.