Alert archive / Maryland / Tornado Watches in 2004
Tornado Watch 834
The Storm Prediction Center issued this tornado watch at Sep 17, 2004, 3:50 PM EDT for 9 counties in Maryland; 4 counties in Virginia; 4 counties in West Virginia. It was in force for 4 hr.
The area
The outline as issued.
The facts
- Issued
- Sep 17, 2004, 3:50 PM EDT (19:50 UTC)
- Expired
- Sep 17, 2004, 8:00 PM EDT
- In force
- 4 hr
- Issued by
- the Storm Prediction Center
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, Washington County, MD, City of Winchester, VA, Clarke County, VA, Frederick County, VA, Loudoun County, VA, Berkeley County, WV, Hampshire County, WV, Jefferson County, WV, Morgan County, WV
The radar
The Sterling radar (KLWX), 39 km from the middle of the area, began a volume at 19:52 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.
Warnings issued inside it
19 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Sep 17, 4:31 PM EDT | Tornado Warning | LWX | Frederick, City of Winchester | 59 min |
| Sep 17, 4:54 PM EDT | Severe Thunderstorm Warning | LWX | Morgan | 51 min |
| Sep 17, 4:58 PM EDT | Tornado Warning | LWX | Fauquier, Loudoun | 62 min |
| Sep 17, 5:04 PM EDT | Severe Thunderstorm Warning | LWX | Berkeley | 41 min |
| Sep 17, 5:19 PM EDT | Tornado Warning | LWX | Berkeley | 41 min |
| Sep 17, 5:30 PM EDT | Tornado Warning | LWX | Frederick, City of Winchester | 45 min |
| Sep 17, 5:55 PM EDT | Tornado Warning | LWX | Loudoun | 65 min |
| Sep 17, 5:57 PM EDT | Tornado Warning | LWX | Frederick | 63 min |
| Sep 17, 6:01 PM EDT | Tornado Warning | LWX | Washington | 59 min |
| Sep 17, 6:06 PM EDT | Tornado Warning | LWX | Berkeley, Morgan | 54 min |
| Sep 17, 6:16 PM EDT | Tornado Warning | LWX | Frederick | 29 min |
| Sep 17, 6:17 PM EDT | Tornado Warning | LWX | Montgomery | 43 min |
| Sep 17, 6:36 PM EDT | Flash Flood Warning | LWX | Frederick, City of Winchester | 3 hr |
| Sep 17, 6:46 PM EDT | Tornado Warning | LWX | Frederick | 59 min |
| Sep 17, 7:00 PM EDT | Tornado Warning | LWX | Clarke | 60 min |
| Sep 17, 7:03 PM EDT | Flash Flood Warning | LWX | Allegany, Washington | 3 hr |
| Sep 17, 7:21 PM EDT | Flash Flood Warning | LWX | Clarke, Culpeper, Fauquier, Orange, Rappahannock, Warren | 3 hr |
| Sep 17, 7:42 PM EDT | Tornado Warning | LWX | Frederick, Washington | 33 min |
| Sep 17, 7:47 PM EDT | Tornado Warning | LWX | Berkeley | 43 min |
Discussions around it
SPC mesoscale discussions over the same counties from four hours before the watch to its end.
The nearest sounding before it
Washington/Dulle, VA (KIAD), launched 12:00Z, 7.8 hours before the alert went out and 45 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.
- Mixed-layer CAPE
- 105 J/kg
- Mixed-layer CIN
- -89 J/kg
- Mixed-layer LCL
- 687 m above ground
- 0-6 km bulk shear
- 49 kt
- 0-1 km storm-relative helicity
- 74 m²/s²
- 0-3 km storm-relative helicity
- 150 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted, in the capitals the NWS used until 2016.
000
WWUS20 KWNS 171953
SEL4
SPC WW 171950
MDZ000-WVZ000-CWZ000-180000-
URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 834
NWS STORM PREDICTION CENTER NORMAN OK
350 PM EDT FRI SEP 17 2004
THE NWS STORM PREDICTION CENTER HAS ISSUED A
TORNADO WATCH FOR PORTIONS OF
NORTHERN MARYLAND
FAR EASTERN WEST VIRGINIA PANHANDLE
COASTAL WATERS
EFFECTIVE THIS FRIDAY AFTERNOON AND EVENING FROM 350 PM UNTIL 800
PM EDT.
TORNADOES...HAIL TO 0.5 INCH IN DIAMETER...THUNDERSTORM WIND GUSTS
TO 70 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.
THE TORNADO WATCH AREA IS ALONG AND 65 STATUTE MILES EAST AND WEST
OF A LINE FROM 40 MILES SOUTHEAST OF MARTINSBURG WEST VIRGINIA TO
15 MILES EAST NORTHEAST OF HAGERSTOWN MARYLAND.
REMEMBER...A TORNADO WATCH MEANS CONDITIONS ARE FAVORABLE FOR
TORNADOES AND SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH AREA.
PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR THREATENING
WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS AND POSSIBLE
WARNINGS.
OTHER WATCH INFORMATION...CONTINUE...WW 832...WW 833...
DISCUSSION...NARROW AREA OF HEATING AND DESTABILIZATION HAS OCCURRED
JUST NORTH OF TORNADO WATCH 833 INTO NRN MD. GIVEN THE EXTREME LOW
LEVEL SHEAR AND PRESENCE OF SEVERAL ROTATING STORMS NOW MOVING
RAPIDLY NWD ACROSS NRN VA...THE THREAT OF ISOLATED TORNADOES APPEARS
TO EXTEND TO THE MD-PA BORDER REGION INTO THE EVENING.
AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL
SURFACE AND ALOFT TO 0.5 INCH. EXTREME TURBULENCE AND SURFACE WIND
GUSTS TO 60 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 500.
MEAN STORM MOTION VECTOR 19035.
...EVANS
385,0784 394,0784 394,0761 385,0761SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Sep 17, 12:33 PM EDT | Mesoscale Discussion | SPC | Charles, Saint Mary's | 117 min |
| Sep 17, 1:15 PM EDT | Tornado Watch | SPC | Anne Arundel, Calvert, Charles, Prince George's, Saint Mary's | 7 hr |
| Sep 17, 3:33 PM EDT | Mesoscale Discussion | SPC | Anne Arundel, Baltimore, Carroll, Frederick, Harford, Howard and 1 more | 117 min |
| Sep 17, 3:53 PM EDT | Mesoscale Discussion | SPC | Calvert, Charles, Prince George's, Saint Mary's | 2 hr |
| Sep 17, 6:19 PM EDT | Mesoscale Discussion | SPC | Anne Arundel, Baltimore, Calvert, Carroll, Charles, Frederick and 6 more | 116 min |
| Sep 17, 6:50 PM EDT | Tornado Watch | SPC | Anne Arundel, Baltimore, Calvert, Caroline, Carroll, Cecil and 14 more | 5 hr |
| Sep 17, 9:26 AM EDT | Mesoscale Discussion | SPC | Bedford, Campbell, Charlotte, Franklin, Halifax, Henry and 9 more | 2 hr |
| Sep 17, 10:10 AM EDT | Tornado Watch | SPC | Amelia, Appomattox, Bedford, Brunswick, Campbell, Charlotte and 19 more | 7 hr |
| Sep 17, 11:03 AM EDT | Mesoscale Discussion | SPC | Brunswick, Dinwiddie, Greensville, Halifax, Lunenburg, Mecklenburg and 3 more | 87 min |
| Sep 17, 1:37 PM EDT | Mesoscale Discussion | SPC | Appomattox, Brunswick, Campbell, Charlotte, Franklin, Halifax and 8 more | 113 min |
| Sep 17, 4:35 PM EDT | Tornado Watch | SPC | Amelia, Brunswick, Dinwiddie, Greensville, Lunenburg, Mecklenburg and 6 more | 3 hr |
| Sep 17, 7:23 PM EDT | Mesoscale Discussion | SPC | Brunswick | 37 min |
Nearby
Tornado Watches in Maryland, 2004Tornado Watches in Virginia, 2004Tornado Watches in West Virginia, 2004Every tornado watch in 2004
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.