Alert archive / Colorado / Tornado Watches in 2004

Tornado Watch 225

May 20, 200415 counties in Colorado

The Storm Prediction Center issued this tornado watch at May 20, 2004, 6:15 PM MDT for 15 counties in Colorado. It was in force for 5 hr.

The area

The outline as issued.

The facts

Issued: May 20, 2004, 6:15 PM MDT (00:15 UTC)
Expired: May 20, 2004, 11:00 PM MDT
In force: 5 hr
Issued by: the Storm Prediction Center

Counties Adams County, CO, Arapahoe County, CO, Boulder County, CO, Broomfield County, CO, Denver County, CO, Douglas County, CO, El Paso County, CO, Elbert County, CO, Jefferson County, CO, Lincoln County, CO, Logan County, CO, Morgan County, CO, Teller County, CO, Washington County, CO, Weld County, CO

The radar

The Denver radar (KFTG), 30 km from the middle of the area, began a volume at 00:15 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

5 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.

Issued	Product	Office	Counties	Lasted
May 20, 6:22 PM MDT	Severe Thunderstorm Warning	BOU	Weld	53 min
May 20, 7:15 PM MDT	Severe Thunderstorm Warning	BOU	Weld	60 min
May 20, 7:34 PM MDT	Tornado Warning	BOU	Morgan, Weld	56 min
May 20, 8:17 PM MDT	Tornado Warning	BOU	Morgan, Weld	58 min
May 20, 8:56 PM MDT	Tornado Warning	BOU	Washington	49 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

Denver, CO (KDNR), launched 00:00Z, 0.3 hours before the alert went out and 101 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: 1364 J/kg
Mixed-layer CIN: -5 J/kg
Mixed-layer LCL: 2205 m above ground
0-6 km bulk shear: 60 kt
0-1 km storm-relative helicity: 128 m²/s²
0-3 km storm-relative helicity: 230 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 6.0

Open this sounding in Storm Lab

The text

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

000 
WWUS20 KWNS 210014
SEL5  
SPC WW 210015
COZ000-210500-

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 225
NWS STORM PREDICTION CENTER NORMAN OK
615 PM MDT THU MAY 20 2004

THE NWS STORM PREDICTION CENTER HAS ISSUED A
TORNADO WATCH FOR PORTIONS OF 

       NORTHEAST COLORADO

EFFECTIVE THIS THURSDAY EVENING FROM 615 PM UNTIL 1100 PM MDT.

TORNADOES...HAIL TO 2 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS
TO 70 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.

THE TORNADO WATCH AREA IS ALONG AND 75 STATUTE MILES NORTH AND
SOUTH OF A LINE FROM 30 MILES WEST OF DENVER COLORADO TO 30 MILES
SOUTHEAST OF AKRON COLORADO.

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 222...WW 223...WW 224...

DISCUSSION...STRONGLY SHEARED PROFILES AND MDT INSTABILITY IN PLACE
E OF FRONT RANGE OF NRN CO.  SURFACE CONVERGENCE VICINITY DEN AND
WEAK CAP EXPECTED TO INITIATE SEVERE THUNDERSTORMS THIS EVENING. 
SUPERCELLS LIKELY... GIVEN THE VEERING SHEAR AND MLCAPE TO 1500 J/KG
ENHANCING THE LARGE HAIL THREAT ALONG WITH POTENTIAL FOR TORNADOES.

AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL
SURFACE AND ALOFT TO 2 INCHES. EXTREME TURBULENCE AND SURFACE WIND
GUSTS TO 60 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 500.
MEAN STORM MOTION VECTOR 26025.


...HALES

405,1052 405,1024 384,1024 384,1052

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
May 20, 9:03 PM MDT	Mesoscale Discussion	SPC	Cheyenne, Kit Carson, Phillips, Yuma	87 min
May 20, 9:04 PM MDT	Mesoscale Discussion	SPC	Adams, Arapahoe, Boulder, Broomfield, Denver, Douglas and 9 more	86 min
May 20, 9:30 PM MDT	Severe Thunderstorm Watch	SPC	Phillips, Sedgwick, Yuma	6 hr

Nearby

Tornado Watches in Colorado, 2004 Every 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.