Alert archive / Nebraska / Mesoscale Discussions in 2005

Mesoscale Discussion 613

April 20, 20059 counties in Colorado; 10 counties in Nebraska; Laramie County, Wyoming

The Storm Prediction Center issued this mesoscale discussion at Apr 20, 2005, 5:23 PM MDT for 9 counties in Colorado; 10 counties in Nebraska; Laramie County, Wyoming. It was in force for 97 min.

The area

The outline as issued.

The facts

Issued: Apr 20, 2005, 5:23 PM MDT (23:23 UTC)
Expired: Apr 20, 2005, 7:00 PM MDT
In force: 97 min
Issued by: the Storm Prediction Center

Counties Adams County, CO, Arapahoe County, CO, Elbert County, CO, Logan County, CO, Morgan County, CO, Phillips County, CO, Sedgwick County, CO, Washington County, CO, Weld County, CO, Banner County, NE, Box Butte County, NE, Cheyenne County, NE, Dawes County, NE, Deuel County, NE, Garden County, NE, Kimball County, NE, Morrill County, NE, Scotts Bluff County, NE, Sioux County, NE, Laramie County, WY

The radar

The Cheyenne radar (KCYS), 111 km from the middle of the area, began a volume at 23:26 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 watches that followed

Watches SPC issued over any of the same counties within four hours of this discussion.

Severe Thunderstorm Watch 170Apr 20, 7:35 PM MDT

The nearest sounding before it

Denver, CO (KDNR), launched 12:00Z, 11.4 hours before the alert went out and 95 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: 578 m above ground
0-6 km bulk shear: 41 kt
0-1 km storm-relative helicity: 61 m²/s²
0-3 km storm-relative helicity: 183 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.

000 
ACUS11 KWNS 202323
SWOMCD
SPC MCD 202323 
NEZ000-COZ000-WYZ000-210100-

MESOSCALE DISCUSSION 0613
NWS STORM PREDICTION CENTER NORMAN OK
0623 PM CDT WED APR 20 2005

AREAS AFFECTED...NERN CO...EXTREME SERN WY AND NEB PNHDL

CONCERNING...SEVERE THUNDERSTORM POTENTIAL 

VALID 202323Z - 210100Z

TSTMS HAVE DEVELOPED ALONG THE CO FRONT RANGE AND WILL LIKELY EXPAND
AND MOVE NEWD THROUGH NERN CO...EXTREME SERN WY AND THE NEB PNHDL
THIS EVENING.  HAIL WILL BE THE PRIMARY SEVERE THREAT AS THE STORMS
BECOME MORE ELEVATED WITH TIME.  ATTM...A WW IS NOT EXPECTED GIVEN
THE APPARENT MARGINALITY OF INSTABILITY.  BUT...IF STORMS INDEED
BECOME STRONGER THAN EXPECTED...A WATCH MAY BE NEEDED.

STRONG LARGE SCALE ASCENT ASSOCIATED WITH A CNTRL ROCKIES UPPER LOW
WAS BEGINNING TO MOVE ONTO THE HIGH PLAINS AND TSTMS HAVE FORMED
VCNTY KDEN SINCE 2300Z.  LATEST ETA AND WRF SUGGEST THAT STORMS WILL
EXPAND TOWARD THE NEB PNHDL THIS EVENING.  FAVORABLE UPSLOPE FLOW
AND MAGNITUDE OF ASCENT WILL ENCOURAGE STORM DEVELOPMENT. 
STEEPENING MID-LEVEL LAPSE RATES WILL BE FAVORABLE FOR STRONGEST
STORMS TO PRODUCE HAIL...DESPITE WEAK MODELED AND OBSERVED
INSTABILITY.

..RACY.. 04/20/2005

...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...LBF...GLD...BOU...CYS...

39320473 40000476 41070514 42250409 42870327 42750251
41620212 40360223 39530283 39500325 39250429

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Apr 19, 6:21 PM MDT	Mesoscale Discussion	SPC	Adams, Arapahoe, Denver, Douglas, Elbert, Kit Carson and 7 more	114 min
Apr 19, 6:38 PM MDT	Mesoscale Discussion	SPC	Antelope, Boone, Burt, Butler, Colfax, Cuming and 22 more	2 hr
Apr 19, 8:30 PM MDT	Severe Thunderstorm Watch	SPC	Blaine, Brown, Buffalo, Custer, Dawson, Garfield and 14 more	8 hr
Apr 19, 9:56 PM MDT	Mesoscale Discussion	SPC	Antelope, Blaine, Boyd, Brown, Buffalo, Cedar and 23 more	94 min
Apr 20, 12:14 AM MDT	Mesoscale Discussion	SPC	Antelope, Boone, Burt, Butler, Cedar, Colfax and 15 more	2 hr
Apr 20, 12:18 AM MDT	Mesoscale Discussion	SPC	Antelope, Boone, Burt, Butler, Cedar, Colfax and 15 more	117 min

Nearby

Mesoscale Discussions in Nebraska, 2005 Mesoscale Discussions in Colorado, 2005 Mesoscale Discussions in Wyoming, 2005 Every mesoscale discussion in 2005

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.