Alert archive / Nebraska / Mesoscale Discussions in 2004

Mesoscale Discussion 2091

August 23, 200411 counties in Nebraska; 5 counties in South Dakota

The Storm Prediction Center issued this mesoscale discussion at Aug 23, 2004, 7:53 PM CDT for 11 counties in Nebraska; 5 counties in South Dakota. It was in force for 97 min.

The area

The outline as issued.

The facts

Issued: Aug 23, 2004, 7:53 PM CDT (00:53 UTC)
Expired: Aug 23, 2004, 9:30 PM CDT
In force: 97 min
Issued by: the Storm Prediction Center

Counties Blaine County, NE, Brown County, NE, Frontier County, NE, Hayes County, NE, Hitchcock County, NE, Hooker County, NE, Keya Paha County, NE, Lincoln County, NE, Logan County, NE, McPherson County, NE, Thomas County, NE, Brule County, SD, Buffalo County, SD, Lyman County, SD, Todd County, SD, Tripp County, SD

The radar

The North Platte radar (KLNX), 28 km from the middle of the area, began a volume at 00:56 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

N. Platte/Lee Bi, NE (KLBF), launched 00:00Z, 0.9 hours before the alert went out and 105 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: 689 J/kg
Mixed-layer CIN: -18 J/kg
Mixed-layer LCL: 2926 m above ground
0-6 km bulk shear: 23 kt
0-1 km storm-relative helicity: 19 m²/s²
0-3 km storm-relative helicity: -1 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.

999 
ACUS11 KWNS 240054
SWOMCD
SPC MCD 240053 
SDZ000-NEZ000-240230-

MESOSCALE DISCUSSION 2091
NWS STORM PREDICTION CENTER NORMAN OK
0753 PM CDT MON AUG 23 2004

AREAS AFFECTED...CNTRL AND SRN SD THROUGH WRN AND CNTRL
NEB...EXTREME NE CO AND NW KS

CONCERNING...SEVERE THUNDERSTORM WATCH 776...

VALID 240053Z - 240230Z

THREAT FOR MAINLY LARGE HAIL AND ISOLATED DAMAGING WIND EXPECTED TO
PERSIST FROM S CNTRL SD SWD THOUGH CNTRL AND SW NEB NEXT 2-3 HOURS.
AREAS E OF WW 776 ACROSS E CNTRL NEB ARE ALSO BEING MONITORED FOR
ADDITIONAL THUNDERSTORM DEVELOPMENT. 

THIS EVENING A DRYLINE EXTENDS FROM CNTRL NEB SWWD TO A WEAK SURFACE
LOW IN SWRN NEB. E OF THIS BOUNDARY...THE ATMOSPHERE REMAINS VERY
UNSTABLE WITH MLCAPE FROM 2500 TO 3000 J/KG. GIVEN THE DEGREE OF
INSTABILITY...SHEAR PROFILES REMAIN SUFFICIENT FOR SUPERCELLS ALONG
AND E OF THE DRYLINE WITH AROUND 30 KT OF 0-6 KM SHEAR. STRONGEST
STORMS REMAIN OVER TRIPP COUNTY IN SRN SD AND CUSTER COUNTY IN NEB
AS OF 0035Z. HOWEVER...WEAK MID LEVEL FLOW IS RESULTING IN VERY SLOW
STORM MOTIONS WITH SOME SWD PROPAGATION WHICH IS ALSO ENHANCING LOW
LEVEL STORM RELATIVE HELICITY.

OTHER STORMS ARE DEVELOPING A LITTLE FARTHER WEST IN W CNTRL NEB
WHERE NUMEROUS OUTFLOW MERGERS ARE OCCURRING. SEVERE THREAT IS MORE
MARGINAL IN THIS AREA DUE TO MORE LIMITED LOW LEVEL MOISTURE.
HOWEVER...STORMS MAY INTENSIFY BRIEFLY AS THEY DEVELOP IN THE
ENHANCED CONVERGENCE ZONE ASSOCIATED WITH MERGING OUTFLOWS. 

OUTFLOW BOUNDARY OVER CNTRL NEB IS SURGING RAPIDLY EWD. THIS MIGHT
PROMOTE ADDITIONAL STORMS DEVELOPING E OF WW 776 THIS EVENING AS IT
INTERCEPTS THE STRONGER INSTABILITY E OF THE DRYLINE.

..DIAL.. 08/24/2004

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

ATTN...WFO...FSD...ABR...GID...LBF...UNR...GLD...

41999971 40310029 40030144 41230159 44210030 44529878

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Aug 24, 3:02 AM CDT	Mesoscale Discussion	SPC	Cass, Gage, Jefferson, Johnson, Lancaster, Nemaha and 4 more	118 min
Aug 24, 5:26 PM CDT	Mesoscale Discussion	SPC	Pawnee, Richardson	3 hr

Nearby

Mesoscale Discussions in Nebraska, 2004 Mesoscale Discussions in South Dakota, 2004 Every mesoscale discussion 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.