Alert archive / Nebraska / Mesoscale Discussions in 2012
Mesoscale Discussion 879
The Storm Prediction Center issued this mesoscale discussion at May 23, 2012, 2:56 PM CDT for 17 counties in Iowa; 45 counties in Nebraska; Union County, South Dakota. It was in force for 94 min.
The area
The outline as issued.
The facts
- Issued
- May 23, 2012, 2:56 PM CDT (19:56 UTC)
- Expired
- May 23, 2012, 4:30 PM CDT
- In force
- 94 min
- Issued by
- the Storm Prediction Center
- Chance of a watch
- 80%
All 63 counties
Buena Vista County, IA, Carroll County, IA, Cherokee County, IA, Clay County, IA, Crawford County, IA, Harrison County, IA, Ida County, IA, Lyon County, IA, Mills County, IA, Monona County, IA, O'Brien County, IA, Plymouth County, IA, Pottawattamie County, IA, Sac County, IA, Shelby County, IA, Sioux County, IA, Woodbury County, IA, Adams County, NE, Antelope County, NE, Boone County, NE, Buffalo County, NE, Burt County, NE, Butler County, NE, Cass County, NE, Cedar County, NE, Clay County, NE, Colfax County, NE, Cuming County, NE, Dakota County, NE, Dixon County, NE, Dodge County, NE, Douglas County, NE, Fillmore County, NE, Franklin County, NE, Greeley County, NE, Hall County, NE, Hamilton County, NE, Harlan County, NE, Howard County, NE, Kearney County, NE, Lancaster County, NE, Madison County, NE, Merrick County, NE, Nance County, NE, Nuckolls County, NE, Otoe County, NE, Phelps County, NE, Pierce County, NE, Platte County, NE, Polk County, NE, Saline County, NE, Sarpy County, NE, Saunders County, NE, Seward County, NE, Sherman County, NE, Stanton County, NE, Thayer County, NE, Thurston County, NE, Washington County, NE, Wayne County, NE, Webster County, NE, York County, NE, Union County, SD
The radar
The Omaha radar (KOAX), 87 km from the middle of the area, began a volume at 19:54 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.
The nearest sounding before it
Omaha, NE (KOAX), launched 12:00Z, 7.9 hours before the alert went out and 87 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
- 0 J/kg
- Mixed-layer CIN
- No buoyant parcel
- Mixed-layer LCL
- 1627 m above ground
- 0-6 km bulk shear
- 19 kt
- 0-1 km storm-relative helicity
- 271 m²/s²
- 0-3 km storm-relative helicity
- 363 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.1
The text
As transmitted, in the capitals the NWS used until 2016.
179
ACUS11 KWNS 231956
SWOMCD
SPC MCD 231956
IAZ000-NEZ000-SDZ000-KSZ000-232130-
MESOSCALE DISCUSSION 0879
NWS STORM PREDICTION CENTER NORMAN OK
0256 PM CDT WED MAY 23 2012
AREAS AFFECTED...FAR SERN SD...WRN IA...CNTRL/ERN NEB
CONCERNING...SEVERE POTENTIAL...WATCH LIKELY
VALID 231956Z - 232130Z
PROBABILITY OF WATCH ISSUANCE...80 PERCENT
SUMMARY...THUNDERSTORM DEVELOPMENT IS FORECAST TO OCCUR BY LATE
AFTERNOON ACROSS PORTIONS OF FAR SERN SD...WRN IA...AND CNTRL/ERN
NEB. LARGE HAIL AND DAMAGING WINDS WILL BE POSSIBLE. WW IS LIKELY.
DISCUSSION...MESOANALYSIS AT 19Z SHOWED A WEAK SURFACE LOW PRESSURE
CENTER LOCATED INVOF SERN SD/NWRN IA/NERN NEB...WITH A COLD FRONT
EXTENDING SWWD FROM THE LOW INTO N-CNTRL KS. SURFACE TEMPERATURES
AHEAD OF THE COLD FRONT ARE WARMING TO AROUND 90F...WITH DEWPOINTS
IN THE 50S TO NEAR 60F. GIVEN THE PRESENCE OF STEEP MIDLEVEL LAPSE
RATES /NEAR 7 C PER KM IN THE 700-500 MB LAYER/...MLCAPE VALUES HAVE
INCREASED TO 1500 J/KG. SURFACE HEATING ALONG AND AHEAD OF THE FRONT
IS ALSO AIDING IN STRONG BOUNDARY LAYER DESTABILIZATION...WHICH IS
RESULTING IN THE DEVELOPMENT OF AN EXPANSIVE CUMULUS FIELD OVER
CNTRL/ERN NEB. COMBINATION OF BROAD MIDLEVEL HEIGHT FALLS AND
EMBEDDED UPPER PERTURBATIONS...AS WELL AS FRONTAL CONVERGENCE
ENHANCED WITHIN EXIT REGION OF 30-50 KT LLJ SHOULD SUPPORT
THUNDERSTORM DEVELOPMENT BY LATE AFTERNOON...WITH COVERAGE
INCREASING TOWARD NIGHT. MOST LIKELY SCENARIO IS FOR STORMS TO
REMAIN ANCHORED VERY CLOSE TO THE FRONTAL BOUNDARY...WITH ACTIVITY
POSING A THREAT FOR LARGE HAIL GIVEN THE THERMODYNAMIC ENVIRONMENT
COUPLED WITH EFFECTIVE BULK WIND DIFFERENCE VALUES FROM 30-50 KT. IN
ADDITION...UPSCALE GROWTH INTO A LINEAR SYSTEM SUGGESTS DAMAGING
WIND THREAT WILL ALSO EXIST.
..GARNER/WEISS.. 05/23/2012
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...DMX...FSD...OAX...TOP...GID...LBF...
LAT...LON 40589956 41879853 43449617 43109488 42119479 40709587
39909795 39989940 40589956SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 23, 4:07 PM CDT | Severe Thunderstorm Watch | SPC | Audubon, Buena Vista, Calhoun, Carroll, Cherokee, Clay and 23 more | 7 hr |
| May 23, 6:49 PM CDT | Mesoscale Discussion | SPC | Buena Vista, Calhoun, Cherokee, Clay, Crawford, Dickinson and 11 more | 86 min |
| May 22, 7:30 PM CDT | Mesoscale Discussion | SPC | Beadle, Brown, Brule, Buffalo, Campbell, Edmunds and 16 more | 90 min |
| May 22, 8:41 PM CDT | Mesoscale Discussion | SPC | Marshall, Roberts | 64 min |
| May 23, 2:04 PM CDT | Mesoscale Discussion | SPC | Brookings, Deuel, Grant, Hamlin, Lake, McCook and 3 more | 86 min |
Nearby
Mesoscale Discussions in Nebraska, 2012Mesoscale Discussions in Iowa, 2012Mesoscale Discussions in South Dakota, 2012Every mesoscale discussion in 2012
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.