Alert archive / Nebraska / Mesoscale Discussions in 2012
Mesoscale Discussion 1882
The Storm Prediction Center issued this mesoscale discussion at Sep 4, 2012, 5:08 PM CDT for Harrison County, Monona County, Iowa; 31 counties in Nebraska. It was in force for 97 min.
The area
The outline as issued.
The facts
- Issued
- Sep 4, 2012, 5:08 PM CDT (22:08 UTC)
- Expired
- Sep 4, 2012, 6:45 PM CDT
- In force
- 97 min
- Issued by
- the Storm Prediction Center
- Chance of a watch
- 40%
All 33 counties
Harrison County, IA, Monona County, IA, Antelope County, NE, Boone County, NE, Burt County, NE, Butler County, NE, Cass County, NE, Cedar County, NE, Colfax County, NE, Cuming County, NE, Dakota County, NE, Dixon County, NE, Dodge County, NE, Douglas County, NE, Fillmore County, NE, Knox County, NE, Lancaster County, NE, Madison County, NE, Merrick County, NE, Nance County, NE, Otoe County, NE, Pierce County, NE, Platte County, NE, Polk County, NE, Saline County, NE, Sarpy County, NE, Saunders County, NE, Seward County, NE, Stanton County, NE, Thurston County, NE, Washington County, NE, Wayne County, NE, York County, NE
The radar
The Omaha radar (KOAX), 87 km from the middle of the area, began a volume at 22:09 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, 10.1 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
- 2282 J/kg
- Mixed-layer CIN
- -145 J/kg
- Mixed-layer LCL
- 807 m above ground
- 0-6 km bulk shear
- 30 kt
- 0-1 km storm-relative helicity
- 101 m²/s²
- 0-3 km storm-relative helicity
- 101 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 1.2
The text
As transmitted, in the capitals the NWS used until 2016.
726
ACUS11 KWNS 042209
SWOMCD
SPC MCD 042208
IAZ000-NEZ000-SDZ000-042345-
MESOSCALE DISCUSSION 1882
NWS STORM PREDICTION CENTER NORMAN OK
0508 PM CDT TUE SEP 04 2012
AREAS AFFECTED...ERN NEB THROUGH EXTREME SERN SD INTO WRN IA
CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE
VALID 042208Z - 042345Z
PROBABILITY OF WATCH ISSUANCE...40 PERCENT
SUMMARY...STORMS DEVELOPING OVER ERN NEB MAY BECOME CAPABLE OF
PRODUCING ISOLATED DAMAGING WIND AND LARGE HAIL. OTHER STORMS MAY
INCREASE OVER WRN IA LATER THIS EVENING. CONVECTIVE TRENDS ARE BEING
MONITORED FOR A POSSIBLE WW.
DISCUSSION...EARLY THIS EVENING A DRYLINE/CONVERGENCE TROUGH AXIS
EXTENDS FROM CNTRL NEB SWWD INTO NWRN KS. A WEAKER CONVERGENCE
BOUNDARY EXISTS OVER SERN NEB. TEMPERATURES HAVE WARMED INTO THE
UPPER 90S TO 100 F AND DEWPOINTS HAVE MIXED INTO THE 40S RESULTING
IN DEEPLY MIXED AND WEAKLY CAPPED BOUNDARY LAYERS. INSTABILITY
REMAINS AOB 1000 J/KG ACROSS MOST OF ERN NEB TO THE WEST OF PRIMARY
MOIST AXIS WITH MUCH STRONGER INSTABILITY WITH EWD EXTENT INTO IA.
HIGH BASED STORMS SHOULD CONTINUE DEVELOPING ALONG PREVIOUSLY
MENTIONED BOUNDARIES AND MAY INTENSITY AS THEY ADVANCE EWD. STEEP
LAPSE RATES AND DRY SUBCLOUD LAYERS WILL PROMOTE A THREAT OF
ISOLATED DAMAGING WIND. LARGE HAIL IS ALSO POSSIBLE...ESPECIALLY AS
STORMS DEVELOP EWD AND INTERCEPT STRONGER INSTABILITY.
OTHER STORMS MAY DEVELOP LATER THIS EVENING FROM NERN NEB INTO WRN
IA WITHIN ZONE OF INCREASING WARM ADVECTION AND ISENTROPIC ASCENT
ASSOCIATED WITH STRENGTHENING SWLY LLJ. THESE STORMS WILL ALSO POSE
A THREAT FOR ISOLATED DAMAGING WIND AND LARGE HAIL.
..DIAL/THOMPSON.. 09/04/2012
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...FSD...OAX...GID...LBF...
LAT...LON 40369781 41369818 42519837 42879814 42799692 41769555
40499608 40369781SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Sep 4, 1:33 PM CDT | Mesoscale Discussion | SPC | Allamakee, Bremer, Chickasaw, Clayton, Delaware, Fayette and 2 more | 117 min |
| Sep 4, 3:27 PM CDT | Severe Thunderstorm Watch | SPC | Allamakee, Black Hawk, Bremer, Buchanan, Butler, Chickasaw and 9 more | 8 hr |
| Sep 4, 6:39 PM CDT | Mesoscale Discussion | SPC | Allamakee, Black Hawk, Bremer, Buchanan, Butler, Chickasaw and 9 more | 66 min |
| Sep 3, 7:18 PM CDT | Mesoscale Discussion | SPC | Boyd, Custer, Garfield, Holt, Loup, Rock and 1 more | 87 min |
Nearby
Mesoscale Discussions in Nebraska, 2012Mesoscale Discussions in Iowa, 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.