Alert archive / Iowa / Mesoscale Discussions in 2012
Mesoscale Discussion 1884
The Storm Prediction Center issued this mesoscale discussion at Sep 4, 2012, 7:27 PM CDT for 9 counties in Iowa; 6 counties in Minnesota; 8 counties in South Dakota. It was in force for 63 min.
The area
The outline as issued.
The facts
- Issued
- Sep 4, 2012, 7:27 PM CDT (00:27 UTC)
- Expired
- Sep 4, 2012, 8:30 PM CDT
- In force
- 63 min
- Issued by
- the Storm Prediction Center
- Chance of a watch
- 80%
All 23 counties
Buena Vista County, IA, Cherokee County, IA, Clay County, IA, Dickinson County, IA, Lyon County, IA, O'Brien County, IA, Osceola County, IA, Plymouth County, IA, Sioux County, IA, Cottonwood County, MN, Jackson County, MN, Murray County, MN, Nobles County, MN, Pipestone County, MN, Rock County, MN, Clay County, SD, Lake County, SD, Lincoln County, SD, McCook County, SD, Minnehaha County, SD, Moody County, SD, Turner County, SD, Union County, SD
The radar
The Sioux Falls radar (KFSD), 55 km from the middle of the area, began a volume at 00:29 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 00:00Z, 0.5 hours before the alert went out and 217 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
- 2236 J/kg
- Mixed-layer CIN
- -21 J/kg
- Mixed-layer LCL
- 2432 m above ground
- 0-6 km bulk shear
- 29 kt
- 0-1 km storm-relative helicity
- 37 m²/s²
- 0-3 km storm-relative helicity
- 172 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 7.2
The text
As transmitted, in the capitals the NWS used until 2016.
825 ACUS11 KWNS 050028 SWOMCD SPC MCD 050027 MNZ000-IAZ000-NEZ000-SDZ000-050130- MESOSCALE DISCUSSION 1884 NWS STORM PREDICTION CENTER NORMAN OK 0727 PM CDT TUE SEP 04 2012 AREAS AFFECTED...SERN SD...NERN NEB...NWRN IA AND SWRN MN CONCERNING...SEVERE POTENTIAL...WATCH LIKELY VALID 050027Z - 050130Z PROBABILITY OF WATCH ISSUANCE...80 PERCENT SUMMARY...STORMS MAY CONTINUE TO POSE A THREAT FOR ISOLATED DAMAGING WIND AND LARGE HAIL AS THEY DEVELOP THROUGH THE REMAINDER OF SERN SD AND NE NEB...EVENTUALLY INTO SWRN MN AND NWRN IA. A SEVERE THUNDERSTORM WATCH MAY BE NEEDED SOON. DISCUSSION...STORMS THAT DEVELOPED ALONG DRYLINE PERSIST ACROSS SERN SD INTO NERN NEB. WV IMAGERY SHOWS A LEAD IMPULSE DROPPING SEWD THROUGH SD...AND VWP DATA INDICATES THERE HAS BEEN SOME RESPONSE TO THE LOW LEVEL WIND PROFILES WITH SIOUX FALLS VWP NOW INDICATING A MORE WELL DEFINED WARM ADVECTION PROFILE. AS SWLY LLJ STRENGTHENS...STORMS ARE EXPECTED TO CONTINUE DEVELOPING EWD ALONG INSTABILITY GRADIENT THROUGH SERN SD...NWRN IA AND SWRN MN. SHEAR PROFILES ARE SUFFICIENT FOR A FEW STORMS TO DEVELOP SUPERCELL STRUCTURES...BUT SOME UPSCALE GROWTH INTO LINES AND CLUSTERS MAY ALSO OCCUR. GIVEN THE LARGE TEMPERATURE-DEWPOINT SPREADS...PRIMARY THREATS WILL BE DAMAGING WIND AND LARGE HAIL. ..DIAL/THOMPSON.. 09/05/2012 ...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT... ATTN...WFO...MPX...DMX...FSD... LAT...LON 42389649 43449749 44379730 44349478 42689472 42389649
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Sep 4, 7:45 PM CDT | Severe Thunderstorm Watch | SPC | Buena Vista, Cherokee, Clay, Dickinson, Ida, Lyon and 5 more | 6 hr |
| Sep 4, 8:30 PM CDT | Mesoscale Discussion | SPC | Allamakee, Black Hawk, Bremer, Buchanan, Butler, Chickasaw and 8 more | 60 min |
| Sep 4, 8:51 PM CDT | Severe Thunderstorm Watch | SPC | Buchanan, Clinton, Delaware, Dubuque, Jackson, Jones | 5 hr |
| Sep 4, 9:51 PM CDT | Mesoscale Discussion | SPC | Buena Vista, Calhoun, Cerro Gordo, Clay, Dickinson, Emmet and 12 more | 54 min |
| Sep 4, 10:19 PM CDT | Severe Thunderstorm Watch | SPC | Black Hawk, Bremer, Butler, Calhoun, Cerro Gordo, Emmet and 14 more | 5 hr |
| Sep 4, 11:16 PM CDT | Severe Thunderstorm Watch | SPC | Allamakee, Chickasaw, Clayton, Fayette, Floyd, Howard and 2 more | 4 hr |
| Sep 5, 1:14 AM CDT | Mesoscale Discussion | SPC | Allamakee, Audubon, Benton, Black Hawk, Boone, Bremer and 54 more | 91 min |
| Sep 5, 3:43 AM CDT | Mesoscale Discussion | SPC | Benton, Cedar, Clinton, Des Moines, Dubuque, Henry and 14 more | 92 min |
Nearby
Mesoscale Discussions in Iowa, 2012Mesoscale Discussions in South Dakota, 2012Mesoscale Discussions in Minnesota, 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.