Alert archive / Iowa / Mesoscale Discussions in 2012
Mesoscale Discussion 843
The Storm Prediction Center issued this mesoscale discussion at May 19, 2012, 8:11 PM CDT for 19 counties in Iowa; Burt County, Washington County, Nebraska. It was in force for 64 min.
The area
The outline as issued.
The facts
- Issued
- May 19, 2012, 8:11 PM CDT (01:11 UTC)
- Expired
- May 19, 2012, 9:15 PM CDT
- In force
- 64 min
- Issued by
- the Storm Prediction Center
All 21 counties
Audubon County, IA, Buena Vista County, IA, Calhoun County, IA, Carroll County, IA, Cass County, IA, Cherokee County, IA, Clay County, IA, Crawford County, IA, Harrison County, IA, Humboldt County, IA, Ida County, IA, Monona County, IA, O'Brien County, IA, Palo Alto County, IA, Pocahontas County, IA, Pottawattamie County, IA, Sac County, IA, Shelby County, IA, Woodbury County, IA, Burt County, NE, Washington County, NE
The radar
The Omaha radar (KOAX), 125 km from the middle of the area, began a volume at 01:11 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
Omaha, NE (KOAX), launched 00:00Z, 1.2 hours before the alert went out and 125 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
- 1597 J/kg
- Mixed-layer CIN
- -7 J/kg
- Mixed-layer LCL
- 1383 m above ground
- 0-6 km bulk shear
- 39 kt
- 0-1 km storm-relative helicity
- 122 m²/s²
- 0-3 km storm-relative helicity
- 188 m²/s²
- Significant tornado parameter
- 0.8
- Supercell composite
- 8.3
The text
As transmitted, in the capitals the NWS used until 2016.
933
ACUS11 KWNS 200111
SWOMCD
SPC MCD 200111
IAZ000-NEZ000-200215-
MESOSCALE DISCUSSION 0843
NWS STORM PREDICTION CENTER NORMAN OK
0811 PM CDT SAT MAY 19 2012
AREAS AFFECTED...ERN NEB...WRN IA
CONCERNING...SEVERE THUNDERSTORM WATCH 281...283...
VALID 200111Z - 200215Z
THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH
281...283...CONTINUES.
SUMMARY...SEVERE WIND/HAIL RISK EXISTS WITH A SMALL MCS MOVING NEWD
ACROSS THE MO VALLEY.
DISCUSSION...GREATEST SEVERE WIND RISK SHOULD PERSIST DURING THE
NEXT COUPLE OF HOURS ALONG THE SERN EXTENT OF A CLUSTER ALONG THE
NEB/IA BORDER...REF 57 KT AND 47 KT WIND GUSTS OBSERVED AT KLNK AND
KTQE SINCE 0035Z. THIS RISK IS SUPPORTED BY DCAPE AOA 1000 J/KG PER
MODIFIED 00Z OAX RAOB AND CO-LOCATION OF A MESOLOW ALONG THE
COMPOSITE OUTFLOW/FRONT. MID-LEVEL RADAR REFLECTIVITY INDICATES
CORES HAVE BEEN LARGELY WEAKENING OVER THE PAST HOUR...SUGGESTIVE OF
A MORE MARGINAL HAIL RISK AND THE PRIMARY TRANSITION TO DAMAGING
WINDS. THE LATTER THREAT SHOULD BE AIDED BY A MID-LEVEL SPEED MAX
ATTENDANT TO THE SHORT WAVE IMPULSE OVER CNTRL NEB...WHICH MAY BE
ABLE TO MITIGATE THE EFFECTS OF NOCTURNAL COOLING AMIDST 20-25 DEG F
SURFACE DEW POINT DEPRESSIONS IN THE WARM SECTOR...AS THE CLUSTER
EVOLVES INTO WW 283.
..GRAMS.. 05/20/2012
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...DMX...FSD...OAX...
LAT...LON 42139650 43059574 43329524 43329475 43249433 43009411
42419419 41389481 41229517 41149551 41139589 41289614
41439626 42139650SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 19, 9:18 PM CDT | Mesoscale Discussion | SPC | Mills, Pottawattamie | 57 min |
| May 19, 10:33 PM CDT | Mesoscale Discussion | SPC | Audubon, Buena Vista, Calhoun, Carroll, Cass, Cherokee and 20 more | 57 min |
Nearby
Mesoscale Discussions in Iowa, 2012Mesoscale Discussions in Nebraska, 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.