Alert archive / Illinois / Mesoscale Discussions in 2012
Mesoscale Discussion 731
The Storm Prediction Center issued this mesoscale discussion at May 6, 2012, 1:22 PM CDT for 26 counties in Illinois; 19 counties in Missouri. It was in force for 53 min.
The area
The outline as issued.
The facts
- Issued
- May 6, 2012, 1:22 PM CDT (18:22 UTC)
- Expired
- May 6, 2012, 2:15 PM CDT
- In force
- 53 min
- Issued by
- the Storm Prediction Center
- Chance of a watch
- 80%
All 45 counties
Adams County, IL, Brown County, IL, Cass County, IL, Fulton County, IL, Grundy County, IL, Hancock County, IL, Knox County, IL, LaSalle County, IL, Livingston County, IL, Logan County, IL, Marshall County, IL, Mason County, IL, McDonough County, IL, McLean County, IL, Menard County, IL, Morgan County, IL, Peoria County, IL, Pike County, IL, Putnam County, IL, Schuyler County, IL, Scott County, IL, Stark County, IL, Tazewell County, IL, Warren County, IL, Will County, IL, Woodford County, IL, Audrain County, MO, Benton County, MO, Boone County, MO, Callaway County, MO, Chariton County, MO, Cooper County, MO, Howard County, MO, Lafayette County, MO, Lewis County, MO, Marion County, MO, Moniteau County, MO, Monroe County, MO, Morgan County, MO, Pettis County, MO, Pike County, MO, Ralls County, MO, Randolph County, MO, Saline County, MO, Shelby County, MO
The radar
The St Louis radar (KLSX), 145 km from the middle of the area, began a volume at 18:23 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
Davenport, (KDVN), launched 12:00Z, 6.4 hours before the alert went out and 196 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
- 2361 J/kg
- Mixed-layer CIN
- -82 J/kg
- Mixed-layer LCL
- 571 m above ground
- 0-6 km bulk shear
- 31 kt
- 0-1 km storm-relative helicity
- 181 m²/s²
- 0-3 km storm-relative helicity
- 188 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 9.6
The text
As transmitted, in the capitals the NWS used until 2016.
535 ACUS11 KWNS 061823 SWOMCD SPC MCD 061822 ILZ000-MOZ000-IAZ000-061915- MESOSCALE DISCUSSION 0731 NWS STORM PREDICTION CENTER NORMAN OK 0122 PM CDT SUN MAY 06 2012 AREAS AFFECTED...NRN MO...WRN/NRN IL CONCERNING...SEVERE POTENTIAL...WATCH LIKELY VALID 061822Z - 061915Z PROBABILITY OF WATCH ISSUANCE...80 PERCENT SUMMARY...SEVERE THUNDERSTORMS SHOULD INCREASE IN AREAL COVERAGE ALONG AN OUTFLOW/FRONTAL ZONE THAT STRETCHES FROM NRN IL INTO NRN MO OVER THE NEXT FEW HOURS. DISCUSSION...STRONG HEATING IS CONTRIBUTING TO A VERY UNSTABLE AIRMASS ACROSS PARTS OF THE MID MS VALLEY THIS AFTERNOON WITH A CORRIDOR OF INSTABILITY ON THE ORDER OF 3000-4000 J/KG ACROSS MO INTO CNTRL IL. ALTHOUGH DEEP LAYER SHEAR IS NOT PARTICULARLY STRONG...IT APPEARS SEVERE THUNDERSTORMS ARE BECOMING INCREASINGLY LIKELY ALONG AN EXTENSIVE OUTFLOW/FRONTAL ZONE THAT STRETCHES FROM NRN IL...INTO NRN MO. RECENT CONVECTIVE DEVELOPMENT ALONG THIS ZONE JUST EAST OF MCI AND EAST OF MLI SUGGEST A MORE FAVORABLE BOUNDARY LAYER FOR ROBUST UPDRAFTS. WITH AN EXPANDING WARM SECTOR CU FIELD IT APPEARS ADDITIONAL STORMS ARE LIKELY TO DEVELOP WITH A SUBSEQUENT ESEWD MOVEMENT OFF THE BOUNDARY INTO A VERY BUOYANT AIRMASS. LARGE HAIL CAN BE EXPECTED ALONG WITH POTENTIALLY DAMAGING WINDS. ALONG THE NRN OUTFLOW ACROSS NRN IL SHEAR PROFILES ARE A BIT MORE FAVORABLE FOR ROTATING UPDRAFTS AND ISOLATED SUPERCELL DEVELOPMENT HOWEVER HAIL/WINDS SHOULD PROVE THE DOMINANT THREAT. ..DARROW.. 05/06/2012 ...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT... ATTN...WFO...LOT...ILX...LSX...DVN...SGF...EAX... LAT...LON 38999401 41338976 41628779 40518836 38199329 38999401
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 6, 8:40 AM CDT | Mesoscale Discussion | SPC | Bureau, Fulton, Hancock, Henderson, Henry, Knox and 12 more | 65 min |
| May 6, 9:29 AM CDT | Severe Thunderstorm Watch | SPC | Bureau, Carroll, Fulton, Hancock, Henderson, Henry and 11 more | 4 hr |
| May 6, 1:42 PM CDT | Severe Thunderstorm Watch | SPC | Adams, Brown, Bureau, Cass, Champaign, Cook and 35 more | 7 hr |
| May 6, 3:56 PM CDT | Mesoscale Discussion | SPC | Adams, Brown, Cass, Champaign, DeWitt, Ford and 32 more | 64 min |
| May 6, 5:07 PM CDT | Mesoscale Discussion | SPC | Clark, Edgar, Iroquois, Vermilion | 53 min |
| May 6, 4:55 AM CDT | Mesoscale Discussion | SPC | Atchison, Nodaway, Worth | 2 hr |
| May 6, 2:40 PM CDT | Mesoscale Discussion | SPC | Platte | 95 min |
| May 6, 3:49 PM CDT | Severe Thunderstorm Watch | SPC | Andrew, Bates, Buchanan, Cass, Clay, Clinton and 10 more | 7 hr |
Nearby
Mesoscale Discussions in Illinois, 2012Mesoscale Discussions in Missouri, 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.