Alert archive / Illinois / Mesoscale Discussions in 2012
Mesoscale Discussion 729
The Storm Prediction Center issued this mesoscale discussion at May 6, 2012, 8:40 AM CDT for 18 counties in Illinois; 15 counties in Iowa. It was in force for 65 min.
The area
The outline as issued.
The facts
- Issued
- May 6, 2012, 8:40 AM CDT (13:40 UTC)
- Expired
- May 6, 2012, 9:45 AM CDT
- In force
- 65 min
- Issued by
- the Storm Prediction Center
- Chance of a watch
- 80%
All 33 counties
Cedar County, IA, Clinton County, IA, Des Moines County, IA, Henry County, IA, Iowa County, IA, Jefferson County, IA, Johnson County, IA, Keokuk County, IA, Lee County, IA, Linn County, IA, Louisa County, IA, Muscatine County, IA, Scott County, IA, Van Buren County, IA, Washington County, IA, Bureau County, IL, Fulton County, IL, Hancock County, IL, Henderson County, IL, Henry County, IL, Knox County, IL, Marshall County, IL, Mason County, IL, McDonough County, IL, Mercer County, IL, Peoria County, IL, Putnam County, IL, Rock Island County, IL, Stark County, IL, Tazewell County, IL, Warren County, IL, Whiteside County, IL, Woodford County, IL
The radar
The Quad Cities radar (KDVN), 57 km from the middle of the area, began a volume at 13:43 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, 1.7 hours before the alert went out and 60 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.
948
ACUS11 KWNS 061341
SWOMCD
SPC MCD 061340
ILZ000-IAZ000-MOZ000-061445-
MESOSCALE DISCUSSION 0729
NWS STORM PREDICTION CENTER NORMAN OK
0840 AM CDT SUN MAY 06 2012
AREAS AFFECTED...ERN IA / NWRN IL
CONCERNING...SEVERE POTENTIAL...WATCH LIKELY
VALID 061340Z - 061445Z
PROBABILITY OF WATCH ISSUANCE...80 PERCENT
SUMMARY...THE THREAT FOR DAMAGING WINDS AND SOME HAIL IS EXPECTED TO
INCREASE ACROSS THE AREA THIS MORNING IN CONJUNCTION WITH BOWING
MCS. A WW WILL LIKELY BE REQUIRED.
DISCUSSION...AS OF 1330Z...DMX RADAR SHOWED A BOWING MCS FROM DALLAS
AND POLK COUNTIES SWD TO CLARK AND DECATUR COUNTIES WITH SYSTEM
MOVING EWD AT AROUND 35 KT. ON IT/S CURRENT TRACK...IT WILL MOVE E
OF WW 255 BY ABOUT 1430Z. 13Z SURFACE ANALYSIS INDICATES THAT THE
BOW IS SITUATED ALONG THE IMMEDIATE COOL SIDE OF A STATIONARY FRONT
WHICH EXTENDS EWD INTO CNTRL IL. 12Z SOUNDINGS FROM DVN AND ILX
REVEALED A NEAR-GROUND STABLE LAYER...BUT A VERY MOIST LOW-LEVEL
ENVIRONMENT AND STEEP MIDLEVEL LAPSE RATES WITH MUCAPE VALUES
ESTIMATED UPWARDS OF 4000-5000 J/KG.
DAYTIME HEATING DOWNSTREAM FROM MCS SHOULD ALLOW IT TO BECOME
PROGRESSIVELY MORE ROOTED WITHIN THE BOUNDARY LAYER THIS MORNING.
AND WHILE DEEP-LAYER WIND FIELD IS NOT OVERLY SUPPORTIVE OF AN
ORGANIZED SYSTEM...THE EXTREME INSTABILITY AND GROWING COLD POOL
SHOULD ALLOW THE BOW TO FURTHER EVOLVE WITH AN ASSOCIATED RISK FOR
DAMAGING WINDS AND PERHAPS SOME HAIL.
..MEAD.. 05/06/2012
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...LOT...ILX...DVN...
LAT...LON 41889227 42159185 42089049 41858980 41368901 40648909
40178962 40159026 40259094 40439157 40609208 41889227SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 6, 9:29 AM CDT | Severe Thunderstorm Watch | SPC | Bureau, Carroll, Fulton, Hancock, Henderson, Henry and 11 more | 4 hr |
| May 6, 1:22 PM CDT | Mesoscale Discussion | SPC | Adams, Brown, Cass, Fulton, Grundy, Hancock and 20 more | 53 min |
| 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 5, 10:03 PM CDT | Severe Thunderstorm Watch | SPC | Buena Vista, Cherokee, Clay, Dickinson, Ida, Lyon and 6 more | 7 hr |
| May 5, 11:31 PM CDT | Mesoscale Discussion | SPC | Lyon | 89 min |
| May 6, 2:12 AM CDT | Mesoscale Discussion | SPC | Buena Vista, Butler, Cerro Gordo, Cherokee, Clay, Dickinson and 17 more | 63 min |
| May 6, 4:55 AM CDT | Mesoscale Discussion | SPC | Adair, Adams, Audubon, Cass, Fremont, Guthrie and 8 more | 2 hr |
| May 6, 7:17 AM CDT | Severe Thunderstorm Watch | SPC | Adair, Adams, Appanoose, Clarke, Dallas, Davis and 16 more | 6 hr |
Nearby
Mesoscale Discussions in Illinois, 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.