Alert archive / Illinois / Mesoscale Discussions in 2012
Mesoscale Discussion 1896
The Storm Prediction Center issued this mesoscale discussion at Sep 5, 2012, 4:02 PM CDT for 13 counties in Illinois; 5 counties in Wisconsin. It was in force for 88 min.
The area
The outline as issued.
The facts
- Issued
- Sep 5, 2012, 4:02 PM CDT (21:02 UTC)
- Expired
- Sep 5, 2012, 5:30 PM CDT
- In force
- 88 min
- Issued by
- the Storm Prediction Center
- Chance of a watch
- 40%
Counties Boone County, IL, Carroll County, IL, Cook County, IL, DeKalb County, IL, DuPage County, IL, Jo Daviess County, IL, Kane County, IL, Lake County, IL, Lee County, IL, McHenry County, IL, Ogle County, IL, Stephenson County, IL, Winnebago County, IL, Green County, WI, Kenosha County, WI, Lafayette County, WI, Rock County, WI, Walworth County, WI
The radar
The Chicago radar (KLOT), 67 km from the middle of the area, began a volume at 21:05 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
Davenport, (KDVN), launched 12:00Z, 9.0 hours before the alert went out and 179 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
- 375 J/kg
- Mixed-layer CIN
- -258 J/kg
- Mixed-layer LCL
- 1604 m above ground
- 0-6 km bulk shear
- 47 kt
- 0-1 km storm-relative helicity
- 244 m²/s²
- 0-3 km storm-relative helicity
- 298 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 1.0
The text
As transmitted, in the capitals the NWS used until 2016.
255
ACUS11 KWNS 052102
SWOMCD
SPC MCD 052102
INZ000-ILZ000-WIZ000-IAZ000-052230-
MESOSCALE DISCUSSION 1896
NWS STORM PREDICTION CENTER NORMAN OK
0402 PM CDT WED SEP 05 2012
AREAS AFFECTED...NRN IL...SRN WI
CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE
VALID 052102Z - 052230Z
PROBABILITY OF WATCH ISSUANCE...40 PERCENT
SUMMARY...A CONDITIONAL THREAT OF SUPERCELLS WITH LARGE HAIL AND
DAMAGING WINDS EXISTS ACROSS FAR NRN IL AND SRN WI...AND THE AREA IS
BEING MONITORED FOR POSSIBLE DEVELOPMENT.
DISCUSSION...THE AIR MASS ACROSS THE REGION WAS AFFECTED BY EARLY
DAY CONVECTION...BUT SOME RECOVERY HAS TAKEN PLACE. STREAMLINES ARE
CONVERGING OVER THE AREA BUT SOME CAPPING EXISTS. THE SURFACE
THETA-E AXIS REMAINS W OF THE AREA...BUT MORE BUOYANT AIR MAY
EVENTUALLY MOVE IN SLOWLY FROM THE SW. IT IS UNCLEAR IF THE FORCING
WILL OVERCOME CAPPING...BUT IF IT DOES...CONDITIONS WILL BE QUITE
FAVORABLE FOR HAIL AND WIND.
..JEWELL/CORFIDI.. 09/05/2012
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...LOT...MKX...DVN...
LAT...LON 41828717 41618750 41728930 41819030 42329053 42799015
42788915 42668760 42288707 41938710 41828717SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Sep 4, 8:30 PM CDT | Mesoscale Discussion | SPC | Jo Daviess | 60 min |
| Sep 4, 8:51 PM CDT | Severe Thunderstorm Watch | SPC | Boone, Carroll, Cook, DeKalb, DuPage, Grundy and 13 more | 5 hr |
| Sep 5, 1:14 AM CDT | Mesoscale Discussion | SPC | Carroll, Henry, Jo Daviess, Rock Island, Stephenson, Whiteside and 1 more | 91 min |
| Sep 5, 3:43 AM CDT | Mesoscale Discussion | SPC | Boone, Bureau, Carroll, DeKalb, Grundy, Henderson and 21 more | 92 min |
| Sep 5, 9:04 AM CDT | Mesoscale Discussion | SPC | Alexander, Bond, Clark, Clay, Clinton, Crawford and 28 more | 86 min |
| Sep 5, 9:37 AM CDT | Severe Thunderstorm Watch | SPC | Bond, Clark, Clay, Clinton, Coles, Crawford and 24 more | 6 hr |
| Sep 5, 1:10 PM CDT | Mesoscale Discussion | SPC | Gallatin, Hardin, Johnson, Massac, Pope | 65 min |
| Sep 5, 1:43 PM CDT | Severe Thunderstorm Watch | SPC | Hardin | 5 hr |
| Sep 5, 2:13 PM CDT | Mesoscale Discussion | SPC | Alexander, Massac, Pulaski | 2 hr |
| Sep 5, 2:29 PM CDT | Severe Thunderstorm Watch | SPC | Alexander, Johnson, Massac, Pope, Pulaski, Union | 8 hr |
| Sep 4, 11:16 PM CDT | Severe Thunderstorm Watch | SPC | Adams, Crawford, Grant, Juneau, La Crosse, Monroe and 2 more | 4 hr |
Nearby
Mesoscale Discussions in Illinois, 2012Mesoscale Discussions in Wisconsin, 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.