Alert archive / Illinois / Mesoscale Discussions in 2012
Mesoscale Discussion 1848
The Storm Prediction Center issued this mesoscale discussion at Aug 31, 2012, 9:05 PM CDT for 5 states. It was in force for 55 min.
The area
The outline as issued.
The facts
- Issued
- Aug 31, 2012, 9:05 PM CDT (02:05 UTC)
- Expired
- Aug 31, 2012, 10:00 PM CDT
- In force
- 55 min
- Issued by
- the Storm Prediction Center
All 68 counties
Clay County, AR, Craighead County, AR, Greene County, AR, Lawrence County, AR, Mississippi County, AR, Poinsett County, AR, Randolph County, AR, Alexander County, IL, Bond County, IL, Brown County, IL, Calhoun County, IL, Cass County, IL, Champaign County, IL, Christian County, IL, Clay County, IL, Clinton County, IL, Coles County, IL, Cumberland County, IL, DeWitt County, IL, Douglas County, IL, Effingham County, IL, Fayette County, IL, Franklin County, IL, Greene County, IL, Jackson County, IL, Jasper County, IL, Jefferson County, IL, Jersey County, IL, Johnson County, IL, Logan County, IL, Macon County, IL, Macoupin County, IL, Madison County, IL, Marion County, IL, Mason County, IL, Menard County, IL, Montgomery County, IL, Morgan County, IL, Moultrie County, IL, Perry County, IL, Piatt County, IL, Pike County, IL, Pulaski County, IL, Randolph County, IL, Saint Clair County, IL, Sangamon County, IL, Schuyler County, IL, Scott County, IL, Shelby County, IL, Union County, IL, Washington County, IL, Williamson County, IL, Ballard County, KY, Carlisle County, KY, Fulton County, KY, Hickman County, KY, Bollinger County, MO, Cape Girardeau County, MO, Dunklin County, MO, Mississippi County, MO, New Madrid County, MO, Pemiscot County, MO, Perry County, MO, Scott County, MO, Dyer County, TN, Lake County, TN, Lauderdale County, TN, Obion County, TN
The radar
The St Louis radar (KLSX), 115 km from the middle of the area, began a volume at 02:07 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
Lincoln, IL (KILX), launched 00:00Z, 2.1 hours before the alert went out and 278 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
- 1227 J/kg
- Mixed-layer CIN
- -5 J/kg
- Mixed-layer LCL
- 718 m above ground
- 0-6 km bulk shear
- 28 kt
- 0-1 km storm-relative helicity
- 59 m²/s²
- 0-3 km storm-relative helicity
- 52 m²/s²
- Significant tornado parameter
- 0.1
- Supercell composite
- 0.6
The text
As transmitted, in the capitals the NWS used until 2016.
436
ACUS11 KWNS 010205
SWOMCD
SPC MCD 010205
ILZ000-KYZ000-TNZ000-MOZ000-ARZ000-010300-
MESOSCALE DISCUSSION 1848
NWS STORM PREDICTION CENTER NORMAN OK
0905 PM CDT FRI AUG 31 2012
AREAS AFFECTED...NE AR...WRN TN...SE MO...WRN KY...IL
CONCERNING...TORNADO WATCH 600...601...
VALID 010205Z - 010300Z
THE SEVERE WEATHER THREAT FOR TORNADO WATCH 600...601...CONTINUES.
SUMMARY...THE TORNADO THREAT ACROSS WW 600 AND WW 601 IS BECOMING
INCREASINGLY ISOLATED THIS EVENING. THIS TREND SHOULD CONTINUE WITH
THE SEVERE THREAT BECOMING MARGINAL LATE THIS EVENING. FOR THIS
REASON...NEW WW ISSUANCE IS NOT ANTICIPATED ACROSS THE REGION. THE
CURRENT WEATHER WATCHES WILL BE ALLOWED TO EXPIRE AT 03Z.
DISCUSSION...SEVERAL CONVECTIVE BANDS ARE STILL ONGOING IN THE MID
MS VALLEY EXTENDING SWD ACROSS SRN IL INTO ERN AR AND WRN TN. THESE
LINES OF STORMS ARE LOCATED BETWEEN MODERATE INSTABILITY TO THE EAST
AND A 40 TO 50 KT LOW-LEVEL JET TO THE WEST. THIS ENVIRONMENT MAY
SUPPORT A SEVERE THREAT FOR ANOTHER HOUR WITH THE THREAT LINGERING
THE LONGEST ACROSS FAR ERN AR AND WRN TN WHERE THE COMBINATION OF
INSTABILITY AND LOW-LEVEL SHEAR IS MAXIMIZED. AS THE CELLS MOVE INTO
AREAS EAST OF THE MS RIVER...A BRIEF TORNADO COULD OCCUR BEFORE THE
SEVERE THREAT DIMINISHES DUE TO DECREASING INSTABILITY.
..BROYLES.. 09/01/2012
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...PAH...LOT...ILX...MEG...LSX...DVN...LZK...
LAT...LON 35429015 35459103 35889103 35899136 36219131 36229125
36489139 36479020 36639018 36618970 37118976 37148994
37028994 37089018 37299018 37309011 37669017 37948992
38109016 38278986 38539020 38829015 38989042 38879052
38899066 39279078 39719138 39759138 39739096 40289092
40289071 40279048 40179045 40179022 40438995 40438972
40288973 40298849 40418848 40398793 38858796 38888821
38628825 38608869 37348870 37338892 36928882 36408883
36428891 36228896 36228911 35978920 35908938 35578947
35648969 35598990 35429015SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Sep 1, 3:49 PM CDT | Tornado Watch | SPC | Arkansas, Clay, Cleburne, Craighead, Crittenden, Cross and 22 more | 7 hr |
| Sep 1, 5:43 PM CDT | Mesoscale Discussion | SPC | Craighead, Crittenden, Cross, Garland, Grant, Greene and 12 more | 92 min |
| Sep 1, 6:11 PM CDT | Severe Thunderstorm Watch | SPC | Arkansas, Bradley, Calhoun, Clark, Cleveland, Dallas and 19 more | 6 hr |
| Sep 1, 12:41 PM CDT | Mesoscale Discussion | SPC | Bond, Cass, Champaign, Christian, Clay, Clinton and 36 more | 64 min |
| Sep 1, 12:46 PM CDT | Tornado Watch | SPC | Cass, Champaign, Christian, Clark, Clay, Coles and 29 more | 7 hr |
| Sep 1, 1:19 PM CDT | Tornado Watch | SPC | Alexander, Bond, Clinton, Edwards, Fayette, Franklin and 20 more | 8 hr |
| Sep 1, 3:30 PM CDT | Mesoscale Discussion | SPC | Alexander, Bond, Christian, Clark, Clay, Clinton and 51 more | 60 min |
Nearby
Mesoscale Discussions in Illinois, 2012Mesoscale Discussions in Missouri, 2012Mesoscale Discussions in Arkansas, 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.