Alert archive / Illinois / Mesoscale Discussions in 2012
Mesoscale Discussion 1983
The Storm Prediction Center issued this mesoscale discussion at Sep 25, 2012, 12:51 AM CDT for 4 states. It was in force for 114 min.
The area
The outline as issued.
The facts
- Issued
- Sep 25, 2012, 12:51 AM CDT (05:51 UTC)
- Expired
- Sep 25, 2012, 2:45 AM CDT
- In force
- 114 min
- Issued by
- the Storm Prediction Center
- Chance of a watch
- 20%
All 75 counties
Bond County, IL, Calhoun County, IL, Clay County, IL, Clinton County, IL, Crawford County, IL, Edwards County, IL, Effingham County, IL, Fayette County, IL, Franklin County, IL, Gallatin County, IL, Greene County, IL, Hamilton County, IL, Hardin County, IL, Jackson County, IL, Jasper County, IL, Jefferson County, IL, Jersey County, IL, Johnson County, IL, Lawrence County, IL, Macoupin County, IL, Madison County, IL, Marion County, IL, Monroe County, IL, Montgomery County, IL, Morgan County, IL, Perry County, IL, Pike County, IL, Pope County, IL, Randolph County, IL, Richland County, IL, Saint Clair County, IL, Saline County, IL, Scott County, IL, Union County, IL, Wabash County, IL, Washington County, IL, Wayne County, IL, White County, IL, Williamson County, IL, Gibson County, IN, Posey County, IN, Vanderburgh County, IN, Union County, KY, Adair County, MO, Audrain County, MO, Boone County, MO, Caldwell County, MO, Callaway County, MO, Carroll County, MO, Chariton County, MO, City of Saint Louis, MO, Daviess County, MO, Franklin County, MO, Gasconade County, MO, Grundy County, MO, Howard County, MO, Jefferson County, MO, Knox County, MO, Lincoln County, MO, Linn County, MO, Livingston County, MO, Macon County, MO, Marion County, MO, Monroe County, MO, Montgomery County, MO, Perry County, MO, Pike County, MO, Ralls County, MO, Randolph County, MO, Saint Charles County, MO, Saint Louis County, MO, Sainte Genevieve County, MO, Shelby County, MO, Sullivan County, MO, Warren County, MO
The radar
The St Louis radar (KLSX), 22 km from the middle of the area, began a volume at 05:54 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, 5.9 hours before the alert went out and 232 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
- 0 J/kg
- Mixed-layer CIN
- No buoyant parcel
- Mixed-layer LCL
- 2454 m above ground
- 0-6 km bulk shear
- 48 kt
- 0-1 km storm-relative helicity
- 85 m²/s²
- 0-3 km storm-relative helicity
- 181 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted, in the capitals the NWS used until 2016.
507
ACUS11 KWNS 250552
SWOMCD
SPC MCD 250551
INZ000-KYZ000-ILZ000-MOZ000-250745-
MESOSCALE DISCUSSION 1983
NWS STORM PREDICTION CENTER NORMAN OK
1251 AM CDT TUE SEP 25 2012
AREAS AFFECTED...MID-MS VALLEY
CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY
VALID 250551Z - 250745Z
PROBABILITY OF WATCH ISSUANCE...20 PERCENT
SUMMARY...ELEVATED TSTMS WILL INCREASE IN COVERAGE FROM NRN/CNTRL MO
INTO SRN IL. A RISK FOR MARGINALLY SEVERE HAIL WILL EXIST WITHIN THE
STRONGER CORES.
DISCUSSION...ELEVATED TSTMS HAVE COMMENCED ACROSS NRN MO WITHIN A
CORRIDOR OF ROBUST 850-700 MB WARM THETA-E ADVECTION. ALTHOUGH BASES
APPEAR TO BE ROOTED AROUND 700 MB PER METAR CEILING HEIGHTS...THIS
DEVELOPMENT IS BEING FED ON THE PERIPHERY OF A N/S-ORIENTED AXIS OF
MUCAPE FROM 1000-1500 J/KG CENTERED ACROSS THE OZARK PLATEAU.
ALTHOUGH STRONG LOW-LEVEL SHEAR EXISTS BELOW THE CLOUD BASE...NEARLY
UNIDIRECTIONAL MODERATE WLYS IN THE CLOUD-BEARING LAYER SHOULD YIELD
ONLY WEAK SPEED SHEAR WHICH WILL LARGELY MITIGATE SUSTAINED UPDRAFT
ROTATION. THIS SHOULD LIMIT HAIL GROWTH POTENTIAL DESPITE THE
PRESENCE OF STEEP MID-LEVEL LAPSE RATES.
00Z WRF-NSSL/NMM RUNS WERE A BIT SLOW WITH DEVELOPMENT...BUT THEIR
SCENARIO APPEARS REASONABLE WITH CONVECTION GROWING UPSCALE INTO A
CLUSTER. RELATIVELY COOL AND DRY SURFACE CONDITIONS /ESPECIALLY
DOWNSTREAM WITH ERN EXTENT/ BENEATH A FAIRLY STOUT EML SHOULD LIMIT
PENETRATION OF STRONGER DOWNDRAFTS TO THE SURFACE.
..GRAMS/THOMPSON.. 09/25/2012
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...IND...PAH...ILX...LSX...EAX...
LAT...LON 40379321 39939097 39128790 38768745 38348736 37568778
37308843 37228901 37638993 38059097 38989286 39619406
39859416 40189405 40379321SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Sep 25, 12:59 PM CDT | Mesoscale Discussion | SPC | Bond, Calhoun, Clay, Clinton, Edwards, Effingham and 21 more | 61 min |
| Sep 25, 5:05 PM CDT | Severe Thunderstorm Watch | SPC | Bond, Clinton, Edwards, Fayette, Franklin, Hamilton and 11 more | 6 hr |
| Sep 25, 6:57 PM CDT | Mesoscale Discussion | SPC | Clinton, Edwards, Franklin, Gallatin, Hamilton, Jefferson and 11 more | 93 min |
| Sep 25, 4:47 PM CDT | Mesoscale Discussion | SPC | Barry, Barton, Bates, Benton, Camden, Cedar and 16 more | 88 min |
| Sep 25, 5:46 PM CDT | Severe Thunderstorm Watch | SPC | Barton, Benton, Camden, Cedar, Dade, Dallas and 12 more | 4 hr |
Nearby
Mesoscale Discussions in Illinois, 2012Mesoscale Discussions in Missouri, 2012Mesoscale Discussions in Indiana, 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.