Alert archive / Missouri / Mesoscale Discussions in 2011
Mesoscale Discussion 475
The Storm Prediction Center issued this mesoscale discussion at Apr 19, 2011, 5:47 PM CDT for 31 counties in Illinois; 37 counties in Missouri. It was in force for 88 min.
The area
The outline as issued.
The facts
- Issued
- Apr 19, 2011, 5:47 PM CDT (22:47 UTC)
- Expired
- Apr 19, 2011, 7:15 PM CDT
- In force
- 88 min
- Issued by
- the Storm Prediction Center
All 68 counties
Bond County, IL, Calhoun County, IL, Christian County, IL, Clark County, IL, Clay County, IL, Clinton County, IL, Coles County, IL, Crawford County, IL, Cumberland County, IL, Douglas County, IL, Edgar County, IL, Effingham County, IL, Fayette County, IL, Greene County, IL, Jasper County, IL, Jersey County, IL, Macon County, IL, Macoupin County, IL, Madison County, IL, Marion County, IL, Menard County, IL, Monroe County, IL, Montgomery County, IL, Morgan County, IL, Moultrie County, IL, Piatt County, IL, Saint Clair County, IL, Sangamon County, IL, Scott County, IL, Shelby County, IL, Washington County, IL, Callaway County, MO, Camden County, MO, Christian County, MO, City of Saint Louis, MO, Cole County, MO, Crawford County, MO, Dallas County, MO, Dent County, MO, Douglas County, MO, Franklin County, MO, Gasconade County, MO, Greene County, MO, Howell County, MO, Iron County, MO, Jefferson County, MO, Laclede County, MO, Lincoln County, MO, Maries County, MO, Miller County, MO, Montgomery County, MO, Osage County, MO, Ozark County, MO, Phelps County, MO, Pike County, MO, Pulaski County, MO, Reynolds County, MO, Saint Charles County, MO, Saint Francois County, MO, Saint Louis County, MO, Sainte Genevieve County, MO, Shannon County, MO, Taney County, MO, Texas County, MO, Warren County, MO, Washington County, MO, Webster County, MO, Wright County, MO
The radar
The St Louis radar (KLSX), 56 km from the middle of the area, began a volume at 22:50 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
Lincoln, IL (KILX), launched 12:00Z, 10.8 hours before the alert went out and 283 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
- 453 m above ground
- 0-6 km bulk shear
- 57 kt
- 0-1 km storm-relative helicity
- 189 m²/s²
- 0-3 km storm-relative helicity
- 345 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 2.4
The text
As transmitted, in the capitals the NWS used until 2016.
238
ACUS11 KWNS 192248
SWOMCD
SPC MCD 192247
ILZ000-MOZ000-200015-
MESOSCALE DISCUSSION 0475
NWS STORM PREDICTION CENTER NORMAN OK
0547 PM CDT TUE APR 19 2011
AREAS AFFECTED...E-CNTRL/S-CNTRL MO...CNTRL IL
CONCERNING...TORNADO WATCH 154...
VALID 192247Z - 200015Z
THE SEVERE WEATHER THREAT FOR TORNADO WATCH 154 CONTINUES.
LATEST SURFACE ANALYSIS PLACES LOW PRESSURE 45 NNW STL WITH A WARM
FRONT EXTENDING EWD FROM THE LOW TO NEAR SPI AND THEN EWD INTO WRN
IND 30 ENE HUF. A COLD FRONT EXTENDS S-SWD FROM THE LOW TO 10 NNW
TBN TO 15 SSE OF UMN. THE MOST VIGOROUS AND WIDESPREAD CONVECTIVE
DEVELOPMENT /INCLUDING DISCRETE AND SEMI-DISCRETE SUPERCELLS/ OVER
THE PAST HOUR HAS BEEN NOTED IN THE ERN SEMICIRCLE OF THE LOW WITHIN
60 NM OF THE LOW CENTER. BACKED SFC FLOW IN THIS REGION...ESPECIALLY
INVOF THE WARM FRONT...IS SUPPORTING STRONG LOW-LEVEL VERTICAL WIND
SHEAR AND EFFECTIVE SRH VALUES OF 300-400 M2/S2. THE SFC LOW IS
FORECAST TO SHIFT E-NEWD INTO CNTRL IL DURING THE NEXT COUPLE OF
HOURS...WHERE PRESSURE FALLS AROUND 2 MB PER 2 HRS HAVE BEEN NOTED.
CORRESPONDINGLY...THE GREATEST THREAT FOR SUPERCELLS WITH DMGG WINDS
AND VERY LARGE HAIL /SUPPORTED BY MLCAPE VALUES AOA 2000 J PER KG
AND STRONG CLOUD-BEARING WIND SHEAR/ WILL OCCUR WITHIN A 60-NM-WIDE
AREA CENTERED ALONG A LINE FROM 45 WSW STL TO 5 ESE DEC THROUGH 00Z.
THIS INCLUDES THE ST LOUIS METRO AREA /ESPECIALLY NRN SECTIONS/
BETWEEN 23Z AND 00Z. TORNADOES WILL REMAIN A CONCERN...AS
WELL...ESPECIALLY WITH ANY SUPERCELLS THAT CAN REMAIN DISCRETE AND
MOVE EWD NEAR THE WARM FRONT.
FARTHER SOUTH ALONG THE COLD FRONT...THE PRESENCE OF SOME CINH HAS
RESULTED IN FAIRLY MORE ISOLATED COVERAGE OF STORMS...EXCEPT IN
S-CNTRL MO WHERE MID-LEVEL ASCENT IS MORE PRONOUNCED. THIS ACTIVITY
WILL MOVE NEWD AROUND 35-40 KT WHILE TRAVERSING STRONG INSTABILITY
AND EFFECTIVE BULK SHEAR MAGNITUDES AOA 45 KT...WITH BOTH LINEAR AND
DISCRETE SUPERCELL MODES FAVORED. DMGG WINDS...VERY LARGE HAIL...AND
TORNADOES WILL REMAIN THREATS WITH EFFECTIVE SRH VALUES OF 200-300
M2/S2.
..COHEN.. 04/19/2011
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...PAH...ILX...LSX...SGF...
LAT...LON 36639334 37029352 37889301 39219169 40078987 40148779
39558755 38818782 38598878 38208970 37219104 36669171
36639334SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Apr 18, 11:41 PM CDT | Mesoscale Discussion | SPC | Calhoun, Jersey | 94 min |
| Apr 19, 2:53 AM CDT | Mesoscale Discussion | SPC | Adams, Bond, Brown, Calhoun, Cass, Christian and 21 more | 67 min |
| Apr 19, 3:11 AM CDT | Severe Thunderstorm Watch | SPC | Adams, Bond, Brown, Calhoun, Cass, Christian and 30 more | 7 hr |
| Apr 19, 5:52 AM CDT | Mesoscale Discussion | SPC | Adams, Bond, Brown, Calhoun, Cass, Christian and 34 more | 83 min |
| Apr 19, 8:29 AM CDT | Mesoscale Discussion | SPC | Christian, Clark, Coles, Crawford, Cumberland, Douglas and 8 more | 61 min |
| Apr 19, 12:40 PM CDT | Mesoscale Discussion | SPC | Jersey, Madison, Monroe, Saint Clair | 95 min |
| Apr 19, 1:00 PM CDT | Tornado Watch | SPC | Bond, Calhoun, Cass, Champaign, Christian, Clark and 36 more | 10 hr |
| Apr 19, 6:24 PM CDT | Mesoscale Discussion | SPC | Alexander, Franklin, Jackson, Johnson, Pulaski, Saline and 2 more | 66 min |
| Apr 19, 6:46 PM CDT | Tornado Watch | SPC | Alexander, Edwards, Franklin, Gallatin, Hamilton, Hardin and 13 more | 9 hr |
Nearby
Mesoscale Discussions in Missouri, 2011Mesoscale Discussions in Illinois, 2011Every mesoscale discussion in 2011
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.