Alert archive / Missouri / Mesoscale Discussions in 2011

Mesoscale Discussion 1850

August 4, 20119 counties in Illinois; Ballard County, Kentucky; 36 counties in Missouri

The Storm Prediction Center issued this mesoscale discussion at Aug 4, 2011, 6:04 AM CDT for 9 counties in Illinois; Ballard County, Kentucky; 36 counties in Missouri. It was in force for 86 min.

The area

The outline as issued.

The facts

Issued
Aug 4, 2011, 6:04 AM CDT (11:04 UTC)
Expired
Aug 4, 2011, 7:30 AM CDT
In force
86 min
Issued by
the Storm Prediction Center
All 46 counties

Alexander County, IL, Jackson County, IL, Johnson County, IL, Monroe County, IL, Perry County, IL, Pulaski County, IL, Randolph County, IL, Union County, IL, Williamson County, IL, Ballard County, KY, Benton County, MO, Bollinger County, MO, Camden County, MO, Cape Girardeau County, MO, Cole County, MO, Crawford County, MO, Dallas County, MO, Dent County, MO, Franklin County, MO, Gasconade County, MO, Greene County, MO, Hickory County, MO, Iron County, MO, Jefferson County, MO, Laclede County, MO, Madison County, MO, Maries County, MO, Miller County, MO, Mississippi County, MO, Morgan County, MO, Osage County, MO, Perry County, MO, Phelps County, MO, Polk County, MO, Pulaski County, MO, Reynolds County, MO, Saint Francois County, MO, Sainte Genevieve County, MO, Scott County, MO, Shannon County, MO, Stoddard County, MO, Texas County, MO, Washington County, MO, Wayne County, MO, Webster County, MO, Wright County, MO

The radar

The St Louis radar (KLSX), 138 km from the middle of the area, began a volume at 11:06 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

Springfield, MO (KSGF), launched 00:00Z, 11.1 hours before the alert went out and 211 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.

Skew-T log-pSkew-T log-p diagram, Springfield, MO at 00:00Z on 2011-08-04Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 3561 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Springfield, MO at 00:00Z on 2011-08-04The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 4 square meters per square second.1939Sfc1 km3 km6 km9 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.
Mixed-layer CAPE
3561 J/kg
Mixed-layer CIN
-36 J/kg
Mixed-layer LCL
2210 m above ground
0-6 km bulk shear
16 kt
0-1 km storm-relative helicity
4 m²/s²
0-3 km storm-relative helicity
81 m²/s²
Significant tornado parameter
0.0
Supercell composite
3.7

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

387 
ACUS11 KWNS 041104
SWOMCD
SPC MCD 041104 
ILZ000-KYZ000-MOZ000-041230-

MESOSCALE DISCUSSION 1850
NWS STORM PREDICTION CENTER NORMAN OK
0604 AM CDT THU AUG 04 2011

AREAS AFFECTED...SCNTRL MO...SRN IL...FAR WRN KY

CONCERNING...SEVERE THUNDERSTORM WATCH 725...

VALID 041104Z - 041230Z

THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 725
CONTINUES.

A SEVERE THREAT WILL LIKELY CONTINUE TO MOVE EWD ACROSS SCNTRL MO
AND MAY REACH SRN IL LATER THIS MORNING. WIND DAMAGE AND HAIL WILL
BE POSSIBLE WITH THE MORE INTENSE LINE-SEGMENTS. WW ISSUANCE MAY BE
NEEDED EAST OF WW 725 AS THE LINE APPROACHES SE MO OVER THE NEXT 1
TO 2 HOURS.

A LINE OF STRONG TO SEVERE THUNDERSTORMS IS ONGOING NEAR SPRINGFIELD
MO LOCATED ALONG THE NRN EDGE OF MODERATE INSTABILITY WHERE MLCAPE
VALUES ARE ESTIMATED IN THE 1000 TO 2000 J/KG RANGE. THE MCS MAY
TURN ESEWD ACROSS SE MO FOLLOWING THE TIGHT GRADIENT OF MODERATE
INSTABILITY. ELY FLOW AT THE SFC ALONG WITH A STRONG FORWARD
PROPAGATION SHOULD HELP MAINTAIN AN ISOLATED WIND DAMAGE THREAT AS
THE LINEAR MCS MOVES INTO THE MS VALLEY. ALTHOUGH SOME WEAKENING
COULD OCCUR...THE LINE MAY ALSO REGENERATE ESPECIALLY AFTER THE SUN
COMES UP AND SFC TEMPS BEGIN TO WARM.

..BROYLES.. 08/04/2011

...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...PAH...LSX...SGF...EAX...

LAT...LON   38369362 37439378 37139305 37099148 36588911 37668865
            38198946 38669205 38369362

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Aug 4, 8:06 AM CDTSevere Thunderstorm WatchSPCAlexander, Pulaski4 hr
Aug 4, 10:21 AM CDTMesoscale DiscussionSPCAlexander84 min
Aug 4, 2:10 AM CDTMesoscale DiscussionSPCBarry, Barton, Bates, Benton, Camden, Cedar and 35 more80 min
Aug 4, 3:28 AM CDTSevere Thunderstorm WatchSPCBarton, Bates, Benton, Camden, Cedar, Christian and 32 more7 hr

Nearby

Mesoscale Discussions in Missouri, 2011Mesoscale Discussions in Illinois, 2011Mesoscale Discussions in Kentucky, 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.