Alert archive / Illinois / Mesoscale Discussions in 2004

Mesoscale Discussion 849

May 23, 200434 counties in Illinois; 21 counties in Missouri

The Storm Prediction Center issued this mesoscale discussion at May 23, 2004, 5:00 PM CDT for 34 counties in Illinois; 21 counties in Missouri. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued
May 23, 2004, 5:00 PM CDT (22:00 UTC)
Expired
May 23, 2004, 7:00 PM CDT
In force
2 hr
Issued by
the Storm Prediction Center
All 55 counties

Adams County, IL, Bond County, IL, Brown County, IL, Calhoun County, IL, Cass County, IL, Christian County, IL, Clinton County, IL, DeWitt County, IL, Fulton County, IL, Greene County, IL, Jersey County, IL, Knox County, IL, Logan County, IL, Macon County, IL, Macoupin County, IL, Madison County, IL, Marshall County, IL, Mason County, IL, McDonough County, IL, McLean County, IL, Menard County, IL, Monroe County, IL, Montgomery County, IL, Morgan County, IL, Peoria County, IL, Pike County, IL, Saint Clair County, IL, Sangamon County, IL, Schuyler County, IL, Scott County, IL, Shelby County, IL, Tazewell County, IL, Warren County, IL, Woodford County, IL, Callaway County, MO, City of Saint Louis, MO, Cole County, MO, Crawford County, MO, Franklin County, MO, Gasconade County, MO, Jefferson County, MO, Lincoln County, MO, Maries County, MO, Miller County, MO, Montgomery County, MO, Osage County, MO, Phelps County, MO, Pike County, MO, Pulaski County, MO, Ralls County, MO, Saint Charles County, MO, Saint Francois County, MO, Saint Louis County, MO, Warren County, MO, Washington County, MO

The radar

The St Louis radar (KLSX), 80 km from the middle of the area, began a volume at 22:03 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, 10.0 hours before the alert went out and 181 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, Lincoln, IL at 12:00Z on 2004-05-23Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 435 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, Lincoln, IL at 12:00Z on 2004-05-23The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 18 square meters per square second.19395878Sfc1 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
435 J/kg
Mixed-layer CIN
-95 J/kg
Mixed-layer LCL
621 m above ground
0-6 km bulk shear
33 kt
0-1 km storm-relative helicity
18 m²/s²
0-3 km storm-relative helicity
59 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.1

Open this sounding in Storm Lab

The text

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

854 
ACUS11 KWNS 232200
SWOMCD
SPC MCD 232200 
ILZ000-MOZ000-240000-

MESOSCALE DISCUSSION 0849
NWS STORM PREDICTION CENTER NORMAN OK
0500 PM CDT SUN MAY 23 2004

AREAS AFFECTED...NERN MO / WRN IL

CONCERNING...TORNADO WATCH 261...

VALID 232200Z - 240000Z

ADDITIONAL TORNADO WATCH WILL BE REQUIRED E OF WW 261.

MASS FIELDS ARE LESS THAN OPTIMAL AT THE MOMENT AS LOW TO THE NORTH
FILLS WITH TIME AND PRESSURES CONTINUE TO RISE OVER MUCH OF THE
REGION DESPITE DIURNAL FALL TIME OF DAY.

NONETHELESS...INSTABILITY REMAINS VERY STRONG AND WIND SHEAR
PROFILES FAVORABLE FOR SUPERCELLS.  TREND HAS BEEN FOR STORMS TO
GRADUALLY STRENGTHEN WITH TIME...AND THIS IS EXPECTED TO CONTINUE
THROUGH THE EARLY EVENING FROM CENTRAL MO NEWD INTO IL.

THE GREATEST THREAT FOR TORNADOES IS OVER W-CENTRAL IL...WHERE LOW
LEVEL WINDS ARE BACKED MORE AND PRESSURES ARE SLOWLY FALLING.  AREA
VWPS STILL EXHIBIT 150-250 0-1 KM SRH...MORE THAN FAVORABLE FOR
TORNADOES GIVEN STRONG INSTABILITY PRESENT.  VISIBLE SATELLITE
IMAGERY SHOWS CLEARING OVER CENTRAL AND W CENTRAL IL WHICH MAY
FURTHER ENHANCE LOW LEVEL CAPE.

..JEWELL.. 05/23/2004

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

ATTN...WFO...LOT...ILX...LSX...DVN...SGF...

41019064 41178861 40348852 39348880 38508935 37939022
37599078 37889256 38419276 39189176 40459108

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
May 22, 8:58 PM CDTMesoscale DiscussionSPCBoone, Bureau, Carroll, DeKalb, DuPage, Grundy and 23 more92 min
May 23, 12:24 AM CDTMesoscale DiscussionSPCBoone, Bureau, Carroll, Cook, DeKalb, DuPage and 32 more66 min
May 23, 12:40 AM CDTSevere Thunderstorm WatchSPCBoone, Bureau, Carroll, Cook, DeKalb, DuPage and 27 more5 hr
May 23, 1:21 AM CDTMesoscale DiscussionSPCAdams, Brown, Calhoun, Cass, Greene, Jersey and 6 more24 min
May 23, 1:40 AM CDTSevere Thunderstorm WatchSPCAdams, Brown, Cass, Fulton, Hancock, Logan and 8 more4 hr
May 23, 4:30 AM CDTMesoscale DiscussionSPCAdams, Boone, Brown, Bureau, Carroll, Cass and 44 more60 min
May 23, 10:45 AM CDTTornado WatchSPCClark, Clay, Coles, Crawford, Cumberland, Edgar and 19 more5 hr
May 23, 12:25 PM CDTMesoscale DiscussionSPCAdams, Brown, Bureau, Calhoun, Carroll, Cass and 31 more95 min
May 23, 12:45 PM CDTMesoscale DiscussionSPCClark, Clay, Coles, Crawford, Cumberland, Edgar and 18 more2 hr
May 23, 1:15 PM CDTTornado WatchSPCAdams, Brown, Calhoun, Cass, Fulton, Greene and 16 more6 hr
May 23, 2:05 PM CDTTornado WatchSPCBoone, Bureau, Carroll, DeKalb, DuPage, Grundy and 18 more8 hr
May 23, 2:53 PM CDTMesoscale DiscussionSPCIroquois, Vermilion67 min
May 23, 3:50 PM CDTTornado WatchSPCCook, DuPage, Iroquois, Kankakee, Vermilion, Will6 hr
May 23, 4:35 PM CDTSevere Thunderstorm WatchSPCMonroe5 hr
May 23, 5:10 PM CDTMesoscale DiscussionSPCBoone, Bureau, Carroll, DeKalb, DuPage, Grundy and 17 more95 min
May 23, 5:30 PM CDTTornado WatchSPCBond, Calhoun, Christian, Clark, Clay, Clinton and 29 more6 hr
May 23, 6:30 PM CDTMesoscale DiscussionSPCCook, DuPage, Iroquois, Kankakee, Vermilion, Will2 hr
May 22, 7:11 PM CDTMesoscale DiscussionSPCAtchison94 min
May 22, 10:40 PM CDTTornado WatchSPCAndrew, Atchison, Buchanan, Daviess, DeKalb, Gentry and 8 more5 hr
May 22, 11:33 PM CDTMesoscale DiscussionSPCAndrew, Atchison, Buchanan, Daviess, DeKalb, Gentry and 7 more87 min
May 23, 2:21 AM CDTMesoscale DiscussionSPCAdair, Andrew, Buchanan, Caldwell, Clinton, Daviess and 11 more54 min

Nearby

Mesoscale Discussions in Illinois, 2004Mesoscale Discussions in Missouri, 2004Every mesoscale discussion in 2004

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.