Alert archive / Illinois / Mesoscale Discussions in 2003
Mesoscale Discussion 804
The Storm Prediction Center issued this mesoscale discussion at May 6, 2003, 7:03 PM CDT for 13 counties in Illinois; 10 counties in Missouri. It was in force for 117 min.
The area
The outline as issued.
The facts
- Issued
- May 6, 2003, 7:03 PM CDT (00:03 UTC)
- Expired
- May 6, 2003, 9:00 PM CDT
- In force
- 117 min
- Issued by
- the Storm Prediction Center
All 23 counties
Clinton County, IL, Franklin County, IL, Hamilton County, IL, Jackson County, IL, Jefferson County, IL, Madison County, IL, Marion County, IL, Monroe County, IL, Perry County, IL, Randolph County, IL, Saint Clair County, IL, Washington County, IL, Williamson County, IL, Bollinger County, MO, Cape Girardeau County, MO, City of Saint Louis, MO, Iron County, MO, Jefferson County, MO, Madison County, MO, Perry County, MO, Reynolds County, MO, Saint Francois County, MO, Sainte Genevieve County, MO
The radar
The St Louis radar (KLSX), 92 km from the middle of the area, began a volume at 00:09 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, 0.1 hours before the alert went out and 257 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
- 208 J/kg
- Mixed-layer CIN
- -120 J/kg
- Mixed-layer LCL
- 1589 m above ground
- 0-6 km bulk shear
- 41 kt
- 0-1 km storm-relative helicity
- 85 m²/s²
- 0-3 km storm-relative helicity
- 187 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.1
The text
As transmitted, in the capitals the NWS used until 2016.
599 ACUS11 KWNS 070004 SWOMCD SPC MCD 070003 ILZ000-MOZ000-070200- MESOSCALE DISCUSSION 0804 NWS STORM PREDICTION CENTER NORMAN OK 0703 PM CDT TUE MAY 06 2003 AREAS AFFECTED...E CNTRL/SE MO INTO SRN IL CONCERNING...TORNADO WATCH 275... VALID 070003Z - 070200Z SEVERE THREAT CONTINUES ACROSS WW AREA. EVOLUTION OF LARGE SEVERE MESOSCALE CONVECTIVE SYSTEM CONTINUES. INTENSE EMBEDDED SUPERCELL ON SOUTHWESTERN FRINGE OF ST. LOUIS METRO AREA...IS PROPAGATING ALONG WEAK SURFACE BOUNDARY ACROSS FRANKLIN/JEFFERSON COUNTIES...WHERE LOW-LEVEL THERMODYNAMIC ENVIRONMENT IS MOIST/UNSTABLE AND SUPPORTIVE OF ADDITIONAL TORNADIC ACTIVITY. BOUNDARY EXTENDS SOUTH SOUTHEAST OF ST. LOUIS INTO THE CARBONDALE IL AREA...BUT MAY LIFT NORTHWARD TOWARD MT. VERNON DURING THE NEXT COUPLE OF HOURS. AS SOUTHERLY LOW-LEVEL JET STRENGTHENS AND VEERS FROM SOUTHEAST MISSOURI INTO SOUTHERN ILLINOIS EARLY THIS EVENING...POTENTIAL FOR MORE WIDESPREAD DAMAGING WINDS WILL GRADUALLY INCREASE. ..KERR.. 05/07/2003 ...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT... ATTN...WFO...PAH...LSX...SGF... 38369057 38939017 38808939 38658884 38258836 37778872 37278979 37229070 37479161 37959088
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 6, 9:35 PM CDT | Mesoscale Discussion | SPC | Alexander, Franklin, Gallatin, Hamilton, Hardin, Jackson and 12 more | 115 min |
| May 6, 11:50 PM CDT | Tornado Watch | SPC | Gallatin, Hamilton, Hardin, Johnson, Massac, Pope and 2 more | 6 hr |
| May 7, 12:42 PM CDT | Mesoscale Discussion | SPC | Champaign, Clark, Clay, Coles, Crawford, Cumberland and 22 more | 2 hr |
| May 6, 7:53 PM CDT | Mesoscale Discussion | SPC | Butler, Carter, Howell, Oregon, Reynolds, Ripley and 2 more | 2 hr |
| May 6, 11:30 PM CDT | Tornado Watch | SPC | Dunklin, Pemiscot | 6 hr |
| May 7, 2:27 AM CDT | Mesoscale Discussion | SPC | Dunklin, Pemiscot | 3 hr |
| May 7, 4:55 AM CDT | Tornado Watch | SPC | Dunklin, Pemiscot | 6 hr |
Nearby
Mesoscale Discussions in Illinois, 2003Mesoscale Discussions in Missouri, 2003Every mesoscale discussion in 2003
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.