Alert archive / Illinois / Mesoscale Discussions in 2004

Mesoscale Discussion 577

May 7, 200415 counties in Illinois; 8 counties in Iowa

The Storm Prediction Center issued this mesoscale discussion at May 7, 2004, 11:44 AM CDT for 15 counties in Illinois; 8 counties in Iowa. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued: May 7, 2004, 11:44 AM CDT (16:44 UTC)
Expired: May 7, 2004, 1:45 PM CDT
In force: 2 hr
Issued by: the Storm Prediction Center

All 23 counties

Cedar County, IA, Clinton County, IA, Jackson County, IA, Johnson County, IA, Jones County, IA, Linn County, IA, Muscatine County, IA, Scott County, IA, Bureau County, IL, Carroll County, IL, DeKalb County, IL, DuPage County, IL, Grundy County, IL, Henry County, IL, Kane County, IL, Kankakee County, IL, Kendall County, IL, LaSalle County, IL, Lee County, IL, Ogle County, IL, Rock Island County, IL, Whiteside County, IL, Will County, IL

The radar

The Quad Cities radar (KDVN), 62 km from the middle of the area, began a volume at 16:47 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

Davenport, (KDVN), launched 12:00Z, 4.7 hours before the alert went out and 55 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-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 915 m above ground
0-6 km bulk shear: 58 kt
0-1 km storm-relative helicity: 96 m²/s²
0-3 km storm-relative helicity: 219 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.3

Open this sounding in Storm Lab

The text

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

190 
ACUS11 KWNS 071645
SWOMCD
SPC MCD 071644 
ILZ000-IAZ000-071845-

MESOSCALE DISCUSSION 0577
NWS STORM PREDICTION CENTER NORMAN OK
1144 AM CDT FRI MAY 07 2004

AREAS AFFECTED...E-CENTRAL IA AND NRN IL

CONCERNING...SEVERE THUNDERSTORM POTENTIAL...HEAVY RAINFALL 

VALID 071644Z - 071845Z

THREAT OF LARGE HAIL AND LOCALIZED HEAVY RAINFALL WILL CONTINUE
ACROSS E-CENTRAL IA AND NRN IL THROUGH 20Z.

AT 1630Z...A BACKBUILDING LINE OF THUNDERSTORMS CONTINUES ALONG AN
E-W ORIENTED AXIS FROM 20S RFD TO 15N CID. STORM UPDRAFTS ARE ROOTED
ABOVE THE BOUNDARY LAYER...WITH ISENTROPIC LIFT BEING PROVIDED OVER
THE QUASI-STATIONARY FRONT ACROSS CENTRAL IL WWD ALONG THE MO/IA
BORDER. VERY STEEP 700-500 MB LAPSE RATES...AROUND 8 C/KM...WILL
CONTRIBUTE TO MODERATE ELEVATED INSTABILITY DURING THE NEXT SEVERAL
HOURS. ELEVATED SHEAR AND INSTABILITY IS SUFFICIENT FOR ROTATING
UPDRAFTS. THIS SHOULD SUSTAIN THE THREAT OF LARGE HAIL WITH
STRONGER...MORE LONG-LIVED CELLS. ADDITIONALLY...TRAINING OF
THUNDERSTORMS SUGGESTS THE THREAT OF LOCALIZED HEAVY RAINFALL TO
2/HR ACROSS THE DISCUSSION AREA. BY LATE AFTERNOON...WARM ADVECTION
ASSOCIATED LIFT SHOULD FOCUS FURTHER NORTH AND WEST DIMINISHING
THREAT OF SEVERE ACTIVITY OVER E-CENTRAL IA AND NRN IL.

..BANACOS.. 05/07/2004

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

ATTN...WFO...LOT...DVN...

42269183 42389092 42208937 42098853 41988789 41578757
41028780 41288992 41499139 41809196

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
May 6, 11:53 PM CDT	Mesoscale Discussion	SPC	Bureau, Carroll, DeKalb, Henry, Jo Daviess, Knox and 10 more	97 min
May 7, 4:24 AM CDT	Mesoscale Discussion	SPC	Boone, Bureau, Carroll, Cook, DeKalb, DuPage and 22 more	96 min
May 7, 5:00 AM CDT	Severe Thunderstorm Watch	SPC	Bureau, Ford, Grundy, Iroquois, Kankakee, Kendall and 10 more	4 hr
May 7, 6:38 AM CDT	Mesoscale Discussion	SPC	Bureau, Champaign, DeWitt, Ford, Grundy, Iroquois and 12 more	97 min
May 7, 4:33 PM CDT	Mesoscale Discussion	SPC	Boone, Carroll, Cook, DeKalb, DuPage, Jo Daviess and 9 more	87 min
May 7, 5:25 PM CDT	Severe Thunderstorm Watch	SPC	Boone, Carroll, Cook, DeKalb, DuPage, Jo Daviess and 6 more	6 hr
May 7, 2:26 PM CDT	Mesoscale Discussion	SPC	Adair, Adams, Audubon, Buena Vista, Calhoun, Carroll and 26 more	3 hr

Nearby

Mesoscale Discussions in Illinois, 2004 Mesoscale Discussions in Iowa, 2004 Every 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.