Alert archive / Illinois / Mesoscale Discussions in 2009

Mesoscale Discussion 821

May 13, 200953 counties in Illinois; Lee County, Iowa; 9 counties in Missouri

The Storm Prediction Center issued this mesoscale discussion at May 13, 2009, 8:35 PM CDT for 53 counties in Illinois; Lee County, Iowa; 9 counties in Missouri. It was in force for 85 min.

The area

The outline as issued.

The facts

Issued
May 13, 2009, 8:35 PM CDT (01:35 UTC)
Expired
May 13, 2009, 10:00 PM CDT
In force
85 min
Issued by
the Storm Prediction Center
All 63 counties

Lee County, IA, Adams County, IL, Boone County, IL, Brown County, IL, Bureau County, IL, Carroll County, IL, Cass County, IL, Champaign County, IL, DeKalb County, IL, DeWitt County, IL, DuPage County, IL, Ford County, IL, Fulton County, IL, Grundy County, IL, Hancock County, IL, Henderson County, IL, Henry County, IL, Iroquois County, IL, Kane County, IL, Kankakee County, IL, Kendall County, IL, Knox County, IL, Lake County, IL, LaSalle County, IL, Lee County, IL, Livingston County, IL, Logan County, IL, Macon County, IL, Marshall County, IL, Mason County, IL, McDonough County, IL, McHenry County, IL, McLean County, IL, Menard County, IL, Mercer County, IL, Morgan County, IL, Ogle County, IL, Peoria County, IL, Piatt County, IL, Pike County, IL, Putnam County, IL, Rock Island County, IL, Sangamon County, IL, Schuyler County, IL, Scott County, IL, Stark County, IL, Stephenson County, IL, Tazewell County, IL, Vermilion County, IL, Warren County, IL, Whiteside County, IL, Will County, IL, Winnebago County, IL, Woodford County, IL, Clark County, MO, Knox County, MO, Lewis County, MO, Macon County, MO, Marion County, MO, Monroe County, MO, Ralls County, MO, Randolph County, MO, Shelby County, MO

The radar

The Lincoln radar (KILX), 116 km from the middle of the area, began a volume at 01:35 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

Davenport, (KDVN), launched 00:00Z, 1.6 hours before the alert went out and 125 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, Davenport, at 00:00Z on 2009-05-14Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1843 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, Davenport, at 00:00Z on 2009-05-14The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 354 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
1843 J/kg
Mixed-layer CIN
-22 J/kg
Mixed-layer LCL
638 m above ground
0-6 km bulk shear
57 kt
0-1 km storm-relative helicity
354 m²/s²
0-3 km storm-relative helicity
384 m²/s²
Significant tornado parameter
4.6
Supercell composite
20.3

Open this sounding in Storm Lab

The text

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

000 
ACUS11 KWNS 140135
SWOMCD
SPC MCD 140135 
ILZ000-WIZ000-IAZ000-MOZ000-140300-

MESOSCALE DISCUSSION 0821
NWS STORM PREDICTION CENTER NORMAN OK
0835 PM CDT WED MAY 13 2009

AREAS AFFECTED...NERN MO/NRN AND CENTRAL IL

CONCERNING...TORNADO WATCH 293...

VALID 140135Z - 140300Z

THE SEVERE WEATHER THREAT FOR TORNADO WATCH 293 CONTINUES.

SEVERE/ISOLATED TORNADO THREAT CONTINUES.

RADAR LOOP REVEALS BROKEN BANDS OF STORMS PROGRESSING EWD AHEAD OF
THE ADVANCING COLD FRONT...WHERE 500 TO 1500 J/KG MIXED-LAYER CAPE
PERSISTS PER OBJECTIVE ANALYSES.  AN OVERALL/SLOW WEAKENING TREND
APPEARS TO HAVE BEGUN IN CONJUNCTION WITH SOME DIURNAL
STABILIZATION...BUT EXPECT ISOLATED STRONG/SEVERE STORMS TO
CONTINUE.  STORMS MAY LINGER ACROSS WW 293 BEYOND THE SCHEDULED
14/03Z EXPIRATION -- WHICH COULD REQUIRE A LOCAL EXTENTION OF THE
WATCH...OTHERWISE MUCH OF THE CONVECTION WILL CONTINUE SHIFTING INTO
WW 294 OVER THE NEXT 1-2 HOURS.

..GOSS.. 05/14/2009

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

ATTN...WFO...LOT...ILX...MKX...LSX...DVN...EAX...

LAT...LON   39359282 39739295 40849119 42608987 42568769 40148761
            39459006 39359282

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
May 13, 7:05 PM CDTMesoscale DiscussionSPCAdams, Brown, Cass, Fulton, Greene, Hancock and 15 more85 min
May 13, 9:56 PM CDTSevere Thunderstorm WatchSPCBond, Calhoun, Cass, Christian, Clark, Clay and 27 more6 hr
May 13, 10:17 PM CDTMesoscale DiscussionSPCChampaign, Cook, DeKalb, DeWitt, Douglas, DuPage and 23 more58 min
May 13, 10:51 PM CDTSevere Thunderstorm WatchSPCChampaign, Cook, DeWitt, DuPage, Ford, Grundy and 12 more4 hr
May 13, 11:27 PM CDTMesoscale DiscussionSPCAlexander, Bond, Calhoun, Clark, Clay, Clinton and 36 more93 min
May 14, 1:01 AM CDTSevere Thunderstorm WatchSPCAlexander, Edwards, Franklin, Gallatin, Hamilton, Hardin and 13 more5 hr
May 13, 8:22 PM CDTMesoscale DiscussionSPCBarry, Barton, Benton, Camden, Cedar, Christian and 30 more53 min

Nearby

Mesoscale Discussions in Illinois, 2009Mesoscale Discussions in Missouri, 2009Mesoscale Discussions in Iowa, 2009Every mesoscale discussion in 2009

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.