Alert archive / Illinois / Mesoscale Discussions in 2009

Mesoscale Discussion 1237

June 19, 200930 counties in Illinois; 18 counties in Iowa

The Storm Prediction Center issued this mesoscale discussion at Jun 19, 2009, 1:54 PM CDT for 30 counties in Illinois; 18 counties in Iowa. It was in force for 96 min.

The area

The outline as issued.

The facts

Issued
Jun 19, 2009, 1:54 PM CDT (18:54 UTC)
Expired
Jun 19, 2009, 3:30 PM CDT
In force
96 min
Issued by
the Storm Prediction Center
All 48 counties

Benton County, IA, Cedar County, IA, Clinton County, IA, Delaware County, IA, Des Moines County, IA, Dubuque County, IA, Henry County, IA, Iowa County, IA, Jackson County, IA, Jefferson County, IA, Johnson County, IA, Jones County, IA, Keokuk County, IA, Linn County, IA, Louisa County, IA, Muscatine County, IA, Scott County, IA, Washington County, IA, Boone County, IL, Bureau County, IL, Carroll County, IL, DeKalb County, IL, DuPage County, IL, Grundy County, IL, Henderson County, IL, Henry County, IL, Jo Daviess County, IL, Kane County, IL, Kankakee County, IL, Kendall County, IL, Knox County, IL, LaSalle County, IL, Lee County, IL, Livingston County, IL, Marshall County, IL, McHenry County, IL, Mercer County, IL, Ogle County, IL, Peoria County, IL, Putnam County, IL, Rock Island County, IL, Stark County, IL, Stephenson County, IL, Warren County, IL, Whiteside County, IL, Will County, IL, Winnebago County, IL, Woodford County, IL

The radar

The Quad Cities radar (KDVN), 43 km from the middle of the area, began a volume at 18:58 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 12:00Z, 6.9 hours before the alert went out and 36 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 12:00Z on 2009-06-19Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 2575 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 12:00Z on 2009-06-19The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 73 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
2575 J/kg
Mixed-layer CIN
-76 J/kg
Mixed-layer LCL
810 m above ground
0-6 km bulk shear
50 kt
0-1 km storm-relative helicity
73 m²/s²
0-3 km storm-relative helicity
167 m²/s²
Significant tornado parameter
1.9
Supercell composite
10.9

Open this sounding in Storm Lab

The text

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

000 
ACUS11 KWNS 191855
SWOMCD
SPC MCD 191854 
ILZ000-IAZ000-192030-

MESOSCALE DISCUSSION 1237
NWS STORM PREDICTION CENTER NORMAN OK
0154 PM CDT FRI JUN 19 2009

AREAS AFFECTED...ERN IA INTO NRN IL

CONCERNING...SEVERE THUNDERSTORM WATCH 477...

VALID 191854Z - 192030Z

THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 477
CONTINUES.

TSTMS ARE EXPECTED TO SPREAD EWD ACROSS WW AREA LATER THIS AFTERNOON
AND EVENING AND A NEW WW WILL BE REQUIRED PRIOR TO 20Z.

LATEST TRENDS IN SURFACE OBSERVATIONAL DATA INDICATE THAT
CONSIDERABLE BOUNDARY LAYER WARMING AND SOME MOISTENING HAS OCCURRED
SINCE MID MORNING IN THE WAKE OF EARLIER...NOCTURNAL TSTM
DEVELOPMENT.  THIS IS GENERALLY SUPPORTED BY THE ENHANCED CUMULUS
FIELD OBSERVED OVER PORTIONS OF SERN IA INTO PARTS OF IL S OF THE
I-80 CORRIDOR.

WHILE IT REMAINS UNCERTAIN AS TO WHETHER IN SITU STORM FORMATION
WILL OCCUR WITHIN DESTABILIZING AIR MASS ACROSS WW AREA...LATEST
RADAR TRENDS AND NUMERICAL GUIDANCE BOTH SUGGEST A HIGH PROBABILITY 
OF TSTMS MOVING INTO THE AREA FROM THE WEST LATER THIS AFTERNOON
INTO EVENING.  GIVEN MODERATE INSTABILITY AND 50-60 KT OF DEEP-LAYER
SHEAR...THE POTENTIAL WILL EXIST FOR BOWING CONVECTIVE STRUCTURES
CAPABLE OF MAINLY DAMAGING WINDS AND HAIL.

..MEAD.. 06/19/2009

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

ATTN...WFO...LOT...ILX...DVN...DMX...

LAT...LON   41809226 42299197 42519129 42478915 42458824 41938779
            41108773 40738784 40658857 40629019 40709147 41129221
            41809226

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Jun 18, 8:23 PM CDTMesoscale DiscussionSPCBoone, Carroll, DeKalb, Jo Daviess, Lee, McHenry and 4 more97 min
Jun 18, 11:07 PM CDTMesoscale DiscussionSPCBoone, Carroll, Cook, DeKalb, DuPage, Grundy and 11 more53 min
Jun 18, 11:30 PM CDTSevere Thunderstorm WatchSPCBoone, Carroll, Cook, DeKalb, DuPage, Grundy and 12 more7 hr
Jun 19, 2:38 AM CDTMesoscale DiscussionSPCBoone, Cook, DeKalb, DuPage, Grundy, Kane and 9 more97 min
Jun 19, 6:58 AM CDTMesoscale DiscussionSPCBureau, Carroll, DeKalb, Henry, Jo Daviess, Kendall and 6 more62 min
Jun 19, 7:14 AM CDTSevere Thunderstorm WatchSPCBoone, Bureau, Carroll, Cook, DeKalb, DuPage and 28 more7 hr
Jun 19, 10:57 AM CDTMesoscale DiscussionSPCAdams, Brown, Hancock, McDonough, Schuyler93 min
Jun 19, 2:24 PM CDTSevere Thunderstorm WatchSPCAdams, Boone, Brown, Bureau, Carroll, Cass and 66 more8 hr
Jun 19, 5:37 PM CDTMesoscale DiscussionSPCAdams, Brown, Bureau, Calhoun, Carroll, Cass and 54 more53 min
Jun 18, 8:58 PM CDTTornado WatchSPCAllamakee, Chickasaw, Clayton, Fayette, Floyd, Howard and 2 more7 hr
Jun 19, 1:33 AM CDTMesoscale DiscussionSPCAdair, Adams, Audubon, Boone, Buena Vista, Calhoun and 26 more57 min
Jun 19, 2:13 AM CDTSevere Thunderstorm WatchSPCAdair, Adams, Appanoose, Audubon, Black Hawk, Boone and 40 more8 hr
Jun 19, 5:01 AM CDTMesoscale DiscussionSPCAdair, Adams, Audubon, Boone, Carroll, Cass and 22 more59 min
Jun 19, 12:37 PM CDTMesoscale DiscussionSPCAdair, Adams, Appanoose, Benton, Black Hawk, Buchanan and 29 more83 min
Jun 19, 1:36 PM CDTSevere Thunderstorm WatchSPCAdair, Adams, Appanoose, Cass, Clarke, Dallas and 20 more4 hr

Nearby

Mesoscale Discussions in Illinois, 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.