Alert archive / Illinois / Mesoscale Discussions in 2003

Mesoscale Discussion 2172

August 17, 200324 counties in Illinois; 7 counties in Indiana; 15 counties in Kentucky

The Storm Prediction Center issued this mesoscale discussion at Aug 17, 2003, 1:48 PM CDT for 24 counties in Illinois; 7 counties in Indiana; 15 counties in Kentucky. It was in force for 117 min.

The area

The outline as issued.

The facts

Issued: Aug 17, 2003, 1:48 PM CDT (18:48 UTC)
Expired: Aug 17, 2003, 3:45 PM CDT
In force: 117 min
Issued by: the Storm Prediction Center

All 46 counties

Clark County, IL, Clay County, IL, Crawford County, IL, Cumberland County, IL, Edwards County, IL, Effingham County, IL, Fayette County, IL, Franklin County, IL, Gallatin County, IL, Hamilton County, IL, Hardin County, IL, Jasper County, IL, Jefferson County, IL, Johnson County, IL, Lawrence County, IL, Marion County, IL, Massac County, IL, Pope County, IL, Richland County, IL, Saline County, IL, Wabash County, IL, Wayne County, IL, White County, IL, Williamson County, IL, Gibson County, IN, Knox County, IN, Pike County, IN, Posey County, IN, Sullivan County, IN, Vanderburgh County, IN, Warrick County, IN, Ballard County, KY, Caldwell County, KY, Carlisle County, KY, Crittenden County, KY, Graves County, KY, Henderson County, KY, Hopkins County, KY, Livingston County, KY, Lyon County, KY, Marshall County, KY, McCracken County, KY, McLean County, KY, Muhlenberg County, KY, Union County, KY, Webster County, KY

The watches that followed

Watches SPC issued over any of the same counties within four hours of this discussion.

Severe Thunderstorm Watch 867Aug 17, 3:10 PM CDT

The nearest sounding before it

Lincoln, IL (KILX), launched 12:00Z, 6.8 hours before the alert went out and 229 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: 1031 J/kg
Mixed-layer CIN: -96 J/kg
Mixed-layer LCL: 1178 m above ground
0-6 km bulk shear: 30 kt
0-1 km storm-relative helicity: 39 m²/s²
0-3 km storm-relative helicity: 71 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 1.3

Open this sounding in Storm Lab

The text

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

525 
ACUS11 KWNS 171849
SWOMCD
SPC MCD 171848 
KYZ000-INZ000-ILZ000-172045-

MESOSCALE DISCUSSION 2172
NWS STORM PREDICTION CENTER NORMAN OK
0148 PM CDT SUN AUG 17 2003

AREAS AFFECTED...SRN IL / SWRN IND / WRN KY

CONCERNING...SEVERE THUNDERSTORM POTENTIAL 

VALID 171848Z - 172045Z

DEVELOPING TSTMS WILL POSE A LARGE HAIL/DAMAGING WIND THREAT AND A
NEW WW WILL LIKELY BE REQUIRED SOON W OF WW 865.

EVV RADAR IMAGERY AND VISIBLE SATELLITE IMAGERY SHOW TSTMS BEGINNING
TO DEVELOP OVER CLARK CO IL AND VIGO CO IND IN A ZONE OF LOCALIZED
LOW-LEVEL CONVERGENCE TO THE NE OF A SURFACE LOW OVER S-CNTRL IL.
HERE...MOSTLY SUNNY SKIES HAVE ALLOWED TEMPERATURES TO WARM INTO THE
LOWER 90S AND WHEN COUPLED WITH SURFACE DEWPOINTS IN THE UPPER 60S
TO LOWER 70S AND MODERATELY COOL MID-LEVEL TEMPERATURES /-9 TO -10 C
AT 500MB/ IS RESULTING IN MLCAPES OF 2000-3000 J/KG. 

CURRENT WATER VAPOR IMAGERY CLEARLY SHOWS A VORTICITY MAX DIVING SWD
THROUGH NRN/CNTRL IL AND THIS IN CONJUNCTION WITH THE LOW-LEVEL
CONVERGENCE INVOF THE SURFACE LOW AND WEAK FRONTAL BOUNDARY SHOULD
BE SUFFICIENT TO SUSTAIN THE DEVELOPING STORMS. FURTHERMORE...RUC
DIAGNOSTIC FIELDS INDICATE THAT AN AXIS OF STRONGER MID AND
UPPER-LEVEL WINDS IS ROTATING AROUND THE WRN SIDE OF THIS VORTICITY
CENTER...EFFECTIVELY ENHANCING THE DEEP-LAYER SHEAR ACROSS THE WARM
SECTOR. GIVEN THESE FACTORS...ORGANIZED TSTMS APPEAR LIKELY WITH THE
POTENTIAL FOR SOME STORMS TO EXHIBIT SUPERCELL STRUCTURES.

..MEAD.. 08/17/2003

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

ATTN...WFO...LMK...IND...PAH...ILX...LSX...

37618918 39128910 39498796 39138731 37088708 36628893

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Aug 17, 3:10 PM CDT	Severe Thunderstorm Watch	SPC	Alexander, Bond, Christian, Clark, Clay, Clinton and 31 more	6 hr
Aug 17, 12:15 PM CDT	Severe Thunderstorm Watch	SPC	Perry	6 hr
Aug 17, 3:27 PM CDT	Mesoscale Discussion	SPC	Perry	2 hr
Aug 17, 11:06 AM CDT	Mesoscale Discussion	SPC	Bell, Breathitt, Clay, Estill, Floyd, Harlan and 10 more	114 min
Aug 17, 5:16 PM CDT	Mesoscale Discussion	SPC	Bell, Clay, Harlan, Jackson, Knox, Laurel and 9 more	59 min
Aug 17, 6:51 PM CDT	Mesoscale Discussion	SPC	Caldwell, Calloway, Carlisle, Christian, Crittenden, Fulton and 12 more	54 min

Nearby

Mesoscale Discussions in Illinois, 2003 Mesoscale Discussions in Kentucky, 2003 Mesoscale Discussions in Indiana, 2003 Every 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.