Alert archive / Illinois / Mesoscale Discussions in 2017
Mesoscale Discussion 596
The Storm Prediction Center issued this mesoscale discussion at Apr 29, 2017, 3:28 PM CDT for 26 counties in Illinois; 9 counties in Indiana; Perry County, Sainte Genevieve County, Missouri. It was in force for 2 hr.
The area
The outline as issued.
The facts
- Issued
- Apr 29, 2017, 3:28 PM CDT (20:28 UTC)
- Expired
- Apr 29, 2017, 5:30 PM CDT
- In force
- 2 hr
- Issued by
- the Storm Prediction Center
- Chance of a watch
- 40%
All 37 counties
Bond County, IL, Clay County, IL, Clinton County, IL, Crawford County, IL, Edwards County, IL, Effingham County, IL, Fayette County, IL, Franklin County, IL, Gallatin County, IL, Hamilton County, IL, Jackson County, IL, Jasper County, IL, Jefferson County, IL, Lawrence County, IL, Madison County, IL, Marion County, IL, Perry County, IL, Randolph County, IL, Richland County, IL, Saint Clair County, IL, Saline County, IL, Wabash County, IL, Washington County, IL, Wayne County, IL, White County, IL, Williamson County, IL, Daviess County, IN, Gibson County, IN, Greene County, IN, Knox County, IN, Pike County, IN, Posey County, IN, Sullivan County, IN, Vanderburgh County, IN, Warrick County, IN, Perry County, MO, Sainte Genevieve County, MO
The radar
The Evansville,IN radar (KVWX), 107 km from the middle of the area, began a volume at 20:31 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
Lincoln, IL (KILX), launched 12:00Z, 8.5 hours before the alert went out and 207 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
- 0 J/kg
- Mixed-layer CIN
- No buoyant parcel
- Mixed-layer LCL
- 776 m above ground
- 0-6 km bulk shear
- 61 kt
- 0-1 km storm-relative helicity
- 242 m²/s²
- 0-3 km storm-relative helicity
- 568 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
856
ACUS11 KWNS 292028
SWOMCD
SPC MCD 292028
INZ000-KYZ000-ILZ000-MOZ000-292230-
Mesoscale Discussion 0596
NWS Storm Prediction Center Norman OK
0328 PM CDT Sat Apr 29 2017
Areas affected...southeast Missouri through southern Illinois and
southwest Indiana
Concerning...Severe potential...Watch possible
Valid 292028Z - 292230Z
Probability of Watch Issuance...40 percent
SUMMARY...Storms will pose some threat for isolated damaging wind as
they continue through eastern Missouri, southern Illinois and
southwest Indiana into the early evening.
DISCUSSION...Line of storms continues from near St. Louis through
northwest AR. The northern portion of the line is moving more
rapidly at around 40 kt, is the most organized, and appears to be
forced by the circulation accompanying a progressive MCV. A warm
front continues to lift north through the OH valley downstream from
the line with dewpoints rising to around 70 F and temperatures in
the 80s in warm sector. Storms may continue to pose a risk for
damaging wind as they interact with destabilizing boundary layer
next few hours and where eastern branch of the low level jet will
continue to support strong convergence and moist and unstable
inflow. A limiting factor has been tendency for upper ridge to build
which has resulted in weaker flow above 500 mb.
..Dial/Weiss.. 04/29/2017
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...LMK...IND...PAH...ILX...LSX...
LAT...LON 37599032 38309009 39128992 39198848 39168691 38048696
37478858 37599032SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Apr 28, 10:01 PM CDT | Severe Thunderstorm Watch | SPC | Alexander, Franklin, Gallatin, Hamilton, Hardin, Jackson and 7 more | 9 hr |
| Apr 28, 11:55 PM CDT | Mesoscale Discussion | SPC | Alexander, Franklin, Gallatin, Hardin, Jackson, Johnson and 6 more | 95 min |
| Apr 29, 3:39 AM CDT | Mesoscale Discussion | SPC | Alexander, Franklin, Gallatin, Hamilton, Hardin, Jackson and 8 more | 96 min |
| Apr 29, 12:50 PM CDT | Mesoscale Discussion | SPC | Monroe, Randolph, Saint Clair | 85 min |
| Apr 29, 3:57 PM CDT | Severe Thunderstorm Watch | SPC | Alexander, Bond, Christian, Clark, Clay, Clinton and 38 more | 6 hr |
| Apr 29, 6:30 PM CDT | Mesoscale Discussion | SPC | Alexander, Clark, Clay, Coles, Crawford, Cumberland and 25 more | 60 min |
| Apr 28, 7:10 PM CDT | Severe Thunderstorm Watch | SPC | Bartholomew, Brown, Dearborn, Decatur, Fayette, Franklin and 8 more | 6 hr |
| Apr 28, 8:27 PM CDT | Tornado Watch | SPC | Clark, Crawford, Dubois, Floyd, Gibson, Harrison and 10 more | 5 hr |
| Apr 28, 10:19 PM CDT | Mesoscale Discussion | SPC | Clark, Crawford, Daviess, Dearborn, Dubois, Floyd and 18 more | 116 min |
| Apr 29, 12:50 AM CDT | Mesoscale Discussion | SPC | Clark, Crawford, Dubois, Floyd, Gibson, Harrison and 11 more | 85 min |
| Apr 29, 6:23 AM CDT | Mesoscale Discussion | SPC | Clark, Dearborn, Floyd, Harrison, Jackson, Jefferson and 6 more | 3 hr |
Nearby
Mesoscale Discussions in Illinois, 2017Mesoscale Discussions in Indiana, 2017Mesoscale Discussions in Missouri, 2017Every mesoscale discussion in 2017
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.