Alert archive / Missouri / Mesoscale Discussions in 2018
Mesoscale Discussion 596
The Storm Prediction Center issued this mesoscale discussion at May 31, 2018, 4:42 PM CDT for 5 states. It was in force for 2 hr.
The area
The outline as issued.
The facts
- Issued
- May 31, 2018, 4:42 PM CDT (21:42 UTC)
- Expired
- May 31, 2018, 6:45 PM CDT
- In force
- 2 hr
- Issued by
- the Storm Prediction Center
All 53 counties
Clay County, AR, Randolph County, AR, Alexander County, IL, Gallatin County, IL, Hardin County, IL, Jackson County, IL, Johnson County, IL, Massac County, IL, Pope County, IL, Pulaski County, IL, Saline County, IL, Union County, IL, Williamson County, IL, Ballard County, KY, Caldwell County, KY, Calloway County, KY, Carlisle County, KY, Christian County, KY, Crittenden County, KY, Fulton County, KY, Graves County, KY, Hickman County, KY, Hopkins County, KY, Livingston County, KY, Lyon County, KY, Marshall County, KY, McCracken County, KY, Trigg County, KY, Union County, KY, Webster County, KY, Bollinger County, MO, Butler County, MO, Cape Girardeau County, MO, Carter County, MO, Dent County, MO, Howell County, MO, Iron County, MO, Madison County, MO, Mississippi County, MO, New Madrid County, MO, Oregon County, MO, Perry County, MO, Reynolds County, MO, Ripley County, MO, Saint Francois County, MO, Scott County, MO, Shannon County, MO, Stoddard County, MO, Wayne County, MO, Lake County, TN, Montgomery County, TN, Obion County, TN, Stewart County, TN
The radar
The Paducah radar (KPAH), 65 km from the middle of the area, began a volume at 21:43 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
Little Rock, AR (KBYH), launched 12:00Z, 9.7 hours before the alert went out and 232 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
- 1378 J/kg
- Mixed-layer CIN
- -146 J/kg
- Mixed-layer LCL
- 988 m above ground
- 0-6 km bulk shear
- 15 kt
- 0-1 km storm-relative helicity
- -96 m²/s²
- 0-3 km storm-relative helicity
- -96 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
803
ACUS11 KWNS 312143
SWOMCD
SPC MCD 312142
KYZ000-TNZ000-INZ000-ILZ000-MOZ000-ARZ000-312345-
Mesoscale Discussion 0596
NWS Storm Prediction Center Norman OK
0442 PM CDT Thu May 31 2018
Areas affected...Southeast Missouri...Far Northeast
Arkansas...Southern Illinois...Western Kentucky
Concerning...Severe Thunderstorm Watch 138...
Valid 312142Z - 312345Z
The severe weather threat for Severe Thunderstorm Watch 138
continues.
SUMMARY...The tornado threat is expected to increase over the next
few hours across WW 138. Large hail and wind damage will also be
possible with the stronger thunderstorms.
DISCUSSION...An outflow boundary is evident on satellite imagery
across southeast Missouri where scattered thunderstorm have
developed over the last few hours. Surface dewpoints near the
boundary are in the lower 70s F which is contributing to moderate
instability. The RAP is estimating MLCAPE values in the 2000 to 2500
J/kg range in most of southern Missouri extending westward into
western Kentucky. A subtle shortwave trough is evident across the
mid Mississippi Valley and lower Missouri Valley according to water
vapor imagery. Large-scale ascent associated with this feature will
aide convective initiation and cell coverage should increase over
the next couple of hours. A mid-level speed max around 50 kt located
just ahead of the shortwave is helping to create moderate to strong
deep-layer shear profiles across southeast Missouri and western
Kentucky which will be favorable for supercells. In addition,
low-level flow is forecast to increase over the next few hours. This
will help create favorable low-level shear for a tornado threat. The
environment will also support a potential for isolated large hail
and wind damage.
..Broyles/Thompson.. 05/31/2018
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...OHX...PAH...MEG...LSX...LZK...SGF...
LAT...LON 36478733 36318899 36339165 36959217 37869133 37788749
36478733SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 31, 2:59 AM CDT | Mesoscale Discussion | SPC | Benton, Boone, Carroll, Crawford, Franklin, Johnson and 3 more | 61 min |
| May 31, 12:24 PM CDT | Mesoscale Discussion | SPC | Baxter, Benton, Boone, Carroll, Clay, Fulton and 4 more | 96 min |
| May 31, 1:57 PM CDT | Tornado Watch | SPC | Clay, Greene, Lawrence, Randolph | 6 hr |
| May 31, 5:46 PM CDT | Mesoscale Discussion | SPC | Clay, Cleburne, Craighead, Fulton, Greene, Independence and 8 more | 2 hr |
| May 31, 10:16 AM CDT | Mesoscale Discussion | SPC | Clay, Crawford, Edwards, Effingham, Gallatin, Hamilton and 9 more | 119 min |
| May 31, 10:31 AM CDT | Severe Thunderstorm Watch | SPC | Clark, Clay, Crawford, Cumberland, Edwards, Effingham and 8 more | 6 hr |
| May 31, 11:26 AM CDT | Mesoscale Discussion | SPC | Anderson, Bath, Bell, Bourbon, Boyle, Breathitt and 39 more | 64 min |
| May 31, 1:05 PM CDT | Mesoscale Discussion | SPC | Anderson, Boone, Bourbon, Bracken, Breckinridge, Bullitt and 25 more | 85 min |
| May 31, 1:30 PM CDT | Severe Thunderstorm Watch | SPC | Boone, Bracken, Campbell, Carroll, Gallatin, Grant and 6 more | 3 hr |
| May 31, 2:29 PM CDT | Mesoscale Discussion | SPC | Adair, Allen, Barren, Clinton, Cumberland, Edmonson and 9 more | 91 min |
| May 31, 2:56 PM CDT | Mesoscale Discussion | SPC | Anderson, Bath, Bourbon, Boyle, Bracken, Breathitt and 37 more | 64 min |
| May 31, 3:27 PM CDT | Mesoscale Discussion | SPC | Bell, Clinton, Harlan, Knox, Leslie, Letcher and 3 more | 93 min |
| May 31, 3:44 PM CDT | Mesoscale Discussion | SPC | Bracken, Lewis, Mason | 91 min |
| May 31, 4:31 PM CDT | Mesoscale Discussion | SPC | Bell, Clinton, Cumberland, McCreary, Russell, Wayne and 1 more | 59 min |
Nearby
Mesoscale Discussions in Missouri, 2018Mesoscale Discussions in Kentucky, 2018Mesoscale Discussions in Illinois, 2018Every mesoscale discussion in 2018
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.