Alert archive / Missouri / Mesoscale Discussions in 2021
Mesoscale Discussion 327
The Storm Prediction Center issued this mesoscale discussion at Apr 7, 2021, 5:04 PM CDT for 19 counties in Illinois; 7 counties in Iowa; 23 counties in Missouri. It was in force for 116 min.
The area
The outline as issued.
The facts
- Issued
- Apr 7, 2021, 5:04 PM CDT (22:04 UTC)
- Expired
- Apr 7, 2021, 7:00 PM CDT
- In force
- 116 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch unlikely
- Chance of a watch
- 20%
All 49 counties
Davis County, IA, Des Moines County, IA, Henry County, IA, Jefferson County, IA, Lee County, IA, Louisa County, IA, Van Buren County, IA, Adams County, IL, Brown County, IL, Calhoun County, IL, Cass County, IL, Fulton County, IL, Greene County, IL, Hancock County, IL, Henderson County, IL, Jersey County, IL, Macoupin County, IL, Madison County, IL, McDonough County, IL, Monroe County, IL, Morgan County, IL, Pike County, IL, Saint Clair County, IL, Schuyler County, IL, Scott County, IL, Warren County, IL, Adair County, MO, Audrain County, MO, Callaway County, MO, City of Saint Louis, MO, Clark County, MO, Franklin County, MO, Gasconade County, MO, Jefferson County, MO, Knox County, MO, Lewis County, MO, Lincoln County, MO, Macon County, MO, Marion County, MO, Monroe County, MO, Montgomery County, MO, Pike County, MO, Ralls County, MO, Saint Charles County, MO, Saint Louis County, MO, Schuyler County, MO, Scotland County, MO, Shelby County, MO, Warren County, MO
The radar
The St Louis radar (KLSX), 96 km from the middle of the area, began a volume at 22:08 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 nearest sounding before it
Lincoln, IL (KILX), launched 12:00Z, 10.1 hours before the alert went out and 237 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
- 56 J/kg
- Mixed-layer CIN
- -173 J/kg
- Mixed-layer LCL
- 1001 m above ground
- 0-6 km bulk shear
- 19 kt
- 0-1 km storm-relative helicity
- 120 m²/s²
- 0-3 km storm-relative helicity
- 88 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
536
ACUS11 KWNS 072204
SWOMCD
SPC MCD 072204
ILZ000-MOZ000-IAZ000-080000-
Mesoscale Discussion 0327
NWS Storm Prediction Center Norman OK
0504 PM CDT Wed Apr 07 2021
Areas affected...Northeastern Missouri...Western
Illinois...southeastern Iowa.
Concerning...Severe potential...Watch unlikely
Valid 072204Z - 080000Z
Probability of Watch Issuance...20 percent
SUMMARY...Potential for damaging wind gusts will likely decrease as
a line of convection moves north and east this afternoon evening. A
narrow area in northeast Missouri into western Illinois appears to
have the most favorable environment for stronger gusts. A downstream
watch is not anticipated this evening.
DISCUSSION...Strong to occasionally severe storms along a line west
of St. Louis will continue to progress to the northeast into the
evening. The most intense portion of this line remains to the
northwest of the St. Louis metro area and is being sustain by strong
mid-level ascent from the upper low in Kansas. Current surface
observations show low to mid 70s F temperatures just ahead of the
line within the Mississippi Valley. There, some cloud cover has kept
dewpoints from mixing out with a few low 60s F being observed. The
Quincy, IL vicinity appears to have the most favorable environment
ahead of the line coupled with the upper-level support. Farther
east, greater sunshine has allowed higher temperatures, but
dewpoints have mixed into the mid/upper 50s F. While a few isolated
damaging wind gusts are possible, particularly in northeast Missouri
into adjacent western Illinois, the over all trend in convective
intensity is expected to decrease the farther north and east the
line moves. An additional downstream watch is not anticipated.
..Wendt/Grams.. 04/07/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...ILX...LSX...DVN...SGF...DMX...EAX...
LAT...LON 38099054 37959144 38449184 39479248 40079280 40269293
40589288 41259194 41249079 40128994 39538968 38848966
38408968 38099054SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Apr 7, 6:40 AM CDT | Mesoscale Discussion | SPC | Barry, Camden, Cedar, Christian, Cole, Dade and 20 more | 2 hr |
| Apr 7, 10:18 AM CDT | Mesoscale Discussion | SPC | Barry, Barton, Bates, Benton, Boone, Buchanan and 42 more | 117 min |
| Apr 7, 12:02 PM CDT | Severe Thunderstorm Watch | SPC | Adair, Audrain, Barry, Benton, Boone, Caldwell and 78 more | 7 hr |
| Apr 7, 1:30 PM CDT | Mesoscale Discussion | SPC | Camden, Christian, Cole, Dallas, Douglas, Greene and 13 more | 90 min |
| Apr 7, 2:22 PM CDT | Mesoscale Discussion | SPC | Howell, Oregon, Ozark, Stone, Taney | 53 min |
| Apr 7, 3:13 PM CDT | Mesoscale Discussion | SPC | Audrain, Boone, Callaway, Cole, Crawford, Dent and 21 more | 92 min |
| Apr 7, 3:40 PM CDT | Mesoscale Discussion | SPC | Ozark | 65 min |
| Apr 7, 5:12 PM CDT | Mesoscale Discussion | SPC | Dunklin, Pemiscot | 2 hr |
Nearby
Mesoscale Discussions in Missouri, 2021Mesoscale Discussions in Illinois, 2021Mesoscale Discussions in Iowa, 2021Every mesoscale discussion in 2021
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.