Alert archive / Missouri / Mesoscale Discussions in 2021
Mesoscale Discussion 501
The Storm Prediction Center issued this mesoscale discussion at May 3, 2021, 4:51 PM CDT for Monroe County, Randolph County, Saint Clair County, Illinois; 34 counties in Missouri. It was in force for 84 min.
The area
The outline as issued.
The facts
- Issued
- May 3, 2021, 4:51 PM CDT (21:51 UTC)
- Expired
- May 3, 2021, 6:15 PM CDT
- In force
- 84 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch possible
- Chance of a watch
- 40%
All 37 counties
Monroe County, IL, Randolph County, IL, Saint Clair County, IL, Bollinger County, MO, Cape Girardeau County, MO, Carter County, MO, Christian County, MO, City of Saint Louis, MO, Crawford County, MO, Dent County, MO, Douglas County, MO, Franklin County, MO, Gasconade County, MO, Howell County, MO, Iron County, MO, Jefferson County, MO, Laclede County, MO, Madison County, MO, Maries County, MO, Osage County, MO, Ozark County, MO, Perry County, MO, Phelps County, MO, Pulaski County, MO, Reynolds County, MO, Saint Charles County, MO, Saint Francois County, MO, Saint Louis County, MO, Sainte Genevieve County, MO, Shannon County, MO, Stone County, MO, Taney County, MO, Texas County, MO, Washington County, MO, Wayne County, MO, Webster County, MO, Wright County, MO
The radar
The Springfield radar (KSGF), 144 km from the middle of the area, began a volume at 21:53 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
Springfield, MO (KSGF), launched 12:00Z, 9.9 hours before the alert went out and 189 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
- 445 J/kg
- Mixed-layer CIN
- -118 J/kg
- Mixed-layer LCL
- 884 m above ground
- 0-6 km bulk shear
- 35 kt
- 0-1 km storm-relative helicity
- 50 m²/s²
- 0-3 km storm-relative helicity
- 70 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- -0.0
The text
As transmitted.
343
ACUS11 KWNS 032152
SWOMCD
SPC MCD 032151
ILZ000-MOZ000-ARZ000-032315-
Mesoscale Discussion 0501
NWS Storm Prediction Center Norman OK
0451 PM CDT Mon May 03 2021
Areas affected...portions of southern Missouri and far southwestern
Illinois
Concerning...Severe potential...Watch possible
Valid 032151Z - 032315Z
Probability of Watch Issuance...40 percent
SUMMARY...An isolated threat for damaging winds and hail is possible
with developing thunderstorms near Springfield, MO. A watch is
possible but high uncertainty remains.
DISCUSSION...Afternoon water vapor imagery showed a small shortwave
trough/ MCV moving across a stalled cold front along the Mississippi
River Valley into the Midwest. Heating along the front has eroded
the majority of MLCINH across southwestern Missouri. SPC
mesoanalysis indicates surface dewpoints in the low to middle 60s F
and lapse mid-level lapse rates near 8 C/km are supporting 1500-2500
J/kg of MLCAPE. Flow aloft is not overly strong, but mid-level flow
around 30 kts maybe be sufficient to support marginal supercells.
Latest WOFS guidance indicates a moderate probability (50-70%) that
the ongoing storms along the I-44 corridor will reach severe
criteria over the next couple of hours. With veered low-level winds
decreasing effective hodograph size, the primary severe threats will
be large hail and damaging wind gusts.
Considerable uncertainty remains on the coverage, longevity, and
severity of storms as they translate northeastward over the next
couple of hours. The favorable thermodynamics and marginal shear
parameter space suggest some severe threat may materialize.
Conditions will be monitored for a possible severe thunderstorm
watch.
..Lyons/Thompson.. 05/03/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...PAH...LSX...SGF...TSA...
LAT...LON 36719371 37379316 37889265 38459207 38759107 38839019
38348969 37638949 36928994 36759100 36539278 36469392
36719371SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 3, 2:08 PM CDT | Mesoscale Discussion | SPC | Adams, Bond, Brown, Calhoun, Cass, Champaign and 55 more | 67 min |
| May 3, 2:47 PM CDT | Severe Thunderstorm Watch | SPC | Adams, Bond, Brown, Bureau, Calhoun, Cass and 43 more | 6 hr |
| May 3, 5:15 PM CDT | Mesoscale Discussion | SPC | Bond, Brown, Calhoun, Cass, Champaign, Christian and 38 more | 90 min |
Nearby
Mesoscale Discussions in Missouri, 2021Mesoscale Discussions in Illinois, 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.