Alert archive / Illinois / Mesoscale Discussions in 2021
Mesoscale Discussion 286
The Storm Prediction Center issued this mesoscale discussion at Mar 27, 2021, 6:16 PM CDT for 27 counties in Illinois; 22 counties in Missouri. It was in force for 89 min.
The area
The outline as issued.
The facts
- Issued
- Mar 27, 2021, 6:16 PM CDT (23:16 UTC)
- Expired
- Mar 27, 2021, 7:45 PM CDT
- In force
- 89 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe thunderstorm watch 62
All 49 counties
Bond County, IL, Christian County, IL, Clark County, IL, Clay County, IL, Clinton County, IL, Coles County, IL, Cumberland County, IL, Douglas County, IL, Edgar County, IL, Effingham County, IL, Fayette County, IL, Jackson County, IL, Jasper County, IL, Jefferson County, IL, Jersey County, IL, Macon County, IL, Macoupin County, IL, Madison County, IL, Marion County, IL, Monroe County, IL, Montgomery County, IL, Moultrie County, IL, Perry County, IL, Randolph County, IL, Saint Clair County, IL, Shelby County, IL, Washington County, IL, Carter County, MO, City of Saint Louis, MO, Crawford County, MO, Dent County, MO, Franklin County, MO, Howell County, MO, Iron County, MO, Jefferson County, MO, Madison County, MO, Oregon County, MO, Perry County, MO, Phelps County, MO, Reynolds County, MO, Saint Charles County, MO, Saint Francois County, MO, Saint Louis County, MO, Sainte Genevieve County, MO, Shannon County, MO, Texas County, MO, Warren County, MO, Washington County, MO, Wayne County, MO
The radar
The St Louis radar (KLSX), 74 km from the middle of the area, began a volume at 23:19 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, 11.3 hours before the alert went out and 269 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
- 1078 m above ground
- 0-6 km bulk shear
- 78 kt
- 0-1 km storm-relative helicity
- 369 m²/s²
- 0-3 km storm-relative helicity
- 384 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
008
ACUS11 KWNS 272317
SWOMCD
SPC MCD 272316
ILZ000-MOZ000-280045-
Mesoscale Discussion 0286
NWS Storm Prediction Center Norman OK
0616 PM CDT Sat Mar 27 2021
Areas affected...Southeast Missouri and Central/Southern Illinois
Concerning...Severe Thunderstorm Watch 62...
Valid 272316Z - 280045Z
The severe weather threat for Severe Thunderstorm Watch 62
continues.
SUMMARY...Severe storms continue across the watch area.
DISCUSSION...Regional radar depicts a couple of discrete supercells
now moving into portions of east-central Illinois. One of these
storms tracked through the St. Louis metro area, producing hail to
the size of golf balls. Another cell farther north has also produced
severe hail and a severe wind gust (53 kt) at the TAZ ASOS. These
storms are riding the northern periphery of a low-level moisture
axis characterized by surface dew point temperatures in the mid 50s
F yielding MUCAPE near 500-1000 J/kg amid a strongly sheared
environment (effective bulk shear near 60 kt). A downstream watch
extension has been coordinated for this area.
Farther south, a line of storms is developing along the advancing
cold front across portions of south-central Missouri, with stronger
cores embedded. These storms may continue to pose a threat for large
hail in the near term, as low-level thermodynamic conditions (MLCAPE
1000-1500 J/kg) is conducive to sustain severe convection. With
time, the primary threat may transition to damaging winds associated
with a linear mode of convection.
..Karstens.. 03/27/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...PAH...ILX...LSX...SGF...
LAT...LON 36599126 36749253 37459243 38959101 39938931 40038759
39078768 37688943 36599126SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Mar 27, 2:34 PM CDT | Mesoscale Discussion | SPC | Adams, Brown, Calhoun, Cass, Greene, Jersey and 5 more | 116 min |
| Mar 27, 4:44 PM CDT | Severe Thunderstorm Watch | SPC | Bond, Calhoun, Christian, Clark, Clinton, Coles and 21 more | 5 hr |
Nearby
Mesoscale Discussions in Illinois, 2021Mesoscale Discussions in Missouri, 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.