Alert archive / Illinois / Mesoscale Discussions in 2021
Mesoscale Discussion 5
The Storm Prediction Center issued this mesoscale discussion at Jan 1, 2021, 1:08 AM CST for 49 counties in Illinois; Saint Charles County, Saint Louis County, City of Saint Louis, Missouri. It was in force for 5 hr.
The area
The outline as issued.
The facts
- Issued
- Jan 1, 2021, 1:08 AM CST (07:08 UTC)
- Expired
- Jan 1, 2021, 6:15 AM CST
- In force
- 5 hr
- Issued by
- the Storm Prediction Center
- Concerning
- Freezing rain
All 52 counties
Bond County, IL, Brown County, IL, Calhoun County, IL, Cass County, IL, Champaign County, IL, Christian County, IL, Clark County, IL, Clay County, IL, Clinton County, IL, Coles County, IL, Crawford County, IL, Cumberland County, IL, DeWitt County, IL, Douglas County, IL, Edgar County, IL, Edwards County, IL, Effingham County, IL, Fayette County, IL, Franklin County, IL, Greene County, IL, Hamilton County, IL, Jasper County, IL, Jefferson County, IL, Jersey County, IL, Logan County, IL, Macon County, IL, Macoupin County, IL, Madison County, IL, Marion County, IL, Mason County, IL, McLean County, IL, Menard County, IL, Monroe County, IL, Montgomery County, IL, Morgan County, IL, Moultrie County, IL, Perry County, IL, Piatt County, IL, Pike County, IL, Randolph County, IL, Richland County, IL, Saint Clair County, IL, Sangamon County, IL, Schuyler County, IL, Scott County, IL, Shelby County, IL, Tazewell County, IL, Washington County, IL, Wayne County, IL, City of Saint Louis, MO, Saint Charles County, MO, Saint Louis County, MO
The radar
The Lincoln radar (KILX), 123 km from the middle of the area, began a volume at 07:08 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 00:00Z, 7.1 hours before the alert went out and 134 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
- 1196 m above ground
- 0-6 km bulk shear
- 20 kt
- 0-1 km storm-relative helicity
- -9 m²/s²
- 0-3 km storm-relative helicity
- 4 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
775
ACUS11 KWNS 010709
SWOMCD
SPC MCD 010708
ILZ000-MOZ000-011215-
Mesoscale Discussion 0005
NWS Storm Prediction Center Norman OK
0108 AM CST Fri Jan 01 2021
Areas affected...Portions of far east Missouri into central Illinois
Concerning...Freezing rain
Valid 010708Z - 011215Z
SUMMARY...Freezing rain potential is increasing across portions of
far eastern Missouri into central Illinois. A couple areas may
briefly see up to .06 in/3 hr rates in the heavier rain bands.
DISCUSSION...Widespread warm-air/moisture advection is underway
across portions of the Middle Mississippi Valley in advance of a
gradually approaching surface and upper low currently positioned
across the southern Plains. Widespread heavier precipitation is also
approaching portions of eastern Missouri into central Illinois,
where a dry 850-700 mb layer continues to moisten. METAR
observations depict sub-freezing surface temperatures, and given the
aforementioned dry air aloft, wet-bulb surface temperatures have
been able to sustain well below 32F for several hours. Multiple ASOS
sites across far eastern MO show that ice accumulations have already
begun.
The 850-700 mb dry layer is expected to sufficiently moisten in the
next couple of hours to support higher freezing rain rates, which
may briefly approach .06 in/3 hrs in some of the stronger rain
bands, especially in the 08-12Z period, as suggested by 00Z HREF
guidance and the last few runs of the HRRR.
..Squitieri/Edwards.. 01/01/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...PAH...LOT...ILX...LSX...DVN...
LAT...LON 38098835 37808891 37798961 37909004 38199045 38639076
39479095 39959084 40199072 40529000 40638907 40228781
39798773 39238766 38868769 38468794 38098835SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jan 1, 2:33 AM CST | Mesoscale Discussion | SPC | Adams, Brown, Calhoun, Cass, Greene, Jersey and 4 more | 5 hr |
| Jan 1, 6:35 AM CST | Mesoscale Discussion | SPC | Adams, Brown, Bureau, Cass, Champaign, DeWitt and 34 more | 4 hr |
| Dec 31, 8:44 PM CST | Mesoscale Discussion | SPC | Barry, Barton, Benton, Camden, Cedar, Christian and 35 more | 6 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.