Mesoscale Discussion 936

Issued

Jun 12, 2021, 1:26 PM CDT (18:26 UTC)

Expired

Jun 12, 2021, 4:00 PM CDT

In force

3 hr

Issued by

the Storm Prediction Center

Concerning

Severe potential...watch unlikely

Chance of a watch

5%

The Lincoln radar (KILX), 95 km from the middle of the area, began a volume at 18:24 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.

830 
ACUS11 KWNS 121827
SWOMCD
SPC MCD 121826 
INZ000-ILZ000-122100-

Mesoscale Discussion 0936
NWS Storm Prediction Center Norman OK
0126 PM CDT Sat Jun 12 2021

Areas affected...portions of northern and central Illinois into far
west Indiana

Concerning...Severe potential...Watch unlikely 

Valid 121826Z - 122100Z

Probability of Watch Issuance...5 percent

SUMMARY...A few damaging gusts or a large hailstone may accompany
the stronger storms this afternoon. A WW issuance is not expected.

DISCUSSION...Convective initiation has recently transpired across
far northeast IL per latest KLOT radar data, with visible satellite
showing deepening CU across northern into central IL in advance of a
700 mb embedded impulse traversing the synoptic mid-level ridge.
Weak ascent ahead of the 700 mb impulse along with continued diurnal
heating/boundary-layer mixing will contribute to a gradual increase
in convective coverage and intensity through the afternoon.
Tropospheric winds are weak, with magnitudes below 20 kts in the
surface-500 mb layer, with only 15-25 kts of effective bulk shear
present (per 16Z RAP forecast soundings). As such, mainly
short-lived single cell storms and perhaps transient multicellular
clusters are expected. 

90+ F surface temperatures and near 70F dewpoints will support
widespread 2000+ J/kg MLCAPE and 8-8.5 C/km low-level lapse rates
given a well-mixed boundary layer in place (already evident via 18Z
mesoanalysis). A few damaging gusts will be possible with the
stronger single cell/multicellular clusters. While a 1.0 inch
diameter stone cannot be ruled out, mainly small hail is expected
with the freezing level being above 4000 m AGL. 18Z mesoanalysis
also shows modest 0-3 km vertically oriented vorticity meandering
across northern IL, where over 175 J/kg 0-3 km is developing. As
such, a very brief landspout cannot be completely ruled out as well,
before storms gust out.

..Squitieri/Grams.. 06/12/2021

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...IWX...IND...LOT...ILX...LSX...DVN...

LAT...LON   40279007 41818890 42238856 42298809 42228787 42038742
            41708718 41048706 40358709 39778741 39478784 39278857
            39378937 39468988 39499020 40279007

Mesoscale Discussions in Illinois, 2021Mesoscale Discussions in Indiana, 2021Every mesoscale discussion in 2021

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.