Alert archive / Indiana / Mesoscale Discussions in 2021

Mesoscale Discussion 1836

October 11, 20216 counties in Indiana

The Storm Prediction Center issued this mesoscale discussion at Oct 11, 2021, 9:16 PM EDT for 6 counties in Indiana. It was in force for 29 min.

The area

The outline as issued.

The facts

Issued
Oct 11, 2021, 9:16 PM EDT (01:16 UTC)
Expired
Oct 11, 2021, 9:45 PM EDT
In force
29 min
Issued by
the Storm Prediction Center
Concerning
Tornado watch 521

Counties Benton County, IN, Jasper County, IN, Lake County, IN, Newton County, IN, Porter County, IN, Warren County, IN

The radar

The Chicago radar (KLOT), 81 km from the middle of the area, began a volume at 01:16 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, 1.3 hours before the alert went out and 161 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.

Skew-T log-pSkew-T log-p diagram, Lincoln, IL at 00:00Z on 2021-10-12Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 10 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Lincoln, IL at 00:00Z on 2021-10-12The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -150 square meters per square second.19395878Sfc1 km3 km6 km9 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.
Mixed-layer CAPE
10 J/kg
Mixed-layer CIN
-9 J/kg
Mixed-layer LCL
743 m above ground
0-6 km bulk shear
37 kt
0-1 km storm-relative helicity
-150 m²/s²
0-3 km storm-relative helicity
-158 m²/s²
Significant tornado parameter
-0.0
Supercell composite
-0.0

Open this sounding in Storm Lab

The text

As transmitted.

651 
ACUS11 KWNS 120117
SWOMCD
SPC MCD 120116 
INZ000-ILZ000-120145-

Mesoscale Discussion 1836
NWS Storm Prediction Center Norman OK
0816 PM CDT Mon Oct 11 2021

Areas affected...northeast Illinois through northwest Indiana

Concerning...Tornado Watch 521...

Valid 120116Z - 120145Z

The severe weather threat for Tornado Watch 521 continues.

SUMMARY...While a strong wind gust or brief weak tornado cannot be
ruled out with low-topped band of convection moving through
northeast Illinois and northwest Indiana during the next hour.
Overall threat is becoming increasingly marginal. Remaining parts of
WW 251 will be allowed to expire at 02Z.

DISCUSSION...Overall trend has been for storms to weaken during the
past hour or so as they move northeast into air that has been
largely overturned by downstream convection developing along the
warm conveyor belt. A band of low-topped convection from the
southeast part of Chicago metro area into northwest Indiana might
remain capable of producing a strong wind gust during the next hour,
but the very marginal thermodynamic environment suggests the severe
threat should continue to wane.

..Dial.. 10/12/2021

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

ATTN...WFO...IWX...IND...LOT...

LAT...LON   41748697 40578701 40308740 40848757 41368760 41838743
            41748697

Nearby

Mesoscale Discussions in Indiana, 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.