Alert archive / Minnesota / Mesoscale Discussions in 2021

Mesoscale Discussion 1856

October 13, 20217 counties in Minnesota

The Storm Prediction Center issued this mesoscale discussion at Oct 13, 2021, 6:46 PM CDT for 7 counties in Minnesota. It was in force for 59 min.

The area

The outline as issued.

The facts

Issued: Oct 13, 2021, 6:46 PM CDT (23:46 UTC)
Expired: Oct 13, 2021, 7:45 PM CDT
In force: 59 min
Issued by: the Storm Prediction Center
Concerning: Severe potential...watch unlikely
Chance of a watch: 5%

Counties Becker County, MN, Benton County, MN, Clearwater County, MN, Hubbard County, MN, Mahnomen County, MN, Morrison County, MN, Wadena County, MN

The radar

The Fargo/Grand Forks radar (KMVX), 191 km from the middle of the area, began a volume at 23:50 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

Minneapolis, MN (KMPX), launched 12:00Z, 11.8 hours before the alert went out and 241 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-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 750 m above ground
0-6 km bulk shear: 41 kt
0-1 km storm-relative helicity: 146 m²/s²
0-3 km storm-relative helicity: 152 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

705 
ACUS11 KWNS 132347
SWOMCD
SPC MCD 132346 
MNZ000-140045-

Mesoscale Discussion 1856
NWS Storm Prediction Center Norman OK
0646 PM CDT Wed Oct 13 2021

Areas affected...Western Minnesota

Concerning...Severe potential...Watch unlikely 

Valid 132346Z - 140045Z

Probability of Watch Issuance...5 percent

SUMMARY...New thunderstorms developing across west-central Minnesota
may pose a brief/weak tornado threat for the next hour, but the
overall threat will remain too limited to warrant a watch issuance.

DISCUSSION...Latest radar imagery shows new thunderstorm development
across parts of west-central MN over the past 30-60 minutes. While
instability continues to wane amid diurnal cooling, RAP forecast
sounding hint that instability remains sufficient (around 250-500
J/kg MLCAPE) to support convection rooted in the boundary layer. VWP
observations from KMPX show 250-300 m2/s2 0-1 km SRH over the
region, which is supports recent Mesoanalysis estimates of 200 m2/s2
effective SRH ahead of the line. Furthermore, surface vorticity
remains elevated along the frontal boundary, and 0-3 km MLCAPE
values between 100-125 J/kg are noted in recent Mesoanalysis.
Consequently, a weak/brief tornado remains possible with this
convection. Given the onset of diurnal cooling and diminishing
instability, this threat will not likely persist beyond 01Z and a
watch is not expected.

..Moore/Guyer.. 10/13/2021

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

ATTN...WFO...DLH...MPX...FGF...

LAT...LON   46559537 47039622 47259646 47649642 47799603 47709547
            47559516 47379485 47029455 46709428 46289405 45919396
            45659399 45709428 46049468 46159494 46559537

Nearby

Mesoscale Discussions in Minnesota, 2021 Every 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.