Alert archive / Minnesota / Mesoscale Discussions in 2021
Mesoscale Discussion 690
The Storm Prediction Center issued this mesoscale discussion at May 19, 2021, 7:51 PM CDT for 20 counties in Minnesota. It was in force for 114 min.
The area
The outline as issued.
The facts
- Issued
- May 19, 2021, 7:51 PM CDT (00:51 UTC)
- Expired
- May 19, 2021, 9:45 PM CDT
- In force
- 114 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch unlikely
- Chance of a watch
- 20%
Counties Blue Earth County, MN, Brown County, MN, Carver County, MN, Cottonwood County, MN, Dakota County, MN, Dodge County, MN, Faribault County, MN, Freeborn County, MN, Goodhue County, MN, Le Sueur County, MN, McLeod County, MN, Nicollet County, MN, Redwood County, MN, Renville County, MN, Rice County, MN, Scott County, MN, Sibley County, MN, Steele County, MN, Waseca County, MN, Watonwan County, MN
The radar
The Minneapolis radar (KMPX), 72 km from the middle of the area, began a volume at 00:52 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 00:00Z, 0.9 hours before the alert went out and 71 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
- 412 J/kg
- Mixed-layer CIN
- -10 J/kg
- Mixed-layer LCL
- 825 m above ground
- 0-6 km bulk shear
- 23 kt
- 0-1 km storm-relative helicity
- 84 m²/s²
- 0-3 km storm-relative helicity
- 92 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 1.4
The text
As transmitted.
968
ACUS11 KWNS 200052
SWOMCD
SPC MCD 200051
MNZ000-200245-
Mesoscale Discussion 0690
NWS Storm Prediction Center Norman OK
0751 PM CDT Wed May 19 2021
Areas affected...Southern Minnesota
Concerning...Severe potential...Watch unlikely
Valid 200051Z - 200245Z
Probability of Watch Issuance...20 percent
SUMMARY...Brief, weak tornadoes are possible over the next one to
two hours across southern Minnesota, but the overall severe threat
should remain limited.
DISCUSSION...Velocity data from KMPX shows a few weakly rotating
thunderstorms across southern MN (as well as one cell with stronger
rotation and a reported tornado) as they transverse a broad and
diffuse warm frontal boundary - noted largely by a subtle shift in
southeasterly flow along the IA/MN border to more easterly across
parts of south-central MN. The KMPX VWP shows modest curvature in
the 0-1 km layer and recent RAP mesosnalysis shows a slowly
strengthening 850 mb jet across the region, which have been
sufficient for storm rotation. Overall, the environment features
only modest instability and weak deep-layer wind shear that will act
to limit the overall severe weather threat. However, as the
low-level jet continues to strengthen through the evening hours one
or two more additional brief, weak tornadoes will be possible as
cells move through a region of slightly enhanced low-level shear
along the warm frontal zone.
..Moore/Dial.. 05/20/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...ARX...MPX...FSD...
LAT...LON 43579333 43709464 43889534 44559539 44999463 44959361
44829305 44599261 44099238 43669279 43579333Nearby
Mesoscale Discussions in Minnesota, 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.