Alert archive / Minnesota / Mesoscale Discussions in 2021
Mesoscale Discussion 1331
The Storm Prediction Center issued this mesoscale discussion at Jul 23, 2021, 1:25 PM CDT for 10 counties in Minnesota; Traill County, North Dakota. It was in force for 2 hr.
The area
The outline as issued.
The facts
- Issued
- Jul 23, 2021, 1:25 PM CDT (18:25 UTC)
- Expired
- Jul 23, 2021, 3:30 PM CDT
- In force
- 2 hr
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch possible
- Chance of a watch
- 40%
Counties Beltrami County, MN, Clearwater County, MN, Hubbard County, MN, Mahnomen County, MN, Marshall County, MN, Norman County, MN, Pennington County, MN, Polk County, MN, Red Lake County, MN, Roseau County, MN, Traill County, ND
The radar
The Fargo/Grand Forks radar (KMVX), 110 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.
The watches that followed
Watches SPC issued over any of the same counties within four hours of this discussion.
The nearest sounding before it
International Fa, MN (KINL), launched 12:00Z, 6.4 hours before the alert went out and 211 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
- 470 J/kg
- Mixed-layer CIN
- -131 J/kg
- Mixed-layer LCL
- 725 m above ground
- 0-6 km bulk shear
- 26 kt
- 0-1 km storm-relative helicity
- 112 m²/s²
- 0-3 km storm-relative helicity
- 115 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
448
ACUS11 KWNS 231825
SWOMCD
SPC MCD 231825
MNZ000-NDZ000-232030-
Mesoscale Discussion 1331
NWS Storm Prediction Center Norman OK
0125 PM CDT Fri Jul 23 2021
Areas affected...Northwest Minnesota
Concerning...Severe potential...Watch possible
Valid 231825Z - 232030Z
Probability of Watch Issuance...40 percent
SUMMARY...Thunderstorms may develop sooner than forecast guidance
has suggested, possibly within the next couple of hours. Large hail
and damaging winds would be the main threats this afternoon/evening.
Trends are being monitored for a possible severe thunderstorm watch.
DISCUSSION...Temperatures in northwestern Minnesota have risen into
the low 90s F. This has occurred quicker than forecast guidance has
suggested. With dewpoints still holding in the low 70s F, MLCAPE is
also increasing to above 1500 J/kg. Within this environment, a field
of cumulus has developed along with a handful of deeper towers in
the vicinity of Thief River Falls. With an upstream shortwave trough
evident on water vapor imagery within western/central North Dakota,
subtle mid-level cooling will occur in northern Minnesota this
afternoon. These factors would suggest that convection initiation is
becoming more probable, perhaps as early as within the next couple
of hours. With all 12Z guidance forecasting initiation during the
late afternoon, timing remains the greatest uncertainty. When storms
develop, long, straight hodographs with 35-40 kts of effective shear
will favor splitting supercells capable of damaging winds and large
hail. A severe thunderstorm watch is possible this afternoon
depending on convective trends over the next few hours.
..Wendt/Hart.. 07/23/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...DLH...FGF...
LAT...LON 47519741 48339689 48949640 49029567 48679464 48199411
47449404 46989473 46969686 47209732 47519741SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jul 23, 4:48 PM CDT | Severe Thunderstorm Watch | SPC | Aitkin, Becker, Beltrami, Carlton, Cass, Clearwater and 12 more | 7 hr |
| Jul 22, 9:04 PM CDT | Mesoscale Discussion | SPC | Burke, Divide, Williams | 116 min |
| Jul 23, 5:04 PM CDT | Mesoscale Discussion | SPC | Barnes, Cass, Dickey, Emmons, Grant, LaMoure and 6 more | 3 hr |
Nearby
Mesoscale Discussions in Minnesota, 2021Mesoscale Discussions in North Dakota, 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.