Alert archive / North Dakota / Mesoscale Discussions in 2023
Mesoscale Discussion 1921
The Storm Prediction Center issued this mesoscale discussion at Aug 9, 2023, 2:59 PM MDT for Dawson County, Richland County, Wibaux County, Montana; 14 counties in North Dakota; 13 counties in South Dakota. It was in force for 3 hr.
The area
The outline as issued.
The facts
- Issued
- Aug 9, 2023, 2:59 PM MDT (20:59 UTC)
- Expired
- Aug 9, 2023, 5:30 PM MDT
- In force
- 3 hr
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch unlikely
- Chance of a watch
- 5%
All 30 counties
Dawson County, MT, Richland County, MT, Wibaux County, MT, Adams County, ND, Billings County, ND, Bowman County, ND, Dickey County, ND, Emmons County, ND, Golden Valley County, ND, Grant County, ND, Hettinger County, ND, McIntosh County, ND, Morton County, ND, Sargent County, ND, Sioux County, ND, Slope County, ND, Stark County, ND, Brown County, SD, Campbell County, SD, Corson County, SD, Day County, SD, Dewey County, SD, Edmunds County, SD, Faulk County, SD, Marshall County, SD, McPherson County, SD, Potter County, SD, Roberts County, SD, Spink County, SD, Walworth County, SD
The radar
The Bismarck radar (KBIS), 72 km from the middle of the area, began a volume at 21:01 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
Bismarck Municip, ND (KBIS), launched 12:00Z, 9.0 hours before the alert went out and 75 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
- 66 J/kg
- Mixed-layer CIN
- -150 J/kg
- Mixed-layer LCL
- 1359 m above ground
- 0-6 km bulk shear
- 35 kt
- 0-1 km storm-relative helicity
- 86 m²/s²
- 0-3 km storm-relative helicity
- 109 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.1
The text
As transmitted.
862
ACUS11 KWNS 092100
SWOMCD
SPC MCD 092059
SDZ000-NDZ000-MTZ000-092330-
Mesoscale Discussion 1921
NWS Storm Prediction Center Norman OK
0359 PM CDT Wed Aug 09 2023
Areas affected...portions of extreme eastern Montana...southern
North Dakota...northern South Dakota
Concerning...Severe potential...Watch unlikely
Valid 092059Z - 092330Z
Probability of Watch Issuance...5 percent
SUMMARY...An instance or two of severe hail or wind may occur later
this afternoon into early evening. The severe threat should remain
isolated and a WW issuance is not expected.
DISCUSSION...Agitated cumulus, along with sparse areas of convective
initiation, are underway ahead of a diffuse trailing cold front from
extreme eastern MT, eastward along the SD/ND border. Ample heating
has mixed the boundary layer, with observed upper 70s/low 80s F
temperatures amid low 60s F dewpoints, overspread by 8.5+ C/km
boundary-layer lapse rates (20Z mesoanalysis). Given the dry
boundary layer, RAP forecast soundings depict the 1000 J/kg MLCAPE
(currently in place) distributed in tall/skinny profiles, though
unidirectional speed shear is in place. As such, a few multicells or
transient supercells may become sustained and support an instance or
two of severe hail/wind. Since the severe threat should be sparse, a
WW issuance is not expected.
..Squitieri/Guyer.. 08/09/2023
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...FGF...ABR...BIS...UNR...BYZ...GGW...
LAT...LON 47890494 47620358 46419934 46079728 45589689 45069696
44809822 44880039 45290175 46080364 46640481 47450509
47890494Nearby
Mesoscale Discussions in North Dakota, 2023Mesoscale Discussions in South Dakota, 2023Mesoscale Discussions in Montana, 2023Every mesoscale discussion in 2023
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.