Mesoscale Discussion 1454

Issued

Aug 9, 2021, 6:34 PM CDT (23:34 UTC)

Expired

Aug 9, 2021, 8:00 PM CDT

In force

86 min

Issued by

the Storm Prediction Center

Concerning

Severe thunderstorm watch 418

Counties Kittson County, MN, Barnes County, ND, Benson County, ND, Cavalier County, ND, Eddy County, ND, Foster County, ND, Grand Forks County, ND, Griggs County, ND, Logan County, ND, Nelson County, ND, Pembina County, ND, Ramsey County, ND, Steele County, ND, Stutsman County, ND, Towner County, ND, Traill County, ND, Walsh County, ND, Wells County, ND

The Fargo/Grand Forks radar (KMVX), 81 km from the middle of the area, began a volume at 23:36 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.

855 
ACUS11 KWNS 092334
SWOMCD
SPC MCD 092334 
MNZ000-NDZ000-100100-

Mesoscale Discussion 1454
NWS Storm Prediction Center Norman OK
0634 PM CDT Mon Aug 09 2021

Areas affected...East-central North Dakota and far northwestern
Minnesota

Concerning...Severe Thunderstorm Watch 418...

Valid 092334Z - 100100Z

The severe weather threat for Severe Thunderstorm Watch 418
continues.

SUMMARY...Supercells across WW418 will continue to pose a risk for
all hazards. Additional development is expected over the next few
hours with an increasing risk for hail/damaging winds later this
evening.

DISCUSSION...Ahead of the compact upper low across the northern
Plains, a cluster of supercells has become established across
central North Dakota. Recent storm reports of golf ball and baseball
sized hail indicate these storms continue to pose a risk for large
to very large hail as they track to the north and east. Ongoing near
a warm front with dewpoints in the mid 60s F, SPC mesoanalysis shows
2000-3000 J/kg of MLCAPE across much of North Dakota. Regional VWPs
also show robust shear profiles with 50-60 kts of effective shear.
With strong instability and vertical shear in place, the environment
will remain highly favorable for supercells capable of large to very
large hail and damaging wind gusts this evening. 

As the cluster of storms continues to track to the north and east,
they will approach a southwest to northeast oriented warm front in
the vicinity of Grand Forks, ND. Along and north of this boundary,
low-level flow is strongly backed, favoring enlarged low-level
hodographs. KMVX VAD data shows 200-300  ESRH in place, suggesting
some potential for tornadoes if storms can remain discrete. However,
additional development and continued upscale growth into one or more
clusters/short line segments may shift the threat towards damaging
winds later this evening. Until then, a tornado or two will remain
possible near the front.

..Lyons.. 08/09/2021

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

ATTN...WFO...FGF...BIS...

LAT...LON   47479976 48969973 49109936 49119723 49099667 48719653
            48119646 47929652 47059710 46319921 46419950 46969960
            47479976

Mesoscale Discussions in North Dakota, 2021Mesoscale Discussions in Minnesota, 2021Every mesoscale discussion in 2021

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.