Mesoscale Discussion 1014

Issued

Jul 7, 2018, 7:55 PM MDT (01:55 UTC)

Expired

Jul 7, 2018, 9:00 PM MDT

In force

65 min

Issued by

the Storm Prediction Center

Chance of a watch

80%

Counties Carter County, MT, Adams County, ND, Bowman County, ND, Burleigh County, ND, Emmons County, ND, Foster County, ND, Grant County, ND, Hettinger County, ND, Kidder County, ND, Logan County, ND, Morton County, ND, Sheridan County, ND, Sioux County, ND, Stutsman County, ND, Wells County, ND, Harding County, SD, Perkins County, SD

The Bismarck radar (KBIS), 87 km from the middle of the area, began a volume at 01:55 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.

• Severe Thunderstorm Watch 264Jul 7, 8:40 PM MDT

130 
ACUS11 KWNS 080156
SWOMCD
SPC MCD 080155 
NDZ000-SDZ000-MTZ000-WYZ000-080300-

Mesoscale Discussion 1014
NWS Storm Prediction Center Norman OK
0855 PM CDT Sat Jul 07 2018

Areas affected...Southeast Montana...Far Northeast
Wyoming...Northwest South Dakota...Southern and Central North Dakota

Concerning...Severe potential...Severe Thunderstorm Watch likely 

Valid 080155Z - 080300Z

Probability of Watch Issuance...80 percent

SUMMARY...A severe threat appears likely to continue developing over
the next couple of hours from southeast Montana east-northeastward
across southern and central North Dakota. Weather watch issuance
will need to be considered as the scenario unfolds this evening.

DISCUSSION...The latest surface analysis shows a cold front
extending from northwest South Dakota northeastward into central
North Dakota. A moist airmass is located in the vicinity of the
front. Surface dewpoints range from the lower 60s F in southeast
Montana to the mid to upper 70s F in parts of central North Dakota.
This is creating strong instability across much of southern and
eastern North Dakota with the instability axis extending
southwestward into northwest South Dakota. Although strong
instability is present, the airmass is capped across much of the
northern Plains. In spite of the cap, thunderstorm development is
taking place in southeast Montana along an corridor of enhanced
low-level convergence. This convection is expected to remain intact
as it moves east-northeastward along a tight gradient of instability
across southwest North Dakota. 

The instability combined with 40 to 50 kt of 0-6 km shear along with
steep mid-level lapse rates evident on the RAP will make supercells
with isolated large hail a possibility. Multicell line segments may
also develop but the cap should minimize the wind damage potential
initially. As the convection moves further to the east-northeast
into increasing instability, the wind damage threat should become
more substantial. Convective coverage is expected to slowly increase
as a cluster of storms moves east-northeastward into southern North
Dakota later this evening.

..Broyles/Grams.. 07/08/2018

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

ATTN...WFO...FGF...ABR...BIS...UNR...BYZ...

LAT...LON   47859993 47849922 47579876 47099870 46619919 45780088
            44910377 44770461 44970545 45450552 45860492 46680215
            47859993

Mesoscale Discussions in North Dakota, 2018Mesoscale Discussions in South Dakota, 2018Mesoscale Discussions in Montana, 2018Every mesoscale discussion in 2018

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.