Mesoscale Discussion 1663

Issued

Jul 19, 2026, 2:55 PM MDT (20:55 UTC)

Expired

Jul 19, 2026, 5:00 PM MDT

In force

2 hr

Issued by

the Storm Prediction Center

Concerning

Severe potential...severe thunderstorm watch likely

Chance of a watch

80%

The Bismarck radar (KBIS), 54 km from the middle of the area, began a volume at 20:57 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 499Jul 19, 3:25 PM MDT

213 
ACUS11 KWNS 192056
SWOMCD
SPC MCD 192055 
NDZ000-SDZ000-192300-

Mesoscale Discussion 1663
NWS Storm Prediction Center Norman OK
0355 PM CDT Sun Jul 19 2026

Areas affected...portions of southern North Dakota into northern
South Dakota

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

Valid 192055Z - 192300Z

Probability of Watch Issuance...80 percent

SUMMARY...Developing, high-based convection will evolve eastward
through this evening, bringing a risk for severe wind gusts (some
potentially significant) and large hail, perhaps to 2-3+ inches in
diameter.

DISCUSSION...A developing cumulus field across far southwestern
ND/northwestern SD has shown some signs of increased vertical growth
over the past hour, with isolated thunderstorms noted across Perkins
and Meade Counties in South Dakota as of 2050 UTC. Additional
development is expected amid continued insolation and along a
southeastward-progressing cold front over the next couple of hours.
A modified 18z BIS sounding indicates steep low- and mid-level lapse
rates are in place across this region along with around 30 kts of
effective shear and relatively straight, elongated hodographs.
Coupled with strengthening upper-level flow and further hodograph
elongation with time, this environment will be supportive of
initial, high-based splitting supercells capable of large hail
(potentially to 2-3+ inches in diameter) and severe outflow wind
gusts to 80+ mph. Efficient evaporative cooling will favor cold pool
development, with upscale growth into one or more clusters (and a
transition towards severe wind gusts as the primary threat) then
expected as convection spreads eastward with time. A Severe
Thunderstorm Watch will likely be needed later this afternoon to
cover this severe potential.

..Chalmers/Thompson.. 07/19/2026

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

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

LAT...LON   46600306 47240277 47560236 47740141 47750043 47659973
            47419909 47049869 46319820 45639824 45119891 44899991
            44790092 44800171 45010249 45300275 45970300 46600306 

MOST PROBABLE PEAK WIND GUST...75-90 MPH
MOST PROBABLE PEAK HAIL SIZE...2.00-3.50 IN

Mesoscale Discussions in North Dakota, 2026Mesoscale Discussions in South Dakota, 2026Every mesoscale discussion in 2026

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; radar from the NEXRAD Level II archive.