ACUS11 KWNS 302003
SWOMCD
SPC MCD 302003
NDZ000-SDZ000-302200-

Mesoscale Discussion 1749
NWS Storm Prediction Center Norman OK
0303 PM CDT Tue Jul 30 2024

Areas affected...North and South Dakota

Concerning...Severe potential...Watch possible

Valid 302003Z - 302200Z

Probability of Watch Issuance...60 percent

SUMMARY...Thunderstorm development is anticipated in the next 1-2
hours across the western Dakotas. Storms are expected to intensify
as they migrate east into central North and South Dakota. Watch
issuance is possible later this afternoon/evening as the severe
threat becomes more prominent.

DISCUSSION...Recent GOES visible imagery shows a gradual increase in
cumulus along a surface trough and within the Black Hills in western
SD. Mid to upper-level cirrus overspreading the region from the west
is indicative of gradually increasing synoptic-scale ascent ahead of
a mid-level shortwave trough over ID/MT. Thunderstorm development
appears likely in the coming hours as ascent continues to increase
and continued daytime heating erodes any lingering MLCIN.

Initial thunderstorms across the western Dakotas will develop within
a relatively dry/well-mixed environment with LCL heights between 3.0
to 3.5 km. This environment will favor strong downdraft
accelerations and rapid cold pool development/expansion with an
attendant severe wind risk. Convection is expected to intensify as
it moves east through the evening hours and encounters a reservoir
of richer low-level moisture (well-sampled by a recent 19 UTC ABR
sounding). Adequate deep-layer wind shear (around 30-35 knots)
should support organized convection. Storm coverage remains somewhat
uncertain given weak forcing for ascent. While the environment may
support a supercell or two this evening, clustering of initial cells
is possible and may promote upscale growth and a more robust wind
threat. Trends will be monitored and watch issuance may be needed
later this afternoon or evening to address this concern.

..Moore/Gleason.. 07/30/2024

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

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

LAT...LON   44930049 44030188 43840218 43790254 43850287 44170313
            44510327 44810330 46100323 46540311 46740298 47060283
            47900222 48380147 48400078 48060016 47429973 46649967
            46039979 45490003 44930049