MD 1726 CONCERNING SEVERE POTENTIAL…WATCH UNLIKELY FOR PORTIONS OF WESTERN SOUTH DAKOTA
Mesoscale Discussion 1726
NWS Storm Prediction Center Norman OK
0809 PM CDT Fri Aug 26 2022
Areas affected...portions of western South Dakota
Concerning...Severe potential...Watch unlikely
Valid 270109Z - 270215Z
Probability of Watch Issuance...20 percent
SUMMARY...A localized but concentrated severe wind threat exists
with a small bow echo across extreme western SD. Since the greater
severe threat may only last a couple of hours, a WW issuance is not
expected.
DISCUSSION...Cold pool mergers of semi-discrete convection have
recently occurred along the WY/SD border, where a small bow echo has
developed from clustering supercell structures. KUDX velocity data
shows 70+ kts of inbound velocities 4000-5000 ft AGL, indicative of
a pronounced rear-inflow jet present. This bow echo is progressing
eastward into a thermodynamic environment characterized by 1500 J/kg
MLCAPE, driven mainly by steep low and mid-level lapse rates (per
the 00Z UNR observed sounding and mesoanalysis). In addition, 40 kt
effective bulk shear values are oriented relatively normal to the
orientation of the bow, which also supports severe winds. Current
thinking is that the bow echo will propagate southeast along the
CAPE/low-level lapse rate gradient for the next couple of hours,
producing severe gusts (perhaps exceeding 65 kts at times). After
sunset, MLCINH should further increase and the severe threat should
gradually wane. Given the relatively short-lived and confined nature
of the severe threat, a WW issuance is unlikely.
..Squitieri/Grams.. 08/27/2022
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...UNR...
LAT...LON 44230416 44380410 44490403 44600387 44780357 44790301
44480235 44270219 43930232 43870263 43900307 43990363
44230416
