463
ACUS11 KWNS 300159
SWOMCD
SPC MCD 300159
MNZ000-IAZ000-SDZ000-NEZ000-300330-
MESOSCALE DISCUSSION 1389
NWS STORM PREDICTION CENTER NORMAN OK
0859 PM CDT MON JUN 29 2026
AREAS AFFECTED...PORTIONS OF SOUTHEASTERN SOUTH DAKOTA INTO
NORTHWESTERN IOWA AND SOUTHWESTERN MINNESOTA
CONCERNING...SEVERE THUNDERSTORM WATCH 417...
VALID 300159Z - 300330Z
THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 417
CONTINUES.
SUMMARY...DEVELOPING THUNDERSTORMS WILL CONTINUE TO GROW UPSCALE
OVER THE NEXT 1-2 HOURS WITH A TRANSITION TOWARDS SEVERE WIND GUSTS
OF 60-80 MPH AS THE PRIMARY THREAT. LARGE HAIL ALSO REMAINS
POSSIBLE.
DISCUSSION...THUNDERSTORM COVERAGE HAS GRADUALLY INCREASED ALONG AN
EASTWARD-PROGRESSING COLD FRONT ACROSS PORTIONS OF EASTERN SOUTH
DAKOTA AND WESTERN MINNESOTA OVER THE PAST HOUR. AS THIS DEVELOPMENT
CONTINUES, RAPID UPSCALE GROWTH INTO ONE OR MORE BOWING COMPLEXES IS
ANTICIPATED OVER THE NEXT 1-2 HOURS. AIDED BY STRONG TO EXTREME
INSTABILITY AND STEEP MID-LEVEL LAPSE RATES (5000-6000 J/KG MLCAPE
AND 9+ C/KM, RESPECTIVELY, INDICATED BY LATEST OBJECTIVE ANALYSIS
AND SAMPLED BY REGIONAL 00Z OBSERVED SOUNDINGS), RICH BOUNDARY LAYER
MOISTURE, AND STRONG EFFECTIVE SHEAR OF 50-60 KTS, THIS TRANSITION
TO A MORE LINEAR MODE WILL FAVOR AN INCREASE IN THE RISK FOR SEVERE
WIND GUSTS OF 60-80 MPH AS CONVECTION EVOLVES EASTWARD. LARGE TO
VERY LARGE HAIL TO 2" IN DIAMETER ALSO REMAINS POSSIBLE,
PARTICULARLY WITH ANY SUPERCELLS THAT CAN REMAIN SEMI-DISCRETE.
..CHALMERS.. 06/30/2026
..PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT
ATTN...WFO...MPX...DMX...FSD...ABR...
LAT...LON 42769694 43249668 44119608 44759607 44829606 45249610
45529607 45709604 45759575 45839533 45799485 45709457
45549430 45269418 44719415 44069430 43549458 42999518
42829564 42599685 42769694
MOST PROBABLE PEAK TORNADO INTENSITY...UP TO 90 MPH
MOST PROBABLE PEAK WIND GUST...65-80 MPH
MOST PROBABLE PEAK HAIL SIZE...1.50-2.50 IN
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