686
ACUS11 KWNS 170429
SWOMCD
SPC MCD 170428
MNZ000-IAZ000-SDZ000-170630-
MESOSCALE DISCUSSION 1159
NWS STORM PREDICTION CENTER NORMAN OK
1128 PM CDT TUE JUN 16 2026
AREAS AFFECTED...EAST-CENTRAL AND SOUTHEAST SD...FAR SOUTHWEST
MN...NORTHWEST IA
CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY
VALID 170428Z - 170630Z
PROBABILITY OF WATCH ISSUANCE...20 PERCENT
SUMMARY...ISOLATED HAIL/WIND POTENTIAL INCREASING WITH SOUTHEAST
EXTENT AND DURING THE 05-08Z (12AM-3AM CDT) PERIOD.
DISCUSSION...A LOBE OF UPPER-LEVEL FORCING FOR ASCENT ASSOCIATED
WITH AN APPROACHING UPPER JET STREAK WILL CONTINUE TO RAPIDLY MOVE
EAST-SOUTHEAST FROM THE MT/DAKOTAS BORDER AND ACROSS THE DAKOTAS
TONIGHT. AS THIS OCCURS, STRENGTHENING LOW-LEVEL WARM-AIR ADVECTION
TO THE NORTH (IMMEDIATE COOL SIDE) OF A WEST-NORTHWEST TO
EAST-SOUTHEAST ORIENTED FRONTAL ZONE (ANALYZED FROM WESTERN SD INTO
SOUTHEAST SD) WILL ACT TO DESTABILIZE THE AIRMASS OVER PARTS OF THE
MID MO VALLEY TONIGHT. FORECAST SOUNDINGS OVER CENTRAL SD (VALID
CURRENTLY AT 04Z) SHOW SCANT BUOYANCY AMIDST STRONG DEEP-LAYER SHEAR
AND ELONGATED HODOGRAPHS. RAP FORECAST SOUNDINGS NEAR SIOUX CITY,
IA OVER THE NEXT FEW HOURS SHOW MOISTURE INCREASING IN THE 900-800
MB LAYER AS THE TERMINUS OF A LLJ FOCUSES OVER THE REGION. AS A
RESULT, ELEVATED PARCELS WILL ATTAIN MUCH GREATER BUOYANCY (E.G.,
LESS THAN 100 J/KG TO 2500 J/KG MUCAPE) THROUGH 08Z. IT IS
PLAUSIBLE AS BOTH THE ELEVATED INSTABILITY AND FORCING FOR ASCENT
DEVELOP AND OVERSPREAD PARTS OF SOUTHEAST SD INTO ADJACENT PORTIONS
OF MN/IA, THAT INTENSIFICATION OF ONGOING STORMS MOVING SOUTHEAST
WILL OCCUR OR ADDITIONAL STORMS WILL DEVELOP AND STRENGTHEN.
ALTHOUGH SOME UNCERTAINTY REMAINS REGARDING THE EVOLUTION OF STORM
ACTIVITY, AT LEAST AN ISOLATED RISK FOR LARGE HAIL AND SEVERE GUSTS
MAY DEVELOP TONIGHT AND BECOME INCREASINGLY POSSIBLE WITH TIME
(I.E., 05 TO 08 UTC).
..SMITH/GLEASON.. 06/17/2026
..PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT
ATTN...WFO...MPX...DMX...FSD...ABR...
LAT...LON 43849910 44169922 44539889 44699854 43749482 43259462
42649505 42449558 43849910
MOST PROBABLE PEAK WIND GUST...55-70 MPH
MOST PROBABLE PEAK HAIL SIZE...UP TO 1.25 IN
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