181
ACUS03 KWNS 150728
SWODY3
SPC AC 150727
DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0227 AM CDT MON JUN 15 2026
VALID 171200Z - 181200Z
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
OF THE MID-MISSISSIPPI VALLEY INTO INDIANA...
..SUMMARY
AN ALL-HAZARDS SEVERE THUNDERSTORM EPISODE IS EXPECTED ACROSS
PORTIONS OF THE MIDDLE MISSISSIPPI VALLEY INTO INDIANA ON WEDNESDAY.
INTENSE THUNDERSTORMS MAY PRODUCE SWATHS OF DAMAGING WIND, AS WELL
AS STRONG TORNADOES AND LARGE HAIL.
..MIDWEST
A MIDLEVEL SHORTWAVE TROUGH IS FORECAST TO MOVE FROM THE NORTHERN
PLAINS THROUGH THE UPPER MIDWEST AND GREAT LAKES REGION ON
WEDNESDAY. AS THIS OCCURS, VERY STRONG DEEP-LAYER FLOW, ESPECIALLY
FOR THIS TIME OF YEAR, WILL MOVE ACROSS PORTIONS OF THE MID-MS
VALLEY INTO THE OHIO VALLEY. A WESTERLY 500 MB JET STREAK
CHARACTERIZED BY AT LEAST 70-80 KT WILL OVERSPREAD PARTS OF
IA/MO/IL/IN IN THE AFTERNOON AND EVENING. MEANWHILE, A 50+ KT
SOUTHWESTERLY 850 MB LOW-LEVEL JET WILL SPREAD ACROSS THE SAME AREA
DURING THE AFTERNOON/EVENING, JUST AHEAD OF AN
EAST/SOUTHEAST-ADVANCING SURFACE COLD FRONT. THESE STRONG WIND
FIELDS, IN CONJUNCTION WITH A SURFACE LOW MOVING EASTWARD ACROSS MN
AND THE UPPER GREAT LAKES, WILL AID IN NORTHWARD TRANSPORT OF RICH
BOUNDARY LAYER MOISTURE (UPPER 60S TO NEAR 70 F SURFACE DEWPOINTS).
COOLING ALOFT WILL STEEPEN MIDLEVEL LAPSE RATES, AND MODERATE TO
STRONG DESTABILIZATION IS EXPECTED ACROSS THE WARM SECTOR. OVERALL,
THIS PATTERN SHOULD SUPPORT NUMEROUS SEVERE STORMS. WHILE CONVECTIVE
EVOLUTION REMAINS UNCERTAIN, IT IS LIKELY THAT AT LEAST SOME INITIAL
SUPERCELL RISK WILL UNFOLD DURING THE AFTERNOON AND EARLY EVENING
(PARTICULARLY ACROSS MO/IL), WITH POTENTIAL FOR ONE OR MORE BOWING
MCSS DEVELOPING WITH TIME. THIS ENVIRONMENT WILL SUPPORT A RISK FOR
ALL SEVERE HAZARDS, AND PARTICULARLY SWATHS OF DAMAGING WINDS, AND
STRONG TORNADOES.
SOME UNCERTAINTY REMAINS REGARDING THE NORTHWARD EXTENT OF THE
SEVERE RISK. MOST MEDIUM RANGE GUIDANCE INDICATES A LEAD SHORTWAVE
IMPULSE MAY MOVE ACROSS IA/IL EARLY IN THE DAY. COUPLED WITH STRONG
WARM ADVECTION ACROSS THE REGION, MORNING THUNDERSTORM DEVELOP
NEAR/NORTH OF A WARM FRONT ORIENTED FROM SOUTHEAST MN INTO NORTHEAST
IL AT MIDDAY COULD SUPPRESS NORTHWARD DEVELOPMENT OF THE WARM FRONT.
LIKEWISE, THE SOUTHWEST EXTENT OF THE RISK AREA INTO PORTIONS OF
KS/OK MAY BE LIMITED BY CAPPING CONCERNS, AND WEAKER FORCING FOR
ASCENT. MEANWHILE, THE SOUTHWARD EXTENT OF THE SEVERE RISK ACROSS
THE OHIO VALLEY WILL BE MODULATED BY THE STRONGER WESTERLY COMPONENT
OF MID/UPPER FLOW OVERNIGHT AND SLOW SOUTHWARD MOVEMENT OF THE
SURFACE COLD FRONT. THE RISK AREA MAY SHIFT SOME IN COMING DAYS AS
SURFACE BOUNDARIES AND OTHER MESOSCALE DETAILS BECOME BETTER
RESOLVED.
..LEITMAN.. 06/15/2026
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