328
ACUS03 KWNS 211917
SWODY3
SPC AC 211916
DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0216 PM CDT SUN JUN 21 2026
VALID 231200Z - 241200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER THE CENTRAL
HIGH PLAINS...
..SUMMARY
SCATTERED SEVERE STORMS ARE EXPECTED ACROSS THE CENTRAL HIGH PLAINS
ON TUESDAY WITH ISOLATED SEVERE STORMS POSSIBLE INTO THE UPPER
MISSISSIPPI VALLEY. LARGE TO VERY LARGE HAIL AND DAMAGING WIND GUSTS
WILL BE THE PRIMARY THREATS.
..SYNOPSIS
AN UPPER LOW INITIALLY OVER SASKATCHEWAN/MANITOBA WILL DRIFT
SOUTHEAST TO ALONG THE INTERNATIONAL BORDER WITH AN ATTENDING BELT
OF 40-50+ KT MID-LEVEL FLOW FORECAST ACROSS THE NORTHERN AND CENTRAL
PLAINS INTO THE UPPER MIDWEST. FARTHER EAST, A SHORT-WAVE TROUGH
TRAILING AN UPPER LOW OVER ONTARIO WILL MOVE THROUGH THE
MID-ATLANTIC. IN THE LOW LEVELS, AN AREA OF LOW PRESSURE IS FORECAST
TO DEVELOP FROM THE NORTHERN PLAINS INTO UPPER MS VALLEY WITH A
TRAILING BOUNDARY EXTENDING SOUTHWEST INTO THE CENTRAL HIGH PLAINS.
ELSEWHERE, A COLD FRONT WILL MOVE OFF THE MID-ATLANTIC COAST WITH
THE TRAILING EXTENSION OF THE BOUNDARY MOVING INTO THE SOUTHEAST.
..CENTRAL AND SOUTHERN HIGH PLAINS
DESPITE THE POTENTIAL FOR EARLY-DAY STORMS ACROSS PORTIONS OF NE,
TX, AND OK, THE EML IS EXPECTED TO REMAIN INTACT OVER THE CENTRAL
HIGH PLAINS. WHEN COUPLED WITH AN INCREASINGLY MOIST UPSLOPE AIR
MASS IN THE VICINITY OF THE FRONT, MODERATE TO STRONG INSTABILITY IS
FORECAST BY AFTERNOON. DIURNALLY ENHANCED THUNDERSTORMS ARE EXPECTED
TO FORM ALONG FAVORED TERRAIN AND PRE-EXISTING SURFACE BOUNDARIES
AMIDST A KINEMATIC ENVIRONMENT FEATURING VERTICALLY VEERING WINDS
WITH HEIGHT WITH SUFFICIENT VERTICAL SHEAR TO SUPPORT SUPERCELLS
CAPABLE OF LARGE TO VERY LARGE HAIL. THE NOCTURNAL STRENGTHENING OF
A LOW-LEVEL JET OVER WESTERN PARTS OF KS, OK, AND TX MAY FAVOR
UPSCALE GROWTH OF STORMS INTO A FORWARD-PROPAGATING MCS TUESDAY
EVENING WITH AN ASSOCIATED INCREASE IN SEVERE-WIND-GUST POTENTIAL.
..UPPER MISSISSIPPI VALLEY INTO THE MID MISSOURI VALLEY
LATEST MODEL DATA ARE IN GOOD AGREEMENT IN DEPICTING AREAS OF
SHOWERS AND STORMS LINGERING THROUGH MUCH OF THE DAY ACROSS THE
PRE-FRONTAL WARM SECTOR. VERTICAL SHEAR IS FORECAST TO BE
SUFFICIENTLY STRONG TO SUPPORT ORGANIZED STORM MODES, ESPECIALLY
ACROSS THE UPPER MS VALLEY. HOWEVER, THE POTENTIAL FOR CLOUDS AND
PRECIPITATION TO LIMIT AIR MASS DESTABILIZATION LEADS TO UNCERTAINTY
IN THE EXTENT OF THE SEVERE-WEATHER THREAT. AS SUCH, THE LOW
SEVERE-WEATHER PROBABILITIES WILL BE MAINTAINED WITH THIS FORECAST
UPDATE.
...MIDDLE AND SOUTHERN ATLANTIC COAST INTO THE CENTRAL GULF COAST
STATES...
A FEW STRONG STORMS CAPABLE OF GUSTY WINDS APPEAR POSSIBLE TUESDAY
AFTERNOON ALONG AND AHEAD OF THE SYNOPTIC FRONT. WHILE POOR
LOW/MID-LEVEL LAPSE RATES ARE EXPECTED TO LIMIT A MORE ROBUST
DAMAGING-WIND THREAT, LOW SEVERE-WEATHER PROBABILITIES MAY
EVENTUALLY BE ADDED ONCE DETAILS IN STORM EVOLUTION BECOME MORE
CLEAR.
..MEAD.. 06/21/2026
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