104
ACUS01 KWNS 201946
SWODY1
SPC AC 201944
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0244 PM CDT SUN SEP 20 2026
VALID 202000Z - 211200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
CENTRAL AND EASTERN OKLAHOMA AND FROM EASTERN COLORADO INTO FAR
WESTERN KANSAS...
..SUMMARY
THUNDERSTORMS WITH SEVERE WIND GUSTS AND LARGE HAIL REMAIN POSSIBLE
THIS AFTERNOON AND EVENING ACROSS PARTS OF OKLAHOMA AND FROM EASTERN
COLORADO INTO FAR WESTERN KANSAS. ISOLATED SEVERE GUSTS AND HAIL
WILL ALSO BE POSSIBLE IN PARTS OF THE SOUTHERN PLAINS AND FROM THE
OZARKS EASTWARD INTO THE OHIO VALLEY.
..20Z UPDATE
THE FORECAST REMAINS GENERALLY ON TRACK, WITH ONLY MINOR ADJUSTMENTS
MADE TO THE EXISTING OUTLOOK. SEE THE DISCUSSION BELOW FOR
ADDITIONAL INFORMATION.
..CHALMERS/WENDT.. 09/20/2026
PREV DISCUSSION
/ISSUED 1126 AM CDT SUN SEP 20 2026/
..CENTRAL/NORTH TX INTO CENTRAL/EASTERN OK
SURFACE ANALYSIS PLACES A LOW OVER CENTRAL OK, ALONG A COLD FRONT
THAT ARCS FROM NORTHEAST OK INTO SOUTHWEST OK AND THEN BACK UP
THROUGH THE CENTRAL TX PANHANDLE. THIS LOW ALSO PRECEDES A SHORTWAVE
TROUGH MOVING INTO WESTERN OK. THE COLD FRONT IS FORECAST TO SHIFT
SOUTHWARD/SOUTHEASTWARD TODAY AS THE SHORTWAVE CONTINUES EASTWARD.
THE AIRMASS AHEAD OF THIS FRONT WILL BE WARM, MOIST, AND MODERATELY
BUOYANT, AND THUNDERSTORM DEVELOPMENT IS EXPECTED FROM
CENTRAL/EASTERN OK INTO CENTRAL TX. MID-LEVEL FLOW IS SLIGHTLY
STRONGER ACROSS OK, SUPPORTING A GREATER POTENTIAL FOR STRONG TO
SEVERE STORMS. A MORE ISOLATED SEVERE RISK EXISTS ACROSS TX WHERE A
MORE DISORGANIZED STORM MODE IS LIKELY. PRIMARY THREAT IS DAMAGING
GUSTS FROM 55 TO 65 MPH.
..CENTRAL HIGH PLAINS
AN EASTERLY COMPONENT TO LOW-LEVEL FLOW NORTH OF THE SURFACE FRONT
WILL MAINTAIN A FETCH OF MOISTURE (50S DEG F SURFACE DEWPOINTS)
ACROSS EASTERN CO THIS AFTERNOON. THIS MOISTURE, COMBINED WITH
HEATING AND COOL TEMPERATURES ALOFT, WILL ENABLE MODERATE
DESTABILIZATION BY AFTERNOON. THUNDERSTORM DEVELOPMENT IS EXPECTED
AS ASCENT ATTENDANT TO THE MID-LEVEL CYCLONE OVER WY PERSISTS ACROSS
THE REGION. MODERATE MID-LEVEL WESTERLY FLOW WILL ALSO PERSIST
THROUGHOUT THE BASE OF THIS CYCLONE, RESULTING IN MODERATE TO STRONG
VERTICAL SHEAR ACROSS THE REGION THIS AFTERNOON AND EVENING. STORM
COVERAGE IS EXPECTED TO REMAIN ISOLATED TO WIDELY SCATTERED (LARGELY
DUE TO COOLER SURFACE TEMPERATURES AND SOME LINGERING CONVECTIVE
INHIBITION), BUT ANY STORMS THAT DO FORM AND MATURE WILL LIKELY BE
SUPERCELLULAR. PRIMARY SEVERE HAZARD IS LARGE HAIL (1 TO 2.5 INCHES
IN DIAMETER), BUT ISOLATED SEVERE GUSTS ARE POSSIBLE AS WELL. SOME
LINGERING SEVERE RISK MAY EVENTUALLY DEVELOP OVER SOUTHEAST CO LATE
THIS EVENING AND SPREAD INTO THE OK PANHANDLE OVERNIGHT.
..OZARKS INTO THE MID MISSISSIPPI AND OHIO VALLEYS
RECENT SURFACE ANALYSIS PLACES LOWS OVER CENTRAL PA, CENTRAL IL,
CENTRAL MO, AND CENTRAL OK. AN ARCING STATIONARY BOUNDARY EXTENDS
BETWEEN THESE FEATURES, WITH THIS BOUNDARY LARGELY DEMARCATED BY A
SUBTLE WIND SHIFT. CURRENT WATER VAPOR SATELLITE IMAGERY SHOWS
SEVERAL CONVECTIVELY AUGMENTED VORTICITY MAXIMA WITHIN THIS CORRIDOR
AS WELL. THESE VORTICITY MAXIMA ARE FORECAST TO PROGRESS
EASTWARD/NORTHEASTWARD ALONG THE NORTHERN PERIPHERY OF A WEAKENED
MID-LEVEL ANTICYCLONE CENTERED OVER THE NORTHWEST GULF COAST,
AUGMENTING LOW-LEVEL CONVERGENCE AND HELPING TO SUPPORT
AFTERNOON/EVENING THUNDERSTORMS FROM THE OH VALLEY INTO
CENTRAL/SOUTHERN MO.
DESPITE AMPLE LOW-LEVEL MOISTURE, RELATIVELY WARM TEMPERATURES ALOFT
WILL LIKELY MITIGATE THE OVERALL BUOYANCY. EVEN SO, STEEP LOW-LEVEL
LAPSE RATES AND MODERATE MID-LEVEL FLOW COULD STILL SUPPORT SOME
BOWING LINE SEGMENTS CAPABLE OF DAMAGING GUSTS. HIGHEST THUNDERSTORM
COVERAGE THIS AFTERNOON AND EVENING IS EXPECTED FROM
CENTRAL/SOUTHERN IN INTO SOUTHERN OH, WITH ANOTHER CORRIDOR OF
RELATIVELY HIGHER COVERAGE DEVELOPING ACROSS CENTRAL MO LATER THIS
EVENING AS WELL. BOTH OF THESE CORRIDORS ARE DOWNSTREAM OF A
PREVIOUSLY MENTIONED VORTICITY MAX, AND REPRESENT AREAS OF GREATER
SEVERE POTENTIAL.
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