232
ACUS01 KWNS 131958
SWODY1
SPC AC 131956
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0256 PM CDT THU AUG 13 2026
VALID 132000Z - 141200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PORTIONS OF
THE MIDWEST INTO THE OHIO VALLEY...
..SUMMARY
ISOLATED TO SCATTERED SEVERE THUNDERSTORMS REMAIN POSSIBLE TODAY
FROM PARTS OF THE SOUTHERN/CENTRAL HIGH PLAINS TO THE MIDWEST.
SEVERE WIND GUSTS SHOULD BE THE MAIN THREAT, BUT SOME HAIL MAY ALSO
OCCUR.
..20Z UPDATE
THE MAIN CHANGE MADE TO THE 20Z DAY 1 CONVECTIVE OUTLOOK UPDATE WAS
TO ADD 5 PERCENT HAIL PROBABILITIES ACROSS PORTIONS OF CENTRAL NV
GIVEN MODESTLY COLD TEMPERATURES ALOFT AND ACCOMPANYING 7.5-8 C/KM
MID-LEVEL LAPSE RATES. THERE WERE CONSIDERATIONS TO TRIM OR REMOVE
THE SLIGHT RISK ACROSS PORTIONS OF THE MIDWEST BEHIND THE ONGOING
CLUSTER OF THUNDERSTORMS. HOWEVER, RECOVERY ALONG A RESIDUAL
BAROCLINIC BOUNDARY, OVERSPREAD BY 2000+ J/KG MLCAPE AND 40+ KTS OF
EFFECTIVE BULKS SHEAR, MAY SUPPORT ADDITIONAL STORM DEVELOPMENT
LATER THIS EVENING WHEN THE LLJ INTENSIFIES. OTHERWISE, THE PREVIOUS
FORECAST REMAINS ON TRACK, WITH ONLY MINOR CHANGES MADE TO ONGOING
THUNDER AND SEVERE PROBABILITIES TO ACCOUNT FOR THE LATEST GUIDANCE
CONSENSUS.
..SQUITIERI.. 08/13/2026
PREV DISCUSSION
/ISSUED 1132 AM CDT THU AUG 13 2026/
..MIDWEST INCLUDING PARTS OF EASTERN IOWA AND ILLINOIS/INDIANA
SUPPORTED BY AN MCV, A LONG-LIVED MCS CONTINUES TO MOVE
EAST-SOUTHEASTWARD INTO WEST-CENTRAL/NORTHWEST ILLINOIS LATE THIS
MORNING. GREATER STABILITY INITIALLY PRECEDES THE MCS ACROSS
NORTHERN ILLINOIS, BUT THE REMNANT CLUSTER AND ADDITIONAL
REDEVELOPMENT WILL LIKELY TEND TO FAVOR A MORE SOUTHEASTWARD
PROGRESSION IN CLOSER PROXIMITY TO THE FRONT/INSTABILITY GRADIENT
THAT EXTENDS ACROSS ILLINOIS/INDIANA, WITH ADDITIONAL/RENEWED
DEVELOPMENT AND INTENSIFICATION POSSIBLE INTO THE AFTERNOON AND
EVENING. DAMAGING WIND GUSTS WILL BE THE PRIMARY SEVERE HAZARD,
ALTHOUGH A BRIEF TORNADO AND MARGINALLY SEVERE HAIL ARE ALSO
POSSIBLE INTO THIS EVENING. WHILE NOT CERTAIN, ADDITIONAL SEVERE
REDEVELOPMENT MAY ALSO OCCUR TONIGHT FARTHER WEST/NORTHEASTWARD
ACROSS AREAS POTENTIALLY INCLUDING EASTERN IOWA AND NORTHERN/CENTRAL
ILLINOIS AS A LOW-LEVEL JET NOCTURNALLY INCREASES.
..SOUTHERN/CENTRAL HIGH PLAINS
HIGH-BASED THUNDERSTORMS ARE EXPECTED TO INITIALLY DEVELOP OVER THE
HIGHER TERRAIN OF THE CENTRAL ROCKIES/FRONT RANGE THIS AFTERNOON,
WITH POST-FRONTAL LOW-LEVEL UPSLOPE FLOW PERSISTING ACROSS THE
CENTRAL HIGH PLAINS. STORM MOTIONS INTO SLIGHTLY RICHER MOISTURE
WILL FAVOR SOME AGGREGATION OF OUTFLOW WITHIN A HOT BOUNDARY LAYER
FEATURING STEEP LAPSE RATES. ISOLATED TO WIDELY SCATTERED SEVERE
WIND GUSTS 60-75 MPH ARE POSSIBLE, ALONG WITH OCCASIONAL HAIL WITH A
FEW OF THE STRONGER CORES.
..GREAT BASIN
MODESTLY ENHANCED SOUTHWESTERLY MID-LEVEL FLOW WILL PERSIST TODAY
ACROSS THE GREAT BASIN DOWNSTREAM OF A WEAK MID-LEVEL TROUGH OVER
CALIFORNIA. WEAK TO LOCALLY MODERATE INSTABILITY IS FORECAST VIA
DIURNAL HEATING. SCATTERED TO NUMEROUS THUNDERSTORMS ARE EXPECTED
AND SOME OF THE STRONGER EVAPORATIVELY COOLED DOWNDRAFTS WILL BE
CAPABLE OF 60-75 MPH GUSTS.
..NORTHEAST
SEASONABLY COOL MID-LEVEL TEMPERATURES ARE FORECAST TODAY ACROSS
PARTS OF THE NORTHEAST, WITH A MID-LEVEL TROUGH EXPECTED TO MOVE
EAST-SOUTHEASTWARD FROM QUEBEC INTO NEW ENGLAND. WHILE INSTABILITY
IS FORECAST TO REMAIN FAIRLY LIMITED, STRONG WEST-NORTHWESTERLY FLOW
ALOFT MAY SUPPORT A RISK FOR ISOLATED DAMAGING WINDS (50-65 MPH)
WITH THUNDERSTORMS THAT DEVELOP AND SPREAD SOUTHEASTWARD THROUGH THE
AFTERNOON. ISOLATED HAIL MAY ALSO OCCUR WITH THE STRONGER CELLS.
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page