211
ACUS03 KWNS 021919
SWODY3
SPC AC 021918
DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0218 PM CDT WED SEP 02 2026
VALID 041200Z - 051200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF
THE SOUTHERN MID-ATLANTIC...
..SUMMARY
WIDELY SCATTERED SEVERE THUNDERSTORMS, MAINLY PRODUCING DAMAGING
GUSTS, ARE EXPECTED ACROSS PORTIONS OF THE SOUTHERN MID-ATLANTIC ON
FRIDAY. MORE ISOLATED SEVERE STORMS CAPABLE OF SEVERE WINDS AND
LARGE HAIL MAY OCCUR OVER PARTS OF THE MIDWEST FRIDAY AFTERNOON INTO
NIGHT.
..SYNOPSIS
A MID-LEVEL RIDGE OVER CENTRAL NORTH AMERICA WILL UNDERGO FURTHER
AMPLIFICATION THIS PERIOD WITH THAT FEATURE BRACKETED BY TROUGHS
OVER THE WESTERN CONUS AND EASTERN CANADA INTO THE NORTHEAST. AS HAS
BEEN THE CASE OVER THE PAST SEVERAL DAYS, SUBTLE DISTURBANCES
EMBEDDED WITHIN THE BROADER-SCALE FLOW REGIME WILL SERVE AS FOCI FOR
THUNDERSTORM DEVELOPMENT. AT THE SURFACE, A LEE CYCLONE WILL EVOLVE
OVER THE NORTHERN HIGH PLAINS WITH AN ASSOCIATED SURFACE FRONT
STRETCHING FROM THE NORTHERN PLAINS THROUGH THE UPPER MIDWEST TO THE
SOUTHERN MID-ATLANTIC COAST.
..LOWER OHIO VALLEY INTO THE SOUTHERN MID-ATLANTIC
THERE IS REASONABLY GOOD AGREEMENT ACROSS THE 12Z PARAMETERIZED
MODELS THAT SCATTERED THUNDERSTORMS MAY BE ONGOING FRIDAY MORNING
ACROSS PORTIONS OF THE OH VALLEY/SOUTHERN GREAT LAKES REGION IN
ASSOCIATION WITH AN EMBEDDED VORTICITY MAXIMUM. WHETHER THAT
CONVECTION PERSISTS INTO AFTERNOON REMAINS UNCERTAIN; HOWEVER, IT
DOES APPEAR THAT THE MID-LEVEL DISTURBANCE WILL PROGRESS INTO THE
MID-ATLANTIC IN TANDEM WITH A BELT OF 35-40 KT WEST-NORTHWEST FLOW
IN THE MID LEVELS. FORCING FOR ASCENT ASSOCIATED WITH THAT
DISTURBANCE WILL PROMOTE RENEWED THUNDERSTORM DEVELOPMENT BY
AFTERNOON ALONG THE EFFECTIVE SURFACE FRONT AND WITHIN A MODERATELY
UNSTABLE AIR MASS. SUFFICIENT VERTICAL SHEAR WILL EXIST TO SUPPORT
ORGANIZED STORM MODES WITH THE PREDOMINANT HAZARD BEING DAMAGING
WIND GUSTS.
THIS FORECAST UPDATE WILL INCLUDE A SLIGHT NORTHWARD EXPANSION OF
THE SLIGHT RISK PROBABILITIES BASED ON 12Z GUIDANCE.
..MIDWEST/CORN BELT
IN THE WAKE OF POSSIBLE EARLY-DAY STORMS DESCRIBED IN THE PREVIOUS
SECTION, STEEP MID-LEVEL LAPSE RATES WITHIN THE EASTERN FRINGE OF AN
ELEVATED-MIXED LAYER (EML) WILL COINCIDE WITH A MOIST BOUNDARY LAYER
TO YIELD A MODERATELY TO STRONGLY UNSTABLE AIR MASS BY AFTERNOON IN
THE VICINITY OF THE SURFACE FRONT. THE PROXIMITY TO THE BUILDING
MID-LEVEL RIDGE AND RESULTANT CAPPING ACROSS THE WARM SECTOR LEAD TO
CONSIDERABLE UNCERTAINTY IN THE EXTENT AND LOCATION OF SURFACE-BASED
THUNDERSTORM DEVELOPMENT FRIDAY AFTERNOON INTO NIGHT. WHILE
DEEP-LAYER SHEAR IS FORECAST TO BE WEAKER THAN THAT EXPECTED ON
THURSDAY, THE DEGREE OF INSTABILITY WILL CONDITIONALLY SUPPORT A
LARGE HAIL AND SEVERE WIND RISK WITH ANY SURFACE-BASED STORMS THAT
DEVELOP.
MARGINAL RISK PROBABILITIES WILL BE MAINTAINED WITH THIS FORECAST
UPDATE DUE TO THE LIMITED PREDICTABILITY IN CONVECTIVE EVOLUTION.
..MEAD.. 09/02/2026
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