599
ACUS03 KWNS 011931
SWODY3
SPC AC 011930
DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0230 PM CDT TUE SEP 01 2026
VALID 031200Z - 041200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE UPPER
OHIO VALLEY TO MID-ATLANTIC COAST...
..SUMMARY
AT LEAST WIDELY SCATTERED SEVERE STORMS, ACCOMPANIED BY DAMAGING
GUSTS AND PERHAPS SOME LARGE HAIL, APPEAR LIKELY ACROSS PORTIONS OF
THE OHIO VALLEY TO THE MID-ATLANTIC COAST ON THURSDAY. MORE ISOLATED
SEVERE STORMS CAPABLE OF LARGE HAIL AND DAMAGING WINDS APPEAR
POSSIBLE OVER THE NORTH DAKOTA-MINNESOTA RED RIVER VALLEY INTO THE
UPPER MIDWEST THURSDAY AFTERNOON INTO NIGHT.
..SYNOPSIS
BROADER-SCALE TROUGHING IS FORECAST OVER THE WESTERN CONUS WITH
LOW-AMPLITUDE RIDGING FROM THE UPPER MS VALLEY AND UPPER GREAT LAKES
INTO THE SOUTHEAST. BETWEEN THE RIDGE AND AN UPPER LOW OVER QC,
LATEST MODEL GUIDANCE INDICATES THE PROGRESSION OF A SHORT-WAVE
TROUGH AND ASSOCIATED 40-50 KT JET STREAK FROM THE LOWER GREAT LAKES
THROUGH THE MID-ATLANTIC AND PORTIONS OF NEW ENGLAND. OTHER MORE
SUBTLE DISTURBANCES ARE DEPICTED WITHIN THE PERIPHERY OF THE RIDGE
OVER THE GREAT LAKES INTO THE UPPER MS VALLEY.
AT THE SURFACE, AN AREA OF LOW PRESSURE IS FORECAST OVER THE DAKOTAS
ON THURSDAY WITH AN ASSOCIATED WARM FRONT SLOWLY LIFTING NORTH
THROUGH THE UPPER MS VALLEY AND UPPER MIDWEST. THE BOUNDARY IS
EXPECTED TO STRETCH EAST THROUGH THE GREAT LAKES INTO THE
MID-ATLANTIC WITH THE SPECIFIC LOCATION OF THE BOUNDARY DICTATED BY
THE EXTENT OF THUNDERSTORM ACTIVITY AND ASSOCIATED CONVECTIVE
OUTFLOW WEDNESDAY NIGHT INTO THURSDAY MORNING.
..GREAT LAKES AND OHIO VALLEY TO MID-ATLANTIC COAST
ONE OR MULTIPLE THUNDERSTORM COMPLEXES MAY BE ONGOING THURSDAY
MORNING FROM THE GREAT LAKES THROUGH THE NORTHEAST, AIDED BY FORCING
FOR ASCENT ATTENDANT TO THE PREVIOUSLY MENTIONED MID-LEVEL
DISTURBANCES. THE PRESENCE OF THE EARLY-DAY STORMS LEADS TO
UNCERTAINTY IN THE EXTENT OF AIR MASS OVERTURNING THAT OCCURS, AND
WHERE THE STRONGEST INSTABILITY WILL DEVELOP BY AFTERNOON. AS SUCH,
THE MARGINAL RISK PROBABILITY ENVELOPE HAS BEEN BROADENED SLIGHTLY
OVER THE MID-ATLANTIC WITH THE SLIGHT RISK PROBABILITIES REMAINING
UNCHANGED.
THE OVERLAP OF 30-40+ KT OF DEEP-LAYER SHEAR WITH A MOIST AND
POTENTIALLY MODERATELY TO STRONGLY UNSTABLE WARM SECTOR WILL
CONDITIONALLY SUPPORT SUPERCELL AND BOWING STORM MODES WITH AN
ATTENDANT RISK FOR DAMAGING WIND GUSTS AND LARGE HAIL FROM THURSDAY
AFTERNOON INTO EVENING.
..NORTH DAKOTA-MINNESOTA RED RIVER VALLEY INTO THE UPPER MIDWEST
A PLUME OF STEEP MID-LEVEL LAPSE RATES/EML IS FORECAST TO OVERLY A
MOIST BOUNDARY LAYER, YIELDING A MODERATELY TO STRONGLY UNSTABLE AIR
MASS BY AFTERNOON IN THE VICINITY OF THE WARM FRONT. THE INSTABILITY
WILL COINCIDE WITH UP TO 40-50 KT OF DEEP-LAYER SHEAR, CONDITIONALLY
YIELDING A VERY FAVORABLE SEVERE STORM ENVIRONMENT. HOWEVER, CAPPING
CONCERNS AND THE TIMING OF ANY WEAK DISTURBANCES CRESTING THE RIDGE
AXIS LIMIT PREDICTABILITY, WITH ONLY AN AREAL INCREASE IN THE
MARGINAL RISK PROBABILITIES INCLUDED IN THIS FORECAST. A CATEGORICAL
UPGRADE TO A LEVEL 2/SLIGHT RISK MAY BECOME NECESSARY IN SUBSEQUENT
FORECASTS.
..MEAD.. 09/01/2026
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