387
ACUS01 KWNS 152002
SWODY1
SPC AC 152000
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0300 PM CDT MON SEP 15 2025
VALID 152000Z - 161200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE
NORTHERN HIGH PLAINS...NORTHERN MINNESOTA...MID MISSISSIPPI
VALLEY...AND COASTAL NC/SC...
..SUMMARY
ISOLATED SEVERE WIND GUSTS ARE POSSIBLE ACROSS WYOMING INTO WESTERN
SOUTH DAKOTA THIS AFTERNOON TO EARLY EVENING, AS WELL AS PORTIONS OF
THE MID MISSISSIPPI VALLEY. ISOLATED SEVERE HAIL AND DAMAGING WINDS
ARE ALSO POSSIBLE ACROSS FAR NORTHERN MINNESOTA THIS AFTERNOON. A
BRIEF TORNADO IS POSSIBLE IN THE NORTHEAST NORTH CAROLINA VICINITY
IN THE EARLY MORNING TUESDAY.
..20Z UPDATE
THE MARGINAL RISK IN THE MID MS VALLEY WAS EXPANDED SLIGHTLY
NORTHWARD ACROSS IA. DIURNAL HEATING/DESTABILIZATION AMID
MIDDLE/UPPER 60S DEWPOINTS IS YIELDING MODERATE-STRONG SURFACE-BASED
BUOYANCY ALONG A REMNANT NORTH-SOUTH-ORIENTED SURFACE BOUNDARY.
GIVEN AROUND 25-30 KT OF EFFECTIVE SHEAR, A COUPLE LOOSELY ORGANIZED
STORMS MAY BECOME CAPABLE OF PRODUCING STRONG GUSTS AND MARGINALLY
SEVERE HAIL.
..WEINMAN.. 09/15/2025
PREV DISCUSSION
/ISSUED 1132 AM CDT MON SEP 15 2025/
..WYOMING TO BLACK HILLS VICINITY
A SHORTWAVE TROUGH OVER WESTERN IDAHO WILL MOVE EAST ACROSS
WYOMING/WESTERN SOUTH DAKOTA DURING THE DAY, AS SEVERAL EMBEDDED
VORTICITY MAXIMA CONTRIBUTE REGIONS OF ENHANCED ASCENT. STEEP
MID-LEVEL LAPSE RATES OF 8-9 DEG C/KM, COMBINED WITH DIURNAL
HEATING, WILL RESULT IN MLCAPE OF A FEW HUNDRED J/KG ACROSS MUCH OF
THE AREA. DESPITE WEAK BUOYANCY, THE FAVORABLY-TIMED ASCENT WILL
CONTRIBUTE TO THUNDERSTORM DEVELOPMENT/INTENSIFICATION THIS
AFTERNOON AS STORMS APPROACH NORTHEAST WYOMING/WESTERN SOUTH DAKOTA.
SOME HAIL COULD OCCUR, AND A DEEP AND WELL-MIXED BOUNDARY LAYER WILL
LEAD TO HIGH-BASED CONVECTION CAPABLE OF ISOLATED STRONG/DAMAGING
GUSTS THROUGH EARLY EVENING, WITH INTENSITIES DIMINISHING THEREAFTER
AS NOCTURNAL COOLING COMMENCES.
..NORTHEAST NORTH CAROLINA/SOUTHEAST VIRGINIA
A SURFACE LOW SOUTHEAST OF CAPE HATTERAS IS FORECAST TO MOVE TOWARDS
THE NORTH CAROLINA COAST THROUGH 12Z TUESDAY, WITH A BELT OF
STRONGER LOW-LEVEL FLOW DEVELOPING NORTH/NORTHWEST OF THE LOW.
VARIABILITY REMAINS REGARDING THE FORECAST LOCATION OF THE LOW AND
STRENGTH OF LOW-LEVEL WINDS, HOWEVER A CONDITIONAL RISK FOR A
TORNADO WOULD EXIST LATE TONIGHT THROUGH EARLY TUESDAY MORNING WITH
STRONGER CONVECTIVE ELEMENTS, SHOULD SUFFICIENT LOW-LEVEL HODOGRAPH
CURVATURE DEVELOP AS HIGH THETA-E AIR IS ADVECTED WEST.
..FAR NORTHERN MINNESOTA
THUNDERSTORM DEVELOPMENT IS EXPECTED THIS AFTERNOON WITHIN A
NORTHWEST-SOUTHEAST ORIENTED ARC FROM SOUTHEAST MANITOBA ACROSS
NORTHEAST ONTARIO AS A SHORTWAVE TROUGH BECOMES INCREASINGLY
NEGATIVELY TILTED WHILE LIFTING NORTHEAST. ALTHOUGH DEVELOPMENT
SOUTH OF THE INTERNATIONAL BORDER IS UNCERTAIN, SOME GLOBAL GUIDANCE
(AND A CONVECTION-ALLOWING MODEL OR TWO) SUGGEST ISOLATED
DEVELOPMENT IS POSSIBLE. MODERATE BUOYANCY AND EFFECTIVE SHEAR OF
35-40 KT OVER FAR NORTHERN MINNESOTA SUGGEST A CONDITIONAL RISK FOR
SEVERE WIND/HAIL WOULD EXIST IF/WHERE STORM DEVELOPMENT OCCURS.
...MISSOURI/MID-SOUTH..
NEAR AND WEST/SOUTHWEST OF A RESIDUAL FRONT, A FEW STRONG/LOCALLY
DAMAGING WIND GUSTS WILL BE POSSIBLE AGAIN THIS AFTERNOON WITH
PULSE-TYPE STORMS WITHIN A WEAKLY-SHEARED BUT STRONGLY UNSTABLE
(MLCAPE OF 2500-3000 J/KG) THERMODYNAMIC ENVIRONMENT.
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