551
ACUS03 KWNS 261930
SWODY3
SPC AC 261929
DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0229 PM CDT THU JUN 26 2025
VALID 281200Z - 291200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS SATURDAY AFTERNOON
INTO SATURDAY NIGHT ACROSS PARTS OF CENTRAL AND EASTERN SOUTH
DAKOTA...NORTHEASTERN NEBRASKA...MUCH OF SOUTHERN AND CENTRAL
MINNESOTA...ADJACENT NORTHWESTERN WISCONSIN...
..SUMMARY
SCATTERED STRONG THUNDERSTORMS, POSING A RISK FOR SEVERE HAIL AND
WIND, ARE POSSIBLE ACROSS PARTS OF THE MIDDLE MISSOURI VALLEY INTO
UPPER MIDWEST SATURDAY AFTERNOON INTO SATURDAY NIGHT.
..DISCUSSION
LITTLE CHANGE IN THE LARGE-SCALE MID/UPPER FLOW IS FORECAST FROM
FRIDAY INTO SATURDAY, WITH MODEST WESTERLIES REMAINING GENERALLY
ZONAL AND CONFINED TO THE NORTHERN TIER OF THE U.S. AND ADJACENT
PORTIONS OF SOUTHERN CANADA. WITHIN THIS REGIME, ONE NOTABLE SHORT
WAVE TROUGH IS FORECAST TO PROGRESS EAST OF THE GREAT LAKES INTO NEW
ENGLAND SATURDAY THROUGH SATURDAY NIGHT, AS BROAD UPSTREAM
TROUGHING (WITH AT LEAST A COUPLE OF EMBEDDED SMALLER-SCALE
PERTURBATIONS) PROGRESSES EASTWARD ALONG THE NORTH CENTRAL
CANADIAN/U.S. BORDER VICINITY.
IN LOWER-LEVELS, COOLER AND DRIER BOUNDARY-LAYER AIR IS LIKELY TO BE
MAINTAINED ACROSS PARTS OF NORTHERN NEW ENGLAND, WITH ANOTHER INFLUX
OF COOLER AIR SPREADING SOUTHEAST OF THE GREAT LAKES THROUGH THE
UPPER OHIO VALLEY, NORTHERN MID ATLANTIC COAST AND SOUTHERN NEW
ENGLAND BY LATE SATURDAY NIGHT. A TRAILING COLD FRONT IS LIKELY TO
CONTINUE SLOWLY ADVANCING EAST/SOUTHEAST OF THE NORTHERN ROCKIES,
THROUGH THE NORTHERN GREAT PLAINS. ELSEWHERE, EAST OF THE HIGH
PLAINS, SEASONABLY MOIST BOUNDARY AIR MAY BECOME CHARACTERIZED BY
MODERATE TO STRONG POTENTIAL INSTABILITY WITH DAYTIME HEATING.
..NORTHERN GREAT PLAINS
THE EXTENT OF CONVECTIVE DEVELOPMENT AND ITS EVOLUTION REMAIN
UNCLEAR FOR THIS PERIOD DUE TO A NUMBER OF LINGERING UNCERTAINTIES.
FOCUS FOR RENEWED THUNDERSTORM DEVELOPMENT COULD BE IMPACTED BY
OUTFLOW FROM CONVECTION DEVELOPING FRIDAY NIGHT INTO EARLY SATURDAY.
ADDITIONALLY, STRONGEST POTENTIAL INSTABILITY BY SATURDAY AFTERNOON
IS LIKELY TO BECOME FOCUSED BENEATH THE NOSE OF THE WARMER AND MORE
STRONGLY CAPPING ELEVATED MIXED-LAYER AIR, ROUGHLY ACROSS THE
NORTHERN/EASTERN SOUTH DAKOTA VICINITY, BEFORE SLOWLY BECOMING
SUPPRESSED SOUTHEASTWARD. HOWEVER, THIS MIGHT TEND TO BECOME
DISPLACED TO THE SOUTH OF THE STRONGER AND MORE FAVORABLY SHEARED
WESTERLIES.
EVEN SO, GIVEN THERMODYNAMIC PROFILES BECOMING CHARACTERIZED BY
STEEP LOWER/MID-TROPOSPHERIC LAPSE RATES AND LARGE CAPE, SCATTERED
STRONG TO SEVERE THUNDERSTORM DEVELOPMENT APPEARS POSSIBLE AHEAD OF
THE SOUTHEASTWARD ADVANCING COLD FRONT BY LATE AFTERNOON. AIDED BY
FORCING FOR ASCENT SUPPORTED BY LOW-LEVEL WARM ADVECTION BENEATH
BROADLY DIFLUENT UPPER FLOW, ACTIVITY MAY CONSOLIDATE INTO ONE OR
TWO EASTWARD/SOUTHEASTWARD PROPAGATING CLUSTERS BY SATURDAY EVENING.
..NORTHERN MID ATLANTIC INTO CHAMPLAIN VALLEY
A CORRIDOR OF MODERATE TO LARGE DEVELOPING MIXED-LAYER CAPE, AHEAD
OF THE SOUTHEASTWARD ADVANCING COLD FRONT, AND WITHIN PRECEDING
DEEPENING SURFACE TROUGHING, SEEMS LIKELY TO PROVIDE THE FOCUS FOR
VIGOROUS THUNDERSTORM DEVELOPMENT BY LATE SATURDAY AFTERNOON.
ALTHOUGH LAPSE RATES MAY BE MODEST, AND STRONGER POTENTIAL
INSTABILITY ACROSS THE NORTHERN MID ATLANTIC MAY BE DISPLACED TO THE
SOUTH OF THE BETTER FLOW/SHEAR ACROSS UPSTATE NEW YORK INTO NEW
ENGLAND, THE ENVIRONMENT MAY STILL BECOME CONDUCIVE TO SCATTERED
STRONG THUNDERSTORMS ACCOMPANIED BY A RISK FOR POTENTIALLY DAMAGING
WIND GUSTS. IF/WHEN LINGERING UNCERTAINTIES BECOME MORE CLEAR, IT
IS POSSIBLE THAT SEVERE PROBABILITIES COULD STILL BE INCREASED A BIT
FURTHER IN LATER OUTLOOKS FOR THIS PERIOD.
..KERR.. 06/26/2025
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