987
ACUS02 KWNS 121733
SWODY2
SPC AC 121732
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1232 PM CDT TUE AUG 12 2025
VALID 131200Z - 141200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS
SOUTH-CENTRAL SOUTH DAKOTA AND FAR NORTH-CENTRAL NEBRASKA...
..SUMMARY
THE EVOLUTION OF AN ORGANIZED CLUSTER OF THUNDERSTORMS ACCOMPANIED
BY STRONG TO SEVERE WIND GUSTS APPEARS POSSIBLE ACROSS PARTS OF
CENTRAL THROUGH EASTERN SOUTH DAKOTA AND FAR NORTH-CENTRAL NEBRASKA
BY WEDNESDAY EVENING.
..SYNOPSIS
UPPER RIDGING WILL REMAIN ANCHORED OVER THE SOUTHWEST/FOUR CORNERS,
WITH SUBTROPICAL RIDGING STAYING OVER FL AS WELL. A PAIR OF
LOW-AMPLITUDE SHORTWAVE TROUGHS WILL PROGRESS THROUGH THE WESTERLY
FLOW NORTH OF THIS RIDGING. THE EASTERNMOST WAVE WILL LIKELY MOVE
THROUGH THE LOWER OH AND TN VALLEYS WHILE THE WESTERNMOST WAVE
PROGRESSES ALONG THE MT/WY BORDER AND THROUGH SD. THIS WESTERN WAVE
IS FORECAST TO INTERACT WITH AN UNSTABLE AIRMASS TO SUPPORT STRONG
TO SEVERE THUNDERSTORMS FROM EASTERN WY INTO THE DAKOTA AND NE.
ADDITIONAL THUNDERSTORMS ARE EXPECTED ACROSS MUCH OF THE EASTERN
CONUS. STORMS OVER THE NORTHEAST WILL BE FOSTERED BY GLANCING ASCENT
ATTENDANT TO A SHORTWAVE TROUGH MOVING THROUGH QUEBEC WHILE THE
PREVIOUSLY MENTIONED SHORTWAVE TROUGH MOVING THE TN VALLEY WILL
PROMOTE DEVELOPMENT FROM KY/TN INTO NORTHERN AL/MS. WEAK SHEAR
SHOULD LIMIT STORM ORGANIZATION AND STRENGTH THROUGHOUT THE EASTERN
CONUS.
..EASTERN WY INTO THE DAKOTAS AND NE
ELEVATED SHOWERS AND THUNDERSTORMS WILL LIKELY BE ONGOING ACROSS
WESTERN/CENTRAL SD WEDNESDAY MORNING. THESE STORMS ARE GENERALLY
EXPECTED TO BE SUBSEVERE BUT WILL LIKELY PERSIST WHILE GRADUALLY
SHIFTING EASTWARD THROUGHOUT THE MORNING INTO THE AFTERNOON. THE
EVOLUTION OF THESE STORMS, AND THEIR ASSOCIATED OUTFLOW AND CLOUD
COVER, INTRODUCES SOME UNCERTAINTY INTO THE FORECAST, PARTICULARLY
ACROSS SOUTHEAST SD AND NORTHEAST NE WHERE THERE IS AT LEAST A LOW
PROBABILITY FOR REINTENSIFICATION OF STORMS WITHIN THIS CLUSTER. AT
THIS TIME, GIVEN POTENTIAL CAPPING AND VARIED MODEL SOLUTIONS
CONFIDENCE IS LOW IN THE REINTENSIFICATION SCENARIO.
A MORE PROBABLE SEVERE POTENTIAL WILL RESULT FROM THE THUNDERSTORM
DEVELOPMENT THAT INITIATES FARTHER WEST ACROSS THE BLACK HILLS.
HERE, INCREASED FORCING FOR ASCENT ATTENDANT TO THE APPROACHING
SHORTWAVE TROUGH AMID A WARM, DEEPLY MIXED, AND UNSTABLE AIRMASS
WILL SUPPORT CONVECTIVE INITIATION LATE WEDNESDAY AFTERNOON. THESE
INITIALLY HIGH-BASED STORMS WILL POSE A RISK FOR DAMAGING GUSTS AND
ISOLATED HAIL. MOISTURE AND BUOYANCY WILL INCREASE WITH EASTERN
EXTENT, WHICH WILL COMBINE WITH MODERATE VERTICAL SHEAR TO SUPPORT A
CORRIDOR OF HIGHER SEVERE-WIND PROBABILITY ACROSS SOUTH-CENTRAL SD
AND NORTH-CENTRAL NE DURING THE LATE EVENING. THEREAFTER, INCREASING
CONVECTIVE INHIBITION SHOULD RESULT IN GRADUALLY DIMINISHING STORM
INTENSITY. ADDITIONALLY, ELEVATED THUNDERSTORMS WITH SOME HAIL RISK
MAY DEVELOP AHEAD OF THE CONVECTIVE LINE ACROSS EASTERN SD DURING
THE LATE EVENING AND OVERNIGHT. HERE, A STRENGTHENING LOW-LEVEL JET
AND ASSOCIATED WARM-AIR ADVECTION AMID STEEP MID-LEVEL LAPSE RATES
AND MODERATE DEEP-LAYER SHEAR COULD SUPPORT A FEW STORMS CAPABLE OF
LARGE HAIL.
..MOSIER.. 08/12/2025
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