577
ACUS01 KWNS 051256
SWODY1
SPC AC 051254
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0754 AM CDT SAT SEP 05 2026
VALID 051300Z - 061200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM PORTIONS OF
THE OHIO VALLEY INTO SOUTHERN MID-ATLANTIC AND CAROLINAS...
..SUMMARY
SEVERE THUNDERSTORMS CAPABLE OF MAINLY DAMAGING GUSTS ARE POSSIBLE
ACROSS PORTIONS OF THE OHIO VALLEY INTO SOUTHERN MID-ATLANTIC AND
CAROLINAS THIS AFTERNOON AND EVENING. ISOLATED OCCURRENCES OF LARGE
HAIL AND SEVERE WIND GUSTS ALSO APPEAR POSSIBLE OVER PARTS OF THE
NORTHERN AND CENTRAL PLAINS TODAY INTO TONIGHT.
..OHIO VALLEY INTO THE CAROLINAS
AN MCS CONTINUES TO PROGRESS SOUTHEASTWARD TOWARDS THE CENTRAL
APPALACHIANS THIS MORNING. THE OUTFLOW HAS SURGED WELL AHEAD OF THE
DEEP CONVECTION ALONG THE WESTERN EDGE OF THIS MCS, BUT REMAINS MUCH
CLOSER TO THE TWO PRIMARY CORES OF DEEP CONVECTION ALONG THE CENTRAL
AND EASTERN PORTIONS OF THE MCS. GENERAL EXPECTATION IS FOR THIS MCS
TO CONTINUE SOUTHEASTWARD ACROSS THE CENTRAL APPALACHIANS AND INTO
THE MID-ATLANTIC, WHILE THE WESTWARD-PROGRESSING OUTFLOW STALLS AND
LOSES DEFINITION.
CURRENTLY, THE AIRMASS DOWNSTREAM ACROSS THE MID-ATLANTIC IS
CHARACTERIZED BY DEWPOINTS RANGING FROM THE UPPER 60S ACROSS
NORTHERN VA INTO THE MID 70S ACROSS SOUTHEAST NC/EASTERN SC. STRONG
HEATING IS ANTICIPATED ACROSS MUCH OF THIS REGION TODAY, WITH HIGH
TEMPERATURES RANGING FROM THE LOW 90S OVER NORTHERN TO THE UPPER
90S/LOW 100S ACROSS CENTRAL/EASTERN SC. THESE WARM AND MOIST SURFACE
CONDITIONS WILL SUPPORT MODERATE TO STRONG AFTERNOON BUOYANCY,
DESPITE POOR MID-LEVEL LAPSE RATES. REINTENSIFICATION AND/OR RENEWED
THUNDERSTORM DEVELOPMENT IS EXPECTED AS THE MCS (AND ASSOCIATED
VORTICITY MAXIMUM) INTERACTS WITH THIS DESTABILIZED AIRMASS. THIS
REGION WILL BE ALONG THE SOUTHERLY PERIPHERY OF A BELT OF MID-LEVEL
NORTHWESTERLIES, AND THE RESULTING VERTICAL SHEAR COULD HELP
MAINTAIN A FAVORABLE COLD POOL/UPDRAFT BALANCE NEEDED TO MAINTENANCE
OF A PROGRESSIVE CONVECTIVE LINE. GUIDANCE VARIES ON WHETHER ONE
COHERENT CONVECTIVE LINE OR A SERIES OF SMALLER BOWING SEGMENTS WILL
DEVELOP, BUT EITHER CASE WOULD YIELD A THREAT FOR DAMAGING GUSTS.
HIGHEST PROBABILITY FOR DAMAGING GUSTS IS EXPECTED ACROSS EASTERN NC
WHERE THE BEST OVERLAP BETWEEN BUOYANCY AND VERTICAL IS EXPECTED.
ADDITIONAL AFTERNOON DEVELOPMENT IS EXPECTED FARTHER WEST, FROM THE
MIDDLE OH VALLEY THROUGH MIDDLE TN, WHERE RESIDUAL OUTFLOW WILL
LIKELY BE PRESENT WITH A DESTABILIZED AIRMASS. WEAK SHEAR SHOULD
LIMIT STORM ORGANIZATION BUT ISOLATED DAMAGING GUSTS ARE POSSIBLE.
..NORTHERN AND CENTRAL PLAINS
ELEVATED THUNDERSTORMS HAVE PERSISTED THROUGHOUT MUCH OF THE NIGHT
FROM NORTHEAST NE ACROSS EASTERN SD. A SECOND AREA OF THUNDERSTORM
ACTIVITY EXISTS FARTHER NORTHER ACROSS NORTH-CENTRAL ND. AN ISOLATED
INSTANCE OF HAIL IS POSSIBLE OVER BOTH OF THESE REGIONS FOR THE NEXT
FEW HOURS BEFORE THUNDERSTORM INTENSITY WANES IN RESPONSE TO THE
CESSATION OF THE NOCTURNAL LOW-LEVEL JET.
DESPITE RISING HEIGHTS THROUGHOUT THE DAY, MOST GUIDANCE SUGGESTS
THAT LOW-LEVEL CONVERGENCE ALONG BOTH THE LEE TROUGH AND
OUTFLOW-MODIFIED FRONT IN NE WILL BE SUFFICIENT FOR CONVECTIVE
INITIATION THIS AFTERNOON. LIMITED VERTICAL SHEAR AND A DEEPLY MIXED
BOUNDARY LAYER SUGGEST AN OUTFLOW-DOMINANT STORM MODE WITH THE
PRIMARY HAZARD BEING WIDELY-SPACED SEVERE WIND GUSTS.
RELATIVELY HIGHER THUNDERSTORM COVERAGE IS POSSIBLE ACROSS THE
CENTRAL HIGH PLAINS THIS EVENING AS WARM-AIR ADVECTION SUPPORTS
ADDITIONAL THUNDERSTORM ACTIVITY. SOME CLUSTERING OF THIS ACTIVITY
IS POSSIBLE, BUT VERTICAL SHEAR WILL BE WEAK AND OVERALL STORM
INTENSITY AND ORGANIZATION SHOULD BE MODEST.
..WESTERN MONTANA
A BELT OF ENHANCED MID/UPPER-LEVEL FLOW WILL EXTEND ACROSS THE
REGION, TO THE EAST OF AN UPPER LOW OVER THE PACIFIC NORTHWEST.
INCREASING MID-LEVEL MOISTURE AND FORCING FOR ASCENT ASSOCIATED WITH
A WEAK MID-LEVEL DISTURBANCE IS EXPECTED TO SUPPORT AN INCREASE IN
HIGH-BASED SHOWERS AND A FEW THUNDERSTORMS DURING THE AFTERNOON AND
EVENING. LAPSE RATES WILL BE STEEP WITH STRONG DEEP-LAYER SHEAR, BUT
THE ABSENCE OF APPRECIABLE MOISTURE WILL LIMIT MLCAPE TO GENERALLY
LESS THAN 250 J/KG. AS SUCH THE POTENTIAL FOR SEVERE WIND GUSTS IS
CURRENTLY TOO LOW TO WARRANT 5% WIND PROBABILITIES.
..MOSIER/LYONS.. 09/05/2026
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