137
ACUS03 KWNS 310731
SWODY3
SPC AC 310730
DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0230 AM CDT FRI JUL 31 2026
VALID 021200Z - 031200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS LOWER GREAT
LAKES INTO THE CAROLINAS AND PARTS OF EASTERN GEORGIA...AND OVER
PARTS OF NORTH DAKOTA...
..SUMMARY
ISOLATED OCCURRENCES OF MAINLY DAMAGING WINDS ARE POSSIBLE FROM THE
LOWER GREAT LAKES INTO THE CAROLINAS AND PARTS OF EASTERN GEORGIA
SUNDAY AFTERNOON AND EVENING. A CONDITIONAL THREAT FOR LARGE HAIL
AND SEVERE WIND GUSTS EXISTS ACROSS PARTS OF NORTH DAKOTA INTO FAR
NORTHWEST MINNESOTA LATE SUNDAY AFTERNOON INTO NIGHT.
..SYNOPSIS
A MID-LEVEL TROUGH WILL ADVANCE SLOWLY THROUGH THE LOWER GREAT
LAKES, OH AND TN VALLEYS, AND THE CENTRAL GULF COAST STATES SUNDAY
AND SUNDAY NIGHT. AHEAD OF THE TROUGH, SOUTH-SOUTHWEST WINDS IN THE
MID LEVELS WILL GRADUALLY STRENGTHEN THROUGH THE FORECAST PERIOD. AT
THE SURFACE, AN AREA OF LOW PRESSURE WILL DEVELOP FROM THE MID INTO
THE UPPER OH VALLEY, WHILE A TRAILING FRONT EDGES EAST THROUGH THE
TN VALLEY AND CENTRAL GULF COAST.
ELSEWHERE, A SEASONABLY STRONG SHORT-WAVE TROUGH IS FORECAST TO MOVE
THROUGH THE CANADIAN PRAIRIE PROVINCES WITH AN ASSOCIATED BELT OF
50-60 KT MID-LEVEL WINDS SPREADING FROM THE NORTHERN ROCKIES INTO
THE NORTHERN PLAINS. AT THE SURFACE, A COLD FRONT WILL ADVANCE INTO
THE NORTHERN PLAINS BY SUNDAY AFTERNOON INTO NIGHT.
..LOWER GREAT LAKES INTO THE SOUTHEAST
SHOWERS AND THUNDERSTORMS ARE EXPECTED TO BE ONGOING SUNDAY MORNING
FROM THE LOWER GREAT LAKES INTO CENTRAL APPALACHIANS WITHIN A ZONE
OF WARM ADVECTION AND MOISTURE TRANSPORT ALONG A LOW-LEVEL JET. SOME
OF THE EARLY-DAY STORMS MAY LINGER INTO AFTERNOON WITH ASSOCIATED
CLOUD COVER LIMITING AIR MASS DESTABILIZATION. WHERE CLOUD BREAKS
CAN OCCUR, INCREASED DAYTIME HEATING AND BOUNDARY-LAYER DEWPOINTS IN
THE 60S TO MID 70S WILL CONTRIBUTE TO CORRIDORS OF MODERATE
INSTABILITY, THE HIGHEST CONFIDENCE OF WHICH IS FROM SOUTHERN VA
INTO THE SAVANNAH RIVER VALLEY.
AIDED BY FORCING FOR ASCENT AHEAD OF THE MID-LEVEL TROUGH,
THUNDERSTORMS ARE EXPECTED TO INCREASE IN COVERAGE AND INTENSITY
THROUGH THE AFTERNOON, ESPECIALLY IN AREAS OF GREATER INSTABILITY
FROM THE UPPER OH VALLEY INTO CAROLINAS. IN GENERAL, STORMS MAY
REMAIN SOMEWHAT DISORGANIZED, POSING MAINLY A DAMAGING WIND RISK
DURING THE AFTERNOON INTO EVENING. A POSSIBLE EXCEPTION IS ACROSS
THE UPPER OH VALLEY, WHERE STRONGER VERTICAL SHEAR WILL BE
SUPPORTIVE OF ORGANIZED STORMS MODES, GIVEN SUFFICIENT
DESTABILIZATION.
..NORTHERN PLAINS
BOUNDARY-LAYER DEWPOINTS IN THE 60S TO 70S LOCALLY WILL COINCIDE
WITH STEEP LOW/MID-LEVEL LAPSE RATES TO YIELD A MODERATELY TO
STRONGLY UNSTABLE, BUT CAPPED AIR MASS BY AFTERNOON AHEAD OF THE
FRONT. THE STRONGEST FORCING FOR ASCENT ASSOCIATED WITH THE CANADIAN
SHORT-WAVE TROUGH IS EXPECTED TO REMAIN NORTH OF THE INTERNATIONAL
BORDER, LEADING TO UNCERTAINTY IN WHETHER THE COMBINATION OF DAYTIME
HEATING AND FRONTAL CONVERGENCE WILL BE SUFFICIENT TO INITIATE
SURFACE-BASED STORMS.
ON THE CONDITION THAT STORMS DEVELOP AND ARE SUSTAINED, THE PRESENCE
OF 30-40 KT OF DEEP-LAYER SHEAR ACROSS THE FRONTAL ZONE WILL SUPPORT
ORGANIZED STORM MODES, INCLUDING SUPERCELLS WITH AN ASSOCIATED LARGE
HAIL AND SEVERE WIND GUST THREAT. THAT CONDITIONAL RISK WILL EXIST
FROM LATE SUNDAY AFTERNOON THROUGH SUNDAY NIGHT. HOWEVER, GIVEN THE
UNCERTAINTY IN STORM DEVELOPMENT, ONLY 5% PROBABILITIES WILL BE
INCLUDED IN THIS FORECAST.
..MEAD.. 07/31/2026
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