727
ACUS02 KWNS 051732
SWODY2
SPC AC 051730
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1230 PM CDT SAT SEP 05 2026
VALID 061200Z - 071200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF
GEORGIA AND THE CAROLINAS...
..SUMMARY
DAMAGING WIND GUSTS ARE LIKELY ACROSS PORTIONS OF THE SOUTHEAST
SUNDAY AFTERNOON AND EARLY EVENING. ADDITIONAL AREAS AT RISK FOR
SEVERE WIND AND HAIL ARE ACROSS PARTS OF NORTHERN UTAH NORTHWARD
INTO MONTANA AND EAST INTO THE NORTHERN PLAINS AND MIDDLE MISSOURI
VALLEY.
.. SYNOPSIS
A HIGH-AMPLITUDE MID-LEVEL RIDGE WILL PERSIST ACROSS THE CENTRAL US
ON SUNDAY, WITH TROUGHING ACROSS BOTH THE EAST AND WEST COASTS.
EMBEDDED WITHIN THE BASAL REGION OF THE WESTERN TROUGH, A CLOSED LOW
SHOULD OPEN UP AND TAKE ON A NEGATIVE TILT AS IT MOVES ALONG THE
NORTHWEST PERIPHERY OF THE CENTRAL RIDGE.
AT THE SURFACE, AN ANTICYCLONE WILL BE LOCATED ACROSS THE UPPER
GREAT LAKES, USHERING IN A COOLER, DRIER AIR MASS FROM THE UPPER
MIDWEST EAST ACROSS THE OHIO VALLEY INTO THE NORTHEAST. DEMARCATING
THE BOUNDARY BETWEEN THIS CONTINENTAL AIR MASS AND THE MORE MARITIME
AIR MASS TO THE SOUTH AND WEST WILL BE A FRONT STRETCHED FROM THE
MINNESOTA-NORTH/SOUTH DAKOTA BORDER SOUTH AND EAST TO SOUTHEAST
MISSOURI AND THEN EAST FROM THERE TO THE EAST COAST.
.. SOUTHEAST
A VERY HUMID AIR MASS WILL BE IN PLACE ACROSS THE REGION, WITH HREF
MEAN DEWPOINT TEMPERATURES IN THE UPPER-60FS TO LOW-70FS. DIURNAL
HEATING WILL ALLOW AFTERNOON TEMPERATURES TO WARM INTO THE
LOW-TO-MID-90FS, YIELDING MUCAPE VALUES IN EXCESS OF 1500 J/KG.
(HIGH-RESOLUTION GUIDANCE IS GENERALLY IN THE 1500-2500 J/KG RANGE,
WITH COARSER-SCALE GUIDANCE, SUCH AS THE RAP, SHOWING PERHAPS AS
HIGH AS 4000 J/KG.)
SCATTERED THUNDERSTORMS WILL DEVELOP DURING THE AFTERNOON AS
CONVECTIVE TEMPERATURES ARE REACHED. PRECIPITABLE WATER VALUES
AROUND 2 INCHES AND DCAPE VALUES IN EXCESS OF 1000 J/KG WILL SUPPORT
HEAVY, WATER-LADEN DOWNBURSTS CAPABLE OF SCATTERED WIND DAMAGE.
SLIGHTLY BETTER DEEP-LAYER SHEAR ACROSS PORTIONS OF GEORGIA AND THE
CAROLINAS MAY SUPPORT AT LEAST TRANSIENT THUNDERSTORM ORGANIZATION
IN THE FORM OF MULTI-CELL CLUSTERS WHICH MAY POSE A SLIGHTLY GREATER
RISK OF ORGANIZED WIND DAMAGE.
.. MID-MISSOURI VALLEY AND NORTHERN PLAINS
THUNDERSTORMS MAY BE ONGOING AT THE START OF THE FORECAST PERIOD
ACROSS PORTIONS OF THE AREA OR DEVELOP SHORTLY THEREAFTER. THESE
THUNDERSTORMS WILL LIKELY BE DRIVEN BY STRONG WARM-AIR ADVECTION
NEAR THE APEX OF THE MID-LEVEL RIDGE. THESE STORMS MAY INITIALLY
POSE A RISK OF LARGE HAIL AND GUSTY WINDS. WITH TIME, DIURNAL
HEATING MAY SUPPORT A TRANSITION FROM ELEVATED-TO-SURFACE BASED
THUNDERSTORMS, INCREASING THE POTENTIAL FOR DAMAGING WINDS,
ESPECIALLY AS LOW-LEVEL LAPSE RATE STEEPEN. DEEP-LAYER SHEAR WILL
SUPPORT INDIVIDUAL STORMS MOVING SOUTHEAST WHILE THE LARGER-SCALE
EVOLUTION WILL BE TOWARD THE SOUTHWEST.
THE EXACT EVOLUTION OF THIS CONVECTION, IN PARTICULAR WHERE THE
NARROW CORRIDOR DEVELOPS, REMAINS A BIT UNCERTAIN. AS CONFIDENCE
INCREASES IN THE LOCATION OF THESE STORMS, HIGHER SEVERE WEATHER
PROBABILITIES MAY BE NEEDED.
.. NORTHWEST UTAH INTO MONTANA
AS THE WESTERN MID-LEVEL LOW OPENS AND TAKES ON A NEGATIVE TILT AS
IT TRAVERSES THE NORTHWEST PERIPHERY OF THE CENTRAL US RIDGE,
LARGE-SCALE ASCENT WILL SUPPORT SCATTERED THUNDERSTORM DEVELOPMENT
ACROSS PORTIONS OF NORTHWEST UTAH, IDAHO, AND WESTERN WYOMING.
STRONG MID-LEVEL FLOW (AROUND 50 KNOTS AT 500 MILLIBARS) COUPLED
WITH A DEEP, WELL-MIXED BOUNDARY LAYER WILL SUPPORT DOWNWARD
MOMENTUM TRANSFER WITHIN THESE THUNDERSTORMS CAPABLE OF PRODUCING
SCATTERED WIND DAMAGE. THESE STORMS WILL QUICKLY MOVE NORTHEAST INTO
MONTANA DURING THE EVENING HOURS. IF COVERAGE OF THESE STORMS IS
GREATER THAN EXPECTED, HIGHER WIND PROBABILITIES WOULD BE WARRANTED
IN SUBSEQUENT OUTLOOKS.
..MARSH.. 09/05/2026
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