361
ACUS48 KWNS 120902
SWOD48
SPC AC 120900
DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0400 AM CDT SUN JUL 12 2026
VALID 151200Z - 201200Z
..DISCUSSION
AN EXPANSIVE MID-LEVEL RIDGE CENTERED OVER THE NORTH-CENTRAL US WILL
CONTINUE TO RETROGRADE DURING THE EARLY PART OF THE FORECAST PERIOD,
BEFORE BECOMING CENTERED OVER THE ROCKIES TOWARD THE END OF THE
UPCOMING WEEK. A SEASONABLY STRONG MID-LEVEL TROUGH WILL BE
POSITIONED OVER NORTHERN QUEBEC, POSITIONING STRONG NORTHWESTERLY
FLOW FROM THE UPPER MIDWEST SOUTHEAST INTO THE MID-ATLANTIC AND
AREAS TO THE NORTHEAST. A COMBINATION OF DETERMINISTIC AND ENSEMBLE
FORECAST SOLUTIONS, INCLUDING AI EMULATORS, SHOW ONE OR MORE
SHORT-WAVE TROUGHS OR JET STREAKS MOVING THROUGH THIS ENHANCED FLOW
FIELD.
THE POSITION OF THESE MID-LEVEL FEATURES WILL HELP DRIVE A SURFACE
FRONT SOUTHWARD ACROSS THE EASTERN US THAT WILL STRETCH FROM
SOMEWHERE IN THE CENTRAL/NORTH-CENTRAL US INTO THE MID-ATLANTIC. TO
THE NORTH OF THIS BOUNDARY, A SEASONABLY COOL, DRY AIRMASS SHOULD BE
FOUND. ALONG AND SOUTH OF THIS SURFACE BOUNDARY, A VERY WARM, MOIST,
AND UNSTABLE AIRMASS WILL BE FOUND.
AS THE AFOREMENTIONED SHORT-WAVE TROUGHS MOVE THROUGH THE ENHANCED
MID-LEVEL FLOW, ONE OR MORE ROUNDS OF THUNDERSTORMS/MESOSCALE
CONVECTIVE SYSTEMS ARE LIKELY TO DEVELOP AND MOVE EAST/SOUTHEAST.
ENSEMBLE GUIDANCE CONTINUES TO SHOW A VERY UNSTABLE AIRMASS (MUCAPE
IN EXCESS OF 2000-3000 J/KG) ALONG AND SOUTH OF WHERE THE SURFACE
BOUNDARY RESIDES, WITH STRONG VERTICAL SHEAR. THE OVERALL PATTERN
WOULD SEEM TO SUGGEST MULTIPLE ROUNDS/DAYS OF SEVERE POTENTIAL, WITH
PRIOR DAYS' CONVECTION LIKELY MODULATING THE WHERE AND INTENSITY OF
SUBSEQUENT DAYS' CONVECTION.
GIVEN THESE SENSITIVITIES TO PRIOR DAYS' CONVECTION, THERE WILL
LIKELY BE RUN-TO-RUN VARIABILITY WITHIN THE DETERMINISTIC GUIDANCE
SUITE AS WE APPROACH THE LATTER HALF OF NEXT WEEK. THUS, WHILE
CONFIDENCE IS HIGH IN SEVERE POTENTIAL DURING THE DAY 4-8 PERIOD
(AND PERHAPS BEYOND), HIGHLIGHTING SPECIFIC LOCATIONS AND DAYS OF
SEVERE POTENTIAL WILL PROVE CHALLENGING, WITH LIKELY AREAS CHANGING
FROM MODEL RUN-TO-RUN.
.. FRIDAY/DAY 6 -- MID-ATLANTIC REGION
THIS EVENING'S DETERMINISTIC GUIDANCE SUITE (20260712 00 UTC), ALONG
WITH YESTERDAY MORNING'S DETERMINISTIC GUIDANCE SUITE (20260711 12
UTC), IS FASTER MOVING THE SURFACE BOUNDARY SOUTH THAN LAST NIGHT'S
GUIDANCE SUITE (20260711 00 UTC). HOWEVER, THE OVERALL ENSEMBLE
GUIDANCE CONTINUES TO SUGGEST SEVERE POTENTIAL ACROSS THE REGION,
OWING TO DIFFERENCES IN THE POSITION OF THE SURFACE BOUNDARY AND THE
TIMING OF MID-LEVEL VORTICITY MAXIMA. SEVERE PROBABILITIES (15%)
HAVE BEEN RETAINED WITH THIS FORECAST IN A NOD TO THE ENSEMBLE
GUIDANCE SUITE, BUT IF THE CURRENT TREND OF PUSHING THE SURFACE
BOUNDARY FARTHER SOUTH ON THURSDAY (DAY 5) CONTINUES, SEVERE WEATHER
PROBABILITIES MAY NEED TO BE REMOVED AS THE SURFACE BOUNDARY WILL
PUSH SOUTH OF THE BETTER DEEP-LAYER SHEAR.
..MARSH.. 07/12/2026
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