758
ACUS48 KWNS 170723
SWOD48
SPC AC 170721
DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0221 AM CDT WED JUN 17 2026
VALID 201200Z - 251200Z
..DISCUSSION
..DAY 4/SATURDAY - CENTRAL PLAINS
A MID/UPPER TROUGH EJECTING ACROSS THE CENTRAL ROCKIES INTO THE
PLAINS WILL BREAK DOWN THE UPPER RIDGE CENTERED OVER THE PLAINS ON
SATURDAY. THIS WILL RESULT IN SOME ENHANCEMENT OF MID/UPPER LEVEL
WEST/NORTHWESTERLY FLOW. SURFACE LEE TROUGHING WILL EXTEND FROM
EASTERN WY THROUGH EASTERN CO, AND INCREASING SOUTH/SOUTHEASTERLY
LOW-LEVEL FLOW WILL TRANSPORT 60S F DEWPOINTS NORTHWARD INTO NE AND
FAR SOUTHWEST SD. INCREASING BOUNDARY LAYER MOISTURE AND STEEPENING
MIDLEVEL LAPSE RATES WILL SUPPORT MODERATE DESTABILIZATION BY LATE
AFTERNOON AND EVENING. THUNDERSTORMS ARE EXPECTED TO DEVELOP BY
21-00Z AND MIGRATE SOUTHEAST, POSING A SEVERE RISK ACROSS PORTIONS
OF THE CENTRAL PLAINS.
..DAY 5/SUNDAY - OK/KS INTO THE MID-MS VALLEY
MEDIUM RANGE GUIDANCE VARIES CONSIDERABLY REGARDING EVOLUTION OF A
MODEST MIDLEVEL SHORTWAVE TROUGH AND ASSOCIATED SURFACE LOW AND COLD
FRONT ON SUNDAY. IT IS POSSIBLE THAT AN MCS RELATED TO DAY
4/SATURDAY CONVECTION COULD BE ONGOING SUNDAY MORNING SOMEWHERE NEAR
THE MID-MO VALLEY. DEPENDING ON HOW SURFACE FEATURE EVOLVE, A SEVERE
RISK COULD DEVELOP ACROSS PARTS OF EASTERN OK/KS INTO THE MID-MS
VALLEY GIVEN A SEASONALLY MOIST/UNSTABLE AIRMASS AND AT LEAST SOME
ENHANCEMENT OF DEEP-LAYER FLOW FROM THE MID/UPPER SHORTWAVE TROUGH.
HOWEVER, PLACEMENT OF THE SURFACE LOW SUNDAY MORNING VARIES BY A FEW
HUNDRED MILES BETWEEN THE ECMWF AND GFS DETERMINISTIC MEMBERS. THE
AIGFS IS MORE SIMILAR TO THE ECMWF, BUT DETAILS REMAIN QUITE
DIFFERENT. THIS PRECLUDES A 15 PERCENT DELINEATION AT THIS TIME, BUT
PROBABILITIES MAY BE NEEDED AT SOME POINT SOMEWHERE FROM OK/KS INTO
THE MID-MS VALLEY/MID-SOUTH REGIONS.
..DAYS 6-8/MONDAY-WEDNESDAY
A MORE JUNE-LIKE PATTERN APPEARS TO EVOLVE THROUGH MID-WEEK WITH
WEAKER DEEP-LAYER FLOW EXPECTED AMID WEAK TROUGHING IN THE EAST AND
UPPER RIDGING ACROSS THE WEST. SOME SEVERE THUNDERSTORM POTENTIAL
COULD DEVELOP ACROSS THE PLAINS AS LOW-LEVEL MOISTURE SPREADS
NORTHWARD BENEATH MODEST NORTHWESTERLY FLOW ALOFT. HOWEVER,
PREDICTABILITY IS LOW GIVEN A LACK OF STRONGER LARGE-SCALE ASCENT.
DAILY THUNDERSTORM CHANCES WILL BE DRIVEN BY MESOSCALE PROCESSES NOT
WELL RESOLVED AT LONGER TIME SCALE.
..LEITMAN.. 06/17/2026
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