921
ACUS02 KWNS 261731
SWODY2
SPC AC 261730
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1230 PM CDT FRI JUL 26 2024
VALID 271200Z - 281200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS
CENTRAL/EASTERN ND INTO FAR NORTHWEST MN...
..SUMMARY
SCATTERED SEVERE THUNDERSTORMS ARE LIKELY ACROSS PORTIONS OF THE
NORTHERN PLAINS VICINITY ON SATURDAY.
..SYNOPSIS
UPPER TROUGHING IS EXPECTED TO EXTEND FROM THE NORTHERN/CENTRAL
CANADIAN PRAIRIE PROVINCES SOUTHWESTWARD INTO NORTHERN/CENTRAL CA
EARLY SATURDAY MORNING. TWO PRIMARY SHORTWAVE TROUGHS WILL BE
EMBEDDED WITHIN THIS TROUGHING, ONE OVER THE NORTHERN/CENTRAL
CANADIAN PRAIRIES AND THE OTHER OVER NORTHERN CA. BOTH SHORTWAVES
ARE EXPECTED TO PROGRESSES EAST-NORTHEASTWARD THROUGHOUT THE DAY
WHILE LOSING AMPLITUDE. EASTWARD PROGRESS OF THIS SYSTEMS WILL BE
SLOWED BY THE REX BLOCK DOWNSTREAM, WITH THE SOUTHERN CYCLONE
INITIALLY OVER NORTHEAST OK/SOUTHEAST KS AND THE NORTHERN
ANTICYCLONE OVER LAKE MICHIGAN. THIS REX BLOCK IS FORECAST TO BREAK
DOWN UNDER THE INFLUENCE OF THE WESTERN TROUGHING, WITH THE UPPER
LOW DRIFTING NORTHEASTWARD INTO SOUTHERN MO AND THE UPPER RIDGE
SHIFTING EASTWARD OVER THE LOWER GREAT LAKES BY EARLY SUNDAY.
SURFACE PATTERN IS FORECAST TO FEATURE AN EASTERN CONUS RIDGE,
INITIALLY CENTERED OVER THE LOWER GREAT LAKES BUT EXTENDING
SOUTHWARD INTO THE SOUTHEAST. THIS RIDGING IS EXPECTED TO REMAIN
LARGELY IN PLACE, WHILE LEE SURFACE TROUGHING SHARPENS ACROSS THE
HIGH PLAINS AND A COLD FRONT ASSOCIATED WITH THE CANADIAN PRAIRIE
SHORTWAVE TROUGH MOVES INTO THE NORTHERN PLAINS. THUNDERSTORM
DEVELOPMENT IS ANTICIPATED ALONG THE COLD FRONT ACROSS ND SATURDAY
EVENING. STORM DEVELOPMENT IS ALSO ANTICIPATED FARTHER SOUTHWEST
ACROSS THE CENTRAL ROCKIES, WITH THE RESULTING STORMS THEN TRACKING
EASTWARD INTO THE CENTRAL HIGH PLAINS.
...NORTHERN PLAINS..
SHOWERS AND THUNDERSTORMS WILL LIKELY BE ONGOING EARLY SATURDAY
MORNING FROM THE EASTERN DAKOTAS INT NORTHWEST MN, REMNANT FROM
OVERNIGHT DEVELOPMENT ACROSS THE WESTERN/CENTRAL DAKOTAS. THIS
ACTIVITY WILL LIKELY BE WEAK, BUT CLOUD COVER AND ASSOCIATED OUTFLOW
COULD ACT TO PROVIDE THE SURFACE BOUNDARIES NEEDED TO PROVIDE THE
IMPETUS FOR ADDITIONAL STORMS DURING THE AFTERNOON/EVENING.
LARGE-SCALE FORCING WILL BE WEAK, BUT LOW-LEVEL CONVERGENCE AND
AMPLE LOW-LEVEL MOISTURE COULD STILL RESULT IN THUNDERSTORM
INITIATION. GIVEN THE STEEP LOW-LEVEL LAPSE RATES AND HIGH CLOUD
BASES, DAMAGING GUST WILL BE THE PRIMARY THREAT. EVEN SO, SOME HAIL
IS POSSIBLE WITH THE EARLY, MORE CELLULAR STORMS. A TORNADO OR TWO
IS POSSIBLE AS WELL IF THE BOUNDARY IS SHARP, WITH SURFACE WINDS
BACKING IN ITS VICINITY. MESOSCALE FACTORS WILL PLAY A LARGE ROLE IN
DETERMINING THE STORM COVERAGE AND ASSOCIATED SEVERE POTENTIAL,
WHICH MERITS KEEPING LOW SEVERE PROBABILITIES WITH THIS OUTLOOK
GIVEN THE FORECAST RANGE.
FARTHER EAST, THUNDERSTORM DEVELOPMENT APPEARS LIKELY ALONG THE
SOUTHEASTWARD-PROGRESSING COLD FRONT EXPECTED TO MOVE ACROSS THE
WESTERN DAKOTAS DURING THE LATE AFTERNOON. AMPLE LOW-LEVEL MOISTURE
WILL SUPPORT AIRMASS DESTABILIZATION DESPITE STRONG MIXING, AND
ROBUST UPDRAFTS ARE LIKELY WITHIN THE INITIAL DEVELOPMENT. HAIL IS
POSSIBLE EARLY, WITH A QUICK TRANSITION TO OUTFLOW-DOMINANT
STRUCTURES ANTICIPATED. HIGHEST COVERAGE IS EXPECTED ACROSS ND,
WHICH CORRESPONDS TO THE GREATEST SEVERE THUNDERSTORM POTENTIAL AS
WELL. STORM LONGEVITY WILL BE LIMITED BY THE ONSET OF NOCTURNAL
COOLING, WHICH SHOULD LEAD TO RELATIVELY QUICK LOW-LEVEL AIRMASS
STABILIZATION.
...NORTHERN GREAT BASIN INTO THE CENTRAL ROCKIES AND CENTRAL HIGH
PLAINS...
A BELT OF ENHANCED MID-LEVEL FLOW IS FORECAST TO STRETCH FROM THE
BASE OF THE NORTHERN/CENTRAL CA SHORTWAVE TROUGH MENTIONED IN THE
SYNOPSIS INTO THE NORTHERN PLAINS. THE CA SHORTWAVE IS EXPECTED TO
PROGRESS NORTHEASTWARD THROUGHOUT THE PERIOD, WITH A SUBTLE,
CONVECTIVELY ENHANCED LEAD SHORTWAVE TROUGH LIKELY PROCEEDING IT
ACROSS THE CENTRAL ROCKIES. LARGE-SCALE ASCENT ATTENDANT TO THESE
SHORTWAVES COUPLED WITH INCREASED MID-LEVEL MOISTURE AND DEEP
BOUNDARY-LAYER MIXING WILL SUPPORT THUNDERSTORMS ACROSS MUCH OF THE
REGION, BEGINNING OVER THE HIGHER TERRAIN AND THEN EVENTUALLY
SPREADING INTO THE HIGH PLAINS. GUSTY OUTFLOW WINDS COULD ACCOMPANY
OF ANY OF THE STRONGER, MORE PERSISTENT STORMS. COVERAGE OF THESE
STRONG STORMS MAY BE HIGH ENOUGH TO MERIT GREATER SEVERE
PROBABILITIES IN LATER OUTLOOKS.
..MOSIER.. 07/26/2024
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page