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View attachment 40437
MULTIPLE CORRIDORS OF SEVERE THUNDERSTORMS ARE EXPECTED ACROSS THE
UPPER MIDWEST ON MONDAY INTO MONDAY NIGHT, WITH A REGIONAL SEVERE
WEATHER OUTBREAK POSSIBLE. THE MOST DANGEROUS PERIOD IS LIKELY
DURING THE LATE AFTERNOON AND EVENING WHEN STRONG TORNADO POTENTIAL
SHOULD BE MAXIMIZED. SCATTERED LARGE TO VERY LARGE HAIL AND DAMAGING
WINDS ARE LIKELY AS WELL.
..SYNOPSIS
A POSITIVE-TILT, UPPER-LEVEL TROUGH WILL CONSIST OF MULTIPLE
EMBEDDED SHORTWAVE IMPULSES, MOVING EAST-NORTHEAST FROM THE CENTRAL
HIGH PLAINS TO THE UPPER MIDWEST. A BELT OF 70+ KT 500-MB
SOUTHWESTERLIES WILL BE PRESENT FROM THE CENTRAL GREAT PLAINS TO THE
UPPER MS VALLEY ON MONDAY AFTERNOON. PRIMARY SURFACE CYCLONE SHOULD
DEEPEN SLIGHTLY DURING THE DAY AS IT ADVANCES FROM EASTERN SD TO THE
UPPER GREAT LAKES. A DRYLINE WILL EXTEND FROM THE MID-MO VALLEY
SOUTH-SOUTHWEST INTO WEST TX. A COLD FRONT WILL OVERTAKE THE DRYLINE
AS IT SURGES SOUTHEAST MONDAY NIGHT.
..UPPER MIDWEST
AFTER COORDINATION WITH AFFECTED WFOS, PRIMARY ADJUSTMENTS HAVE
OCCURRED ALONG THE SOUTHERN EXTENT OF THE SEVERE PROBABILITIES TO
ACCOUNT FOR A MORE CONDITIONAL, BUT STILL POTENTIALLY SIGNIFICANT
SEVERE THREAT.
AN ARC OF ELEVATED THUNDERSTORMS WILL BE ONGOING AT 12Z MONDAY FROM
ND ACROSS THE UPPER MS VALLEY. ISOLATED LARGE HAIL WILL BE POSSIBLE
WITH THESE MORNING STORMS AS THEY MOVE EAST-NORTHEAST. ADDITIONAL
ELEVATED STORMS WILL REDEVELOP TOWARDS MIDDAY/EARLY AFTERNOON TO THE
NORTHEAST OF THE AFOREMENTIONED SURFACE LOW. THIS WILL SLOW THE
ADVANCEMENT OF THE SURFACE WARM FRONT INTO CENTRAL MN, BUT
STRENGTHEN DIFFERENTIAL SURFACE HEATING ACROSS THE BAROCLINIC ZONE,
WITH GREATER WARMING NOSING NORTH FROM NE INTO SOUTHEAST SD.
SURFACE-BASED STORM DEVELOPMENT SHOULD OCCUR BY MID-AFTERNOON ACROSS
A PORTION OF THE MID-MO VALLEY INTO SOUTHWEST/WEST-CENTRAL MN ALONG
THE DRYLINE TO SURFACE LOW. LARGE HAIL SHOULD BE THE PRIMARY INITIAL
THREAT, BUT CELLS MAY CONGEAL INTO LINEAR CLUSTERS, ESPECIALLY
NEAR/ACROSS THE WARM FRONT. A MIX OF HAIL/WIND/EMBEDDED TORNADOES IS
LIKELY, WITH THE LATTER INCREASING WITH SOUTHERN/EASTERN EXTENT
DURING LATE AFTERNOON OWING TO STRONGER LOW-LEVEL SHEAR ACROSS
SOUTHEAST MN/NORTHEAST IA INTO WESTERN WI.
OPEN WARM-SECTOR STORM DEVELOPMENT AHEAD OF THE DRYLINE IS NEBULOUS
WITH LOW CONFIDENCE ON THE DEGREE OF ASCENT AHEAD OF THE DRYLINE
GIVEN THE SYNOPTIC SETUP. CONDITIONALLY, BOTH THE BUOYANCY/SHEAR
PARAMETER SPACE IS VOLATILE AND SUPPORTIVE OF POTENTIAL FOR MULTIPLE
LONG-TRACK, TORNADIC SUPERCELLS. TIMING OF MID-LEVEL HEIGHT FALLS
TENDS TO FAVOR THE EVENING PERIOD AFTER PEAK HEATING BUT CAM
SIGNALS, OUTSIDE OF THE 12Z FV3, ARE SPARSE. GREATER LARGE-SCALE
ASCENT APPEARS FOCUSED FROM FAR NORTHEAST IA INTO WI. THIS REGION
REMAINS THE MOST FAVORABLE FOR DISCRETE WARM-SECTOR DEVELOPMENT
DURING THE EVENING. OTHERWISE, UPSTREAM LINEAR CLUSTERS FROM
SOUTHERN/EASTERN MN WILL LIKELY SPREAD ACROSS NORTHERN/CENTRAL WI
INTO PARTS OF UPPER MI WITH A MIXED MODE OF ALL HAZARDS PERSISTING,
BEFORE EVENTUALLY WEAKENING OVERNIGHT.
