Severe Storm Outlook Narrative (AC)
Issued by NWS

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000
ACUS01 KWNS 050602
SWODY1
SPC AC 050600

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0100 AM CDT SUN JUL 05 2015

VALID 051200Z - 061200Z

...THERE IS AN ENH RISK OF SVR TSTMS ACROSS PORTIONS OF SD/FAR
NORTHERN NEB INTO SOUTHERN MN/NORTHWEST IA...

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS THE NORTHERN
PLAINS/UPPER MIDWEST...

...THERE IS A MRGL RISK OF SVR TSTMS FROM THE NORTH-CENTRAL HIGH
PLAINS TO THE UPPER GREAT LAKES...

...THERE IS A MRGL RISK OF SVR TSTMS ACROSS THE LOWER MS RIVER
VALLEY/SOUTHEAST STATES...

...SUMMARY...
THUNDERSTORMS CAPABLE OF PRODUCING LARGE HAIL AND DAMAGING WINDS ARE
EXPECTED ESPECIALLY THIS AFTERNOON AND EVENING ACROSS PARTS OF THE
NORTHERN PLAINS AND UPPER MIDWEST INCLUDING SOUTH DAKOTA AND FAR
NORTHERN NEBRASKA INTO MINNESOTA AND FAR NORTHERN IOWA.

...SYNOPSIS...
THE LARGE-SCALE PATTERN WILL BE HIGHLIGHTED BY AN AMPLIFYING UPPER
TROUGH/STRENGTHENING POLAR JET OVER THE CENTRAL CANADIAN PRAIRIES
AND THE ADJACENT DAKOTAS/UPPER MIDWEST...WITH A RELATED COLD FRONT
EXPECTED TO GENERALLY ADVANCE SOUTHEASTWARD ACROSS THE
DAKOTAS/NORTH-CENTRAL HIGH PLAINS AND UPPER MIDWEST THROUGH EARLY
MONDAY. IN THE SOUTHERN STREAM OVER THE SOUTHERN CONUS...A
SLOW-MOVING UPPER LOW WILL MOVE NORTHEASTWARD OVER THE TN
VALLEY/SOUTHERN APPALACHIANS.

...NORTHERN PLAINS/UPPER MIDWEST...
ONGOING STORMS ACROSS NORTHERN MT EARLY IN THE OVERNIGHT SHOULD
PERSIST EAST-SOUTHEASTWARD TODAY INTO PARTS OF ND/NORTHERN SD...WITH
SOME EARLY DAY SEVERE POTENTIAL REMAINING A POSSIBILITY. PENDING
THEIR OVERNIGHT EVOLUTION...THE LINGERING STORM CLUSTERS/MCS AND
RELATED COOL POOL/CLOUD COVER CAST SOME UNCERTAINTY ON THE
EXTENT/MAGNITUDE OF NEAR-FRONTAL DESTABILIZATION WITH NORTHWARD
EXTENT ACROSS ND/NORTHWEST MN. HOWEVER...ANY RESIDUAL COLD POOL/MCV
MAY BE A PRE-FRONTAL IMPETUS FOR RENEWED CONVECTIVE
DEVELOPMENT/INTENSIFICATION THIS AFTERNOON SOMEWHERE WITHIN A
CORRIDOR FROM FAR EAST/SOUTHEAST ND INTO NORTHERN MN. REGARDLESS OF
THE EVOLUTION DETAILS...AT LEAST SOME DAMAGING WINDS/SEVERE HAIL
POTENTIAL WILL BE POSSIBLE ON THE PRESUMPTIONS OF MODERATE
NEAR/PRE-FRONTAL DESTABILIZATION THIS AFTERNOON/EARLY EVENING.

FARTHER SOUTH/SOUTHWEST...A SOMEWHAT MORE CONCENTRATED/CERTAIN
SEVERE THUNDERSTORM DEVELOPMENT SHOULD OCCUR NEAR/JUST BEHIND THE
SOUTHEASTWARD-ADVANCING FRONT BY LATE AFTERNOON/EARLY EVENING
PARTICULARLY IN A CORRIDOR SPANNING SOUTHWEST/CENTRAL/NORTHEAST SD.
THIS REGION WILL BE INFLUENCED BY DPVA/HEIGHT FALLS AND
STRENGTHENING MID/HIGHER-LEVEL CYCLONIC WESTERLIES. VERY STEEP
MID-LEVEL LAPSE RATES/AMPLE BUOYANCY AND 40+ KT OF EFFECTIVE SHEAR
/MAXIMIZED NEAR AND JUST BEHIND THE FRONT/ WILL SUPPORT INITIAL
SUPERCELLS WITH THE POSSIBILITY OF VERY LARGE /2+ INCH DIAMETER/
HAIL. A TORNADO OR TWO COULD ALSO OCCUR EARLY THIS EVENING...BUT THE
OVERALL TORNADO POTENTIAL WILL TEND TO BE LIMITED BY RELATIVELY HIGH
CLOUD BASES.

TOWARD/AFTER SUNSET...STORM MERGERS/PROBABLE COLD POOL DEVELOPMENT
IN CONJUNCTION WITH A NOCTURNALLY STRENGTHENING SOUTHWESTERLY
LOW-LEVEL JET SHOULD LEAD TO AN UPSCALE GROWING/FORWARD PROPAGATING
MCS EAST-SOUTHEASTWARD INTO EASTERN SD AND SOUTHERN MN/NORTHERN IA.
ACCORDINGLY...A CORRIDOR OF DAMAGING WIND POTENTIAL SHOULD
INCREASE/CONTINUE THROUGH AT LEAST THE EVENING HOURS...AND POSSIBLY
EVEN PERSIST OVERNIGHT ACROSS SOUTHERN MN/NORTHERN IA TOWARD THE
UPPER MS RIVER VALLEY.

...ARKLATEX/LOWER MS VALLEY/SOUTHEAST STATES...
RESIDUAL OUTFLOWS/DIFFERENTIAL HEATING SHOULD LEAD TO MULTIPLE
CORRIDORS OF THUNDERSTORM INTENSIFICATION BY AFTERNOON SPANNING THE
ARKLATEX/LOWER MS VALLEY...EAST-NORTHEASTWARD TO THE SOUTHEAST
STATES/CAROLINAS ON THE EAST/SOUTHEAST PERIPHERY OF THE TN VALLEY
UPPER LOW. WHILE MID-LEVEL LAPSE RATES AND VERTICAL SHEAR WILL BE
RELATIVELY WEAK...STEEPENING LOW-LEVEL LAPSE RATES COINCIDENT WITH
POCKETS OF STRONGER HEATING WILL ALLOW FOR STRONGER PULSE-TYPE
STORMS AND THE EVOLUTION OF SOME LINE SEGMENTS. THE STRONGER STORMS
WILL PRODUCE DOWNBURSTS CAPABLE OF LOCALIZED WIND DAMAGE THIS
AFTERNOON/EARLY EVENING.

..GUYER/GLEASON.. 07/05/2015




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