Severe Storm Outlook Narrative (AC)
Issued by NWS

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ACUS01 KWNS 310537
SWODY1
SPC AC 310534

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1234 AM CDT SUN JUL 31 2016

VALID 311200Z - 011200Z

...THERE IS A SLGT RISK OF SVR TSTMS OVER ND...

...THERE IS A MRGL RISK OF SVR TSTMS OVER THE NRN AND CNTRL PLAINS
INTO THE MS VALLEY...

...SUMMARY...
SCATTERED THUNDERSTORMS...SOME SEVERE...ARE EXPECTED TO DEVELOP LATE
THIS AFTERNOON INTO THE EVENING ACROSS NORTH DAKOTA. OTHER STRONG
STORMS MAY ALSO DEVELOP ACROSS PORTIONS OF THE CENTRAL PLAINS AND
LOWER MISSOURI VALLEY. DAMAGING WIND AND LARGE HAIL WILL BE THE
PRIMARY THREATS.

...SYNOPSIS...

STRONGER BELT OF WLYS WILL EVOLVE FROM THE PACIFIC NW THROUGH THE
NRN HIGH PLAINS IN ASSOCIATION WITH A SLOW BUT PROGRESSIVE UPPER
TROUGH NOW CENTERED OVER SRN BRITISH COLUMBIA. A SIGNIFICANT
SHORTWAVE TROUGH IS FORECAST TO ROTATE THROUGH THE BASE OF THIS
FEATURE INTO THE HIGH PLAINS OF MT AND WRN ND LATE THIS AFTERNOON
AND EVENING. AT THE SFC A LEE TROUGH/DRYLINE WILL DEVELOP OVER MUCH
OF THE HIGH PLAINS. A COLD FRONT WILL ACCOMPANY THE NRN STREAM
SHORTWAVE TROUGH AND MOVE THROUGH ERN MT AND WRN  ND DURING THE
EVENING AND OVERNIGHT.

...ND...

SLY NEAR-SFC WINDS WILL PERSIST OVER THE PLAINS IN ASSOCIATION WITH
EVOLVING LEE TROUGH AND WILL RESULT IN RICHER LOW-LEVEL MOISTURE
ADVECTING NWD BENEATH AN EWD-EXPANDING EML PLUME. THESE PROCESSES
WILL CONTRIBUTE TO STRONG INSTABILITY /3000-3500 J/KG MLCAPE/ AS THE
BOUNDARY LAYER DESTABILIZES DURING THE AFTERNOON. SHORTWAVE RIDGING
PRESENT OVER THE NRN PLAINS MOST OF TODAY WILL GIVE WAY TO MODEST
HEIGHT FALLS THIS EVENING IN ASSOCIATION WITH APPROACHING SHORTWAVE
TROUGH. THIS IN CONJUNCTION WITH EWD EXPANDING EML WILL LIMIT
SFC-BASED THUNDERSTORM INITIATION MOST OF TODAY. INITIAL STORMS MAY
DEVELOP OVER THE DEEPLY MIXED REGIME ACROSS ERN MT AND INTENSIFY AS
THEY INTERCEPT GREATER MOISTURE ALONG/EAST OF THE LEE TROUGH ACROSS
WRN ND. 0-6 KM SHEAR WILL INCREASE TO 30-35 KT BY EVENING...AND SOME
STORMS WILL LIKELY DEVELOP SUPERCELL STRUCTURES. ACTIVITY MAY
CONTINUE INTO THE OVERNIGHT AND EVOLVE INTO ONE OR MORE CLUSTERS
SUPPORTED BY A STRENGTHENING SLY LLJ. LARGE HAIL AND DAMAGING WIND
WILL BE THE MAIN THREATS.

...CNTRL PLAINS THROUGH MID MS VALLEY...

HAVE INCLUDED THIS AREA IN A MARGINAL RISK DUE TO POTENTIAL FOR A
FEW DOWNBURST WINDS WITH HIGH BASED STORMS SPREADING OFF THE HIGHER
TERRAIN INTO THE HIGH PLAINS AND ALSO DEVELOPING ALONG LEE TROUGH.
ADDITIONAL STORMS ARE LIKELY OVERNIGHT TOWARD THE MS VALLEY REGION
WITHIN ZONE OF INCREASING WARM ADVECTION/ISENTROPIC ASCENT AS THE
LLJ STRENGTHENS AND INTERACTS WITH NW-SE ORIENTED BAROCLINIC ZONE.

..DIAL/GLEASON.. 07/31/2016

$$



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