Severe Storm Outlook Narrative (AC)
Issued by NWS

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000
ACUS01 KWNS 271632
SWODY1
SPC AC 271630

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1130 AM CDT SAT AUG 27 2016

VALID 271630Z - 281200Z

...THERE IS A MRGL RISK OF SVR TSTMS ACROSS THE MIDWEST...

...THERE IS A MRGL RISK OF SVR TSTMS ACROSS THE EASTERN
DAKOTAS/WESTERN MN...

...THERE IS A MRGL RISK OF SVR TSTMS ACROSS THE SOUTH-CENTRAL HIGH
PLAINS...

...SUMMARY...
ISOLATED DAMAGING WINDS WILL BE POSSIBLE ACROSS PARTS OF THE MIDWEST
THIS AFTERNOON...WHILE ISOLATED SEVERE HAIL AND WIND COULD OCCUR
ACROSS PARTS OF THE EASTERN DAKOTAS/WESTERN MINNESOTA AND
SOUTH-CENTRAL HIGH PLAINS THIS AFTERNOON AND EVENING.

...INDIANA/LOWER MI/OH/IL...
MULTIPLE ONGOING QUASI-LINEAR CLUSTERS...EXTENDING FROM
SOUTH-CENTRAL MI SOUTHWARD INTO EAST-CENTRAL/SOUTHEAST INDIANA AT
MIDDAY...WILL CONTINUE EAST-NORTHEASTWARD TODAY WITH SOME
DIURNAL-RELATED INTENSIFICATION PROBABLE. A VERY MOIST AIR MASS
RESIDES NEAR/SOUTH OF A WARM FRONT...AND STORM PERSISTENCE WILL BE
INFLUENCED BY MULTIPLE NORTHEASTWARD-MOVING WEAK/CONVECTIVELY
RELATED MID-LEVEL DISTURBANCES. AS ADDITIONAL DESTABILIZATION/CINH
EROSION OCCUR THIS AFTERNOON IN THE PRESENCE OF MODERATELY
STRONG/NEARLY UNIDIRECTIONAL SOUTHWESTERLY WINDS...THE BOUNDARY
LAYER WILL LIKELY BECOME MORE CONDUCIVE FOR ISOLATED DAMAGING WINDS
FROM EXTREME EASTERN INDIANA INTO SOUTHEAST LOWER MI AND
WESTERN/NORTHERN OH.

FARTHER WEST...THERE ALSO MAY BE SOME POTENTIAL FOR THUNDERSTORM
REDEVELOPMENT /INCLUDING A CONDITIONAL LOW-END SEVERE RISK/ LATE
THIS AFTERNOON AND EARLY EVENING ACROSS FAR EASTERN IA INTO NORTHERN
IL. THAT SAID...MID-LEVEL LAPSE RATES WILL BE WEAK AND CONVERGENCE
WILL ALSO TEND TO BE WEAK WITH A TENDENCY FOR MID-LEVEL HEIGHT
RISES.

...EASTERN DAKOTAS/UPPER MIDWEST...
AN UPPER TROUGH CENTERED OVER THE DAKOTAS THIS MORNING WILL CONTINUE
EAST-NORTHEASTWARD TOWARD NORTHERN MN/LAKE SUPERIOR VICINITY THROUGH
TONIGHT. THIS TROUGH IS ACCOMPANIED BY VERY COOL MID-LEVEL
TEMPERATURES BY LATE AUGUST STANDARDS /-18C AT 500 MB PER 12Z
BISMARCK SOUNDING/. AS CLEARING OCCURS IN THE WAKE OF SOME EARLY-DAY
THUNDERSTORMS ACROSS FAR EASTERN ND/NORTHWEST MN...THE BOUNDARY
LAYER ACROSS THE EASTERN DAKOTAS/FAR WESTERN MN SHOULD BECOME
MODERATELY UNSTABLE THIS AFTERNOON...AS COOL MID-LEVEL
TEMPERATURES/STEEP LAPSE RATES WILL BE COMPENSATORY FACTORS FOR A
BOUNDARY LAYER THAT WILL NOT BE OVERLY MOIST /SOME LOWER 60S F
SURFACE DEWPOINTS/.

WHILE THE LARGER-SCALE FORCING RELATED TO THE UPPER TROUGH WILL
STEADILY SHIFT EAST-NORTHEASTWARD AWAY FROM THE MAIN CORRIDOR OF
DESTABILIZATION AROUND PEAK HEATING...THERE IS AT LEAST A
CONDITIONAL POTENTIAL FOR SEVERE-CALIBER DEVELOPMENT INCLUDING A
SUPERCELL OR TWO LATE THIS AFTERNOON AND EVENING AMID WEAK
INHIBITION AND MODEST LOW-LEVEL CONVERGENCE/CONFLUENCE. WHERE
THUNDERSTORMS DEVELOP/REMAIN SUSTAINED LATER TODAY...ISOLATED SEVERE
STORMS WILL BE POSSIBLE. THIS CURRENTLY APPEARS MOST PROBABLE ACROSS
FAR EASTERN ND INTO NEARBY WESTERN MN.

FARTHER SOUTH INCLUDING EASTERN SD/SOUTHWEST MN...THERE ARE STILL
CONCERNS THAT LITTLE TO NO CONVECTION MAY OCCUR AS MID-LEVEL
SUBSIDENCE OVERSPREADS THE WEAK SURFACE BOUNDARY DURING THE
AFTERNOON.

...SOUTH-CENTRAL HIGH PLAINS...
WHILE FORCING/VERTICAL SHEAR WILL NOT BE OVERLY STRONG ACROSS THE
REGION...SUFFICIENTLY STEEP LAPSE RATES AND BUOYANCY MAY YIELD SOME
RISK FOR MARGINAL/ISOLATED SEVERE WIND AND/OR MARGINALLY SEVERE HAIL
LATE THIS AFTERNOON INTO EVENING.

..GUYER/PICCA.. 08/27/2016

$$



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