Severe Storm Outlook Narrative (AC)
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000
ACUS11 KWNS 311945
SWOMCD
SPC MCD 311945
NEZ000-312215-

MESOSCALE DISCUSSION 1572
NWS STORM PREDICTION CENTER NORMAN OK
0245 PM CDT FRI JUL 31 2015

AREAS AFFECTED...PORTIONS OF CENTRAL AND EASTERN NEBRASKA...FAR
SOUTHWEST IOWA...FAR NORTHWEST MISSOURI

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

VALID 311945Z - 312215Z

PROBABILITY OF WATCH ISSUANCE...20 PERCENT

SUMMARY...THUNDERSTORMS ARE DEVELOPING ALONG A WEAKENING FRONT.
SEVERE HAIL AND MARGINALLY SEVERE WIND GUSTS ARE POSSIBLE WITH THE
STRONG STORMS BUT THEY ARE EXPECTED TO BE ISOLATED ENOUGH TO
PRECLUDE A WATCH AT THIS TIME.

DISCUSSION...THUNDERSTORMS HAVE DEVELOPED ALONG THE WESTERN FRINGES
OF AN OUTFLOW BOUNDARY/WEAKENING FRONTAL ZONE DRAPED ACROSS
NORTHEAST NEBRASKA...MOST CONCENTRATED IN BOONE COUNTY WHERE CELLS
ARE NOW TOPPED ABOVE 50K FT.  HIGH INSTABILITY HAS DEVELOPED SOUTH
OF THIS ZONE /ESPECIALLY OVER EASTERN NEBRASKA/ WITH BOUNDARY-LAYER
DEWPOINTS HOLDING FROM THE MID 60S TO LOW 70S UNDER STRONG SURFACE
HEATING AND MODESTLY STEEP MID-LEVEL LAPSE RATES IN THE EASTERN
EXTENSION OF AN ELEVATED MIXED LAYER PLUME FROM THE CENTRAL ROCKIES.
 THE MAIN NEGATIVE FACTORS PREVENTING AN ORGANIZED SEVERE THREAT
INCLUDE WEAK SUSTAINED CONVERGENCE ALONG THE
OUTFLOW/FRONT...NEBULOUS MID-TO-UPPER LEVEL FORCING FOR ASCENT...DRY
MID-LEVEL AIR IN THE WAKE OF A MID-LEVEL SHORTWAVE THAT TRAVERSED
THE AREA THIS MORNING...AND VERY WEAK VERTICAL WIND SHEAR IN THE
SFC-TO-750 MB LAYER.  NONETHELESS...THE FLOW /AND UNIDIRECTIONAL
SHEAR/ INCREASES SUBSTANTIALLY ABOVE 500 MB WHICH COULD PROVIDE SOME
ORGANIZED MULTICELL/TRANSIENT SUPERCELL STRUCTURES TO THE STORMS
THAT CAN PERSIST.  SEVERE WIND GUSTS ARE POSSIBLE GIVEN THE STEEP
LOW-LEVEL LAPSE RATES AND HIGH LCLS...AND SEVERE HAIL IS POSSIBLE
WITH THE ADEQUATE MID-LEVEL LAPSE RATES AND IN ANY STORMS THAT CAN
DEVELOP MID-LEVEL ROTATION.

..CONIGLIO/HART.. 07/31/2015

...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...OAX...GID...LBF...

LAT...LON   42429827 42219715 41739622 41189601 40489586 40079647
            40359817 40629985 41220076 42200150 42970158 42940075
            42699926 42429827




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