259  
ACUS11 KWNS 140457  
SWOMCD  
SPC MCD 140456  
IAZ000-MNZ000-NEZ000-SDZ000-140730-  
 
MESOSCALE DISCUSSION 0730  
NWS STORM PREDICTION CENTER NORMAN OK  
1156 PM CDT WED JUN 13 2018  
 
AREAS AFFECTED...PARTS OF THE MID MISSOURI VALLEY  
 
CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY  
 
VALID 140456Z - 140730Z  
 
PROBABILITY OF WATCH ISSUANCE...20 PERCENT  
 
SUMMARY...INCREASING THUNDERSTORM DEVELOPMENT, WHICH COULD BE  
ACCOMPANIED BY A RISK FOR SEVERE HAIL, APPEARS POSSIBLE BY 3-4 AM  
CDT. IT IS NOT ANTICIPATED THAT THIS WILL REQUIRE A SEVERE WEATHER  
WATCH, BUT TRENDS WILL BE MONITORED.  
 
DISCUSSION...A FAIRLY BROAD AREA OF LOWER/MID TROPOSPHERIC WARM  
ADVECTION HAS EVOLVED ACROSS MUCH OF THE NORTH CENTRAL PLAINS/MID  
MISSOURI VALLEY REGION. THIS IS GENERALLY FOCUSED BENEATH AND ON  
THE NORTHEASTERN PERIPHERY OF A BROAD PLUME OF WARM ELEVATED MIXED  
LAYER AIR EMANATING FROM THE GREAT BASIN. ASSOCIATED FORCING FOR  
ASCENT NEAR THE EDGE OF THE STRONGER CAPPING APPEARS TO BE  
CONTRIBUTING TO ONGOING CONVECTIVE DEVELOPMENT NEAR SIOUX CITY IA.  
THIS IS LIKELY BEING SUPPORTED BY WEAK CAPE ASSOCIATED WITH ELEVATED  
MOISTURE RETURN (PERHAPS NEAR/ABOVE 700 MB), EMANATING FROM RICHER  
LOW-LEVEL MOISTURE BENEATH THE CAP, GENERALLY ACROSS THE HIGHER  
PLAINS TO THE WEST OF THE MISSOURI RIVER.  
 
HOWEVER, LATEST VWP DATA FROM HASTINGS AND NORTH PLATTE INDICATE  
THAT SOUTHERLY LOW-LEVEL JET STRENGTHENING TO 40-50 KT CENTERED  
AROUND 1 KM AGL HAS TAKEN PLACE DURING THE PAST FEW HOURS. PEAK  
SPEEDS WILL LIKELY BE REACHED WITHIN THE NEXT HOUR OR TWO, WITH A  
SUBSEQUENT WEAKENING, BUT GRADUALLY VEERING OF THE JET TO A  
SOUTHWESTERLY COMPONENT THROUGH 07-09Z. AS THIS TAKES PLACE,  
ADVECTION OF LOW-LEVEL MOISTURE INTO THE VICINITY OF THE MID-LEVEL  
MOISTURE GRADIENT IS EXPECTED TO CONTRIBUTE TO CONSIDERABLE  
DESTABILIZATION NEAR/NORTHEAST OF THE MISSOURI RIVER. MOST  
CONVECTION ALLOWING GUIDANCE, INCLUDING THE NCEP HRRR INDICATE THAT  
THIS WILL COINCIDE WITH INCREASING/INTENSIFYING THUNDERSTORM  
DEVELOPMENT. IN THE PRESENCE OF AT LEAST MODEST VERTICAL SHEAR,  
SUPPORTED BY CONSIDERABLE VEERING OF WINDS WITH HEIGHT, THE  
DEVELOPMENT OF MODERATELY LARGE CAPE MAY SUPPORT A SEVERE HAIL  
THREAT IN STRONGER STORM DEVELOPMENT.  
 
..KERR/WEISS.. 06/14/2018  
   
..PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT
 
 
ATTN...WFO...DMX...FSD...OAX...  
 
LAT...LON 44059777 44059597 42219416 41549473 41759584 42709670  
43509781 44059777  
 
CLICK HERE TO GO TO PREVIOUS BULLETINS.

The Nexlab SPC Page Main Text Page