255  
FXUS63 KEAX 282325  
AFDEAX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO  
625 PM CDT WED JUN 28 2017  
   
DISCUSSION
 
 
ISSUED AT 310 PM CDT WED JUN 28 2017  
 
DEEPENING SURFACE TROUGH OVER THE WESTERN HIGH PLAINS HAS MADE FOR A  
TIGHT SURFACE PRESSURE GRADIENT OVER THE CENTRAL PLAINS AND THE MID-  
LOWER MISSOURI RIVER VALLEY. GUSTY SOUTHERLY WINDS HAVE RESPONDED  
THROUGH THE DAY TO THE TIGHTENING GRADIENT AND HAVE PERSISTED IN THE  
20 TO 30 MPH RANGE, WITH GUSTS APPROACHING 40 MPH. THIS HAS CAUSED A  
NICE MOISTENING OF THE LOWER ATMOSPHERE OVER NORTHERN MISSOURI AND  
SOUTHERN IOWA, AND PRIMED THE AREA FOR ROBUST CONVECTIVE DEVELOPMENT  
LATER THIS EVENING, LIKELY IN THE NEXT HOUR OR TWO. VISIBLE  
SATELLITE IMAGERY INDICATES SOME AGITATED AND DEEPENING CUMULUS IN  
THE VICINITY OF A SUBTLE BOUNDARY CHARACTERIZED BY SURFACE WIND  
SHIFT OF AROUND 20-30 DEGREES IN SOUTHERN IOWA AND NORTHERN  
MISSOURI. HI-RES MODELS INDICATE SCATTERED TO NUMEROUS THUNDERSTORMS  
ORIENTED SW TO NE THROUGH NORTHERN MISSOURI AND SOUTHERN/CENTRAL  
IOWA LATER THIS AFTERNOON AND THIS EVENING. DESPITE SURFACE WINDS  
BEING A BIT VEERED (SOUTH/SOUTHWEST) GOOD VEERING-WITH-HEIGHT  
THROUGH 500 MB WHERE FLOW IS OUT OF THE WEST/NORTHWEST AROUND 50 KTS  
IS CREATING A WIND PROFILE CONDUCIVE TO HIGH SHEAR. THE  
AFOREMENTIONED WARM/MOIST SURFACE, BENEATH FAIRLY STEEP LOW/MID  
LEVEL LAPSE RATES IS YIELDING ML CAPE VALUES IN THE 3000 TO 3500  
J/KG RANGE. DEEP LAYER SHEAR VALUES APPROACHING 40 KTS ACROSS THE  
AREA WILL COMBINE WITH THE HIGH INSTABILITY TO BRING AN ENVIRONMENT  
CONDUCIVE TO SUPERCELLULAR DEVELOPMENT. INITIAL DEVELOPMENT SHOULD  
BE SEMI-DISCRETE, BUT DUE TO STORM COVERAGE, INTERFERENCE COULD  
DIMINISH TORNADO CONCERNS AND ON A LARGER SCALE PERHAPS THE OVERALL  
ORGANIZATION OF ANY STORM THAT FORMS. EXPECT UPGROWTH TO A MCS,  
WHICH WILL BRING MORE OF A WIND THREAT AND HEAVY RAIN THREAT TO  
NORTHERN MISSOURI. IN THE MEANTIME, WITH SEMI-DISCRETE CONVECTION  
ALL HAZARDS WOULD BE POSSIBLE WITH LARGE HAIL AND STRONG WINDS BEING  
THE PRIMARY CONCERNS. ONE THING TO CONSIDER WITH THIS EVENT WOULD BE  
THE POTENTIAL FOR SOME MESOVORTEX TORNADOES AFTER SUNSET ACROSS THE  
AREA. SIGNIFICANT TORNADO PARAMETER WILL MAX OUT IN THE 3 TO 5  
RANGE, AND THAT'S BEING DRIVEN BY 0-1 SRH VALUES REMAINING IN THE  
200 TO 300 M2/S2 RANGE AFTER DARK. EVEN WITH UPSCALE GROWTH THERE  
WILL STILL BE AMPLE LOW LEVEL SHEAR TO PRODUCE AN EMBEDDED TORNADO  
OR TWO WITHIN THE MCS ACTIVITY.  
 
BY FRIDAY MORNING THE BULK OF THE ACTIVITY WILL BE OFF TO THE EAST,  
BUT ANOTHER ROUND OF THUNDERSTORMS WILL BE POSSIBLE LATER IN THE  
MORNING HOURS AS A SHORTWAVE TROUGH GLIDES THROUGH THE AREA. THESE  
MORNING SHOWERS SHOULD BE SUBSEVERE, BUT AN ISOLATED SEVERE  
HAILSTONE COULD FORM WITH THIS ACTIVITY. THAT WILL THEN SET THE  
STAGE FOR ANOTHER ROUND OF SEVERE THUNDERSTORMS ON FRIDAY, GENERALLY  
ALONG A BOUNDARY WHICH WILL SET UP IN NORTHEAST KANSAS AND SOUTHEAST  
NEBRASKA. ONCE AGAIN, GIVEN GOOD INSTABILITY AND SHEAR PARAMETERS ON  
THURSDAY AFTERNOON SEVERE STORMS SHOULD FORM IN THE AFTERNOON WITH  
ALL HAZARDS POSSIBLE ONCE AGAIN, MAINLY LARGE HAIL AND DAMAGING  
WINDS. THESE STORMS SHOULD BE A LITTLE FURTHER SOUTH THAN THE ROUND  
ON WEDNESDAY, WHICH WILL PUT THE KC METRO AREA IN PLAY FOR SOME OF  
THE STRONGER STORMS. THE BEST CHANCE FOR WIDESPREAD SEVERE STORMS  
WILL BE LATE IN THE EVENING AND OVERNIGHT THURSDAY ONCE THE COLD  
FRONT PUSHES THROUGH THE AREA. EXPECT THIS ACTIVITY TO BE MORE OF A  
WIND AND HYDRO THREAT TO THE KC METRO AND AREAS OF MISSOURI SOUTH OF  
THE MISSOURI RIVER THROUGH EARLY FRIDAY MORNING.  
 
THE EARLY PART OF THE WEEKEND SHOULD BE FAIRLY CALM AND COOLER, OR  
AT LEAST DRIER AS THE AREA COMES UNDER THE INFLUENCE OF THE SURFACE  
RIDGE THAT NOSES IN FRIDAY NIGHT. THROUGH THE REST OF THE WEEKEND  
AND INTO EARLY NEXT WEEK THERE WILL BE OFF-AND-ON CHANCES FOR  
SHOWERS AND THUNDERSTORMS ACROSS THE AREA AS THE MID LEVEL FLOW  
REMAINS ZONAL AND ACTIVE AND THE LOWER LEVELS RELOAD WITH WARM AND  
MOIST AIR. BY MID WEEK LARGE SCALE RIDGING WILL DOMINATE THE  
UPSTREAM REGION, WHICH WILL CAUSE TEMPERATURES TO BE ON THE INCREASE  
THROUGH MID WEEK.  
 

 
   
AVIATION
 
(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING)  
ISSUED AT 625 PM CDT WED JUN 28 2017  
 
ONGOING STORMS NEAR THE MO/IA BORDER WILL STAY MAINLY NORTH OF  
THE TERMINALS TONIGHT, EVEN AS THEY BEGIN TO DIVE SOUTH SOUTHEAST  
LATE THIS EVENING. ANOTHER ROUND OF STORMS MAY DEVELOP IN  
NORTHEAST KANSAS AFTER MIDNIGHT AND IMPACT TAF SITES AROUND  
12Z-15Z, BUT THE PROBABILITY IS TOO LOW TO WARRANT MORE THAN A  
VCTS AT THIS TIME. GUSTY SOUTH SOUTHWEST WINDS WILL BEGIN TO  
DIMINISH SLIGHTLY OVER THE NEXT FEW HOURS, DROPPING TO ABOUT 8-10  
KTS SUSTAINED OVERNIGHT. ANOTHER ROUND OF STORMS IS POSSIBLE JUST  
BEYOND THE END OF THE TAF PERIOD.  
 

 
   
EAX WATCHES/WARNINGS/ADVISORIES
 
 
KS...NONE.  
MO...NONE.  

 
 

 
 
DISCUSSION...LEIGHTON  
AVIATION...LAFLIN  
 
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