891  
FXUS63 KOAX 190015  
AFDOAX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE  
715 PM CDT WED JUL 18 2018  
   
SHORT TERM
 
(TONIGHT THROUGH SATURDAY)  
ISSUED AT 403 PM CDT WED JUL 18 2018  
 
MAIN FORECAST PROBLEM IS SEVERE WEATHER OVERNIGHT.  
 
CLOSED UPPER LOW IS FORECAST TO MOVE SOUTHEAST INTO THE MID  
MISSISSIPPI VALLEY TONIGHT. AIRMASS IS UNSTABLE SOUTH OF A  
NORTHWEST-SOUTHEAST WARM FRONT. LATEST ML CAPE VALUES WERE BETWEEN  
1000 TO 1500 J/KG. A NORTH-SOUTH ORIENTED SURFACE TROUGH OVER  
NORTH CENTRAL NEBRASKA IS FORECAST TO MOVE SLOWLY EASTWARD DURING  
THE EVENING. 0-6 KM BULK SHEAR AT 20Z IS 35 TO 50 KNOTS OVER  
EASTERN NEBRASKA.  
 
BELIEVE THE SCENARIO WILL BE ISOLATED STORMS, MOST LIKELY  
SUPERCELLS, TO OCCUR IN NORTHEAST NEBRASKA DURING THE EARLY  
EVENING. DAMAGING WINDS AND AN ISOLATED TORNADO IS POSSIBLE.  
 
THEN LATER ON THIS EVENING, A COMPLEX OF SEVERE THUNDERSTORMS WITH  
DAMAGING WIND THREAT IS EXPECTED TO DEVELOP OVER NORTHEAST  
NEBRASKA AFTER 03Z AND MOVE SOUTHEAST ACROSS EASTERN NEBRASKA AND  
SOUTHWEST IOWA. HRRR MODEL FORECASTS THAT THE COMPLEX WILL BE  
THROUGH EASTERN NEBRASKA AND SOUTHWEST IOWA BY 11 TO 12Z.  
 
AFTER THIS COMPLEX MOVES THROUGH, DRY WEATHER IS FORECAST THROUGH  
SATURDAY AS HIGH PRESSURE MOVES IN.  
   
LONG TERM
 
(SATURDAY NIGHT THROUGH WEDNESDAY)  
ISSUED AT 403 PM CDT WED JUL 18 2018  
 
BELOW NORMAL TEMPERATURES, WITH HIGHS IN THE LOWER 80S IS  
FORECAST. ANOTHER CHANCE OF THUNDERSTORMS IS ON SUNDAY NIGHT INTO  
MONDAY MORNING AS A WEAK COLD FRONT MOVES SOUTHEAST. THIS MAY ONLY  
AFFECT WESTERN PORTIONS OF OUR CWA. THE NEXT SYSTEM WITH MORE  
WIDESPREAD THUNDERSTORM ACTIVITY WILL BE NEXT WEDNESDAY AS ANOTHER  
COLD FRONT MOVES SOUTHEAST IN NORTHWEST UPPER FLOW.  
 

 
   
AVIATION
 
(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING)  
ISSUED AT 715 PM CDT WED JUL 18 2018  
 
MAIN AVIATION CONCERN DURING THE TAF PERIOD IS THE COVERAGE AND  
EVOLUTION OF STRONG TO SEVERE THUNDERSTORMS THAT CURRENTLY ARE  
ONGOING NORTHWEST OF KOFK. ISOLATED CONVECTION IS EXPECTED TO  
CONGEAL INTO LINEAR CLUSTER OF SEVERE STORMS AND THEN SPREAD  
SOUTHEAST ACROSS EASTERN NEBRASKA LATE EVENING AND OVERNIGHT. TIMING  
INTO KOFK AROUND 03Z, WITH POTENTIAL IMPACT THROUGH 07Z. RIGHT NOW,  
LOOKS LIKE STORMS WILL NOT ARRIVE IN VICINITY OF KOMA UNTIL 07-08Z,  
AND WILL PERSIST THROUGH 10-11 UTC. TIMING INTO LINCOLN 08-09Z,  
WITH IMPACT THROUGH 12Z. CEILINGS WITH STORMS WILL DROP TO LOW  
VFR OR HIGH END MVFR.  
 

 
   
OAX WATCHES/WARNINGS/ADVISORIES
 
 
NE...NONE.  
IA...NONE.  

 
 

 
 
SHORT TERM...SMITH  
LONG TERM...SMITH  
AVIATION...FORTIN  
 
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