013  
FXUS63 KDMX 161054  
AFDDMX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE DES MOINES IA  
554 AM CDT TUE JUL 16 2019  
   
DISCUSSION
 
/TODAY THROUGH MONDAY/  
ISSUED AT 330 AM CDT TUE JUL 16 2019  
 
IOWA CONTINUES TO REST ON THE SOUTHERN EDGE OF THE WESTERLIES AS  
THE REMNANTS OF BARRY PASS JUST SOUTHEAST OF THE STATE. THE  
PROXIMITY OF THE WESTERLIES WILL CONTINUE TO PRESENT CHALLENGES  
THROUGH LATE WEDNESDAY PRIOR TO A NORTHWARD MIGRATION OF THE FLOW  
BY LATE IN THE WORK WEEK. CURRENTLY, CONVECTION HAS MOVED SOUTH  
INTO THE STATE OVERNIGHT AS THE OUTFLOW HAS SURGED SOUTHWARD.  
CONVECTION HAS MAINTAINED THE BEST ACROSS THE NORTHWEST WHERE THE  
INSTABILITY AXIS RESIDES AND LOW LEVEL INFLOW IS STRONGEST.  
MEANWHILE, CONVECTION IN NEBRASKA CONTINUES TO MOVE EAST TOWARD  
THE STATE AND SHOULD PUSH INTO THE WEST BY DAYBREAK. CAMS OUTPUT  
HAS THE BULK OF THIS ACTIVITY DISSIPATING AS IT MOVES INTO THE  
WESTERN CWA THIS MORNING. HOWEVER, OUTFLOW AND SURFACE BOUNDARY  
WILL RESIDE MOSTLY LIKELY IN NORTHERN IOWA THIS AFTERNOON AND  
SHOULD PROVIDE A FOCUS FOR THUNDERSTORM REDEVELOPMENT AS  
INSTABILITY INCREASES. STORMS WILL LIKELY BE STRONG WITH A SEVERE  
STORM OR TWO GIVEN THE STRONGER INSTABILITY ALONG WITH LOCALLY  
HEAVY RAINFALL WITH PLENTY OF MOISTURE AROUND. THESE STORMS ARE  
FORECAST TO MOVE ESE INTO THE EVENING WITH SOME BREAK IN ACTIVITY  
BY LATE EVENING. ADDITIONAL CONVECTION IN THE PLAINS IS THEN  
FORECAST TO MOVE ESE OVERNIGHT ON NOSE OF DECENT LOW LEVEL JET  
TOWARDS THE FORECAST AREA LATE TONIGHT. THIS WILL LIKELY PRODUCE  
ANOTHER ROUND OF STORMS ACROSS THE NORTH AND WEST LATE TONIGHT  
INTO WEDNESDAY MORNING.  
 
AT THIS POINT, HEIGHTS BEGIN TO INCREASE ACROSS THE STATE WITH THE  
MAIN SYNOPTIC BOUNDARY LIFTING NORTHWARD. THIS SHOULD LIMIT ANY  
ADDITIONAL CONVECTION LATER WEDNESDAY AND WEDNESDAY NIGHT IN  
NORTHERN IOWA AS CAP BUILDS INTO THE STATE. THERMAL RIDGING INTO  
THE PLAINS WILL BEGIN TO MOVE INTO IOWA ON WEDNESDAY BECOMING  
FIRMLY ENTRENCHED ON THURSDAY, FRIDAY AND LIKELY MUCH OF SATURDAY.  
THIS WILL BE THE WARMEST PERIOD WITH HIGHS WELL INTO THE 90S AND  
DEWPOINTS IN THE 70S. HEAT INDEX VALUES FROM 100-110 WILL BE  
COMMON DURING THIS TIME WITH OVERNIGHT LOWS HOLDING IN THE MID TO  
UPPER 70S, THEREFORE THE HEAT WATCH IS STILL LOOKING GOOD. HAVE  
EXTENDED THE WATCH INTO SATURDAY AS THE THERMAL RIDGE APPEARS TO  
REMAIN IN PLACE DURING THIS TIME. HOWEVER, NORTHERN IOWA MAY BEGIN  
TO SEE SOME RELIEF AS THE WESTERLIES BEGIN TO DROP FARTHER SOUTH  
ALLOWING A SURFACE BOUNDARY TO APPROACH IOWA BY LATER SATURDAY.  
BEYOND THIS TIME, MUCH MORE UNCERTAINTY EXISTS IN THE FORECAST  
BUT COOLER AIR APPEARS LIKELY INTO EARLY NEXT WEEK AS THE  
WESTERLIES CONTINUE TO DROP FARTHER SOUTH PROVIDING SOME RELIEF  
FROM THE HEAT.  
 

 
   
AVIATION
 
/FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING/  
ISSUED AT 555 AM CDT TUE JUL 16 2019  
 
SCATTERED CONVECTION THIS MORNING WILL GRADUALLY DIMINISH WITH  
MVFR CONDITIONS IN AND AROUND THE STORMS. OTHERWISE, VFR  
CONDITIONS ARE EXPECTED IN ALL LOCATION BUT SOUTHEAST IOWA WHERE  
THE REMAINS OF BARRY WILL PRODUCE IFR CEILINGS THIS MORNING. THESE  
CEILINGS ARE FORECAST TO DISSIPATE BY THIS AFTERNOON AS WELL.  
REDEVELOPMENT OF STORMS IS EXPECTED IN NORTHERN IOWA BY AFTERNOON  
INTO THE EVENING WITH MVFR TO IFR CONDITIONS ONCE AGAIN IN AND  
AROUND THE STORMS. OTHERWISE, VFR CONDITIONS ARE EXPECTED TO  
PREVAIL INTO TONIGHT.  
 

 
   
DMX WATCHES/WARNINGS/ADVISORIES
 
 
EXCESSIVE HEAT WATCH FROM WEDNESDAY AFTERNOON THROUGH SATURDAY  
EVENING FOR IAZ004>007-015>017-023>028-033>039-044>050-057>062-  
070>075-081>086-092>097.  
 

 
 

 
 
DISCUSSION...COGIL  
AVIATION...COGIL  
 
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