112  
FXUS63 KDMX 060336  
AFDDMX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE DES MOINES IA  
1036 PM CDT FRI SEP 5 2025  
 
...UPDATED FOR THE 06Z AVIATION DISCUSSION...  
   
KEY MESSAGES  
 
- FORECAST IS DRY THROUGH THE WEEKEND.  
 
- COOL WEATHER PERSISTS FOR A COUPLE MORE DAYS. SUNDAY MORNING  
LOW TEMPERATURES IN THE UPPER 30S ACROSS PART OF NORTHERN AND  
WESTERN IOWA.  
 
- WARMING NEXT WEEK, WITH RAIN CHANCES RETURNING INTERMITTENTLY  
(40-60% CHANCE AROUND MONDAY NIGHT, OTHERWISE LOWER THAN 30%).  
 
 
   
DISCUSSION  
 
ISSUED AT 138 PM CDT FRI SEP 5 2025  
 
A LARGE CYCLONE IS CURRENTLY PARKED OVER ONTARIO, WITH ITS  
CYCLONIC FLOW EXTENDING DOWN ACROSS THE UPPER MIDWEST. A LOBE OF  
VORTICITY IS EVIDENT IN WATER VAPOR SATELLITE IMAGERY, CROSSING  
SOUTH DAKOTA AND HEADED TOWARD NORTHERN IOWA THIS AFTERNOON AND  
EVENING. VISIBLE SATELLITE IMAGERY SHOWS A LARGE FIELD OF  
DIURNALLY GENERATED STRATOCUMULUS CLOUDS, COVERING MUCH OF THE  
REGION AND ENHANCED BY MODEST LOW-LEVEL COLD AIR ADVECTION. AS  
THE VORTICITY LOBE SWINGS OVERHEAD LATER TODAY AND PROVIDES SOME  
MID-LEVEL LIFT, IT MAY BE SUFFICIENT TO GENERATE A FEW  
SPRINKLES OR LIGHT SHOWERS MAINLY IN OUR NORTHERN COUNTIES.  
HOWEVER, FORECAST SOUNDINGS ILLUSTRATE MOST OF THE ASSOCIATED  
LIFT WILL OCCUR ABOVE THE CLOUD LAYER, AND THE MOISTURE IS QUITE  
SHALLOW SO ANY PRECIPITATION THAT DOES OCCUR WILL LIKELY BE  
VERY LIGHT AND MAY NOT EVEN REACH THE GROUND. INDEED, REGIONAL  
RADAR IMAGERY DEPICTS A FEW LIGHT ECHOES APPROACHING THE  
SD/MN/IA TRI-STATE AREA, BUT SO FAR NO PRECIPITATION HAS  
REGISTERED AT SURFACE OBSERVING SITES BENEATH THESE RETURNS.  
NEVERTHELESS, WITH THE POSSIBILITY OF SLIGHT ENHANCEMENT AS THE  
AFTERNOON PROGRESSES AND IN THE INTERESTS OF CONSISTENCY, WILL  
MAINTAIN THE SLIGHT CHANCE (20%) OF SHOWERS FORECAST IN OUR  
NORTH AND NORTHEAST LATE THIS AFTERNOON AND EVENING. IN ANY  
EVENT, NO IMPACTS ARE ANTICIPATED.  
 
FROM TONIGHT ONWARD THE ONTARIO GYRE WILL BEGIN TO MOVE OFF  
SLOWLY TO THE EAST, GRADUALLY WEAKENING THE CYCLONIC FLOW OVER  
IOWA. ANOTHER LOBE OF VORTICITY WILL ROUND THE SOUTHWESTERN  
PERIPHERY OF THE SYSTEM AGAIN ON SATURDAY, BUT FARTHER NORTHEAST  
THAN TODAY WITH ANY ASSOCIATED SHOWERS MORE LIKELY OVER  
WISCONSIN OR FAR NORTHEASTERN IOWA, SO THE FORECAST REMAINS DRY  
FOR OUR SERVICE AREA. CONCURRENTLY, A RIDGE OF SURFACE HIGH  
PRESSURE WILL BUILD INTO IOWA FROM THE NORTHEAST ON SATURDAY  
NIGHT AND REMAIN OVERHEAD ON SUNDAY. THIS WILL RESULT IN LIGHT  
WINDS AND MOSTLY CLEAR SKIES, WITH TEMPERATURES FALLING TO THEIR  
LOWEST POINT OF THE WEEK ON SUNDAY MORNING BUT THEN REBOUNDING  
BY SUNDAY AFTERNOON TO LEVELS HIGHER THAN THOSE SEEN THE  
PRECEDING COUPLE OF DAYS. THE CURRENT FORECAST CALLS FOR LOWS IN  
THE UPPER 30S ACROSS PARTS OF NORTHERN AND WESTERN IOWA SUNDAY  
MORNING, WITH HIGHS RANGING IN THE MID 60S TO LOWER 70S ACROSS  
IOWA BY SUNDAY AFTERNOON.  
 
FROM MONDAY THROUGH MOST OF NEXT WEEK A SYNOPTIC PATTERN CHANGE  
WILL OCCUR, WITH ROUGHLY ZONAL 500 MB FLOW OVER IOWA ON MONDAY  
WHILE A BROAD RIDGE DEVELOPS OVER THE ROCKIES. A WEAK TROUGH  
WILL DIG OVER THE MIDWEST AROUND MONDAY NIGHT AFTER WHICH THE  
LARGER RIDGE WILL SLOWLY TRAVERSE THE CENTRAL U.S. DURING THE  
LATTER HALF OF THE WEEK. LONG-RANGE MODELS SHOW SIGNIFICANT  
VARIANCE IN THEIR DEPICTION OF THE STRENGTH OF THE RIDGE, AS  
WELL AS THE TIMING AND NATURE OF VARIOUS SUBTLE IMPULSES MOVING  
THROUGH OR OVER IT DURING THIS TIME FRAME. THE RESULT IS  
INTERMITTENT, GENERALLY LOW (20-30%) RAIN CHANCES NEXT WEEK, BUT  
WITH LITTLE IN THE WAY OF LARGE OR STRONG STORM SYSTEMS  
FORESEEN AT THIS RANGE. THE BEST CHANCE FOR RAIN AND  
THUNDERSTORMS (40-60%) WILL COME FROM AROUND MONDAY NIGHT INTO  
TUESDAY IN ASSOCIATION WITH THE AFOREMENTIONED TROUGH COMING  
OVERHEAD, BUT EVEN THEN IT APPEARS INSTABILITY AND SHEAR WILL BE  
MODEST. TEMPERATURES WILL ALSO BE MILDER IN THIS SCENARIO, WITH  
DAILY HIGHS LIKELY IN THE MID-70S TO MID-80S FOR MUCH OF THE  
WEEK.  
 
 
   
AVIATION /06Z TAFS THROUGH 06Z SUNDAY/  
 
ISSUED AT 1036 PM CDT FRI SEP 5 2025  
 
CONFIDENCE REMAINS HIGH IN VFR CONDITIONS PREVAILING THROUGH  
THE PERIOD AT ALL TERMINALS. WINDS WILL BE LIGHT FROM THE WEST  
OVERNIGHT BEFORE BECOMING FROM THE NORTHWEST AT AROUND 10 KNOTS  
BY LATE SATURDAY MORNING THROUGH THE AFTERNOON HOURS. CUMULUS  
CLOUDS WITH BASES AS LOW AS FL050 WILL ALSO DEVELOP BY LATE  
MORNING INTO THE AFTERNOON WITH COVERAGE UP TO BKN OVER PARTS OF  
NORTH CENTRAL, NORTHEAST, AND EAST CENTRAL IOWA. THESE CLOUDS  
WILL DISSIPATE AND THE WINDS WILL DIMINISH AROUND SUNSET.  
 
 
   
DMX WATCHES/WARNINGS/ADVISORIES  
 
NONE.  
 
 
 
 
 
DISCUSSION...LEE  
AVIATION...ANSORGE  
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