530
FXUS63 KDMX 052053
AFDDMX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
353 PM CDT SAT SEP 5 2026
KEY MESSAGES
- PERIODIC CHANCES FOR STORMS THROUGH MONDAY, MAINLY OVER THE
WESTERN HALF OF IOWA. DAMAGING WINDS ARE POSSIBLE WITH STORMS.
- GRADUAL COOLING INTO MONDAY FOLLOWED BY MORE SEASONAL
TEMPERATURES.
SHORT TERM /THROUGH TUESDAY/
ISSUED AT 239 PM CDT SAT SEP 5 2026
CONVECTIVE DEBRIS AND AN OUTFLOW BOUNDARY IMPACTED PARTS OF CENTRAL
AND NORTHERN IOWA TODAY. THE OUTFLOW BOUNDARY HAS BEEN ERODING EARLY
THIS AFTERNOON BUT THIS BOUNDARY IN ADDITION TO THE CLOUDS, HAVE
KEPT THE HIGHWAY 30 CORRIDOR AND NORTHWARD COOLER YET STILL HUMID
TODAY. A FEW SHOWERS DID LINGER OVER FAR NORTH CENTRAL IOWA BUT
TRENDS HAVE CONTINUED DOWNWARD.
THAT CONVECTIVE TRENDS WILL THE PRIMARY CHALLENGE OVER THE NEXT 36-
48 HRS. THERE IS ALREADY DIURNALLY DRIVEN ISOLATED THUNDERSTORMS
OVER FAR NORTHERN MISSOURI. THIS POTENTIAL MAY REACH FAR SOUTH
CENTRAL IOWA WHERE AGITATED CUMULUS ALONG A WIND SHIFT LINE IS
PRESENT. THE LOW LEVEL JET WILL RAMP UP AGAIN TONIGHT ACROSS THE
WESTERN HIGH PLAINS WHILE THE INSTABILITY AXIS DOES MOVE FARTHER
EAST INTO CENTRAL IOWA. THUNDERSTORMS ARE EXPECTED TO DEVELOP OVER
PARTS OF SOUTH DAKOTA AND SOUTHWEST MINNESOTA AND EVENTUALLY BECOME
ORGANIZED AND FOLLOW THE CORFIDI VECTORS SOUTHEAST INTO IOWA ALONG
THE INSTABILITY AXIS. THESE STORMS MAY POSE A DAMAGING WIND THREAT
LATER TONIGHT AND INTO SUNDAY MORNING. THIS PROCESS MAY REPEAT AGAIN
SUNDAY NIGHT INTO MONDAY MORNING. THE ELEVATED MIXED LAYER (EML) IS
EXPECTED TO BECOME RE-ESTABLISHED MONDAY AFTERNOON AND SHOULD END
PRECIPITATION CHANCES FOR A PERIOD. AN UPPER LEVEL LOW MOVING
INTO MONTANA THEN MANITOBA WILL SQUASH THE UPPER RIDGE ENOUGH TO
ALLOW A BOUNDARY TO ENTER IOWA BY TUESDAY, WHICH WILL BRING THE
NEXT CHANCES FOR THUNDERSTORMS AND COOLER WEATHER.
LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/
ISSUED AT 239 PM CDT SAT SEP 5 2026
THE FLATTENING OF THE SUB-TROPICAL HIGH WILL CONTINUE WEDNESDAY WITH
A WESTERLY/ZONAL FLOW FOR THE MID TO END OF THE WEEK. LESS CERTAINTY
LATE NEXT WEEK WITH SPATIAL AND TEMPORAL DIFFERENCES WITH THE
NEXT STRONG UPPER LEVEL SHORT WAVE THAT WILL ARRIVE INTO THE
PACIFIC NORTHWEST. THIS WILL DETERMINE HOW MUCH THE SUB-TROPICAL
HIGH RIDGING CAN BECOME RE-ESTABLISHED OVER THE WESTERN CONUS
AND THE DIFFERENCE BETWEEN SEASONAL WESTERLY FLOW OR COOLER
NORTHWEST FLOW AND ATTENDANT PRECIPITATION CHANCES ASSOCIATED
WITH EACH.
AVIATION /18Z TAFS THROUGH 18Z SUNDAY/
ISSUED AT 1238 PM CDT SAT SEP 5 2026
A WIDE ASSORTMENT OF AVIATION CONDITIONS ARE ACROSS IOWA TO
BEGIN THE PERIOD. IFR TO LIFR STRATUS IS IN THE KMCW/KALO AREAS.
AN OUTFLOW BOUNDARY IS MOVING INTO CENTRAL IOWA AND NEAR KDSM
AND JUST WEST OF KMCW. SOME UNCERTAINLY IF THIS WILL HELP CLEAR
THE STRATUS AT KMCW AND THE RECOVERY TO SYNOPTIC SCALE WINDS
ELSEWHERE AS THE OUTFLOW MIXES OUT. THE REMAINDER OF THE
TERMINAL PERIOD FOCUSES ON ADDITIONAL THUNDERSTORM CHANCES
LATER TONIGHT AND INTO SUNDAY MORNING, MAINLY AT KFOD/KDSM/KMCW.
DMX WATCHES/WARNINGS/ADVISORIES
HEAT ADVISORY UNTIL 7 PM CDT THIS EVENING FOR IAZ033>039-
044>050-057>062-070>075-081>086-092>097.
SHORT TERM...DONAVON
LONG TERM...DONAVON
AVIATION...DONAVON
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