760
FXUS63 KDMX 052336
AFDDMX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
636 PM CDT SAT SEP 5 2026
...UPDATED FOR THE 00Z AVIATION DISCUSSION...
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 /00Z TAFS THROUGH 00Z MONDAY/
ISSUED AT 629 PM CDT SAT SEP 5 2026
VFR CONDITIONS PREVAIL OVER THE AREA THIS EVENING, ALTHOUGH A
FEW TO SCT CLOUD DECK AROUND 1500 TO 2500 FT IS STILL FLOATING
AROUND OUT THERE. REMNANT BOUNDARIES COULD LEAD TO BRIEF,
ISOLATED SHOWERS THROUGH THIS EVENING, BUT CHANCES OF THIS ARE
LOW SO HAVE NOT INCLUDED IN TAFS.
LATER TONIGHT AND INTO SUNDAY MORNING, SHOWER AND STORM CHANCES
WILL INCREASE, PRIMARILY AT KFOD, KMCW, AND KDSM. WHILE RAIN
CHANCES ARE HIGHER LATER TONIGHT, COVERAGE WILL BE SCATTERED, SO
HAVE STUCK WITH PROB30 MENTION AT IMPACTED TERMINALS.
CONVERSELY, IN AREAS THAT REMAIN CLEAR TONIGHT, SOME PATCHY FOG
IS POSSIBLE. THIS SEEMS MOST LIKELY OVER NORTHERN AND EASTERN
IOWA, SPECIFICALLY KMCW, KALO, AND KOTM. THAT SAID, IF SHOWERS
OCCUR AT KMCW, FOG WILL BE LESS OF AN IMPACT. A BREAK IN
PRECIPITATION IS EXPECTED THROUGH SUNDAY MORNING, WITH MORE RAIN
AND STORM CHANCES PUSHING INTO WESTERN IOWA SUNDAY AFTERNOON,
MAINLY IMPACTING KFOD AND KDSM.
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...DODSON
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page