788
FXUS63 KDMX 290344
AFDDMX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
1044 PM CDT TUE JUL 28 2026
...UPDATED FOR THE 06Z AVIATION DISCUSSION...
KEY MESSAGES
- SIGNIFICANT HEAT RELIEF ARRIVES TODAY WITH HIGHS IN THE UPPER
80S TO LOWER 90S.
- MAINLY DRY CONDITIONS PREVAIL THROUGH WEDNESDAY.
- SHOWER AND STORM CHANCES (60-80%) RETURN BY THURSDAY
AFTERNOON.
SHORT TERM /THROUGH THURSDAY/
ISSUED AT 156 PM CDT TUE JUL 28 2026
THE LATEST SURFACE ANALYSIS SHOWS A DEPARTING COLD FRONT. LINGERING
SPRINKLES TO LIGHT SHOWERS PERSIST ON THE BACKSIDE OF THE BOUNDARY,
PRIMARILY NORTH OF U.S. 71. CURRENT TEMPERATURES RANGE FROM THE
UPPER 70S TO LOWER 80S ACROSS NORTHERN IOWA, WARMING TO THE MID-TO-
UPPER 80S ALONG AND SOUTH OF THE I-80 CORRIDOR. LASTLY, GOES
GEOCOLOR SATELLITE IMAGERY HIGHLIGHTS WIDESPREAD WILDFIRE SMOKE
ACROSS MUCH OF THE AREA.
BEHIND THE DEPARTING FRONT, UPPER-LEVEL HEIGHT RISES WILL SUPPORT
DRY CONDITIONS ALONGSIDE A RETURN TO TEMPERATURES IN THE UPPER 80S
TO LOWER 90S THIS AFTERNOON AND AGAIN WEDNESDAY. WHILE THESE WARM
TEMPERATURES ARE CURRENTLY MATERIALIZING SOUTH OF THE I-80 CORRIDOR,
WIDESPREAD CLOUD COVER ACROSS NORTHERN IOWA COULD LIMIT DAYTIME
BOUNDARY-LAYER HEATING. ADDITIONALLY, SOLAR ATTENUATION FROM THE
SMOKE LAYER VISIBLE ON SATELLITE IMAGERY COULD TEMPER AFTERNOON
HIGHS BY A FEW DEGREES. NONETHELESS, UPPER-LEVEL RIDGING BUILDING IN
FROM THE SOUTHWEST WILL FAVOR DRY WEATHER STARTING THIS AFTERNOON
AND PERSISTING THROUGH THE MID-WEEK FORECAST PERIOD. HOWEVER,
ATTENTION WILL SHIFT AWAY FROM THE BUILDING HEAT AS THE RIDGE BREAKS
DOWN LATE WEDNESDAY NIGHT INTO THURSDAY MORNING WITH THE APPROACH OF
A SHORTWAVE TROUGH.
A DEPARTING COLD FRONT LEAVES BEHIND LINGERING LIGHT SHOWERS NORTH
OF U.S. 71 ALONGSIDE WIDESPREAD WILDFIRE SMOKE. AN UPPER-LEVEL RIDGE
BUILDING FROM THE SOUTHWEST WILL BRING DRY CONDITIONS AND HIGH
TEMPERATURES IN THE UPPER 80S TO LOWER 90S THROUGH WEDNESDAY;
HOWEVER, LINGERING CLOUD COVER AND SMOKE MAY SLIGHTLY TEMPER
AFTERNOON HEATING. THE PATTERN TURNS MORE ACTIVE LATE WEDNESDAY
NIGHT INTO THURSDAY AS THE RIDGE BREAKS DOWN AHEAD OF AN APPROACHING
SHORTWAVE TROUGH.
LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/
ISSUED AT 156 PM CDT TUE JUL 28 2026
AN APPROACHING SHORTWAVE TROUGH IS FORECAST TO EJECT OFF THE HIGH
PLAINS OF COLORADO TOWARD THE UPPER CENTRAL PLAINS AND GREAT LAKES.
AS THIS OCCURS, A SURFACE LOW WILL TRACK EASTWARD TOWARD IOWA,
BRINGING INCREASING CHANCES FOR SHOWERS AND THUNDERSTORMS STARTING
THURSDAY AFTERNOON. THE PRIMARY FOCUS FOR STRONG TO SEVERE STORMS
WILL REMAIN MOSTLY WEST OF THE CWA; HOWEVER, THE FAR WESTERN
PERIPHERY OF THE CWA IS IN A DAY 3 SPC MARGINAL RISK, WITH DAMAGING
WINDS AS THE PRIMARY THREAT.
WHILE A MARGINAL RISK EXISTS FOR SEVERE WEATHER, THE PARAMOUNT
CONCERN FOR THURSDAY INTO LATE FRIDAY IS HEAVY RAINFALL. TALL,
SKINNY CAPE PROFILES ALONGSIDE PWS RANGING FROM 2.00 TO 2.50 INCHES
FAVOR HIGHLY EFFICIENT WARM-RAIN PROCESSES. IN ADDITION TO THESE
MOISTURE PARAMETERS, THE SLOW-MOVING NATURE OF THE UPPER-LEVEL
TROUGH WILL SUPPORT SEVERAL ROUNDS OF HEAVY RAINFALL THROUGH THE
FRONTAL PASSAGE LATE FRIDAY. GIVEN THE ELEVATED FLOOD POTENTIAL, THE
WPC HAS PLACED THE AREA IN DAY 3 AND DAY 4 SLIGHT RISK EROS.
BEHIND THE DEPARTING SHORTWAVE, SURFACE HIGH PRESSURE BUILDS INTO
THE REGION FOR THE WEEKEND. TEMPERATURES BEHIND THE FRONT WILL RUN
ROUGHLY 10 DEGREES COOLER COMPARED TO FORECAST HIGHS ON WEDNESDAY.
ALTHOUGH MODEL CONFIDENCE DEGRADES LATE IN THE WEEKEND INTO EARLY
NEXT WEEK, TEMPERATURES ARE EXPECTED TO GRADUALLY REBOUND TOWARD
SEASONAL SUMMERTIME VALUES.
AN APPROACHING SHORTWAVE TROUGH AND SURFACE LOW WILL BRING
INCREASING CHANCES FOR SHOWERS AND THUNDERSTORMS THURSDAY AFTERNOON
THROUGH LATE FRIDAY. ELEVATED PWS AND TALL, SKINNY CAPE PROFILES
WILL SUPPORT MULTIPLE ROUNDS OF HEAVY RAINFALL, PROMPTING DAY 3 AND
DAY 4 SLIGHT RISK EROS FROM THE WPC, ALONGSIDE A DAY 3 SPC MARGINAL
RISK FOR SEVERE STORMS ALONG THE WESTERN CWA PERIPHERY. SURFACE HIGH
PRESSURE BRINGS DRIER AND ROUGHLY 10 DEGREES COOLER WEATHER FOR THE
WEEKEND BEFORE TEMPERATURES GRADUALLY REBOUND EARLY NEXT WEEK.
AVIATION /06Z TAFS THROUGH 06Z THURSDAY/
ISSUED AT 1045 PM CDT TUE JUL 28 2026
MAIN AVIATION CHALLENGE IS THE POTENTIAL FOR PATCHY FOG TOWARD
12Z/7AM. PROBABILITIES OF MVFR RESTRICTIONS ARE BETWEEN 20 TO
40% AT FOD, MCW, AND DSM; HOWEVER, CONFIDENCE IS LOW IN
PREVAILING MVFR RESTRICTIONS SO HAVE INCLUDED 6SM BR AND WILL
MONITOR FOR POSSIBLE AMD. AFTER ANY FOG DISSIPATES, DIURNAL
CUMULUS WILL DEVELOP MID TO LATE MORNING. WHILE THERE COULD BE A
BRIEF PERIOD OF MVFR, CEILINGS WILL TREND HIGHER SO HAVE OPTED
TO KEEP SCT035.
DMX WATCHES/WARNINGS/ADVISORIES
NONE.
SHORT TERM...VORST
LONG TERM...VORST
AVIATION...ANSORGE
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