018
FXUS63 KDMX 291735
AFDDMX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
1235 PM CDT WED JUL 29 2026
...UPDATED FOR THE 18Z AVIATION DISCUSSION...
KEY MESSAGES
- HIGHS IN THE UPPER 80S TO LOWER 90S ACROSS CENTRAL IOWA TODAY.
- SHOWER AND STORM CHANCES (60-80%) RETURN BY THURSDAY
AFTERNOON. LOCALLY HEAVY RAINFALL COULD LEAD TO FLASH
FLOODING INTO FRIDAY MORNING.
- MARGINAL RISK (LEVEL 1 OF 5) ISSUED FOR WESTERN IOWA FOR
THURSDAY AFTERNOON. MAIN CONCERN GUSTY WINDS.
SHORT TERM /THROUGH THURSDAY/
ISSUED AT 134 AM CDT WED JUL 29 2026
WE KICK OFF OUR WEDNESDAY MORNING WITH AN UPPER LEVEL RIDGE TO OUR
WEST OVER IN NEBRASKA AND SOUTH DAKOTA. CONDITIONS REMAIN QUIET
OVERNIGHT, THOUGH A SHORTWAVE OVER CENTRAL NEBRASKA IS PROMPTING A
FEW SHOWERS AND THUNDERSTORMS. AS THIS SHORTWAVE PROGRESSES EASTWARD
TOWARD DAYBREAK, IT WILL BRING A (20-30%) CHANCE FOR SHOWERS AND
STORMS INTO EASTERN NEBRASKA AND POTENTIALLY FAR SOUTHWEST IOWA.
SEVERE WEATHER IS NOT EXPECTED, AND ANY ACTIVITY SHOULD TAPER OFF BY
LATE MORNING.
DRY WEATHER WILL PREVAIL THROUGH THE AFTERNOON ALONGSIDE SLIGHTLY
WARMER TEMPERATURES. CENTRAL IOWA SHOULD SEE HIGHS RETURN TO THE
UPPER 80S, WHILE WESTERN IOWA STANDS A BETTER CHANCE OF TOUCHING THE
LOWER 90S DUE TO DEEPER MIXING AND MINIMAL WILDFIRE SMOKE IMPACTS.
THICKER WILDFIRE SMOKE ACROSS NORTHERN AND NORTHWESTERN IOWA COULD
KEEP HIGH TEMPERATURES CAPPED IN THE MID TO UPPER 80S.
FOCUS SHIFTS TO THURSDAY AS A MORE ACTIVE PATTERN APPROACHES. A
SLIGHT CHANCE FOR SHOWERS AND STORMS RETURNS TO FAR WESTERN IOWA
THURSDAY MORNING. BY THURSDAY AFTERNOON, MLCAPE VALUES OF
1000-1500 J/KG AND 35-45 KTS OF 0-6 KM SHEAR WILL SUPPORT
ISOLATED STRONG TO SEVERE THUNDERSTORMS ACROSS WESTERN IOWA.
DAMAGING WIND GUSTS WILL BE THE PRIMARY THREAT, ENHANCED BY DRY
LOW LEVEL AIR. TO HIGHLIGHT THIS SEVERE POTENTIAL, THE STORM
PREDICTION CENTER HAS PLACED WESTERN IOWA UNDER A LEVEL 1 OF 5
MARGINAL RISK. THIS ACTIVITY THEN SPREADS EASTWARD ACROSS
CENTRAL IOWA THURSDAY NIGHT.
LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/
ISSUED AT 156 PM CDT TUE JUL 28 2026
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 /18Z TAFS THROUGH 18Z THURSDAY/
ISSUED AT 1235 PM CDT WED JUL 29 2026
VFR CONDITIONS WILL PREVAIL THROUGH THE TAF PERIOD. CURRENTLY
SOME CUMULUS CLOUDS ARE DEVELOPING AND GENERALLY BASED AT
FL025-028, HOWEVER, BASE HEIGHTS ARE STEADILY RISING AND BY THE
TIME ANY LOCALIZED CEILINGS FORM THEY WILL LIKELY BE ABOVE
FL030. THERE MAY BE A NARROW OPPORTUNITY FOR BRIEF MVFR CEILINGS
IN THE NEXT HOUR OR SO. ALSO, SMOKE FROM CANADIAN WILDFIRES
CONTINUES TO STREAM OVERHEAD, BUT SO FAR AS NOT REACHED THE
SURFACE SUFFICIENTLY TO PRODUCE ANY VISIBILITY RESTRICTIONS, AND
IS UNLIKELY TO TODAY OR TONIGHT, SO FU HAS BEEN LEFT OUT OF THE
TAFS.
DMX WATCHES/WARNINGS/ADVISORIES
NONE.
SHORT TERM...TDR
LONG TERM...VORST
AVIATION...LEE
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