346
FXUS63 KDMX 120329
AFDDMX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
1029 PM CDT SAT JUL 11 2026
...UPDATED FOR THE 06Z AVIATION DISCUSSION...
KEY MESSAGES
- WARM AND DRY CONDITIONS TODAY THROUGH AT LEAST MID-WEEK. HIGHS
IN THE UPPER 80S AND 90S THIS WEEK.
- SHALLOW, PATCHY FOG POSSIBLE AGAIN EARLY SATURDAY MORNING.
SHORT TERM /THROUGH TUESDAY/
ISSUED AT 225 PM CDT SAT JUL 11 2026
AFTER YESTERDAY'S SHOWERS AND STORMS, THE WEATHER WILL NOW TREND
DRIER TODAY THROUGH AT LEAST THE BEGINNING OF THE WORK WEEK. THE
UPPER LEVEL PATTERN DEPICTS A BROAD 500 MB RIDGE BUILDING IT'S WAY
EASTWARD INTO THE CENTRAL U.S. THE SURFACE PATTERN WILL REFLECT
THIS, AS HIGH PRESSURE ESTABLISHES ITSELF OVER MUCH OF IOWA THROUGH
TUESDAY. THE RESULTING WEATHER WILL BE TYPICAL LATE SUMMER
CONDITIONS, WITH MULTIPLE DAYS OF WARM TEMPERATURES, LIGHT WINDS,
AND MOSTLY CLEAR SKIES. LIKEWISE, THESE CONDITIONS WILL BE FAVORABLE
FOR STRONG RADIATIONAL COOLING OVERNIGHT, SUGGESTING AT LEAST PATCHY
FOG MAY ONCE AGAIN DEVELOP SUNDAY MORNING. GUIDANCE ISN'T
NECESSARILY HAMMERING THE FOG RISK, BUT WITH MOIST ANTECEDENT
CONDITIONS AND COOLING EXPECTED OVERNIGHT, SHALLOW FOG IS CERTAINLY
POSSIBLE.
WITH DRY CONDITIONS EXPECTED THROUGH THE NEXT FEW DAYS, THE PRIMARY
FORECAST CHALLENGE IN THE SHORT TERM IS THE TEMPERATURE AND DEWPOINT
TRENDS. WITH THE SURFACE HIGH PRESSURE BUILDING OVER THE MISSISSIPPI
RIVER VALLEY REGION, DRASTIC AIR MASS CHANGES AREN'T EXPECTED BUT
TEMPERATURES WILL BE STEADILY WARMING THROUGH MID-WEEK. THIS WILL BE
A SLOW PROCESS, AS OUR EAST SOUTHEASTERLY LOW LEVEL FLOW WILL
GENERALLY PROMOTE EITHER NEUTRAL OR VERY WEAK COOL AIR ADVECTION,
KEEPING THE MAIN THERMAL RIDGE AND HIGHER 850 MB TEMPERATURES JUST
OFF TO OUR WEST AND NORTH. HOWEVER, WITH MULTIPLE DAYS OF PEAK
HEATING AND NO SIGNIFICANT ADVECTIVE COMPONENTS, THE AIR MASS
OVERHEAD WILL SILL WARM WITH EACH DAY. RESULTING HIGH TEMPERATURES
AT THE SURFACE WILL GENERALLY BE IN THE MID- TO UPPER- 80S SUNDAY,
THEN CREEPING INTO THE LOW TO MID 90S DURING THE WORK WEEK.
IN ADDITION TO THE TEMPERATURE TRENDS, OUR MOISTURE PROFILE WILL
ALSO BE INFLUENCED BY THE HIGH AND THE EAST SOUTHEASTERLY FLOW. THIS
FLOW REGIME WILL ALLOW DRIER AIR TO BE ADVECTED INTO THE STATE FROM
THE EAST THROUGH SUNDAY, HELPING PROMOTE MORE EFFICIENT THERMAL
MIXING. THIS BETTER MIXING COULD ALLOW TEMPERATURES TO OVERPERFORM
BY A DEGREE OR TWO TOMORROW, BUT THE LACK OF THOSE HIGHER 850
TEMPERATURES ALOFT WILL PUT A CEILING ON HOW WARM TEMPERATURES ARE
ABLE TO MIX OUT TO. AT THE SURFACE, THIS DRIER AIR WOULD ALSO
SUGGEST LOWER DEWPOINTS AND RELATIVELY LESS HUMID CONDITIONS, WHICH
IS BEING SEEN OVER EASTERN IOWA TODAY. THAT SAID, WE ARE ALSO
NEARING PEAK EVAPOTRANSPIRATION TIME AS CORN BEGINS TO TASSEL
AND CROPS THROUGHOUT IOWA REACH MATURITY. RECENT RAINFALLS AND
WET SOILS WILL LIKELY ALSO CONTRIBUTE TO HIGHER DEWPOINTS, AT
LEAST LOCALLY. THIS ADDED SURFACE MOISTURE WON'T INFLUENCE THE
ENTIRE BOUNDARY LAYER, BUT IT WILL CONTRIBUTE TO WHAT WE FEEL
RIGHT AT THE SURFACE. REGARDLESS, ANY RELIEF WE GET FROM THE DRY
EASTERLY FLOW WILL BE SHORT-LIVED, AS BETTER MOISTURE ADVECTION
RETURNS DURING THE WORK WEEK AND PUSHES DEWPOINTS BACK INTO THE
UPPER 60S AND LOW 70S AGAIN. FORTUNATELY, FORECAST TEMPERATURES
AND DEWPOINTS SHOULD STAY LOW ENOUGH TO NEGATE THE NEED FOR ANY
HEAT HEADLINES IN THE SHORT TERM, BUT CONDITIONS WILL STILL BE
ON THE WARMER SIDE OF NORMAL FOR MID- JULY IN IOWA (NORMAL BEING
ROUGHLY 82F NORTH TO 86F SOUTH).
LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/
ISSUED AT 225 PM CDT SAT JUL 11 2026
THE WARM AND HUMID CONDITIONS GENERALLY STICK AROUND THROUGH THE
REMAINDER OF THE WEEK, ALTHOUGH THE INFLUENCE OF THE SURFACE HIGH
AND UPPER RIDGING BEGINS TO WEAKEN THROUGH THE SECOND HALF OF THE
WORK WEEK. AN AMPLIFIED CANADIAN TROUGH WILL BEGIN TO PUSH THE 500
MB RIDGE BACK WESTWARD, PUTTING IOWA ON THE PERIPHERY BETWEEN THE
NORTHWEST FLOW TO OUR NORTHEAST AND RIDGING TO OUR WEST. AT THE
SURFACE, THIS WILL EQUATE TO A MESSY SURFACE PATTERN WITH WEAK HIGH
PRESSURE OVERHEAD AND LOW PRESSURE TO OUR WEST, FAVORING SOUTH
SOUTHWESTERLY FLOW. THIS TRANSITION WILL TAKE PLACE WEDNESDAY AND
THURSDAY, ULTIMATELY NOT RESULTING IN MUCH NOTICEABLE CHANGE AT THE
SURFACE ASIDE FROM CONTINUED WARMING BOTH DAYS. HIGHS ARE EXPECTED
TO REACH THE MID-90S WITH DEWPOINTS AROUND 70, PUSHING HEAT INDICES
INTO THE UPPER 90S AND NEAR 100F. WITH THE WEAKENING HIGH,
SUBSIDENCE ALSO WON'T BE AS STRONG AND THE POTENTIAL FOR DIURNALLY-
DRIVEN THUNDERSTORMS COULD CREEP BACK INTO THE FORECAST THROUGH THE
SECOND HALF OF THE WEEK. WITH THE LACK OF ANY PROMINENT SYSTEMS,
GUIDANCE AND NBM ARE STRUGGLING TO RESOLVE THIS, BUT A SIGNAL DOES
EXIST WHEN LOOKING AT THE LONGER RANGE MODELS. THERE'S OF COURSE NO
SHORTAGE OF INSTABILITY THIS TIME OF YEAR BUT THE FLOW IN THIS
REGIME SHOULD BE FAIRLY WEAK, SO THE SEVERE RISK APPEARS LOW AT THIS
TIME. WITH THE LOW UNCERTAINTY, THE FORECAST REMAINS DRY THROUGH
MID-WEEK, BUT WILL BE SOMETHING TO WATCH FOR AS WE GET CLOSER.
AVIATION /06Z TAFS THROUGH 06Z MONDAY/
ISSUED AT 1029 PM CDT SAT JUL 11 2026
CONFIDENCE IS HIGH IN VFR CONDITIONS AND LIGHT WINDS UNDER 10
KNOTS THROUGH THE PERIOD AT ALL TERMINALS.
DMX WATCHES/WARNINGS/ADVISORIES
NONE.
SHORT TERM...DODSON
LONG TERM...DODSON
AVIATION...ANSORGE
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