265
FXUS63 KDMX 131733
AFDDMX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
1233 PM CDT WED MAY 13 2026
...UPDATED FOR THE 18Z AVIATION DISCUSSION...
KEY MESSAGES
- DRY, QUIET, AND GENERALLY PLEASANT WEATHER THROUGH THURSDAY
MORNING. LOWS IN THE MID-40S TO LOWER 50S BOTH THIS MORNING
AND THURSDAY MORNING, WITH HIGHS THIS AFTERNOON IN THE 70S
BENEATH CLEAR SKIES.
- BREEZY ON THURSDAY WITH SOME SHOWERS AND STORMS LATE IN THE
DAY INTO THURSDAY NIGHT. A FEW STRONG TO SEVERE STORMS MAY BE
POSSIBLE IN SOUTHERN IOWA, NEAR THE MISSOURI BORDER.
- WARMER AND MORE ACTIVE AT TIMES FROM FRIDAY INTO EARLY NEXT
WEEK. HIGHS GENERALLY IN THE UPPER 70S TO UPPER 80S EACH DAY,
AND THUNDERSTORM CHANCES AT TIMES, MAINLY FROM SATURDAY
ONWARD.
SHORT TERM /THROUGH THURSDAY/
ISSUED AT 118 AM CDT WED MAY 13 2026
IT IS A QUIET NIGHT ACROSS THE REGION. A LARGE SURFACE HIGH
PRESSURE RIDGE IS SINKING DOWN THE HIGH PLAINS TOWARD WESTERN
IOWA, PROVIDING CLEAR SKIES AND GRADUALLY DIMINISHING
NORTHWESTERLY WINDS IN OUR AREA. TEMPERATURES ARE FALLING
THROUGH THE 50S TOWARD LOWS IN THE MID-40S TO LOWER 50S AT
SUNRISE THIS MORNING. THE HIGH PRESSURE RIDGE WILL THEN MOVE
SLOWLY EASTWARD ACROSS IOWA TODAY AND TONIGHT. BEFORE IT
ARRIVES, THIS AFTERNOON, MOST OF OUR SERVICE AREA WILL STILL
REMAIN EAST OF THE RIDGE WITH NORTH NORTHWEST BREEZES
PERSISTING THROUGH THE DAY. FORECAST SOUNDINGS ILLUSTRATE A
WELL-MIXED LAYER UP TO ABOUT 750 MB, WITH WINDS ALOFT
SUPPORTING SURFACE SPEEDS OF AROUND 15 KT WITH GUSTS TO 25 KT
AT TIMES, MAINLY IN OUR EASTERN COUNTIES. THIS WILL BE WELL
UNDER THE WIND SPEEDS EXPERIENCED ON TUESDAY, CERTAINLY.
TEMPERATURES WILL ALSO BE COOLER TODAY, DESPITE SUNNY SKIES,
WITH HIGHS RANGING IN THE 70S ACROSS OUR AREA AND MAKING FOR A
GORGEOUS DAY FOR MOST OUTDOOR INTERESTS. AS THE RIDGE AXIS MOVES
THROUGH THIS EVENING INTO TONIGHT WINDS WILL DIE OFF QUICKLY
WITH SUNSET, AND TEMPERATURES WILL ALSO FALL SHARPLY AFTER DARK.
HOWEVER, SOUTH SOUTHEASTERLY BREEZES ON THE BACKSIDE OF THE
RIDGE WILL RETURN RELATIVELY QUICKLY OVERNIGHT, PREVENTING
TEMPERATURES FROM BOTTOMING OUT. LOWS ARE FORECAST IN THE
MID-40S TO LOWER 50S ONCE AGAIN, HOWEVER, IF WINDS REMAIN CALM
LONGER THAN ANTICIPATED THEY COULD FALL A BIT FARTHER.
BY THURSDAY MORNING SOUTH SOUTHEASTERLY SURFACE FLOW WILL BE IN
PLACE ACROSS IOWA, WHILE AT 500 MB A THERMAL RIDGE MOVES
OVERHEAD. THIS WOULD TYPICALLY SUPPORT WARMER TEMPERATURES,
HOWEVER, A 500 MB TROUGH WILL BE SWINGING ACROSS SOUTH CENTRAL
CANADA DURING THE DAY, AND ON THE LEADING FLANK OF THE CYCLONIC
FLOW OVER THE HIGH PLAINS, BROAD FORCING FOR ASCENT COMBINED
WITH MODEST MOISTURE ADVECTION WILL RESULT IN CLOUD
DEVELOPMENT THAT WILL SPREAD EASTWARD ACROSS IOWA DURING THE
DAY. THE COMBINATION OF CLOUDS LIMITING SOLAR INSOLATION AND OUR
SURFACE FLOW BEING SOUTH SOUTHEAST RATHER THAN A MORE FAVORABLE
SOUTHWESTERLY COMPONENT, SHOULD KEEP TEMPERATURES IN CHECK
SOMEWHAT AND HAVE NUDGED DOWN THURSDAY HIGHS JUST A TOUCH
ACCORDINGLY, INTO THE UPPER 70S ACROSS OUR FORECAST AREA.
ANOTHER SENSIBLE EFFECT OF THE APPROACHING SYSTEM WILL BE BREEZY
CONDITIONS ONCE AGAIN ON THURSDAY, WITH A TIGHTENING PRESSURE
GRADIENT MOVING THROUGH AND STRONGER WINDS ALOFT. HOWEVER, THE
AFOREMENTIONED CLOUD COVER WILL SUPPORT A MORE SHALLOW MIXED
LAYER, AND THE LACK OF DEEPER OR MORE EFFICIENT MIXING WILL
MITIGATE HIGHER WIND SPEEDS THAT MIGHT OTHERWISE HAVE BEEN
REALIZED. THAT BEING SAID, IF CLOUD COVER IS THINNER OR PATCHIER
THAN ANTICIPATED, THEN BETTER MIXING COULD LEAD TO HIGHER WIND
SPEEDS AND GUSTS CLOSER TO WHAT WE SAW ON MONDAY. FINALLY, A
500 MB SHORTWAVE IMPULSE, ROUNDING THE BASE OF THE CYCLONIC FLOW
AROUND THE LARGER SOUTHERN CANADA SYSTEM, WILL MOVE ACROSS IOWA
AND MINNESOTA LATE THURSDAY INTO THURSDAY NIGHT AND SUPPORT
SOME SHOWER AND THUNDERSTORM DEVELOPMENT IN OUR AREA,
PARTICULARLY AS STRONG THETA-E ADVECTION MOVES THROUGH AFTER
SUNSET. HOWEVER, STORMS WILL BE ELEVATED, AND WHILE DEEP-LAYER
SHEAR OF 30-40 KT SUPPORTS SOME SEVERE WEATHER POTENTIAL, THIS
WILL BE LIMITED BY A RELATIVE LACK OF INSTABILITY WITH MUCAPE
ONLY AROUND 500-1000 J/KG. STILL, IN SOUTHERN IOWA WHERE THE
INSTABILITY IS HIGHEST, THERE IS SOME POTENTIAL FOR A FEW STRONG
TO SEVERE STORMS WITH HAIL AND GUSTY WINDS. STAY TUNED FOR
UPDATES AS WE REFINE DETAILS ON THE COMPLEX THURSDAY/THURSDAY
NIGHT FORECAST.
LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/
ISSUED AT 238 PM CDT TUE MAY 12 2026
THE HIGH PRESSURE MOVES OFF TO THE EAST ON THURSDAY WITH THE
UPPER RIDGE MOVING OVERHEAD BEFORE A SERIES OF WAVES PASS
THROUGH THE REGION TO END THE WEEK AND INTO THE WEEKEND. ON THE
BACKSIDE OF THE HIGH PRESSURE, WINDS RETURN TO OUT OF THE SOUTH
AND INCREASE WITH THE THERMAL RIDGE RESULTING IN MUCH WARMER
TEMPERATURES IN THE 80S TO TOUCHING 90 FRIDAY INTO THE WEEKEND.
THESE WARMER TEMPERATURES WILL BE ACCOMPANIED BY THE RETURN OF
AMPLE MOISTURE OFF THE GULF AS DEW POINTS SURGE INTO THE 50S IN
AT LEAST SOUTHERN IOWA AND POTENTIALLY INTO THE 60S BY SUNDAY.
AS ONE MAY BE ABLE TO GUESS, INCREASING TEMPERATURES AND
MOISTURE ALSO RESULT IN THUNDERSTORMS RETURNING TO THE FORECAST
FIRST LATER THURSDAY INTO FRIDAY AND AGAIN SATURDAY AND SUNDAY.
INSTABILITY CLIMBS INTO FRIDAY AFTERNOON, THOUGH STORMS MAY BE
OFF TO THE EAST WHERE THE BETTER FORCING IS, AS ALSO SEEN WITH
GOOD AGREEMENT IN THE GLOBAL MODELS. MORE WIDESPREAD STORM
CHANCES LOOK TO OCCUR LATER SATURDAY INTO SUNDAY AND AGAIN LATER
SUNDAY INTO MONDAY THOUGH THERE REMAINS A FAIR BIT OF MODEL
SPREAD. WILL CONTINUE TO ASSESS THE SEVERE THREAT OVER THE NEXT
FEW DAYS, BUT SOME STRONGER STORMS ARE CERTAINLY POSSIBLE AND
SPC IN PARTICULAR HAS OUTLINED MUCH OF THE AREA IN A 15% FOR DAY
5/SUNDAY.
AVIATION /18Z TAFS THROUGH 18Z THURSDAY/
ISSUED AT 1226 PM CDT WED MAY 13 2026
VFR CONDITIONS ONGOING AND EXPECTED TO CONTINUE THROUGH THE TAF
PERIOD WITH FEW CLOUDS THROUGH THE NIGHT. WINDS OUT OF THE
NORTH-NORTHWEST 10-20 KNOTS WITH GUSTS TO AROUND 25 KNOTS WILL
QUICKLY DIMINISH NEAR TO AFTER SUNSET WITH LIGHT AND VARIABLE
WINDS THROUGH THE EVENING BEFORE WINDS SETTLE OUT OF THE
SOUTHEAST LATE TONIGHT. CLOUDS AND WINDS WILL THEN INCREASE
AGAIN THURSDAY MORNING.
DMX WATCHES/WARNINGS/ADVISORIES
NONE.
SHORT TERM...LEE
LONG TERM...05
AVIATION...05
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