335
FXUS63 KDMX 242026
AFDDMX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
226 PM CST WED DEC 24 2025
KEY MESSAGES
- AREAS OF FOG THROUGH CHRISTMAS DAY AND NIGHT. DENSE FOG COULD
DEVELOP, MAINLY OVER WEST AND SOUTHWEST IOWA.
- ABOVE NORMAL TEMPERATURES WILL PERSIST THROUGH SATURDAY.
- COLDER WITH GUSTY WINDS AND SNOW SHOWERS ON SUNDAY.
DISCUSSION
ISSUED AT 224 PM CST WED DEC 24 2025
MUCH OF THE FORECAST WAS FOCUSED ON TONIGHT AND TOMORROW AND ANY
IMPACTS FOG COULD HAVE ON HOLIDAY TRAVEL. HIGHER DEW POINTS HAVE
BEEN ADVECTING INTO IOWA TODAY WITH VALUES IN THE 40S TO NEAR 50
OVER THE SOUTHWEST THIRD OF THE STATE. FOG HAS BEEN DEVELOPING IN
AREAS WHERE THESE DEW POINTS BEGIN TO EXCEED GROUND TEMPERATURES.
DENSE FOG HAS ALREADY DEVELOPED OVER PARTS OF NORTHWEST IOWA AS DEW
POINTS IN THE MID TO UPPER 30S MOVE OVER AREAS WITH 1 INCH OR MORE
OF SNOW COVER. THIS ADVECTION OF DEW POINTS NORTHWARD WILL SLOW THIS
EVENING THEN BEGIN TO RETREAT SOME BACK TO THE SOUTH. THIS LEADS TO
THE QUESTION IF THE DENSE FOG WILL PERSIST OVER NORTHWEST IOWA AS
THE DEW POINTS BEGIN TO SETTLE BACK TOWARDS FREEZING. TYPICALLY,
WIDESPREAD DENSE FOG DOES NOT FORM UNDER STRATUS WITHOUT LOW LEVEL
MOISTURE ADVECTION SO IT IS POSSIBLE THAT AREAS OF DENSE FOG WILL BE
MORE CLOSELY ASSOCIATED WITH THE CLEARING AREAS THAT ARE BEGINNING
TO OCCUR OVER NEBRASKA AND FAR WESTERN IOWA. OVERALL, EXPECT FOG TO
DEVELOP WITH VISIBILITIES DROPPING BELOW ONE MILE AND SOME POCKETS
OF ONE QUARTER MILE OR LESS. MORE WIDESPREAD DENSE FOG COULD REACH
THE WEST/FAR SOUTHWEST CLOSER TO THE CLEARING AREAS. AT THIS POINT,
PLAN TO REMAIN HEADLINE FREE DUE TO SOME UNCERTAINTY AND THIS WILL
ALLOW FOR FOLLOWING SHIFTS TO BETTER ALIGN ANY NEEDED HEADLINES. THE
FOG WILL SLOWLY IMPROVE CHRISTMAS MORNING BEFORE REDEVELOPING IN THE
EVENING WITH ALL OF THIS MOISTURE BELOW A STEEP LOW LEVEL INVERSION.
LIGHT DRIZZLE COULD OCCUR, PARTICULARLY THURSDAY NIGHT OVER THE
SOUTH CLOSER THE SURFACE BOUNDARY AND WHEN DEEP MOISTURE AND MORE
FAVORABLE VERTICAL ASCENT AND MOIST LAYER SHEAR, ARE IN PLACE.
OTHERWISE, MOISTURE DEPTHS ARE MEAGER OVERALL AT LESS THAN 3 KFT AND
ONLY WEAK FORCING LEADING TO ONLY PATCH LIGHT DRIZZLE.
NARROWED THE DIURNAL RANGE FOR TONIGHT AND TOMORROW BY TRENDING LOW
TEMPERATURES TONIGHT CLOSER TO THE NBM 75TH PERCENTILE AND TOMORROWS
HIGHS NEAR THE 25TH PERCENTILE. TEMPERATURES UNDER THIS STRATUS WILL
BE CLOSELY RELATED TO THE DEW POINT TEMPERATURES AND MAINLY WITHIN 1
TO 4 DEGREES. THE NBM CONTINUES TO SUGGEST VERY MILD TEMPERATURES FOR
FRIDAY AND SATURDAY. IT IS NOT A FORGONE CONCLUSION THAT THIS
STRATUS WILL COMPLETELY MOVE OUT OF IOWA WHILE A SUBSTANTIAL LOW
LEVEL INVERSION REMAINS. ESPECIALLY SATURDAY WHEN ANOTHER SURGE OF
LOW LEVEL MOISTURE LIFTS INTO IOWA WITH DEW POINTS IN THE 40S TO
PERHAPS EVEN 50 SOUTH. A COLD FRONT MOVES THROUGH SATURDAY NIGHT
BRINGING COLDER TEMPERATURES, GUSTY WINDS AND PERHAPS SNOW SHOWERS
TO THE STATE.
AVIATION /18Z TAFS THROUGH 18Z THURSDAY/
ISSUED AT 1137 AM CST WED DEC 24 2025
MVFR CIGS ARE OVER NORTHEAST IOWA WITH IFR TO LIFR OVER THE
SOUTHWEST HALF OF THE STATE TO START THE PERIOD. CIGS WILL
GRADUALLY LOWER THIS AFTERNOON AND WILL BECOME MORE WIDESPREAD
LIFR OVERNIGHT. FOG WILL CONTINUE TO EXPAND TODAY AND OVERNIGHT.
VSBYS AOB 1SM ARE EXPECTED AT MOST SITES EXCEPT KOTM AND
POSSIBLY KALO. CONDITIONS WILL GRADUALLY IMPROVE THURSDAY
MORNING. SOUTHEAST WIND EARLY THIS AFTERNOON WILL BECOME LIGHT
AND VARIABLE MUCH OF TONIGHT THEN TURNING MORE EASTERLY AGAIN
THURSDAY.
DMX WATCHES/WARNINGS/ADVISORIES
NONE.
DISCUSSION...DONAVON
AVIATION...DONAVON
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