507
FXUS63 KDMX 241139
AFDDMX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
539 AM CST WED DEC 24 2025
...UPDATED FOR FOG HEADLINE DECISION, LATEST TRENDS FOR A FOGGY
CHRISTMAS EVE, AND THE 12Z AVIATION DISCUSSION...
KEY MESSAGES
- AREAS OF FOG OVER NORTHWEST IOWA THIS MORNING. A FOGGY
CHRISTMAS EVE AS WIDESPREAD FOG, POSSIBLY DENSE, DEVELOPS
THIS EVENING AND LASTS INTO CHRISTMAS DAY MORNING.
- CLOUDY AND MILD WITH DRIZZLE POSSIBLE AT TIMES TODAY THROUGH
CHRISTMAS DAY NIGHT.
- COLD FRONT MOVES THROUGH SATURDAY AFTERNOON WITH CONDITIONS
TURNING MUCH COLDER AS IT BECOMES WINDY INTO SUNDAY. THE COLD
WILL PERSIST INTO MONDAY.
UPDATE
ISSUED AT 539 AM CST WED DEC 24 2025
VISIBILITIES HAVE REMAINED IMPROVED OVER KOSSUTH, EMMET, AND
PALO ALTO COUNTIES AND WEBCAMS IN THE AREA CONFIRM THIS AS WELL.
SO, HAVE CANCELLED THE DENSE FOG ADVISORY. FOG MAY STILL
REDEVELOP OR MOVE OVER NORTHERN IOWA LATER TODAY, BUT THE MORE
WIDESPREAD AND POSSIBLY DENSE FOG LOOKS TO DEVELOP SHORTLY AFTER
SUNSET MAKING FOR A FOGGY CHRISTMAS EVE. LATEST TRENDS WOULD
SUGGEST QUARTER MILE VISIBILITY AS EARLY AS 9PM OVER PORTIONS
OF NORTHWEST AND NORTH CENTRAL IOWA, WHICH EXPANDS TO MUCH OF
OUR FORECAST AREA WEST OF I-35 BY MIDNIGHT. FOG FORECASTING IS
OFTEN NOT SIMPLE AND WITH THE STRATUS LINGERING AROUND, THAT
COULD BE A POTENTIAL FAILURE MODE FOR THE DENSE FOG TO FORM.
DISCUSSION
ISSUED AT 326 AM CST WED DEC 24 2025
GOES-EAST NIGHTTIME MICROPHYSICS RGB SHOWS LOTS OF HIGH CLOUDS
OVER THE STATE STREAMING IN FROM THE WEST AS THE MID-LEVEL RIDGE
BECOMES CENTERED OVER THE CENTRAL CONUS. THERE ARE A FEW BREAKS
THAT ALLOW US TO SEE THE LOW STRATUS OVER NORTHERN MISSOURI
LIFTING INTO FAR SOUTHWEST IOWA. THERE IS ALSO AN AREA OF FOG
WITH VISIBILITIES UNDER A MILE FROM AROUND ESTHERVILLE UP TO
WINDOM, MN, WHICH IS WHERE A DENSE FOG ADVISORY IS IN EFFECT
UNTIL EARLY THIS MORNING. SURFACE OBSERVATIONS ALSO SHOW LIGHTER
FOG A BIT FARTHER SOUTH TOWARDS HIGHWAY 20. OVERALL, THE DENSE
FOG IS LIMITED IN AREA WITH GUIDANCE POINTING TO VISIBILITY
INCREASING AFTER SUNRISE.
LOW LEVEL THETA-E ADVECTION IS ALSO ONGOING AND WILL AID IN THE
STRATUS LIFTING INTO SOUTHWEST AND SOUTH CENTRAL IOWA BY AROUND
SUNRISE AND WILL THEN MOVE NORTHEASTWARD ACROSS THE STATE TODAY.
GUIDANCE POINTS TO VISIBILITIES STAYING UP OVER SOUTHERN IOWA AS THE
STRATUS MOVES IN, BUT WILL MONITOR TRENDS AS DENSE FOG IS PRESENT TO
THE SOUTH AND WEST OF IOWA. AS THE STRATUS MOVES IN, THERE WILL BE A
PERIOD OF AT LEAST A FEW HOURS WHERE THE DEPTH OF MOISTURE REACHES
TO AROUND 1KM. THIS DEPTH IS ON THE LOWER END OF FAVORABLE DRIZZLE
PRODUCTION, BUT NUDGERS TOWARDS DRIZZLE ARE THE WEAK OMEGA IN
THE SATURATED LAYER AND THE DIRECTIONAL SHEAR FOR COLLISION
COALESCENCE. THIS LOOKS MOST LIKELY TO OCCUR FROM SOUTHERN IOWA
THIS MORNING MOVING INTO EASTERN IOWA THIS AFTERNOON, WHICH IS
WHERE PATCHY DRIZZLE HAS BEEN INCLUDED. TEMPERATURES WILL BE
RISING, BUT IN A FEW PLACES OVER CENTRAL IOWA LATER THIS MORNING
THEY COULD BE NEAR FREEZING AND WILL HAVE TO MONITOR
TEMPERATURES FOR FREEZING DRIZZLE POTENTIAL. OVERALL,
TEMPERATURES SHOULD BE RISING SO ANY FREEZING DRIZZLE WINDOW
WOULD BE SHORT-LIVED. WHILE TEMPERATURES WILL BE ABOVE NORMAL
AND MILD, THE CLOUDS AND DRIZZLE WILL LIMIT TEMPERATURES TO THE
UPPER 30S OVER NORTHEAST IOWA TO THE LOW 50S IN FAR SOUTHERN
IOWA, THOUGH DEPENDING ON THE DURATION OF DRIZZLE THIS MAY NEED
TO BE LOWERED INTO THE 40S. WHILE FORECAST SOUNDINGS SHOW THE
MOISTURE DEPTH BECOMING SHALLOWER BY THIS EVENING AS THE WAVE OF
THETA-E ADVECTION PUSHES EAST, THE NEAR SURFACE MOISTURE
REMAINS. THUS, TONIGHT IS LOOKING PRIMED FOR A FOGGY CHRISTMAS
EVE AS WINDS BECOME LIGHT. AREAS OF FOG MAY BE DENSE WITH HREF
PROBABILITY OF A QUARTER MILE OR LESS OVER 60% IN PORTIONS OF
NORTH CENTRAL AND WESTERN IOWA, WHICH MAY NECESSITATE A DENSE
FOG ADVISORY LATER TODAY FOR TRAVELING IOWANS AND REINDEER.
THE FOG WILL LIKELY LINGER INTO CHRISTMAS DAY WITH VISIBILITIES
IMPROVING BY MID TO LATE MORNING, BUT THE CLOUD COVER WILL REMAIN
STOUT. TEMPERATURES WILL BE SIMILAR TO TODAY. THERE WILL BE ANOTHER
CHANCE OF DRIZZLE OR PERHAPS LIGHT RAIN AS MOISTURE DEPTHS INCREASE
TO AROUND 1KM LATER IN IN THE DAY INTO THE NIGHT WITH THETA-E
ADVECTION OCCURRING IN ADVANCE OF A WEAK SURFACE LOW PRESSURE. THIS
WILL AID WITH LIFT AND THERE IS ONCE AGAIN WEAK OMEGA WITHIN THE
SATURATED LAYER, BUT THE DIRECTIONAL SHEAR DOES NOT LOOK AS IDEAL.
THE CLOUDS WILL FINALLY BEGIN TO DECREASE THROUGH THE DAY FRIDAY
OVER MUCH OF SOUTHERN AND WESTERN IOWA ALLOWING FOR SOME SUNSHINE.
BOTH FRIDAY AND SATURDAY WILL OFFER WHAT WILL LIKELY BE THE LAST
MILD DAYS OF 2025 AS A MORE AMPLIFIED TROUGH MOVES ALONG THE US
CANADIAN BORDER APPROACHING OUR REGION. THIS TROUGH WILL SEND A COLD
FRONT THROUGH THE STATE SATURDAY AFTERNOON INTO THE NIGHT. WHILE
INITIAL NATIONAL BLEND OF MODELS ARRIVED DRY, THERE ARE
DETERMINISTIC MODELS AND THE ENSEMBLE MEANS THAT POINT TO AT LEAST
SOME LIGHT QPF, WHICH WOULD LIKELY BE LIGHT SNOW LOOKING AT MAX LOW
LEVEL WET BULB AND SURFACE TEMPERATURES. IN ADDITION, WINDS FROM THE
NORTHWEST WILL QUICKEN AS THE FRONT PASSES WITH GUSTS OVER AT
LEAST 35 MPH POSSIBLE. THESE WINDS WILL DELIVER MUCH COLDER
AIR, ESPECIALLY AFTER THIS MILD WEEK, FOR SUNDAY INTO EARLY NEXT
WEEK. HIGHS ON SUNDAY WILL BE ANYWHERE FROM 15 TO 30 DEGREES
LOWER THAN SATURDAY'S HIGHS WITH MONDAY MORNING LOWS IN THE
SINGLE DIGIT ABOVE ZERO. CONDITIONS WILL MODERATE BACK CLOSER TO
NORMAL TO END THE YEAR.
AVIATION /12Z TAFS THROUGH 12Z THURSDAY/
ISSUED AT 539 AM CST WED DEC 24 2025
THOSE WITH FLIGHT PLANS THIS CHRISTMAS EVE, INCLUDING THOSE
FROM THE POLAR REGION, WILL HAVE TO CONTEND WITH CEILING AND
VISIBILITY RESTRICTIONS OVER IOWA DUE TO INCOMING STRATUS AND
FOG, RESPECTIVELY. VFR CONDITIONS ARE MOSTLY PRESENT AT THE
START OF THIS PERIOD, BUT CEILINGS WILL LOWER INTO MVFR AND
LATER IFR FROM SOUTHWEST TO NORTHEAST THIS MORNING INTO THIS
AFTERNOON AS STRATUS AND LOW LEVEL MOISTURE SPREAD OVER THE
STATE. PATCHY DRIZZLE MAY OCCUR FOR A SEVERAL HOUR PERIOD AND
LOOKS MOST LIKELY AT DSM, ALO, AND OTM LATER THIS MORNING AND
AFTERNOON. VISIBILITY RESTRICTIONS DUE TO DRIZZLE OR FOG ARE NOT
EXPECTED DURING THE DAYLIGHT HOURS, BUT WIDESPREAD FOG WILL
DEVELOP TONIGHT WITH RESTRICTIONS AS LOW AS LIFR AND POSSIBLY
VLIFR. CEILING RESTRICTIONS WILL ALSO SLIP INTO LIFR LATE TODAY
INTO TONIGHT.
DMX WATCHES/WARNINGS/ADVISORIES
NONE.
UPDATE...ANSORGE
DISCUSSION...ANSORGE
AVIATION...ANSORGE
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page