076
FXUS63 KDMX 191728
AFDDMX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
1128 AM CST FRI DEC 19 2025
...UPDATED FOR THE 18Z AVIATION DISCUSSION...
KEY MESSAGES
- WHILE NOTHING COMPARED TO YESTERDAY, IT WILL TURN BREEZY THIS
AFTERNOON AND A BIT LESS SO ON SATURDAY.
- ABOVE NORMAL TEMPERATURES NEXT WEEK AND FAVORING A MOSTLY DRY
FORECAST.
- WILL NEED TO MONITOR FOR POSSIBLE FOG DEVELOPMENT OVER AREAS
THAT HAVE SNOWPACK, WHICH WILL MELT OVER THE NEXT WEEK.
DISCUSSION
ISSUED AT 330 AM CST FRI DEC 19 2025
GOES-EAST UPPER LEVEL WATER VAPOR IMAGERY SHOWS THE TROUGH MOVING
THROUGH THE GREAT LAKES REGION EARLY THIS MORNING, WHICH BROUGHT
SIGNIFICANT WINTER WEATHER IMPACTS TO PARTS OF OUR REGION YESTERDAY.
WITH THE ASSOCIATED SURFACE LOW PRESSURE PUSHING INTO SOUTHEASTERN
CANADA, THIS IS ALLOWING THE PRESSURE GRADIENT TO RELAX AND OUR
WINDS TO DIMINISH. WHILE IT WILL BE A COLD MORNING, STRONG LOW LEVEL
WARM AIR ADVECTION (WAA) WILL PUSH OVER THE STATE AND HELP TO LIFT
TEMPERATURES TO THE MIDDLE 20S OVER NORTHEASTERN IOWA TO THE LOW 40S
IN SOUTHWEST IOWA THIS AFTERNOON. WINDS FROM A SOUTHERLY
DIRECTION WILL INCREASE AND BE SUSTAINED AT 10 TO 20 MPH WITH
GUSTS OF 25 TO 35 MPH BY THIS AFTERNOON. THESE WINDS COMBINED
WITH WHATEVER FRESH SNOW FELL ON THURSDAY MAY BE ENOUGH FOR
STREAMERS/BLOWING AND DRIFTING SNOW AT GROUND LEVEL THIS
AFTERNOON OVER NORTHWEST INTO A BIT OF NORTH CENTRAL IOWA. ALSO
TODAY, THE MID-LEVEL FLOW WILL BECOME ZONAL AND AS A SHORTWAVE
AND SURFACE LOW PRESSURE TRACKS OVER THE SOUTHERN CANADIAN
PRAIRIES, WILL SEE A COLD FRONT MOVE THROUGH THE STATE LATE
TONIGHT INTO SATURDAY MORNING. CROSS SECTIONS AND SOUNDINGS SHOW
THAT THE COLUMN OVERALL REMAINS TOO DRY FOR ANY PRECIPITATION.
THIS WILL, HOWEVER, BRING A GLANCING SHOT OF COLD AIR ADVECTION
(CAA) THAT WILL MAKE SUNDAY MORNING LOWS AND HIGHS LOWER
COMPARED TO SATURDAY. WINDS FROM THE NORTHWEST WILL AVERAGE 10
TO 15 MPH ON SATURDAY AND DIMINISH SATURDAY NIGHT AS SURFACE
HIGH PRESSURE MOVES OVER THE STATE. WITH THE LIGHT WINDS AND A
CLEAR SKY BY SUNDAY MORNING, WILL KEEP AN EYE ON POSSIBLE FOG
DEVELOPMENT DEPENDING ON THE DEGREE OF MELTING THAT OCCURS ON
SATURDAY, WHICH DOES NOT LOOK EXCELLENT BASED ON THE FORECAST
WET BULB TEMPERATURES. AS THE HIGH MOVES OFF TO THE EAST,
ANOTHER ROUND OF LOW LEVEL WAA WILL DEVELOP SUNDAY NIGHT INTO
MONDAY MORNING. DETERMINISTIC MODELS ALL TRY TO GENERATE
PRECIPITATION IN THIS WAA REGIME TO VARYING DEGREES OVER NORTH
CENTRAL OR NORTHEASTERN IOWA OR ADJACENT AREAS WITH CROSS
SECTIONS SHOWING SOME DEPTH OF SATURATION. ENSEMBLES ALSO
SUPPORT THIS IDEA AND FAVOR JUST TO THE NORTHEAST OF THE
FORECAST AREA SO WILL CONTINUE WITH INITIAL NATIONAL BLEND OF
MODELS (NBM) THAT SHOWS SPLOTCHY, LOW CHANCES OF LIGHT SNOW OVER
SOUTHEASTERN MINNESOTA, FAR NORTHEAST IOWA, INTO SOUTHERN
WISCONSIN.
AS WE MOVE INTO THE BUSY CHRISTMAS HOLIDAY TRAVEL PERIOD, THERE IS
HIGH CONFIDENCE IN ABOVE NORMAL TEMPERATURES AND NO SIGNAL FOR ANY
SIGNIFICANT, STRONG PRECIPITATION SYSTEMS OVER IOWA. MID-LEVEL
RIDGING WILL BUILD OVER THE CENTRAL US WITH THE MID-LEVEL HIGH OVER
THE WESTERN GULF COAST STATES. THE THERMAL RIDGE LOOKS TO PEAK OVER
IOWA CHRISTMAS EVE INTO CHRISTMAS DAY. PREVIOUS DISCUSSIONS HAVE
NOTED THE NBM COLD BIAS/SLOW TO CATCH ONTO THE WARMING TREND AND
NOTE THAT THIS NBM CYCLE IS 5 TO 6 DEGREES HIGHER THAN THE PREVIOUS
ON CHRISTMAS DAY. THIS COULD STILL BE UNDERDONE WITH THE 75TH
PERCENTILE OF NBM NEARING RECORD HIGH VALUES OVER SOUTHERN IOWA (DES
MOINES, OTTUMWA) AND BELOW RECORD HIGHS BY AROUND 5 DEGREES OVER
NORTHERN IOWA (WATERLOO, MASON CITY). AS FOR PRECIPITATION CHANCES,
THEY ARE SLIM WITH THE ECMWF AND CANADIAN AS WELL AS ENSEMBLES
SHOWING LIGHT QPF OVER EASTERN IOWA ON WEDNESDAY. QUITE A BIT OF
SPREAD STILL SO OUR FORECAST WILL CARRY NO MENTION (<14%) AT THIS
TIME, BUT WILL BE SOMETHING WILL KEEP AN EYE ON IN THE COMING
DAYS.
AVIATION /18Z TAFS THROUGH 18Z SATURDAY/
ISSUED AT 1125 AM CST FRI DEC 19 2025
VFR CIGS TO PREVAIL FOR MUCH OF THE PERIOD, ALTHOUGH THERE COULD
BE A WINDOW OF CIG RESTRICTIONS WILL THE PASSING OF A FRONT
AROUND 12Z FOR NORTHERN SITES, NAMELY KMCW. LLWS LIKELY FOR ALL
SITES OVERNIGHT, HIGHEST FOR KDSM AND KOTM. WINDS WILL BECOME
NORTHWESTERLY THROUGH THE MORNING AS THE FRONT PASSES.
DMX WATCHES/WARNINGS/ADVISORIES
NONE.
DISCUSSION...ANSORGE
AVIATION...JIMENEZ
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