177
FXUS63 KDVN 260914
AFDDVN
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
314 AM CST FRI DEC 26 2025
KEY MESSAGES
- DENSE FOG RESULTING IN SLOWED AND IN PLACES HAZARDOUS TRAVEL
TO START TODAY, WITH THIS FOG DIMINISHING BETWEEN 8 AND 10 AM.
- A STRONG SYSTEM TO AFFECT THE AREA LATER IN THE WEEKEND, FIRST
WITH SHOWERS AND FOR ALONG AND SOUTH OF I-80 EVEN T-STORM
POTENTIAL (20-30%) SATURDAY NIGHT THROUGH MIDDAY SUNDAY.
- THE SYSTEM WILL THEN BRING A CHANCE OF SNOW, BUT MORE SO WINDY
AND MUCH COLDER CONDITIONS SUNDAY AFTERNOON AND NIGHT INTO
EARLY MONDAY, WITH GUSTS POTENTIALLY NEARING 45 MPH AND WIND
CHILLS OF 0 TO 15 BELOW ZERO LIKELY TO START MONDAY.
SHORT TERM /THROUGH SATURDAY/
ISSUED AT 300 AM CST FRI DEC 26 2025
ANOTHER CLOUD-FILLED START TO A DAY WHICH WILL CONTINUE TO BE A
THEME FOR A FEW MORE DAYS. FOG IS AGAIN A PROBLEM WITH TEMPORARY
REDUCED WINDS UNDER THE PASSAGE OF A 1003 MB LOW PRESSURE CENTER
AND RESIDUAL BOUNDARY LAYER MOISTURE TRAPPED BELOW A STOUT
INVERSION AS SAMPLED ON LAST EVENING'S SOUNDING (5C INCREASE
BETWEEN 1 AND 2 KFT AGL). SOME OF THIS FOG PER WEBCAM AND
VISIBILITY OBSERVATIONS IS QUITE THICK (FEW HUNDRED YARDS OR
LESS), AND WITH ADVECTION FOG IN THE WINTERTIME IS NOT SURPRISING.
ON THE BACKSIDE OF THE LOW'S PASSAGE BETWEEN 7 AND 10 AM, A
STRENGTHENING PRESSURE GRADIENT WILL ALLOW FOR WEST-NORTHWEST
WINDS TO QUICKLY UPTICK TO 10-15 MPH. UPSTREAM ACROSS THE
WESTERN HALF OF IA AND NORTHWEST MO, THIS HAS ALLOWED VISIBILITY
TO IMPROVE. SO ENVISION A SOUTHWEST TO NORTHEAST IMPROVEMENT IN
VISIBILITY DURING THAT FEW HOUR WINDOW. SOME TWEAKS TO THE
DENSE FOG ADVISORY AREA AND TIMING VERY WELL MAY BE NEEDED
THOUGH, INCLUDING IN THE FAR SOUTH WHERE MIXING IN THE WARM
SECTOR HAS ALREADY ALLOWED FOR SOME IMPROVEMENT.
CLOUDS WILL BE SLOWER TO IMPROVE THAN VISIBILITIES TODAY, AND
AS THE PREVIOUS AFD STATED, ANY SUN MIGHT BE QUITE TRANSIENT AND
PROBABLY LIMITED TO SOUTH OF I-80 IF IT OCCURS. THROUGH LATE
MORNING, THE STRATUS WILL STILL BE DEEP ENOUGH THAT PATCHY
DRIZZLE MAY CONTINUE. THE STRATUS WILL ALSO MEAN A LOW DIURNAL
RANGE, WITH ANY WARMING OFFSET BY THE NORTHWEST WINDS, RESULTING
IN "STEADY TEMPERATURES" BEING A REASONABLE FORECAST FOR TODAY.
FOR TONIGHT INTO SATURDAY, MORE OF THE SAME WITH CONTINUED
CLOUDS AND PROBABLE LOWER DIURNAL RANGES THAN WHAT THE NBM
INDICATES. HAVE ADAPTED THAT INTO THE FORECAST. COULD BE SOME
FOG TONIGHT JUST DUE TO RESIDUAL MOISTURE, BUT WE SHOULD NOT BE
IN AS FAVORABLE OF ENVIRONMENT FOR AN EXISTING STRATUS DECK TO
LOWER TO THE GROUND SUCH AS IN RECENT NIGHTS.
LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/
ISSUED AT 300 AM CST FRI DEC 26 2025
THE SYSTEM OF INTEREST FOR LATER IN THE WEEKEND IS ACTUALLY A
PHASING OF TWO SYSTEMS -- A STRONGER ONE NEAR THE CONUS BORDER AND
A MORE SUBTROPICAL JET-ROOTED ONE. MOST DETERMINISTIC MODELS
AGREE WITH A PHASING IN THE MIDWEST TO GREAT LAKES REGION. WITH
A FAIRLY WIDE OPEN GULF AND AN EXISTING BAROCLINIC ZONE IN THE
REGION, WARM AND MOIST ADVECTION SATURDAY NIGHT SHOULD RESULT IN
A REGIONAL INCREASE IN ISENTROPIC ASCENT AND SHOWERS. THIS IS
SUPPORTED IN THE END OF CAM SOLUTIONS. THE LOW-LEVEL WARM
ADVECTION WILL ALLOW FOR CAPE TO LIKELY EXPAND INTO AT LEAST THE
SOUTHERN CWA, WITH AVAILABLE ENSEMBLE PROBABILITIES OF MUCAPE
EXCEEDING 200 J/KG OF AROUND 50%. ALSO NOTEWORTHY IS A TIGHT
GRADIENT IN LOW-LEVEL BASED CAPE EXCEEDING 100 J/KG NEAR THE
SOUTHERN CWA EDGE SUNDAY MORNING. CONTINUE WITH THE CHANCE OF
THUNDER IN THAT AREA, BUT WITH THE KINEMATICS AND WHERE THE
LOW-LEVEL CAPE/SHEAR SPECTRUM IS WITH RESPECT TO CLIMATOLOGY
(AS SHOWN BY ECMWF EFI), WILL ALSO HAVE TO WATCH FOR CONVECTIVE
INDUCED WIND POTENTIAL IN THE SOUTHERN AND FAR EASTERN CWA. AS
NOTED IN THE PREVIOUS AFD, PRECIPITABLE WATERS ARE FORECAST AOA
ONE INCH IN THE SOUTHERN CWA (NEAR LATE DECEMBER MAXES ON
CLIMATOLOGY), SO TEMPORARY HEAVY RAIN RATES COULD OCCUR, BUT
QUICK CELL MOVEMENTS AND GROUND CONDITIONS SHOULD NOT YIELD
NOTABLE HYDRO ISSUES. ONE FINAL NOTE FOR SATURDAY NIGHT/SUNDAY
MORNING, IS FOR ANY AREA THAT SEE LESS SHOWERS, THERE COULD BE
DENSE FOG AGAIN GIVEN SIMILAR DEW POINTS TO THIS MORNING.
WITH A PROJECTED DEEPENING OF THE SYSTEM FAVORED TO OUR EAST
SUNDAY AFTERNOON INTO NIGHT, THAT MEANS A STRENGTHENING PRESSURE
GRADIENT IN TANDEM WITH COLD AIR ADVECTION. THE ISALLOBARIC
INFLUENCE AND THE STRONGEST TOP OF THE CHANNEL WINDS LOOK TO
MAXIMIZE SUNDAY EVENING INTO OVERNIGHT, AND DURING THAT PERIOD
HAVE COLLABORATIVELY GONE WITH NBM'S UPPER QUARTILE SUSTAINED
WINDS OF AROUND 25 MPH, WITH GUSTS PROBABLE (50-80%) TO EXCEED
40 MPH. THESE PROBABILITIES DROP OFF FOR GUSTS OVER 45 MPH, BUT
LOOKS TO BE AT LEAST CLOSE TO WIND ADVISORY CRITERIA.
FORCING FOR PRECIPITATION WITHIN THE COLD AIR ADVECTION LOOKS TO
STILL BE PRESENT SUNDAY P.M. THROUGH SUNDAY NIGHT AND POSSIBLY
EVEN INTO MONDAY MORNING WHEN THE UPPER TROUGH SWINGS OVER OR
JUST NORTH OF THE AREA. SO THIS PROVIDES FORECAST SNOW CHANCES,
BUT OVER HOW MUCH OF THE AREA AND HOW IMPACTFUL ARE UNCERTAIN.
CONCEPTUALLY, THE FORECAST PATH OF THE SYSTEM WOULD FAVOR NORTH
OF I-80 FOR SNOW CHANCES, AND THE NBM MEMBERSHIP DOES HAVE
30-50% PROBABILITIES OF SNOWFALL > 1 INCH IN THIS AREA FOR
SUNDAY AFTERNOON THROUGH MONDAY MORNING. WITH MILDER PAVEMENT
AFTER THIS PROLONGED ABOVE FREEZING STRETCH, ROAD IMPACTS MAY BE
LIMITED EVEN IF SNOW DOES MATERIALIZE. PREDICTABILITY OF THIS
~60 HOURS OUT IS STILL ON THE LOWER END.
CONFIDENCE IS HIGH IN TEMPERATURES BEING 30 TO 35 DEGREES COLDER
MONDAY MORNING THAN SUNDAY MORNING AS TEMPERATUERS IN THE UPPER
SINGLE DIGITS TO TEENS START THE LAST MONDAY OF 2025. ATTENDANT
WIND CHILLS ARE PRESENTLY FORECAST IN THE ZERO TO 15 BELOW ZERO
RANGE. WHILE NOT TO COLD ADVISORY CRITERIA LEVEL, IT WILL BE A
BIT HARSH OF A SNAP BACK TO REALITY. WHILE SOME MODERATION
ALREADY MIDWEEK, TEMPERATURES LOOK TO STAY AT TO BELOW NORMAL
FOR AT LEAST A FEW DAYS.
AVIATION /06Z TAFS THROUGH 06Z SATURDAY/
ISSUED AT 1139 PM CST THU DEC 25 2025
A MURKY START TO FRIDAY EXPECTED AREA-WIDE, WITH LIFR CIGS AND
VISIBILITIES LIKELY TO EXPAND NORTHEAST ACROSS MUCH OF THE AREA
BY 11Z. THIS EXPANSION WILL HAPPEN UNDER A CENTER OF LOW PRESSURE,
AND AS THIS LOW MOVES SOMEWHAT QUICKLY EAST, VISIBILITY SHOULD
IMPROVE FROM WEST TO EAST BETWEEN 13Z AND 16Z. CONFIDENCE IS
HIGH THAT CEILINGS SHOULD RESPOND SLOWER THAN VISIBILITIES, AND
THESE CIGS ARE LIKELY TO REMAIN IN THE IFR CATEGORY INTO EARLY
AFTERNOON IF NOT THROUGH THE AFTERNOON.
NORTHWEST WINDS WILL PICK UP BY MID-MORNING WITH SPOTTY GUSTS
BETWEEN 16 AND 19 KTS THROUGH MID-AFTERNOON. WINDS WILL
DIMINISH QUICKLY AGAIN AFTER SUNSET, AND WHILE CONDITIONS WILL
NOT BE AS MOIST AS RECENT NIGHTS, CIGS ARE LIKELY TO GRADUALLY
LOWER TOWARD OR INTO LIFR CATEGORY AGAIN FRIDAY NIGHT/EARLY
SATURDAY MORNING, AND VISIBILITY MAY ALSO FOLLOW SUIT.
DVN WATCHES/WARNINGS/ADVISORIES
IA...DENSE FOG ADVISORY UNTIL 9 AM CST THIS MORNING FOR IAZ040>042-
051>054-063>068-076>078-087>089-098-099.
IL...DENSE FOG ADVISORY UNTIL 9 AM CST THIS MORNING FOR ILZ015-016-
024>026-034-035.
MO...DENSE FOG ADVISORY UNTIL 9 AM CST THIS MORNING FOR MOZ009-010.
SHORT TERM...FRIEDLEIN
LONG TERM...FRIEDLEIN
AVIATION...FRIEDLEIN
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