371
FXUS63 KDVN 250240 AAA
AFDDVN

Area Forecast Discussion...UPDATED
National Weather Service Quad Cities IA IL
840 PM CST Mon Nov 24 2025

.KEY MESSAGES...

- More fog tonight into Tuesday morning, with highest likelihood
  (>50 percent) of areas of dense fog north and west of the Quad
  Cities; Dense Fog Advisory possible by daybreak.

- Strong cold front remains on track to sweep through the area
  Tuesday evening into early Wednesday, bringing much colder
  temperatures for mid to late week. Strong winds are probable,
  gusting to around 30 to 40 mph Tuesday night and Wednesday
  morning.

- A wintry system appears possible to move through the area late
  Friday into the weekend, with additional systems beyond that,
  making for a busy weather pattern. Uncertainty remains with
  the timing and impacts from the weekend system, given model
  variance.

&&

.UPDATE...
Issued at 840 PM CST Mon Nov 24 2025

The going forecast messages are largely on track, including the
likelihood of some areas of dense fog by daybreak.

Water vapor imagery and regional radar indicate the presence of
a couple waves bringing concentrated showers, with a low
amplitude one just north of the CWA to exit by 11 PM, and one
in northern Missouri to bring the southern and likely far
eastern CWA widespread showers. Between these waves exists low-
level moist isentropic ascent supporting patchy drizzle /
occasional light rain. All of this continues to saturate an
already moist boundary layer, and in the wake of most of the
showers (after ~2 AM), conditions should be overall favorable
for the 200-700 ft ceilings to lower even more toward the ground
as dense fog. The plethora of latest short term guidance (~70%
of guidance), especially those handling observational trends the
best at present, continue to support west and north of the Quad
Cities for dense fog. For the rest of the area, there is
certainly some signal too, but if it occurs it will very likely
not develop until near daybreak.

Some potential failure modes for Advisory-level fog include 1.)
10-15 kt winds off the deck as observed on our 00Z sounding and
VWP data that is expected to continue for several more hours
before dropping off late, and 2.) temperatures may drop only
1-2F more the rest of the night under this established stratus,
and that may not support that full saturation for widespread
dense fog.

Will continue to monitor observational trends, including
webcams, for Advisory need, and message the potential.

&&

.SHORT TERM /THROUGH TUESDAY/...
Issued at 156 PM CST Mon Nov 24 2025

A gloomy forecast remains on track for the rest of today through
Tuesday, as low clouds and fog will stick with us (`tis the
season!). Fog from this morning has largely burned off, except for
some lingering light to moderate fog over the Highway 20 corridor.
The 24.12z HREF ensemble soundings show a strong signal for
continued low clouds, thanks to low-level moisture and a persistent
thermal inversion. Another night of fog is likely tonight, with a
return of dense fog likely. The HREF has probabilities of 1/4 mile
visibilities of 50 to 80% (highest north of Interstate 80), so
confidence is medium to high for dense fog. We will have to keep a
close eye on conditions tonight for another Dense Fog Advisory.

Meanwhile, a well-advertised shortwave trough is starting to move
into the area, bringing increasing chances (50-80%) of rain showers.
The signal for generally light rainfall amounts continues, with the
latest HREF PMM QPF staying less than a tenth of an inch for most
locations. Amounts could exceed a tenth of an inch, particularly
along our far southeastern CWA where lift will be more enhanced
closer to the passing shortwave/PVA maxima. For locations that
receive appreciable rainfall, this could help tamper the fog
potential. Locations that see less rain will be more likely to see
dense fog. Overnight lows should dip to the middle to upper 40s for
most locations.

As we go into Tuesday, the aforementioned shortwave will quickly exit
the region, which will bring a period of dry conditions Tuesday
morning. Clouds and some lingering fog will be with us, however. As
we go into the afternoon, a potent cold front will begin to sweep
across the area from west to east. There will be a brief period of
rain along the boundary, but it should be a narrow corridor of
moisture, so not much in terms of accumulations are expected. The
bigger impact from this front will be strong winds after fropa. More
on that in the Long Term section.

&&

.LONG TERM /TUESDAY NIGHT THROUGH MONDAY/...
Issued at 156 PM CST Mon Nov 24 2025

A northern stream mid-level shortwave will accompany the surface
cold front and approach the area from the Pacific NW Tuesday night,
bringing a cyclonic flow/cold air advection (CAA) regime and result
in colder and more brisk conditions in the wake of the fropa. The
NBM suggests high temperatures going from the lower to middle 50s on
Tuesday to the middle to upper 30s on Wednesday, so it will feel
noticeably cooler (just in time for busy Thanksgiving travel). As
previously mentioned, winds will be quite gusty in the wake of the
front, with the ECMWF EFI showing values of 0.7 to 0.9 for wind
gusts on Wednesday, indicating an unusually windy day, with gusts of
30 to 40 mph possible. Coupled with the cooler temperatures, it will
feel pretty brisk, with wind chills Wednesday morning falling to the
teens and lower 20s (bundle up!). In terms of precipitation, we`re
not expecting much to develop except for perhaps some light snow
showers or flurries in the cyclonic flow along the Highway 20
corridor.

Thanksgiving and Friday: it will continue to be on the chilly side,
with low temperatures each morning in the teens to lower 20s.
Coupled with the winds, wind chills will fall to the teens area-
wide, and even some single digits are possible across our north.
However, this period looks to stay dry.

We continue to keep an eye on a wintry system slated to move through
the area Friday night through the Thanksgiving weekend. This looks
to be our first potential for widespread accumulating snow this
season. There remains considerable uncertainty on how this system
will evolve as there are some questions about where the baroclinic
zone will set up, which will dictate precipitation types as there is
potential for a wintry mix late in the weekend. An ensemble approach
paints a potential for at least one to two inches of snow, given the
NBM shows exceedance probabilities of one inch of snow of 50 to 80%,
with probs of two inches of snow around 40 to 60%. WPC has
probabilities of three inches being less than 20%, so this would
suggest some accumulating snow, but remaining less than three
inches. The probabilistic WSSI has probabilities of "minor" impacts
(i.e., minor travel impacts) around 40 to 60% for Saturday, so keep
a close eye on the forecasts if you have travel plans this
weekend.

&&

.AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/...
Issued at 536 PM CST Mon Nov 24 2025

Difficult next 18 hours for aviation as cigs and vsbys could
bounce to MVFR for a few hours. Otherwise, expect IFR turning
rapidly to LIFR with minimums met at most sites overnight. While
daybreak may lead to cigs and vsbys returning to IFR, real
recovery doesnt look to happen until Tuesday PM into Wednesday.
Rain is possible through the overnight, but should not lead to
changes to flight cats.

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...None.
IL...None.
MO...None.

&&

$$

UPDATE...Friedlein
SHORT TERM...Schultz
LONG TERM...Schultz
AVIATION...Gibbs