536
FXUS63 KDVN 011100
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
500 AM CST Mon Dec 1 2025

.KEY MESSAGES...

- A burst of accumulating dry, fluffy snow will move through the area
  today, mainly this afternoon and evening. A Winter Weather
  Advisory remains in effect, with travel impacts expected for
  the PM commute.

- Below normal temperatures are forecast for the entire week. Wednesday
  and Thursday nights look particularly cold, with around 60-
  90+% chance of overnight lows below zero Thursday morning.

- Active pattern remains through the week, with periodic chances
  of snow mid-week and again late week.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 309 AM CST Mon Dec 1 2025

After a cold morning for locations north of Interstate 80 (with
morning lows starting off in the single digits above zero),
attention quickly turns to a mid-level shortwave trough that will
translate eastward today from the Four Corners region. On the
northeastern flank of the shortwave, enhanced 850-700 mb layer
frontogenetical forcing and increasing moisture will result in a
burst of accumulating snow, mainly for this afternoon and evening.
Model sounding analysis shows top-down saturation occurring as the
FGEN band approaches, with an impressively deep dendritic growth
zone aloft (roughly 9000 feet deep!). This is a strong indication
that the snow will be of the dry, fluffy variety, with snow ratios
of 16:1 to 19:1 expected. The latest HREF ensemble suggest snowfall
rates most likely around 0.25 to 0.5 inches per hour, with the
potential for rates to exceed a half inch per hour this afternoon.
The timing of this snow will be problematic, given this will impact
the PM commute today. Fortunately, the winds look to be on the weak
side, so the threat for blowing and drifting snow looks quite
limited. Forecast snowfall amounts appear to be on track, with most
locations seeing between 1-4", with 2+" likely to be seen along and
southeast of a Sigourney, IA to Mount Carroll, IL line. These are
very much in line with the latest HREF probability-matched mean
snowfall totals. A Winter Weather Advisory remains in effect for
these locations. Make sure to take it slow on the roadways during
the snow, and allow plenty of following distance if out traveling.

As we head into the overnight hours, the accumulating snow should
diminish by midnight, when our advisory expires, as drier air
filters in from the west. High pressure will also nose into the
region, leading to a period of dry weather through Tuesday night.
The main thing to watch for tonight is another night of very cold
conditions, with lows expected in the single digits and lower
teens.

&&

.LONG TERM /TUESDAY THROUGH SUNDAY/...
Issued at 309 AM CST Mon Dec 1 2025

The main theme of the long term period will be below normal
temperatures (very cold temperatures and wind chills at times),
along with a few bouts of precipitation. First, let`s talk
temperatures. Tuesday and Wednesday high temperatures will generally
be in the 20s to lower 30s, so seasonably cold for this time of the
year. This is all thanks to a high pressure ridge axis that will
sweep through the area, leading to southerly return flow and
enhanced warm air advection.

Temperatures actually look to be their coldest of the week on
Wednesday and Thursday nights as a cold front is progged to sweep
through the area during the daylight hours Wednesday. Post-frontal,
an arctic air mass looks to build into the region, characterized by
850 mb temperatures near -11 to -14 degrees C per the GEFS and ECMWF
ensembles. This is quite cold for early December, and the ECMWF EFI
shows a strong signal for consensus in the ECMWF ensembles for very
cold conditions, with values of -0.8 to -0.99. In short, Wednesday
night/Thursday morning is likely to be the coldest night of the
season so far. NBM probabilities of low temperatures below zero
Thursday morning are around 60-90+% for most locations (highest over
northeastern Iowa), and even values of 20-50% for morning lows of 10
below zero or colder! Northwesterly winds post-frontal could also
result in bitterly cold wind chills of less than 20 below zero, so
keep an eye on the forecast as we approach Wednesday night. Thursday
night could also be quite cold, although early indications
suggesting not as cold as Thursday morning. Temperatures do look to
moderate some next week.

Back to the precipitation potential on Wednesday with the cold
front: overall, the front appears to be moisture-starved, so there
doesn`t appear to be much in terms of snow accumulations with it.
There is a signal for a larger system to move through the area next
weekend Saturday night, but there isn`t as much model consensus on
the timing, coverage, and intensity of the precipitation, so
confidence remains low on this potential system.

&&

.AVIATION /12Z TAFS THROUGH 12Z TUESDAY/...
Issued at 500 AM CST Mon Dec 1 2025

Mostly MVFR conditions continue to be observed over much of the
area early this morning, thanks to a low stratus deck that
continues to expand northward. Some IFR/LIFR conditions have
been reported farther north, but confidence remains low that
they will become widespread.

Attention will then turn to a quick burst of accumulating snow
that will move through the area, mainly during the PM hours
today. Confidence is quite high that this snow will be the dry,
fluffy variety, with the latest HREF ensemble suggesting
snowfall rates between 0.25 to 0.5 inches per hour, perhaps
exceeding 0.5 inches per hour at times this afternoon. This
should lead to IFR conditions (ceilings and visibilities), with
LIFR conditions possible in the heavier snowfall (probabilities
of 1/2SM visibilities between 50-70% per the HREF for BRL and
MLI). Winds will generally be light and variable, so blowing
snow doesn`t appear to be an issue. Visibilities will improve
this evening as the snow tapers off, but IFR to MVFR ceilings
should continue.

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...Winter Weather Advisory from noon today to midnight CST
     tonight for IAZ066>068.
     Winter Weather Advisory from 9 AM this morning to 9 PM CST
     this evening for IAZ076>078-087>089-098-099.
IL...Winter Weather Advisory from noon today to midnight CST
     tonight for ILZ007-009-015>018-024>026-035.
     Winter Weather Advisory from 9 AM this morning to 9 PM CST
     this evening for ILZ034.
MO...Winter Weather Advisory from 9 AM this morning to 9 PM CST
     this evening for MOZ009-010.

&&

$$

SHORT TERM...Schultz
LONG TERM...Schultz
AVIATION...Schultz