235
FXUS63 KDVN 180822
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
222 AM CST Thu Dec 18 2025

.KEY MESSAGES...

- A strong storm system will bring very windy conditions to the
  area this afternoon/evening with falling temperatures. A wind
  advisory has been issued for the entire area.

- Scattered snow showers will be possible this
  afternoon/evening. Some of the snow showers may be robust
  creating brief but significant visibility reduction and a
  dusting of accumulation.

- Mainly dry conditions with large temperature swings over the
  weekend. A persistent trend of above normal temperatures will
  be seen next week.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 220 AM CST Thu Dec 18 2025

The initially dry atmosphere has prevented any rain from developing
so far. However, the rate of the top-down saturation is starting to
accelerate so isolated to scattered showers should begin breaking
out across eastern Iowa through 6 AM.

Once sunrise occurs, the areal coverage of the rain will rapidly
increase with the first of two fronts moving through the area. A
temperature drop of 5-10 degrees over 1-2 hours is expected with the
first frontal passage.

A sudden jump in wind speeds and gusts will be seen with the first
frontal passage. The very short range models have been indicating a
brief period of wind gusts of 40-45 mph. Gusts of this strength
immediately along/behind the first front have been showing up in the
Plains with a few gusts over 60 mph.

The rain will quickly end from west to east during the late morning
hours as the elevated dry punch moves into the area. Clouds will
break up and temperatures should hold steady or may rise a few
degrees in response to the sunshine.

The second front arriving during the afternoon will bring in the
much colder air and very windy conditions. Temperatures will be in
free fall during the afternoon with readings in the teens and 20s by
6 PM.

Winds at the top of the mixed layer continue to be 38-43 knots which
will translate down to the surface from the strong cold advection.

Interestingly, the probabilities of winds exceeding 45 mph are over
50 percent across central Iowa but drop to 10-20 percent across
eastern Iowa. That is strange given isallobaric pressure changes of
5-6 mb and the strong winds at the top of the mixed layer.

So, a wind advisory has been issued for the entire area from 12 PM
to midnight tonight. Marginal wind events have a nasty habit of over-
performing where the cold advection and isallobaric pressure
gradient are both strong.

As the cold air pours into the area this afternoon, strong forcing
is present for isolated to scattered snow showers to develop. Like
yesterday the signal is there that some of the snow showers may be
robust and create significant but brief reductions in visibility.
Thus the overall scenario suggests the potential of low end snow
squalls developing mid to late afternoon and continuing into the
evening hours. This will need to be watched carefully as there may
be impacts to the evening commute as the snow showers may result in
a localized dusting of accumulation.

Tonight, the snow showers will end during the first part of the
evening. The possibility does exist that some flurries may persist
further into the evening.

After midnight winds will slowly diminish but breezy conditions will
result in wind chills below zero through sunrise Friday.

&&

.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
Issued at 220 AM CST Thu Dec 18 2025

Friday through Wednesday
Assessment...high (60-80%) confidence of mainly dry conditions

The late week and weekend will seen large temperature swings. Colder
than normal temperatures will be seen Friday in the wake of the
departing storm system with a warm-up commencing Friday night under
breezy conditions.

Another front is progged by the models to move through the area
Saturday afternoon/evening. Atmospheric profiles are quite dry so
the frontal passage should be marked by an increase in clouds. At
the very worst some sprinkles or flurries `may` occur.

After a cooler than normal Sunday, a prolonged warm-up will commence
again as the storm track shift well north of the area. The models
prog another weaker front through the area Tuesday afternoon/evening
but there is hardly any forcing associated with it and the
atmospheric profiles are very dry. Thus like the previous front,
only an increase in clouds should mark its passage.

&&

.AVIATION /06Z TAFS THROUGH 06Z FRIDAY/...
Issued at 1127 PM CST Wed Dec 17 2025

WSR-88D VAD profiles shows LLWS is well underway across eastern
Iowa and northern Illinois. SHRA will rapidly develop 09-12z/18
as the dry air gives way to saturation with CIGS quickly
dropping to MVFR. HRRR model shows a potential of wind gusts
35-40 knots during the first frontal passage 12-17z/18.
Secondary front to bring another jump in sustained winds with
gusts up to 40 knots. 10-30 percent coverage of SHSN 21z/18
through 03z/19 have the potential of brief IFR/LIFR conditions
if they impact a TAF site.

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...Wind Advisory from noon today to midnight CST tonight for
     IAZ040>042-051>054-063>068-076>078-087>089-098-099.
IL...Wind Advisory from noon today to midnight CST tonight for
     ILZ001-002-007-009-015>018-024>026-034-035.
MO...Wind Advisory from noon today to midnight CST tonight for
     MOZ009-010.

&&

$$

SHORT TERM...08
LONG TERM...08
AVIATION...08