551
FXUS63 KDVN 230457
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
1057 PM CST Fri Nov 22 2024

.KEY MESSAGES...

- Temperatures briefly going above normal for the weekend.

- One or more systems will be moving through the Midwest during
  the holiday weekend. Considerable uncertain exists regarding
  the track and potential for any impacts to the area.

- The pattern change that occurred last week will remain active
  through early December. The temperature probability of well
  below normal temperatures is 70-80%. There is no clear signal
  that favors above or below normal precipitation into early
  December. However, the probability for snow is increased due
  to the colder than normal temperatures.

&&

.SHORT TERM /THROUGH SATURDAY/...
Issued at 225 PM CST Fri Nov 22 2024

Winds will continue to diminish through sunset. Overnight and
Saturday winds will be light and gradually turning to the west and
eventually southwest Saturday afternoon.

Cloud cover will persist overnight with breaks developing by mid-day
Saturday with a continued slow clearing Saturday afternoon. The
possible change to the overall cloud cover is a weak upper level
disturbance moving from Minnesota into Wisconsin Saturday. This
disturbance may cause clouds to linger through the day. Although not
zero, some very isolated sprinkles may occur in the highway 20
corridor during the passage of the disturbance. The better moisture
profiles are progged to be across Wisconsin thus the probability of
seeing any precipitation in the highway 20 corridor is about 5
percent at best.

Temperatures look to not get as cold tonight due to the cloud cover.
Once clouds start breaking up Saturday, temperatures should see a
jump to readings around normal for late November.

&&

.LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/...
Issued at 225 PM CST Fri Nov 22 2024

Saturday night through Sunday night
Assessment...high confidence on above normal temperatures.
Medium to high confidence on dry conditions.

A weak system will move through the area during the second half of
the weekend. Moisture is very sparse with the system so only an
increase in clouds will mark its passage. The system will, however,
bring above normal temperatures to the area for the second half of
the weekend.

Monday through Tuesday night
Assessment...medium to high confidence on mainly dry conditions.
High confidence on temperatures turning colder.

Right behind the late weekend system, an upper level disturbance
will move through the area for Monday. The better forcing is from
Minnesota into Wisconsin along with what moisture is available. With
the better forcing/moisture north of the area, the probability of
any precipitation occurring is low. Thus other than turning colder,
90 percent of the area will likely remain dry Monday into Tuesday
night. A few isolated showers are possible during the day Monday
when the disturbance passes through the area with areas generally
north of highway 30 favored. Windy conditions will also be seen
Monday into Monday night.

The disturbance, however, will pull down much colder air behind it
for Tuesday. Temperatures Tuesday are expected to average 5 to 10
degrees below normal.

Wednesday through Friday
Assessment...high confidence on one, possibly two storm systems
moving through the Midwest for the holiday weekend and much colder
conditions. Low confidence on track and potential impacts.

One and potentially two storm systems will move through the Midwest
during the holiday weekend time frame. Considerable uncertainty
exists regarding the timing and overall track which plays into what
potential impacts they would bring to the area.

The energy centers than will produce the systems are out over the
Pacific. Other than satellite data and some aircraft reports, not
much information is known about these systems toward the surface.
Mosaic water vapor imagery suggests the first system is quite potent.

The overall trend with the deterministic runs of the
GFS/ECMWF/CMC/ICON models has been a slow drift to the south in
regards to a potential track. Such a trend with the track is
consistent with a longwave trof developing along the east coast.

The overall trend in the ensemble means from the GEFS/GEPS/ECMWF-
EPS/ICON-EPS is also a slow drift to the south. However, there are
ensemble members from each global model that have tracks that are
much further north.

Where there is general agreement between all the global models is
that temperatures will trend well below normal after Wednesday and
remain that way into early December. Thus any system moving through
the Midwest after Wednesday poses a higher probability of the
precipitation type being in the form of snow.

Given the differences in potential timing and track, the model
consensus currently places a low confidence on precipitation
chances. Once the energy centers over the Pacific are sampled by the
more dense land networks early next week, timing and track
differences will become better refined.

Right now the model consensus has a 20-30 percent chance for
precipitation Wednesday through Thursday night. Areas south of
highway 30 are favored Wednesday and the entire area Wednesday
night. Areas along and east of the Mississippi are favored Thursday
into Thursday night.

The track of the system will determine the precipitation type.
However, given the trend toward colder temperatures, a rain/snow mix
is possible during the day both Wednesday and Thursday with possibly
all snow Wednesday night and Thursday night.

Right now Friday looks to be dry with windy and cold conditions with
temperatures at or below freezing.

&&

.AVIATION /06Z TAFS THROUGH 06Z SUNDAY/...
Issued at 1042 PM CST Fri Nov 22 2024

Low stratus continues to sit across eastern Iowa and northwest
Illinois tonight bringing mainly IFR to LIFR conditions to the
area with ceilings ranging from 400 at KCID to 900 ft at KMLI.
Ceilings are currently forecast to lift to MVFR after 12 UTC and
then gradually lift ceilings into clearing cloud cover from
west to east from 18 UTC at KCID to 21 UTC at KBRL and to KMLI
and KDBQ around 00 UTC. Winds are forecast to be around 5 knots
through the period and turn from northwest overnight to
southeast after 21 UTC on Saturday.

&&

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

&&

$$

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