877
FXUS63 KDVN 101045
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
445 AM CST Fri Jan 10 2025

...Updated for 12z Aviation...

.KEY MESSAGES...

- Light snowfall and minor accums ending by midday.

- Potential for more light snow accumulations late Saturday
  night into Sunday.

- Colder early to mid next week before some moderation occurs
  late next week.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 304 AM CST Fri Jan 10 2025

Upper air analysis places a positive tilt trough across the central
CONUS. Within this trough a shortwave, responsible for widespread
wintry precipitation and travel impacts across the Southern
Plains and Lower Mississippi Valley, was shifting eastward.
We`re seeing a glancing shot of some weaker lift from this
system leading to some light snow across portions of our far
southern counties early this morning. A reservoir of dry air
sampled by the 00z DVN raob was limiting the northward
progression, and will likely once again yield a very sharp
cutoff from snow (with around 1 inch or so of accum) to nothing.
This gradient will likely reside in or near parts of Hancock,
McDonough, Warren, Bureau and Putnam counties before the light
snow departs by midday-ish. Something to note is an embedded
shortwave tracking across Minnesota early this morning, which is
aiding in a surface front traversing our area currently. As
the front interacts with this system there is the potential for
some light snow to develop further northward for a brief time
this morning. Also, forecast soundings show some potential for a
loss of in-cloud ice and GOES 16 cloud top phase shows
supercooled liquid water post-frontal, and so can`t rule out some
freezing drizzle with light snow near and behind the front for a
short period of time with the low level saturation. Ceiling
heights remain rather high (generally above 1500-2000 ft agl)
supporting of any freezing drizzle being exceedingly light should
it occur, but roads may become slick for the morning commute and
have issued and SPS to highlight this potential.

For this afternoon into evening, the focus will shift northward
with that trough, as an associated vort max swings through the
region. Moisture is primarily located between 950 mb and 800 mb
and this may lead to predominantly flurries given the cyclonic
flow aloft. However, soundings also show some low level
instability to where a few snow showers can`t be ruled out as
well. The instability looks weak (below 50 J/kg) and not seeing
any indications of a strong low level Fgen band, thus not
anticipating any snow squalls. But, something to just keep an
eye on for any changes (more solar insolation, greater
instability), as the layer snow squall parameter from the NAM
does pop values to 0.5 into parts of southern Wisconsin which
typically we look for values greater than 1.

The trough looks to pass through by 06z tonight, thus expect
a decrease from W/NW to E/SE in both flurries/isolated snow
showers and cloud cover by mid evening into the early overnight.
With colder conditions by morning with lows mainly in the teens
and chills in the single digits to around 10 degrees aided by
NNW winds 5-15 mph.

&&

.LONG TERM /SATURDAY THROUGH THURSDAY/...
Issued at 304 AM CST Fri Jan 10 2025

Quiet weather is expected for the start of the weekend with
surface ridging moving through on Saturday. Clouds will
be on the increase later in the day ahead of our next
weather system quick on the heels of this first departing
system. The low track still has good agreement on passing
to our north Saturday night into Sunday. Lift will come in
two rounds, with the first being a ramping bout of warm, moist
advection Saturday evening/night. PoPs are primarily low
(20-40%) for precipitation for the evening into the overnight,
with dry air lingering owing to uncertainties with saturation.
Model soundings however show an unsaturated DGZ and in-cloud
temps that are warmer than -10C suggesting more in the way of
super-cooled water, and the potential for freezing drizzle with
low level saturation. Confidence is low, but enough signal in
the soundings to support a slight chance of freezing drizzle
mention. If it were to occur it would be exceedingly light to
where no ice accumulation is anticipated. Late Saturday night
and Sunday the second round of forcing swings through attendant
to a mid level shortwave and surface cold front. This looks
to foster deeper saturation and the likelihood of a period of
snow, especially north of I-80. Accumulations would appear to
be an inch or two at most from the looks of it right now.

Behind this system, we`ll see another bout of colder air and
a drop on temps Monday through Wednesday. Highs will be
in the teens/lower 20s and lows in the single digits/lower
teens. Can`t rule out some clipper systems in the NW flow
aloft, but difficult to assess at this range given the low
amplitude nature.

Heading into the end of next week some moderation in
temperatures is expected, as the flow turns semi-zonal
allowing for some MP airmass influx.

&&

.AVIATION /12Z TAFS THROUGH 12Z SATURDAY/...
Issued at 440 AM CST Fri Jan 10 2025

Some pockets of VFR at the start of the period, but overall
predominantly MVFR with some IFR is expected this morning in
low clouds and a period of light snow with a cold frontal
passage. Some patchy freezing drizzle is also possible, but
confidence is low. Accumulations from a dusting to a few tenths
of an inch are possible at the terminals. There is a chance for
a return to VFR for a time by mid to late morning from west to
east in the wake of the precipitation, with increasing NW winds
post-frontal of 10-15+ kt. However, cyclonic flow should
promote additional low clouds and areas of MVFR CIGs this
afternoon into evening. In addition, flurries and isolated to
widely scattered snow showers are expected. Have handled the
snow shower potential with PROB30 mention. Late this evening
and overnight decreasing clouds and widespread VFR conditions
are expected.

&&

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

&&

$$

SHORT TERM...McClure
LONG TERM...McClure
AVIATION...McClure