964
FXUS63 KDVN 070606
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
1206 AM CST Sun Dec 7 2025

.KEY MESSAGES...

- A fast moving clipper system will bring accumulating snow to
  the area tonight. Winter weather headlines are in effect for
  much of the area. A small part of the winter weather
  advisories have been upgraded to a winter storm warning.

- An active weather pattern will persist into next week with
  several more rounds of precipitation.

- Another surge of arctic air will settle into the Midwest for
  the end of next week and weekend following the passage of the
  Thursday clipper system.

&&

.UPDATE...
Issued at 749 PM CST Sat Dec 6 2025

Intense, focused WAA is taking place across central and eastern
Iowa. Thus far, this has been a snow event, but radar does
suggest that some mixed precip is possible in far southern Iowa.
Visibility has been seen between 1/4 mile and 1 mile in the
banded snow to our west, and that lines up with our forecast
showing a sharp gradient from low amounts south of I-80, to 3-6
inches just north of the I-80. A maxima of 5-8 remains possible
roughly along Highway 30, and this is in the warning already.
Thus, no headline adjustment seems warranted at this point, and
since this is an event into the overnight, we`re unlikely to do
any adjustments before it ends. The rest of tonight will see
light to moderate snow, with some periods of heavy snow, and
like the past two recent storms, plenty of snow covered roads at
night, into the morning hours Sunday.

&&

.SHORT TERM /THROUGH SUNDAY/...
Issued at 232 PM CST Sat Dec 6 2025

Very short range model guidance continues a gradual southward trend
in the axis of the heaviest snow accumulations.

Parts of the winter weather advisories have been upgraded to a low
end winter storm warning.

Through sunset clouds will continue to thicken and lower across the
area. After sunset snow will begin in the far western areas and
overspread the area from west to east through the early morning
hours of Sunday.

As noted earlier, the model guidance has done a gradual shift to the
south with the axis of the heaviest snow. In looking over the
incoming data, there are suggestions of banded snow with this
clipper system. This is somewhat reflected in accumulation
probabilities at various locations across the area. There are
indications that there will be a narrow (approximately 20 mile wide)
band of snow accumulation of 5-7 inches. Probabilities on this
occurring are at 55-70 percent. The rough axis is approximately just
south of Waterloo, IA to Milledgeville, IL.

Outside of the axis of the heaviest snow snow, amounts of 2 to 5
inches are expected with a sharp gradient in snow accumulations
south of I-80. South of a Washington, IA to Aledo, IL line snowfall
amounts will quickly drop to an inch of accumulation.

Further to the south, there is still the potential for a mix or even
a light glaze generally south of an Ottumwa, IA to Galesburg, IL
line. The potential does exist for a brief change over to all rain.
Snowfall accumulations in this area will be one half inch or less.

Snowfall rates generally look to be 0.5 to 1 inch per hour for this
event. However, in the axis of the heaviest snow, there is a 50-70
percent probability of 1-1.5 inch/hour snowfall rates between 11 PM
and 3 AM.

After 3 AM, snowfall rates will quickly drop to 0.5 inch/hour or
less as the snow ends from west to east through sunrise.

On Sunday, lingering light snow and flurries will be seen through
mid-morning east of the Mississippi as the system exits the area.
Skies will gradually clear through the remainder of the day but
breezy conditions will be seen in the wake of the departing
system.

&&

.LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/...
Issued at 232 PM CST Sat Dec 6 2025

Sunday night/Monday
Assessment...Very high (>90%) confidence of colder than normal
temperatures

A quick shot of high pressure combined with the fresh snow cover
will keep temperatures below normal along with dry conditions.
Attention then turns to the next system.

Monday night/Tuesday
Assessment...medium to high (60-80%) confidence of a clipper
system side-swiping parts of the area.

The next clipper system races through the Midwest and Great Lakes
Monday night and Tuesday morning. The better forcing and moisture is
well north of the area. Thus right now it appears that areas east of
a Manchester, IA to Princeton, IL line will get a period of flurries
or at worst several hours of light snow. The model consensus
currently has 20-25% pops for the area. If the light snow scenario
would occur, accumulations would be a dusting at worst.

Tuesday night through Thursday
Assessment...medium (40-60%) confidence of two additional systems.
Low (20-30%) confidence regarding precipitation type for the first
system.

Another clipper system moves through the Midwest Tuesday night and
Wednesday. Like the previous system the models project the track to
be north of the area. However, the track is further south than the
previous system.

Such a track would put the area initially on the warm side of the
system until the low passes. Being on the warm side of the system
raises questions regarding precipitation type. Thermal profiles of
the atmosphere suggest the precipitation may initially develop as
rain or possibly a rain/snow mix. If the precipitation arrives
shortly after sunset (suggested by all models), then rain would be
the primary precipitation type until the atmosphere cools and allows
a rain/snow mix to develop later in the evening and much of the
overnight hours.

Once the low passes, cold advection will quickly change any mix over
to all snow late Tuesday night and Wednesday morning but
accumulations right now look to be a dusting at best. The cold
advection looks impressive with winds of 15-25 mph expected and
potential gusts of 30-35 mph. The diurnal recovery of temperatures
on Wednesday will be minimal from the overnight lows.

Following almost immediately on the heels of the second clipper
system will be a hybrid clipper/colorado low system that arrives
Wednesday night into Thursday. The more southern track of this
system means there is a high (>80%) probability of seeing another
round of accumulating snow.

Given the proximity of this system with the previous clipper system,
there will not be much moisture in place ahead of the system. Thus
the moisture associated with the system will be what is available
for precipitation production.

While there are timing differences, there is loose agreement that
the precipitation will be arriving after sunset. Thus with the
atmosphere cooling, the precipitation type will be in the form of
snow.

While not certain, this snow will have a medium to high (60-80%)
probability of being the dry, fluffy type. Thus the rain/snow ratio
will be minimally in the 12-15 to 1 range. Given the limited system
moisture, snowfall amounts generally look to be light.

Thursday night through Saturday
Assessment...A certainty (>98%) of another round of arctic air
for the Midwest

Lingering light snow/flurries will end Thursday evening as the
system departs the area. Behind the system, another surge of arctic
air will move into the Midwest keeping temperatures well below
normal for the end of the week and next weekend.

&&

.AVIATION /06Z TAFS THROUGH 06Z MONDAY/...
Issued at 1142 PM CST Sat Dec 6 2025

KBRL sits on the southern end of precipitation moving eastward
across eastern Iowa TAf sites early this morning. Periods of
-FZRA or FZDZ are possible there through 8 UTC this morning
 before rain or FZRA begins to mix with snow. Conditions are VFR
 there but expect MVFR Conditions to occur through 12 UTC there
 before a gradual improvement takes place this morning. At the
 other TAF sites, MVFR ceilings and IFR to LIFR visibility are
 possible at KDBQ, KCID, and KMLI. A period of a mix of SN and
 PL are possible at KMLI through 7 UTC. Conditions will
 gradually improve from 12 to 18 UTC on Sunday with widespread
 VFR conditions. Norther winds of 10 to 15 knots with gusts up
 to 20 knots are possible through 18 UTC before winds begin to
 diminish.

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...Winter Storm Warning until 6 AM CST Sunday for IAZ040-051>054-
     066.
     Winter Weather Advisory until 6 AM CST Sunday for IAZ041-042-
     063>065-067-068-076>078-087>089-098-099.
IL...Winter Storm Warning until 6 AM CST Sunday for ILZ007-009.
     Winter Weather Advisory until 6 AM CST Sunday for ILZ001-002-
     015>018-024>026-034-035.
MO...None.

&&

$$

UPDATE...Ervin
SHORT TERM...08
LONG TERM...08
AVIATION...Cousins