Iowa City, Iowa 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

245
FXUS63 KDVN 290155
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
755 PM CST Fri Nov 28 2025

.KEY MESSAGES...

- A significant winter storm will impact the area tonight
  through Saturday night. Probabilities are high (80-90%) for at
  least 8 inches of snow over much of the area. Probabilities
  for 12+ inches of snow are high (70-80%) north of a Sigourney,
  IA to Aledo, IL line. Winter storm warnings continue for the
  entire area.

- Below normal temperatures will be seen next week with a chance
  of snow on Monday.

&&

.UPDATE...
Issued at 745 PM CST Fri Nov 28 2025

The 00z UA sounding at DVN shows a rapidly saturating air mass
above 700mb, with a wetbulb temperature profile that shows we`ll
be seeing a deep dendritic profile once fully saturated. This
seems to match the depiction on radar, showing numerous areas of
25 to 30 Dbz over Iowa. I have noticed reports of 1/2 mile
visibility in moderate snow as close by at Marshalltown Iowa,
with MPING and obs showing the band extending along and north of
I-80 is reaching the ground. This saturation process is not
taking long, and an accumulating snow should begin in our west
in the next hour, and several inches by midnight remain a good
possibility west of I-380. Our current headlines are well
supported by analysis and radar/roads trends. This had the look
of a major winter storm, and we expect impacts to reach winter
storm warning levels during the overnight hours tonight.

If you are traveling, be aware that conditions will deteriorate
as the night progresses, even in Illinois where it will be
mainly after midnight.

&&

.SHORT TERM /THROUGH SATURDAY NIGHT/...
Issued at 128 PM CST Fri Nov 28 2025

Clouds will continue to increase late this afternoon and evening
ahead of the storm.

Forecast profiles of the atmosphere show a very deep column of dry
air that will have to saturate before the snow reaches the ground.
However, the forcing and moisture above the dry layer is impressive
so it will not take long for top-down saturation to occur.

That being said areas along/west of I-380 should see snow quickly
develop between 8 and 10 PM. Snow will then overspread the remainder
of the area through sunrise Saturday.

Based on the HREF, the initial shot of warm advection snow has a
medium to high probability (60-80%) of seeing snowfall rates of 1
inch/hour at times through sunrise Saturday.

On Saturday, the main system snow settles in across the area.
Snowfall rates generally look to be 0.5-0.7 inches/hour. The
exception will be during the late afternoon/early evening when the
main low moves through the area. During this time frame, snowfall
rates of 1-1.5 inches/hour will be possible. During the passage of
the low, the snow will become mixed with rain and may briefly change
over to all rain along/south of a Keosauqua, IA to Macomb, IL line.

The character of the snow will change during the event. It will
initially start out as a fairly dry snow tonight but will become
more wet during the day on Saturday. Saturday night the snow will
trend back to being dry again and slowly end from west to east after
midnight.

Winds will be increasing to 15-25 mph tonight and will continue
during the day Saturday. The potential is there for wind gusts of 30-
35 mph at times during the day Saturday. There will be a lull in the
winds during the passage of the low in the 3-8 PM time frame. After
the low passes, winds will again increase to 15-25 mph with gusts of
30-35 mph possible Saturday night. Drifting snow is possible
Saturday night as the character of the snow becomes drier.

As for amounts, they have trended a bit higher. It is not uncommon
for early and late season events to over-perform on snowfall amounts
because moisture is more plentiful.

Right now it appears that widespread 10-15 inch accumulations are
possible north of an Ottumwa, IA to Galesburg, IL line. South of
this line, 7-10 inch amounts are possible.

This storm has a high probability (>80%) of being in the top 3
heaviest snowfalls for November, depending upon the location.

&&

.LONG TERM /SUNDAY THROUGH FRIDAY/...
Issued at 128 PM CST Fri Nov 28 2025

Sunday
Assessment...A certainty (>99%) of below normal temperatures

The slight southward shift in the track of the pivoting storm system
means light snow will linger east of the Mississippi Sunday morning
before ending. Windy conditions through the day will keep wind
chills in the single digits and teens.

Sunday night through Friday
Assessment...Very high confidence (>90%) of below normal
temperatures

Polar air will overspread the Midwest in the wake of the departing
storm system and essentially remain in place for the week.

Single digit lows will be seen Sunday night and Monday night across
the area. However, winds will be light so wind chills will be close
to the actual ambient temperature.

All global models bring a weak upper level disturbance through the
area Monday afternoon/evening and show this with 30-50% pops. The
system is moisture starved but the forcing is good. Thus there
should be a quick shot of light snow Monday afternoon/evening for
areas generally south of Highway 30. Early estimates suggest a
dusting of accumulation in the Highway 30 corridor with amounts
approaching an inch south of a Sigourney, IA to Aledo, IL line.

A very weak system is progged to move through the area on Wednesday
which will allow a brief warm-up in temperatures. The models
disagree on track and timing but agree that the system is moisture
starved. As we get closer to the event some better resolution may
result in low snow chances being generated.

Outside of these two snow chances, the remainder of the week looks
to be dry and colder than normal.

&&

.AVIATION /00Z TAFS THROUGH 00Z SUNDAY/...
Issued at 523 PM CST Fri Nov 28 2025

Poor flying weather is expected in a 24+ hour period, beginning
this evening and lasting well into Saturday night as a winter
storm brings heavy snow, fog, LIFR winter storm conditions to
all of eastern Iowa and western Illinois.

VFR conditions early evening will quickly deteriorate to
MVFR/IFR 02-06z as the winter storm arrives. There is a high
(>80%) probability of LIFR conditions developing by or after
10z/29. Snowfall rates generally look to be around 0.5
inch/hour. However, snowfall rates of 1-1.5 inch/hour are
possible after 10z/29. Between wind gusts with some blowing snow
and falling snow, LIFR conditions are expected to last into
Saturday night.

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...Winter Storm Warning until 6 AM CST Sunday for IAZ040-051-052-
     063-064-076-077-087-088.
     Winter Storm Warning from midnight tonight to 6 AM CST Sunday
     for IAZ041-042-053-054-065>068-078-089-098-099.
IL...Winter Storm Warning from midnight tonight to 6 AM CST Sunday
     for ILZ001-002-007-009-015>018-024>026-034-035.
MO...Winter Storm Warning from midnight tonight to 6 AM CST Sunday
     for MOZ009-010.

&&

$$

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