Iowa City, Iowa 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

943
FXUS63 KDVN 180854
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
254 AM CST Sat Jan 18 2025

.KEY MESSAGES...

- The coldest air of the season so far expected this weekend through
  early next week

- A Cold Weather Advisory has been expanded over eastern Iowa
  into portions of northwestern Illinois for late tonight
  through Sunday morning

- The period of very dangerous cold will continue through
  Tuesday morning, with additional cold weather headlines
  expected

&&

.SHORT TERM /THROUGH SUNDAY/...
Issued at 253 AM CST Sat Jan 18 2025

Today will see our transition to a period of colder conditions that
will last through Tuesday morning. Early this morning, colder air
continues to surge southward behind a departing cold front that
swept through the area last evening. Additionally, northwest winds
have strengthened due to the enhanced cold air advection and steep
near-surface lapse rates, with gusts between 25 to 35+ mph being
reported across the area. It will definitely be a far cry from the
relatively warm temperatures we had yesterday, with wind chills
reported as low as two degrees at the Independence, IA airport, so
make sure to bundle up for these brisk conditions if planning to
head outdoors!

The synoptic pattern that will keep the arctic air mass in place
will take shape today, with a large upper-level trough developing
over the majority of the contiguous US and an upper-level low
loitering over Hudson Bay in Canada. The northwest winds should
weaken by the time we head into the afternoon today with a weakening
wind profile, but winds should remain breezy through the overnight
hours into Sunday morning, gusting between 20 to 25 mph during that
time. A weak mid-level impulse along with a secondary push of even
colder air will lead to overnight lows falling to the single digits
both above and below zero. These temperatures, coupled with the
aforementioned northwest winds, will lead to wind chills falling to
the -15 to -30 degrees. We did make some refinements to the ongoing
Cold Weather Advisory, with a slight expansion in coverage to the
south and east. The worst of these conditions look to begin after
midnight tonight, lasting through noon Sunday. One thing to watch
for is cloud cover associated with the mid-level impulse. The latest
HREF seems to suggest a bit more cloud cover than the previous run,
and we have increased cloud cover for a time before being scoured
out. If clouds were to stick around longer, then temperatures may
not fall quite as much. Still, the push of cold air is looking
impressive, with both the GEFS and EPS ensemble means suggesting 850
mb level temperatures around -20 to -25 degrees over the area at
12z/6 AM Sunday morning.

Even during the daylight hours Sunday, it will still feel downright
frigid, with highs warming only to the single digits above zero
across the area. While wind chills will improve Sunday afternoon,
they are forecast to remain in the teens below zero.

&&

.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
Issued at 253 AM CST Sat Jan 18 2025

The bitterly cold pattern continues Sunday night through Tuesday
morning, with the stagnant upper-level trough remaining in place.
Confidence in this overall synoptic pattern remains very high given
nearly unanimous consensus among the GEFS, EPS, and GEPS ensemble
cluster analysis. The coldest of the arctic air mass looks to move
through Monday night and Tuesday morning, with 850 mb temperatures
progged between -25 to -30 degrees C across the forecast area. Not
only are these 850 mb temperatures progged in the lowest 1% of
climatology per the ECMWF ensembles, but with 850 mb temps around -
27 to -29 degrees C possible over the Quad Cities at 12z/6 AM
Tuesday, if these values come to fruition for DVN, they will fall in
the top 10 coldest 850 mb temps in the entire SPC sounding
climatology (period of record goes back to 1995)! Overnight lows in
the single digits and teens below zero are forecast for Monday
morning and Tuesday morning, and daytime highs only in the single
digits and lower teens above zero for Monday and Tuesday. Minimum
wind chills should fall to the -15 to -30 degree F range at times,
so expect some additional cold weather headlines to be needed before
all is said and done.

Relief from the dangerous cold will come Wednesday as the large-
scale pattern changes, with southerly flow returning to help
temperatures warm up closer to seasonal values and the upper trough
breaking down. Highs by Wednesday are progged to warm back up to the
middle 20s northeast to the lower 30s southwest. These temperatures
look to continue through Friday, with overnight lows in the teens
above zero each night.

In terms of precipitation, the forecast remains dry through the
week, but we can`t rule out some waves embedded in the N/NW flow.
Given the low amplitude nature of these, they are hard to resolve in
the models at this juncture, and as such the NBM offers no
measurable PoPs. But, something to keep an eye on as the arctic air
will be very efficient at producing some flakage.

&&

.AVIATION /06Z TAFS THROUGH 06Z SUNDAY/...
Issued at 1050 PM CST Fri Jan 17 2025

Observation trends shows an extensive area of MVFR CIG across
northwest Iowa and southern Minnesota behind the arctic front.
HREF cloud categories indicate MVFR CIGS moving into eastern
Iowa by 12z/18 along with some flurries. Some transient wind
gusts up to 35 knots will also be possible. HREF cloud
categories show a rapid breaking up of the MVFR CIGS 15-18z/18
across eastern Iowa and eventually into northern Illinois. Wind
gusts above 20 knots will persist past 00z/19.

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...Cold Weather Advisory from 3 AM to noon CST Sunday for
     IAZ040>042-051>054-063>068-076>078.
IL...Cold Weather Advisory from 3 AM to noon CST Sunday for ILZ001-
     002-007-015.
MO...None.

&&

$$

SHORT TERM...Schultz
LONG TERM...Schultz/McClure
AVIATION...08