Des Plaines, Illinois 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

797
FXUS63 KLOT 060739
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
239 AM CDT Mon Apr 6 2026

.KEY MESSAGES...

- Low (<30%) chance for scattered snow showers near Lake
  Michigan tonight into early Tuesday.

- Sub-freezing temperatures expected tonight, but warmer
  conditions develop Wednesday and into the weekend.

- Brief chance for a light snow/rain mix Tuesday night.

- Periods of showers and storms are possible late in the week
  into next weekend.

&&

.DISCUSSION...
Issued at 239 AM CDT Mon Apr 6 2026

Early morning GOES vapor imagery shows a low-amplitude short
wave tracking quickly east-southeast across the western Great
Lakes region. At the surface, a cold frontal trough associated
with this wave extended from central Lake Michigan, southwest
into far southeastern IA as of 06Z. A cluster of showers (with a
couple of isolated lightning strikes noted over the past 1-2
hours) was noted ahead of the cold front, from La Salle county
to southern Lake Michigan and northwest Indiana. These showers
will exit the forecast area to the east during the predawn
hours, with the cold front following shortly behind them. Breezy
northwest winds gusting around 30 mph will usher in slightly
cooler temperatures today, resulting in highs from the mid-upper
40s along the IL/WI border to the mid-50s well south of I-80.
Sky cover will vary from partly to mostly cloudy (more clouds
likely north, more sun to the south).

Another sheared mid-level short wave is progged to transit the
upper Midwest this afternoon, which will send another
reinforcing, sharp lake-assisted cold front southward into the
area this evening. This will turn still-blustery winds more
north-northeast tonight, while also dropping temperatures into
the mid-20s to low-30s. There also continues to be guidance
support from high-res models for scattered snow showers
along/behind the frontal zone late this evening into the
overnight hours, with lake to 850 mb delta-Ts around 15/16C and
equilibrium heights around 6 kft. This may support some
scattered lake-induced snow showers overnight as the mid-level
trough axis passes overhead. While blended pop guidance isn`t
too excited, did add some slight chance (~20%) pops over the
lake and adjacent counties of northeast IL/northwest IN for the
overnight hours as well as some patchy trace to 0.1 accumulation
amounts. We`ll have to keep an eye on trends later
today/tonight in case these snow showers end up being more
robust. Low-level winds ramp down quickly Tuesday morning as
surface high pressure builds in from the northwest, though a
weak convergence axis is progged to linger into the northwest IN
shore during the morning, thus scattered snow showers would
likely persist into early Tuesday there before dissipating.

Temperatures should fall off quickly Tuesday evening, dipping
into the 20s again over far northeast IL (especially northern
Chicago suburbs) as the center of the surface high shifts just
to our east across the Great Lakes. Surface winds back south-
southeast overnight however as the high drifts away, and warm
advection flow ramps up downstream of an upper trough over the
Plains. This, in addition to increasing cloud cover, should
produce slowly rising temperatures into the low-mid 30s
overnight. There also remains decent model and ensemble
agreement in resulting moist isentropic ascent and frontogenetic
forcing within the northward advancing mid-level baroclinic
zone to result in development of light snow (potentially
changing to rain as the column warms/moistens) overnight,
primarily across the northwest half or so (generally northwest
of the I-55 corridor). As the previous discussion indicated,
NBM pops can be underdone in these lighter QPF scenarios, but
did come in slightly higher than previous runs. Also can`t rule
out a brief period of freezing rain as the column warms, though
surface temps will also be rising with time as well and expect
any FZRA would be short-lived.

Any lingering precipitation should lift north of the cwa early
Wednesday morning, with a dry, breezy (windy?) and much warmer
day in store. NBM blended wind guidance currently tops out near
35 mph, though higher gusts around 40 mph would be possible if
cloud cover clears out sufficiently in the afternoon. Current
forecast highs in the mid-upper 60s could also be a little
underdone if we were to mix more deeply with more sunshine.

Shower chances then return to the area Wednesday night and
Thursday, as a deep upper trough lifts across the upper Midwest
and trails a cold front into the region during the
Thursday/Thursday night period. Can`t rule out some embedded
thunderstorms, though instability continues to look fairly muted
within the relatively narrow moist axis ahead of the front,
with guidance maintaining greater SB/MUCAPE values back across
the Plains and lower Missouri Valley. Details remain somewhat
unclear later in the forecast period, as surface high pressure
eventually builds into the upper Midwest while the
aforementioned cold front stalls across our south of our area.
If the front stalls nearby, additional short waves transiting
the baroclinic zone could support additional rounds of showers
and possibly thunderstorms Friday into the weekend. If the high
builds in more strongly, the front could end up far enough south
of the forecast area for a period of dry weather early in the
weekend. In either case, global ensembles continue to suggest an
active weather pattern persists early next week.

Ratzer

&&

.AVIATION /06Z TAFS THROUGH 12Z TUESDAY/...
Issued at 1242 AM CDT Mon Apr 6 2026

Key Aviation Messages for the current TAF period:

- Scattered showers (and any chance for MVFR cigs) are expected
  to be east of the terminals by 07Z.

- Gusty northwest winds are expected through the day today.

- Winds diminish and turn north-northeasterly at the end of the
  current TAF window

A band of showers is visible on the KLOT radar ahead of cold
front moving across the airspace. Most cigs with these showers
remain VFR, but there is a chance that localized MVFR cigs are
possible during a shower. Regardless, these showers are expected
to be east of the terminals by 07Z. Prevailing winds are
currently out of the west, but a brief burst of 20 knot
northwest wind gusts are possible as the showers pass through.

Winds are expected to turn to the northwest behind the front
with intermittent gusts up to 20 knots in the cold air advection
regime. A patch of MVFR cigs in northern Minnesota will be
monitored through the night. There is still a non-zero chance
that those lower cigs make there way into northern Illinois
(best chances near KRFD and the state line), but for now was
kept out of the TAF. After sunrise, deeper mixing will allow for
more persistent gusts between 20 to 25 knots through the day.
Otherwise, VFR and dry conditions are expected.

As surface high pressure expands over northern Wisconsin after
00Z tomorrow, a weak surface trough will exit the northern
Great Lakes to the east. As this occurs, winds will gradually
become more northerly and flip to the northeast closer to 06Z.
There is a less than 30 percent chance for a brief shower
(potentially some flurries) around 06Z as the trough moves
east. However, the amount of dry air depicted in model
soundings prohibit mention of any precip in the TAFs presently.

DK

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...Small Craft Advisory from 11 AM this morning to 10 AM CDT
     Tuesday for the IL and IN nearshore waters.

&&

$$

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