Plainfield, Illinois 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

750
FXUS63 KLOT 222347
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
547 PM CST Sun Feb 22 2026

.KEY MESSAGES...

- Accumulating lake effect snow will result in travel impacts
  across parts of NW Indiana (Porter County in particular)
  through Monday.

- Tuesday will be windy and milder with southwesterly gusts to
  ~35 mph.

- Monitoring potential for accumulating snow somewhere in the
  region in the Wednesday night-Thursday timeframe. Too early to
  have much confidence in track of system and any local impacts
  just yet.

&&

.DISCUSSION...
Issued at 256 PM CST Sun Feb 22 2026

Through Monday:

The main focus continues to be on lake effect snow trends into
northwest Indiana. However, in the near term, we`re also
assessing the recent blossoming of enhanced snow showers over
eastern Wisconsin to just off the Wisconsin shore. While the
primary vort lobe is over northern Illinois as of this writing,
a more subtle elongated 500 mb vort/impulse appears to be over
north central WI, just west of the Green Bay to Sheboygan
corridor. This appears to be contributing to the recent
enhancement of snow showers, with possibly some upstream
connection to moisture from Lake Superior as well.

Given the current south-southeasterly trajectory of the snow
showers, it`s unclear if these will make it into northeast
Illinois. The associated mid-level impulse may start to weaken
as well. Even if these snow showers make it down in some fashion
into the Chicago metro, it doesn`t *currently* look to be a
repeat of Saturday evening over parts of Chicago. That said,
we`ll certainly keep a close eye on radar and observational
trends and upstream webcams with respect to the potential for
localized travel impacts.

Of greater note, the passage of the aforementioned mid-level
impulse is forecast to veer winds to more northerly over Lake
Michigan (340-350 deg flow vs. 310-320 deg as of this writing).
Forecast soundings show a noticeable improvement of overlap of
strong low-level lift with favorable lake induced thermodynamics.
This could yield moderate to briefly heavy snowfall rates into
parts of Porter County, and even as far west as the northeast
half of Lake County (considering the decent returns already
present there this afternoon). The big question mark is the
behavior of the lake effect banding - i.e. are there a couple
of enhanced bands that evolve out of multi-cellular activity
and then one band becomes more dominant and intense?

Recent runs of the HRRR and RAP in particular have been
consistently farther west with a more intense band Monday
morning, reaching the LaPorte/Porter line, or even just into
Porter County. The HRRR and RAP do tend to have a westward bias
with lake effect banding, so did not quite jump on this idea,
but did bump up PoPs to categorical Monday morning for northeast
half of Porter County (and likely into northeast Lake). Will
advertise additional accumulations of 1 to as much as 4".
Strengthening northerly winds tonight may also yield at least
patchy blowing and drifting snow. If the signal increases for
higher accums to reach into Lake County, we may need to consider
issuing a Special Weather Statement this evening (or even
perhaps expanding the advisory). Finally, if the heavier band
does reach farther west Monday morning, we may need to extend
the Porter County advisory, but confidence is low.

Outside of the lake effect potential, intermittent non-
accumulating flurries across the entire area will gradually come
to an end from west to east overnight into Monday morning with
the dissipation of the persistent stratus deck. It will be a
cold start to the workweek, with wind chills within a few to
several degrees of zero either side during the commute owing to
still blustery north-northwesterly winds. Highs will reach the
upper 20s to locally around 32F Monday afternoon west of the
lake induced cloud cover.

Castro

Monday Night through Sunday...

Northerly low-level winds will likely maintain shallow lake-
induced stratocu across parts of northwest Indiana Monday
evening and perhaps even some poor quality flurries. This
stratus layer should erode overnight however, as large-scale
subsidence and drying in the wake of the deep east coast upper
trough works to further lower inversion heights, decrease winds
and erode the stratocu layer. An associated north-south oriented
surface high pressure ridge will transit the forecast area
overnight, allowing light winds to turn southerly by morning.

Meanwhile, guidance remains in good agreement in depicting a
clipper system dropping east-southeast toward the upper Midwest
toward daybreak Tuesday, with its surface tracking from northern
Minnesota into the northern Lakes during the day while
deepening to around 995 mb. While guidance continues to track
the mid-level vort and strongest ascent north of the forecast
area, the diffluent/divergent left exit region of a 150 kt upper
level jet streak associated with the wave is progged to provide
additional forcing to cool and saturate mid-levels, steepen
lapse rates aloft and potentially produce some precipitation as
far south as far north/northeast IL and far northern IN Tuesday.

NBM blend has maintained the trend of 20-30% pops north of the
I-80 corridor, highest toward the IL/WI border. If any
precipitation occurs, which isn`t a lock, P-type would be snow
during the morning/midday, with some rain or rain/snow mix later
in the day as surface temps warm on strong south-southwest
winds. The ensembles then trend dry in the evening and
overnight. Speaking of those winds, as the surface low deepens
to our north, gusts approaching 30-35 mph appear likely. Drier
ECMWF/EPS guidance still indicates daytime RH values to the 25-
30% range in the afternoon. This would continue to present some
potential for a heightened grass/brush fire threat across our
south/southwest counties where precip is less likely and temps
warm into the low-mid 40s.

12z global ensembles were in fair agreement with their
depiction of an amplifying short wave tracking southeast from
the Northern Plains into the Midwest during the Wednesday night
through Thursday timeframe. EPS/GEFS/CMCE means remain loosely
clustered with a surface low track near/south of our forecast
area, and in the potential for accumulating snow across parts of
the region. Confidence remains low in the fine details at this
distance however, given differences in degree of phasing and
amplitude of the wave. A fully phased stronger system could
introduce p-type issues to parts of the area, while a weaker,
farther south system would result in a sharp gradient on the
northeast edge of the precip shield. Nonetheless, this period
bares watching for the potential for some wintery impacts
associated with this system. A brief warm-up to close out the
workweek then looks to give way to another pronounced cool down
as we close out February and start March (and meteorological
spring!)

Ratzer/Castro

&&

.AVIATION /00Z TAFS THROUGH 06Z TUESDAY/...
Issued at 547 PM CST Sun Feb 22 2026

Key messages:

- Continued light snow/flurries through tonight with a period
  of MVFR VSBYs possible mid-late evening (30% chance).

- Lake effect snow may drift back west to near/over GYY ~15-19Z
  with associated VSBY/CIG reductions (30% chance).

- Low confidence on CIG trends overnight with a period of high-
  end MVFR possible.

A broad area of VFR flurries is ongoing early this evening with
embedded snow showers in northwest Indiana. This activity will
continue through tonight and may enhance during the mid-to-late
evening timeframe, associated with a brief period of slightly
better forcing currently diving south out of Wisconsin. The
arrival of this feature has slowed somewhat so have shifted the
start time of the PROB30 for MVFR VSBYs in -SN to 2Z with this
update. Expect any VSBY reductions that occur to gradually
improve toward the 5-6Z timeframe.

The flurries will end from west to east early Monday morning in
Illinois, however, snow showers will continue over portions of
northwest Indiana through the day (which may include GYY).
Opted to introduce a PROB30 at GYY for reduced VSBYs/CIGs in -SN
to account for the low potential for a westerly wobble of the
lake effect band, though at this time confidence is higher
farther east into Porter County.

Winds will remain breezy out of the northwest tonight through
Monday morning with gusts around 25 kt. Winds then gradually
ease from west to east in the afternoon and becoming light and
variable after sunset.

Petr

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...Winter Weather Advisory until noon CST Monday for INZ002.

LM...Small Craft Advisory until 3 AM CST Tuesday for Winthrop
     Harbor IL to Gary IN.

     Small Craft Advisory until 6 PM CST this evening for Gary to
     Burns Harbor IN-Burns Harbor to Michigan City IN.

     Gale Warning until 3 PM CST Monday for Gary to Burns Harbor IN-
     Burns Harbor to Michigan City IN.

&&

$$

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