Plainfield, Illinois 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

924
FXUS63 KLOT 070512
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
1112 PM CST Fri Mar 6 2026

.KEY MESSAGES...

- Strong to severe thunderstorms with damaging winds and large
  hail are possible across northern Illinois through early
  evening, particularly around and south of Interstate 80.

- Another round of scattered thunderstorms may bring strong to
  locally damaging winds across the area late tonight through
  around sunrise Saturday.

- Chance for thunderstorms next Tuesday into Tuesday night.

&&

.MESOSCALE...
Issued at 923 PM CST Fri Mar 6 2026

A recent surface analysis revealed a cold front stretching from
far southeastern Minnesota through central Iowa and into eastern
Nebraska within a low pressure trough. A coherent surface low
appears to be consolidating in central Iowa ahead of an upper-
level shortwave evident in water vapor imagery approaching the
Missouri River. Regional radar-derived VWPs indicate a strong
low-level jet characterized by some 50 to 60 kt of flow at 2kft
across the Mississippi River Valley ahead of the cold front.
Convection continues to organize in several regimes between the
Missouri and Mississippi Rivers, including two separate areas of warm-
air advection-driven storms in Missouri and central Iowa,
storms developing along the true cold front in eastern Kansas,
and thunderstorms developing well behind the cold front across
western Iowa.

The area of convection of greatest interest to our local area
appears to be the warm-air advection-driven activity in central
Missouri, which has recently evolved into a somewhat
disorganized squall line. Per the 00Z RAOBS from DVN and ILX,
the downstream environment in Illinois is characterized by
around 250 to 500 J/kg of MUCAPE, which is largely being
facilitated by modestly steep mid-level lapse rates of 7 to 7.5
K/km. With the upper-level jet streak associated with the
aforementioned shortwave approaching the Missouri River poised
to lift into Iowa and Wisconsin, deep-layer shear decreases with
eastward extent into Illinois. When taken together, the
increasingly marginal thermal and kinematic environment should
encourage the line of storms to weaken after crossing the
Mississippi River, perhaps becoming quite outflow dominant and
only supportive of highly slanted convective elements that tilt
rearward atop the residual outflow boundary. With this in mind,
am not currently expecting a threat for severe weather on a
widespread basis as the line of decaying storms moves across the
area overnight. A reasonable worst case scenario appears to be
a localized opportunity for a damaging wind gust or two (50 to
60 mph), mainly if any bowing segment were to develop and
survive into Illinois tonight. At this point, such a threat
appears to be on the lower end of the spectrum (a 5 to 15%
chance, highest west of I-39).

Based on the current position of the line of storms, it should
approach I-39 in the 1 to 3 AM time window, the I-55/I-57
corridors in the 2 to 5 AM timeframe, and the IL/IN state line
in the 4 to 6 AM timeframe, give or take an hour (and again, in
decaying fashion). Note that we expect a healthy region of
showers to follow the decaying storms and prior to the passage
of the cold front owing to increasing upper-level diffluence in
the right entrance region of the upper-level jet moving
overhead. So, tomorrow morning looks wet for most areas even if
not overtly stormy. The cold front will move across the area
after daybreak.

Borchardt

&&

.DISCUSSION...
Issued at 216 PM CST Fri Mar 6 2026

See updated mesoscale discussion for information regarding
storms in the area through early evening.

An overall lull in precip is expected mid-evening into the
early overnight hours, a somewhat disorganized band of showers
and storms ahead of an approaching cold front is expected to
cross the area overnight into Saturday morning. With strong low-
level SW flow and a very moist airmass becoming anchored in the
warm sector through much of the night, low-level inhibition
should remain relatively weak ahead of any storms. With deeper-
layer forcing expected to remain somewhat disorganized,
convective mode lends toward broken linear segments as opposed
to a solid QLCS line. Either way, the relatively weak static
stability combined with an impressive kinematic field indicates
an inherent damaging wind risk with any storm.

The cold front will cross the forecast area through the day on
Saturday, with temperatures reaching the high in the morning
before steadily falling through the afternoon on breezy WNW
winds. Unseasonably warm conditions will persist Sunday and
Monday before a low passing well to the north pushes a cold
front over or through the area Monday night into Tuesday. A
trough ejecting from the southwest will interact with the
existing baroclinic zone somewhere over the region Tuesday into
Wednesday, bringing unsettled and cooler weather to the forecast
area during this time.

Kluber

&&

.AVIATION /06Z TAFS THROUGH 12Z SUNDAY/...
Issued at 1112 PM CST Fri Mar 6 2026

The TAF period will start relatively quiet with south to
southwest winds and broken VFR cloud cover. A stout low-level
jet (sampled at nearly 50-60kt at 2kft) will continue to meet
LLWS thresholds through the early portion of the TAF period.

Thunderstorms spreading northeastward across the Mississippi
River are expected to gradually decay while approaching the
terminals overnight. Nevertheless, still believe there will be a
2 to 3 hour window of thunder at any given terminal, which will
be reflected in targeted TEMPO groups centered generally
between 07Z-12Z. Showers will continue past daybreak and may
transition into drizzle as low-level southwesterly flow
increases ahead of a cold front. Gusts in the 25-30kt should be
common through mid-morning.

A cold front will sweep across the region generally between
16Z-19Z, leading to a wind shift toward the west-northwest.
Expansive MVFR cigs are expected to develop and prevail behind
the cold front, first starting near 1200-1500 feet before rising
to 2000-2500 feet by late afternoon. Cigs should attempt to
scatter after sunset as winds ease in response to a surface
pressure ridge building into the area. Have noted a modest
signal for the development of fog toward the end of the TAF
period, but currently expect enough surface flow to prevent
widespread fog from developing.

Borchardt

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...Small Craft Advisory until noon CST Saturday for the IL and IN
     nearshore waters.

&&

$$

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