Tinley Park, Illinois 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

103
FXUS63 KLOT 070323
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
923 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 /00Z TAFS THROUGH 06Z SUNDAY/...
Issued at 632 PM CST Fri Mar 6 2026

Ongoing convection across the southeastern ZAU airspace will
continue to move away from the terminals. Otherwise, winds this
evening will remain out of the south to southwest with speeds
around 10 kt. A modest increase in speeds with gusts up to
20-25kt may occur in the coming hours as the southwesterly low-
level jet intensifies. With that said, surface flow should
remain largely decoupled from the low-level jet, leading to LLWS
criteria being met through the overnight hours.

Convection developing across the Upper Mississippi River Valley
is expected to consolidate into several linear segments and
shift into the region during the early morning hours of
Saturday. Will go ahead and convert the PROB30 groups to TEMPO
groups with the expectation for at least scattered coverage in
the terminals overnight (though will maintain a PROB30 for GYY
where coverage may tend to become isolated). Convection
overnight may produce northwesterly gusts up to 30 kt.

After daybreak, a period of MVFR cigs and drizzle is expected
before a cold front moves through by early afternoon. Cigs
should gradually rise thereafter, as winds turn northwesterly
and routinely gust above 20kt.

Borchardt

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...Dense Fog Advisory until 9 PM CST this evening for the IL
     nearshore waters.

     Small Craft Advisory until noon CST Saturday for the IL and IN
     nearshore waters.

&&

$$

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