501
FXUS63 KLOT 300518
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
1218 AM CDT Fri Oct 30 2026

.KEY MESSAGES...

- Periods of showers and/or drizzle are expected at times
  Friday through this weekend (greatest chances/coverage
  expected Friday night through Saturday morning).

- Additional periods of wet weather are likely next week.

&&

.DISCUSSION...
Issued at 201 PM CDT Thu Oct 29 2026

A cold front is tracking southeastward across our forecast area
at the time of this writing. Some pre-frontal convection that
developed and affected areas near and east of I-57 a little
while ago has since moved off to our east into IWX`s CWA. GOES
satellite imagery shows that cumulus in the trailing portion of
the same pre-frontal confluence zone is still attempting to
grow, and additional isolated to widely scattered shower and
thunderstorm development could still in our far southeastern CWA
over the next few hours. However, the convergence/confluence
here isn`t quite as good as it was earlier farther to the north,
so not anticipating any greater convective coverage in our CWA
through the remainder of this afternoon.

Heading into Halloween weekend, a couple of disturbances of
Pacific origin are expected to lift northeastward into the
Midwest. While these disturbances are progged to remain somewhat
disorganized, their arrival -- paired with modest isentropic
ascent, broad synoptic forcing within the right entrance region
of a 100+ kt upper- level jet streak over the Great Lakes, and
an associated influx of tropospheric column moisture -- will
result in some showery/drizzly periods through the weekend.

The first raindrops could be seen in our forecast area as early
as midday tomorrow, though with dry low-mid-level air to work
through and the better forcing still lagging to our southwest,
much of the area likely won`t see any measurable rainfall until
Friday night into Saturday morning as the more coherent forcing
and better moisture spreads into the area. Couldn`t rule out a
few isolated lightning strikes occurring during this Friday
night into Saturday morning time period as slightly steepened
mid-level lapse rates attempt to creep into our CWA. However,
forecast soundings indicate that most of any associated meager
instability should remain concentrated below the -20C level --
suggesting that even the taller convective cells may struggle to
achieve electrification. Deterministic and ensemble guidance
broadly suggests that the shower activity should tend to
decrease in coverage going into Halloween evening, though at
this time, it remains possible that at least isolated pockets of
rain and/or drizzle could manage to hang around past sunset and
affect trick-or-treating activities for some. Additional
periods of rain and/or drizzle may be seen in our area on Sunday
as well, though forecast confidence in this is lower compared
to Saturday.

Early next week, multiple additional upper-level disturbances
are expected to conglomerate somewhere over the western or
central CONUS and yield a slow-moving, high-amplitude composite
longwave trough. The exact details of how everything will come
together remains unclear at this time, but it`s likely that
we`ll see additional rainy periods next week as this troughing
meanders towards and across our longitude. Temperatures for next
week will also largely hinge on the evolution of this trough
and when any associated rainfall works its way through our area.

Ogorek

&&

.AVIATION /06Z TAFS THROUGH 12Z SATURDAY/...
Issued at 1218 AM CDT Fri Oct 30 2026

VFR conditions are expected this period with no significant
flying concerns. Non-impactful sprinkles may occur this
afternoon, with no formal mention of this in the TAFs yet. On
and off -SHRA are expected to develop late this evening and
overnight, earliest at/near RFD, and then continue into Saturday
morning. There may be occasional VSBY reductions after the
current 30-hour ORD/MDW TAF period.

Light northerly to calm/VRB winds early this morning will become
northeast after daybreak, east-northeast this afternoon, and
then east to east-southeast tonight into early Saturday morning.

Castro

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...None.

&&

$$

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