678
FXUS63 KLOT 031200
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
600 AM CST Tue Nov 3 2026

.KEY MESSAGES...

- Windy and unseasonably warm today.

- Showers likely later today and tonight, with a good soaking
  rainfall expected over much of the area before tapering off
  Wednesday morning.

- A return to more seasonable temperatures expected late this
  week into the upcoming weekend.

&&

.DISCUSSION...
Issued at 225 AM CST Tue Nov 3 2026

Early morning surface analysis depicts a pair of low pressure
systems across the Plains and upper Midwest, one across
northeast MN and the other across south-central KS. The southern
low is forecast to lift northeast into eastern IA through this
evening, before deepening to around 997 mb and continuing into
western WI by early Wednesday. This deepening is in response to
a strong mid-level short wave trough rotating around the base of
the larger scale upper trough across the central CONUS.
Eventually, the mid-level closed low is progged to become
vertically stacked above the occluding surface cyclone and drift
east-northeast across the northern Great Lakes region Wednesday
night into Thursday.

In the near term, a broad region of enhanced low-level
southerly flow was in place east of the low across the Midwest.
Warm/moist advection on south winds gusting to 20-25 mph
continue to produce an extensive low-stratus deck and drizzle at
this hour, in addition to unseasonably warm overnight temps in
the low-60s. Current obs trends indicate cloud bases lifting
from south to north, which will end the drizzle early this
morning. The tight surface pressure gradient will continue to
support strong/gusty southerly winds across the area today into
tonight, with gusts 35-40 mph especially later this morning
through this afternoon/early evening. Depending on how deeply
the boundary layer can mix, 40+ mph gusts are possible
especially across our southern/eastern counties where cloud
cover looks to be thinner allowing warmer low-mid 70s temps.
Farther north/northwest, more cloud cover and increasing shower
chances may limit temps to the mid-upper 60s.

Large scale forcing will begin to increase later this
morning/today however, as the strong Plains short wave lifts
northeast into the region. Rain/showers and some embedded
thunderstorms (currently evident across MO/southern IA) will
spread into the forecast area from the southwest later this
morning into this afternoon. This strongest forcing continues to
appear to be focused over the area this evening and overnight,
ahead of the slightly negatively-tilted wave and approaching
surface cold front. The combination of this forcing, deep
moisture (PWATs approaching 1.70" or nearly 300% of normal) and
north-south mid-level frontogenetic banding, will likely support
fairly widespread rain amounts in excess of a half inch, with
some locally higher amounts especially across the western half
of the forecast area.

Rainfall will taper off from west to east Wednesday morning
behind the cold front, though scattered showers may linger at
times into the end of the week as the upper trough drifts slowly
over the area. In fact, the upper trough is progged to be slow
to exit to the east through the end of the week, with some
guidance (notably the EC/ECE) keeping the remnant upper level
low across the Great Lakes region through Friday. Eventually
mid-level short wave ridging should develop behind the departing
trough, at least temporarily, with current ensembles indicating
dry weather from late Friday into Saturday. Additional
shortwaves rippling into the region in northwest flow aloft
later in the weekend may bring back some scattered shower
chances in the Sunday-Monday timeframe.

Temperature-wise, after well-above average warmth today,
readings will trend cooler behind the cold front on Wednesday
with highs in the upper 50s/low 60s. Daytime highs in the 50s
and lows in the 30s/40s are expected Thursday through the
weekend, which are around our averages for this time of year.

Ratzer

&&

.AVIATION /12Z TAFS THROUGH 18Z WEDNESDAY/...
Issued at 600 AM CST Tue Nov 3 2026

Main Concerns:

- Strong/gusty southerly winds today-tonight, but especially mid
  to late morning through early to mid afternoon

- Showers initially in RFD area and points west later this
  morning will gradually expand eastward into the Chicago metro,
  with showers then continuing Wednesday morning, ending by midday

- Lower CIGs will remain primarily confined to RFD area and
  points north/west today, and then return to the Chicago metro
  terminals tonight into Wednesday morning

A slow moving low pressure system will affect flying conditions
across the ZAU and C90 air spaces today through Wednesday
morning. With primarily VFR conditions at the Chicago metro
terminals today, the main item of note is strong southerly winds
(180-200 deg) expected to peak from about 15z until 21z
(earlier decrease with westward extent). During this time,
forecast soundings suggest gusts to around 30 kt, and a
plausible upside potential to the mid-upper 30s kt range.

Prevailing rain showers are expected several hours earlier at
RFD than at the IL Chicago metro terminals, with an even later
start at/near GYY. Scattered SHRA may affect the IL Chicago
metro terminals at times this afternoon. Later today into
tonight, there`s a 15-20% chance for embedded TS, mainly at RFD,
though confidence remains too low for any mention. During the
most widespread SHRA (overnight-early to mid Wed AM at the Chicago
metro terminals), at least occasional MVFR VSBY is favored.

Winds (gusts to 20-25 kt) will likely shift to south-southeast
tonight and then back to southerly Wednesday morning, followed
by a wind shift to southwest mid to late morning with the cold
frontal passage.

Castro

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...Small Craft Advisory until 6 AM CST Wednesday for the IL
     nearshore waters.

     Small Craft Advisory from 9 AM this morning to 6 AM CST
     Wednesday for the IN nearshore waters.

&&

$$

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