Wedron, Illinois Weather Forecast Discussion

414
FXUS63 KLOT 182001
AFDLOT
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
301 PM CDT Thu Sep 18 2025
.KEY MESSAGES...
- Warm and primarily dry conditions persist through Friday
  afternoon.
- Periodic chances for showers and some thunderstorms will
  return Friday night into next week, though there will continue
  to be plenty of dry hours too.
&&
.DISCUSSION...
Issued at 300 PM CDT Thu Sep 18 2025
Through Friday Night:
Mid-level blocking that has been a prominent feature across
central North America over the past week will begin to shift as
the main upper-level low centered over South Dakota drifts ENE
into the weakening ridge over central Canada. A wave over west
Texas will track NE on the periphery of the upper-level low late
tonight and brush the area to the west with a few high-based
showers. The antecedent airmass remains quite dry with eastward
extent, but it is possible some of the showers survive to the
ground as sprinkles west of I-39 after midnight and before
sunrise Friday.
As we have seen the past several nights, the longer September
nights and continued lights winds on the edge of the departing
surface ridge will again support patchy shallow for interior
locations of northern Illinois late tonight. The incoming cloud
cover should limit coverage of the fog compared to last night.
A stronger compact wave embedded in the upper-level low over
Nebraska tonight will rotate toward the Upper Mississippi River
Valley Friday through Friday night. Meanwhile, a ribbon of mid-
level moisture will advect NE toward the area. Though the bulk
of the forcing from the wave is expected to pass northwest of
the forecast area, a trailing and increasingly sheared trough
axis will drag across the area during this time and interact
with the incoming moisture. Lapse rates will also be marginally
favorable for some embedded thunderstorms. While the exact
coverage of showers and storms remains unclear, indications are
that coverage will be at least widely scattered. Additionally,
mostly unidirectional and seasonably weak deep-layer flow nearly
parallel to the slowing trough will support slower/training
showers and storms in narrow SSW to NNE corridors.
Kluber
Saturday through Thursday:
On the heels of the extended warm and dry stretch we`ve been in,
the more unsettled regime beginning Friday-Friday night will
continue into next week.
Heading into Saturday, past sunrise, there should be a general
weakening of any activity lingering from overnight. The strongest
large scale forcing will lift towards the northwestern Lakes. A
quasi-stationary front bisecting the area early Saturday will
lift north as a warm front, packing daytime dew points several
degrees higher than has been common of late (into the 60s). With
modest mid-level lapse rates and forcing, the extent of
afternoon convective redevelopment is a bit unclear. Modest
destabilization (and weak capping) of the warm and fairly humid
air mass may set the stage for isolated to widely scattered
showers and storms that should tend to decay with sunset. Our
highest PoPs in the 30-40% range are focused primarily
near/north of I-80 closer to the stronger forcing north of our
area.
Following the diurnal decay of PM showers and any storms
Saturday evening, there may be some additional activity
overnight on the nose of a veering low-level jet, although
timing may tend to somewhat limit thunderstorm coverage. Looking
into Sunday, while the highest chance PoPs (~50%) are
technically in the afternoon, there appears to be a scenario in
which the coverage of showers and any storms maximizes in the
morning as a weak cold front moves across the area. It will
otherwise be a warm (highs in the mid 70s to lower 80s) and
fairly humid (dew points low-mid 60s) last full day of
astronomical summer.
A series of short-waves embedded in a trough into the northern
and central Lakes will move through Sunday night through Monday
night, bringing additional rounds of showers and some storms
(PoPs generally in the 40-60% range during this timeframe).
While there`s uncertainty in specifics, and there will be plenty
of dry hours, this could provide opportunities for some areas
to pick up needed rainfall. Unfortunately for notable
drought/dryness improvement prospects, this upcoming unsettled
stretch doesn`t appear favorable for an area- wide multi-day
soaking rain event.
For the midweek period next week (Tuesday-Thursday),
uncertainty abounds, tied to the potential for a closed mid-
upper level low to meander somewhere over the central US. Where
the core of the upper low sets up will determine whether we get
into a drier stretch with persistent northeasterly low level
flow, or if opportunities for showers and some storms continue
deeper into the week. For now, our PoPs seem to favor the latter
(farther southwest upper low) scenario, with low (~20%) PoPs by
Wednesday-Thursday.
Castro
&&
.AVIATION /18Z TAFS THROUGH 00Z SATURDAY/...
Issued at 1222 PM CDT Thu Sep 18 2025
There are no significant aviation weather concerns anticipated
through the period.
Overall, our period of quiet weather will continue this period.
The only notable weather feature of interest for this afternoon
is the easterly wind shift expected with the inland shifting
lake breeze. Current trends suggest this easterly wind shift
will occur in the 19 to 20z time period at the main Chicago
terminals, and late this afternoon at KDPA and KRFD. While wind
speeds with the lake breeze look to be in the 8-10 kt range,
speeds should ease tonight before picking back up again from the
east on Friday. Otherwise, aside from another chance of some
patchy ground fog outside of the main Chicago terminals towards
daybreak Friday morning, VFR conditions are expected through the
period.
KJB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...None.
&&
$$
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NWS LOT Office Area Forecast Discussion