Lostant, Illinois Weather Forecast Discussion

475
FXUS63 KLOT 060602
AFDLOT
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
102 AM CDT Mon Oct 6 2025
.KEY MESSAGES...
- July-like warmth continues for much of the area on Monday.
- A cold front will bring rain chances and some thunderstorms
  Monday afternoon and night.
- Dry conditions and more seasonable temperatures are in store
  mid to late week.
&&
.DISCUSSION...
Issued at 241 PM CDT Sun Oct 5 2025
Elevated fire weather concerns will persist for a few more
hours this afternoon due to dry conditions and gusty southerly
winds. RH values have fallen as low as 25 percent across the
southern CWA while winds have gusted up to 30 mph across
northern Illinois. The associated Special Weather Statement for
elevated fire weather conditions remains in effect through 6pm
CDT.
A deep trough over south-central Canada will track eastward
across northern Ontario through Tuesday. An associated cold
front stretching from northern Minnesota to western Kansas will
track southeast across the area Monday into Monday night,
bringing our first notable chance of rain in nearly two weeks.
The initial chances for precip will occur with isolated mid-
level showers brushing the northwest CWA late tonight into
Monday morning. However, precip at the surface will remain
sparse and light as the showers evaporate through a rather dry
sub-cloud layer.
Poor mid-level lapse rates and diurnal mixing in the warm
sector across the southeast half of the CWA ahead of the front
will limit intensity and coverage of precip, but with the
environment expected to be mostly uncapped, could see some
attempts at isolated thunderstorm during the afternoon. Farther
northwest, low-level forcing along the front (albeit with
overall weak convergence) will provide an impetus for isolated
to scattered showers and some thunderstorms during the
afternoon. Mixing should erode MLCAPE values while mid-level dry
air induces decent entrainment of cells, but appreciable deep-
layer shear and freezing levels around 10kft will support the
potential for small hail and gusty winds with any stronger
shower/storm.
As higher low and mid-level moisture advects toward the area
this evening and especially overnight, larger scale ascent from
the right- entrance region of a slow-moving jet core will
enhance shower/rain coverage and intensity. With a modestly
strong low-level f-gen signal along the front and marginal mid-
level lapse rates above the LPL, narrow bands of heavy rain with
embedded storms are possible. The coverage of heavy rain bands
will be low, so widespread beneficial rain to partially
alleviate the growing drought does not appear likely.
After the rain ends from north to south on Tuesday, dry
conditions are favored through the remainder of the week and
potentially through next weekend as a broad, low-amplitude ridge
settles across the central CONUS. However, a moisture-starved
impulse tracking southeast across the ridge could bring a few
high based showers or sprinkles late Thursday night into Friday.
Otherwise, seasonable temperatures midweek will gradually
moderate back to above normal to well-above normal temperatures
for the weekend.
Kluber
&&
.AVIATION /06Z TAFS THROUGH 12Z TUESDAY/...
Issued at 102 AM CDT Mon Oct 6 2025
Main Concerns:
- Periods of rain/showers mid-late afternoon onward, along with
  a chance of thunderstorms into or through the evening
- Timing of wind shift to northerly late this afternoon-early
  evening
- Deteriorating CIGs late tonight-early Tuesday, with reduced
  VSBY also possible in BR and any drizzle
The first real weather of note in over two weeks will cause
some impacts to flying later today through tonight. VFR, rain-
free conditions should persist until just ahead of, and
especially behind a cold front passage later today. Expect
breezy southwest winds by mid morning until the anticipated
frontal wind shift. A majority of available guidance is a bit
later with the wind shift to north and north-northeast early
this evening, so conservatively adjusted the TAF, but only
slightly later. Right behind the wind shift should bring showers
and perhaps embedded TS. The chance for embedded TS should end
earliest at RFD, while likely lingering through the evening over
the Chicago metro.
CIGs are expected to deteriorate to IFR late tonight, with LIFR
possible. Drizzle and light fog may accompany continued on and
off rain, potentially knocking visibility down into the 3-5
mile range.
Castro
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...None.
&&
$$
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NWS LOT Office Area Forecast Discussion