Mitchell, Illinois Weather Forecast Discussion

273
FXUS63 KLSX 220748
AFDLSX
Area Forecast Discussion
National Weather Service Saint Louis MO
248 AM CDT Mon Sep 22 2025
.KEY MESSAGES...
- Southeastern Missouri and southwestern Illinois will be the
  focus for rounds of showers and thunderstorms through the day
  today. Strong thunderstorms are not anticipated, but frequent
  lightning and heavy rainfall are still threats.
- Another round of widespread rainfall is forecast from the
  latter half of Tuesday through Wednesday.
&&
.SHORT TERM... (Through Wednesday Night)
Issued at 245 AM CDT Mon Sep 22 2025
The area of rain with embedded convective elements that is ongoing
across southeastern Missouri and southwestern Illinois this morning
is being aided by subtle disturbances rounding the base of an upper-
level trough and lift from the low-level jet. As the main
disturbance moves eastward and the jet veers, this rain will exit
the CWA eastward through the morning hours. There is a low chance
(30-40%) that isolated to scattered convection will linger through
the daylight hours across far southeastern Missouri and southwestern
Illinois thanks to continuous weak warm air advection and subtle
disturbances moving through the flow aloft. Also in this part of the
CWA, more continuous cloud cover will aid in keeping temperatures
cooler this afternoon (mid to upper 70s) compared to elsewhere in
the CWA (around 80 degrees).
The chance for rain will increase yet again through the day on
Tuesday as a shortwave moves into the Central Plains and lift
increases over the Middle Mississippi Valley. A low-level jet will
ramp up and nose into the CWA through the day, supporting widespread
rainfall expanding across the CWA through the afternoon and evening.
The shortwave will induce surface cyclogenesis over the Southern
Plains, with the low tracking east-northeastward through the Mid
South or Middle Mississippi Valley through Wednesday. The track of
this low will dictate where the best chances for another round of
soaking rain will peak. Despite the fluctuations in guidance,
ensemble-based probabilities for higher thresholds of rainfall have
remained focused generally across far southeastern Missouri and
southern Illinois. For areas south of I-70, as much as an inch of
additional rain may fall (40-50% chance), while areas north of I-70
could see up to around 0.5" (40-50% chance).
Elmore
&&
.LONG TERM... (Thursday through Sunday)
Issued at 245 AM CDT Mon Sep 22 2025
The evolution of the upper-level pattern from the middle of the week
through the weekend continues to fluctuate notably among guidance
sources and initializations. The recent trend has been for a slower
cutoff/fracturing of Wednesday`s trough/shortwave over the Midwest
into the weekend. Despite this trend, the impact on our sensible
weather from previous forecasts will be mostly negligible.
As the core of the trough pulls eastward through Thursday, the
surface low will depart the area, with deep northerly flow setting
up over the Middle Mississippi Valley as a portion of the trough
cuts off somewhere over the center of the CONUS. This flow will
support our temperatures running around seasonal normals through
Thursday night, and moisture wrapping around the backside of the low
will keep a low chance (20-40%) of rain going through then. A
majority of guidance keeps this cutoff meandering over the eastern
half of the CONUS through Friday, with guidance then diverging
significantly in the phasing of the upper-level pattern. Even with
the spread in solutions, a majority of global ensemble members
support calm weather into the weekend with temperatures warming to
just above average.
Elmore
&&
.AVIATION...  (For the 06z TAFs through 06z Monday Night)
Issued at 1055 PM CDT Sun Sep 21 2025
Adjustments have been made in the latest update to address timing
of developing showers and thunderstorms, along with categorical
trends as precipitation move overhead.
A broad area of showers and embedded thunderstorms continues to
blossom over central and southeast Missouri, approaching the
KJEF/KCOU terminals just prior to 04z. Precipitation is delayed by
1-2 hours from prior updates, now placing it over the metro
terminals after 06z. Showers will be more persistent over the
metro area, while central Missouri terminals ride along the
western edges of the shield of precipitation. On the other hand,
KUIN may avoid this round with intermittent sprinkles or light
rain in the first couple hours of the 06z TAF package.
The worst of the impacts are favored late tonight into early
morning as the system pivots over southern Missouri into southern
Illinois. Instability is limited, which should keep thunder
probabilities low, but not necessarily zero. Showers will be the
most common mode with a few claps of thunder possible. The best
chances for thunder remain southeast of the terminals. Ceilings
are expected to lower into MVFR with occasional visibility
restrictions under more intense rainfall. Some of the guidance
indicates there is the potential for IFR conditions for a few
hours early Monday morning. However, guidance has been rather
bullish in the past couple of days, only to later back off.
Upstream observations show pocket of MVFR condition accompanying
more persistent rainfall. Opted to include MVFR and monitor trends
overnight in the event amendments are need to account for IFR.
Rainfall moves eastward mid-morning into early afternoon.
Additional showers/thunderstorms are expected to flare up Monday
afternoon, largely southeast of the metro terminals. Conditions
trend drier and gradually into VFR from west to east.
Maples
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...None.
IL...None.
&&
$$
WFO LSX

NWS LSX Office Area Forecast Discussion