Fairmount, Illinois Weather Forecast Discussion

233
FXUS63 KILX 081111
AFDILX
Area Forecast Discussion...Updated Aviation
National Weather Service Lincoln IL
611 AM CDT Mon Sep 8 2025
.KEY MESSAGES...
- A warming trend could push temperatures near 90 F by the end of
  the week.
- Little or no rainfall is forecast over the next 7 days.
&&
.DISCUSSION...
Issued at 144 AM CDT Mon Sep 8 2025
Early morning satellite analysis shows decaying convection moving
into the Plains. This activity is linked to a mid-level shortwave
trough currently overriding the ridge. Model guidance
consistently predicts this disturbance will continue eastward
across the Mississippi Valley by Tuesday morning.
The primary effect of this disturbance will be a temperature
increase as low-level winds gradually shift southwest by Tuesday
evening. While there is a slight (10-20%) chance of scattered
showers Tuesday evening due to warm advection, central Illinois is
most likely to remain dry, as the best column moisture is
displaced north of the region.
While temps are likely to trend warmer today (mid 70s) and
Tuesday (upper 70s), the real jump occurs by Wednesday (mid 80s)
as 500-mb heights steadily increase beneath low-level warm
advection. Hot and continued dry weather will then stretch through
at least Friday as the 500-mb ridge amplifies over the central
US. Daily afternoon highs are forecast to warm into the upper 80s
both Thursday and Friday, which is about 5-10 deg F warmer than
what is considered normal for early September.
Model guidance indicates some significant divergence for the
upcoming weekend. The most probable outcome suggests the
continuation of hot and dry conditions into early next week, as
the 500-mb ridge is expected to remain stationary over the central
US. However, a few guidance members, notably the ECMWF, suggest a
breakdown of this ridge due to low pressure moving equatorward
into the Great Lakes between Saturday and Monday. Most other
available guidance is less aggressive than the ECMWF, leading us
to consider it an outlier for now, though it has shown some run-
to-run consistency.
Mid-range guidance typically struggles with resolving blocking
patterns. Therefore, next weekend presents two scenarios: either
dry weather with temperatures around 90 F (the most likely
scenario) or slightly less dry and hot conditions as a backdoor
cold front enters the area (the less likely scenario). Even if the
less likely scenario materializes, precipitation is not
anticipated to be particularly beneficial, with both the Mean and
75th percentile QPF (ECMWF ENS) indicating less than 0.50 inches.
MJA
&&
.AVIATION...  (For the 12z TAFs through 12z Tuesday Morning)
Issued at 611 AM CDT Mon Sep 8 2025
High pressure will result in VFR conditions through the TAF period.
Expect light southeast winds and just a few clouds at times.
NMA
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$

NWS ILX Office Area Forecast Discussion