Area Forecast Discussion...Updated Aviation
National Weather Service Lincoln IL
605 PM CDT Fri Oct 31 2025
.KEY MESSAGES...
- Dry conditions will dominate most of the area through the middle
of next week.
- Below normal temperatures on Saturday will turn a few degrees above
normal for much of next week.
&&
.DISCUSSION...
Issued at 123 PM CDT Fri Oct 31 2025
A weak surface trough/cool front was pushing into western IL
early this afternoon. Ahead of this, winds will back WSW this
afternoon with sporadic 20-25 mph gusts, and with plentiful
sunshine highs should get close to seasonable levels around 60
degrees.
Upper air data and water vapor imagery indicated a closed mid
level low located over central MN. Guidance shows this sliding
southeast into west central IL Saturday afternoon. Suite of CAM
guidance suggests any showers associated with the low will be
quite sparse locally which is not surprising given a dry column
and PWATs below 0.50". The best shot of seeing any showers will be
over the western CWA after 18z Sat and have a 20% PoP for this.
If these do occur, forecast soundings show weak instability poking
above the -12C level so graupel can`t be ruled out in any more
intense showers. Separate from forcing associated with the upper
low, areas south of I-70 will be brushed by the northern edge of
an f-gen band behind the departing cool front, midday through
Saturday afternoon. For this we have a low (30%) chance of showers
south of a Flora to Lawrenceville line. Otherwise Saturday is
shaping up as a mostly cloudy and chilly day. With the cool pocket
aloft overhead, upper 40s to lower 50s highs will be common,
coolest west of I-55.
The upper low quickly sinks southeast of the area Sunday, replaced
by shortwave ridging. This will signal the start of a warming
trend which looks to last through much of next week. Medium range
ensemble guidance shows quasi-zonal mid level flow through the
week, with a couple weak/non-ipmactful/dry cold frontal passages
Monday and Wednesday with minor temperature fluctuations
associated with each. By the end of the week a stronger shortwave
over the Plains could bring a more significant system to the
region on Friday, however the guidance envelope is large at this
range leading to low confidence in timing/impacts.
25
&&
.AVIATION... (For the 00z TAFs through 00z Saturday Evening)
Issued at 605 PM CDT Fri Oct 31 2025
Ceilings expected to gradually descend as upper level low pressure
drops southeast into the area on Saturday. Currently looks like
cloud heights for the most part should be above 5000 feet, though
ensemble guidance brings some MVFR conditions on KPIA`s doorstep
late in the morning. Forecast soundings suggest the ceiling there
should be around 4000 feet, so will hold off on any MVFR
conditions for now, though the period around 17-18Z would be the
most likely if it did occur.
