677
FXUS63 KILX 312306
AFDILX

Area Forecast Discussion...Updated Aviation
National Weather Service Lincoln IL
606 PM CDT Sat May 31 2025

.KEY MESSAGES...

- There is a 15% chance of a stray shower this evening.

- Wildfire smoke has degraded air quality into the moderate
  category. The Illinois Environmental Protection Agency (EPA) is
  forecasting this to continue through at least tomorrow.

- Seasonably warm conditions return early next work week,
  especially with increasing humidity on Tuesday. There is a
  20-40% chance heat indices reach 90 degrees on Monday and
  Tuesday, increasing the risk of heat illness to those at a
  higher risk.


&&

.DISCUSSION...
Issued at 240 PM CDT Sat May 31 2025

It has been a pleasant last day of meteorological spring, with the
Canadian wildfire smoke being the center of attention. The smoke is
giving us some hazy skies. IL EPA still has us in a moderate risk
for poor air quality. This smoke will linger into tomorrow morning.
One side effect of the smoky skies will be potentially colorful, and
gorgeous sunsets tonight. HRRR smoke model is still showing a decent
concentration moving across the state today and tomorrow on the near
surface and vertically integrated smoke model runs. The upper level
winds will shift to a more westerly direction Monday, shoving the
lingering smoke out of the region.

There is a 15% chance of showers and thunderstorms late this
afternoon as a weak cold front droops south across central IL. The
low level are quite dry this afternoon. Current dewpoint depressions
are around 30 degrees. Soundings show an elevated capping layer as
well. Any showers or shallow thunderstorms will struggle to develop,
but one or two can`t be ruled out. Then, a surface high pressure
sets up behind the cold front, keeping dry conditions around into
Tuesday afternoon.

Just in time for meteorological summer, highs will be in the upper
70s to low 80s tomorrow, same as today. Temperatures will max out in
the upper 80s, near 90s, by Monday and Tuesday, ahead of the next
major frontal system Wednesday. Lows will get down into the upper
60s to low 70s. There remains a 20-40% chance of temperatures
exceeding 90 degrees both days. Behind the front, temperatures
during the day will drop into the mid 70s with lows in the upper
50s to low 60s.

Tuesday night into Wednesday is the next best chance for severe
weather to central IL with a low pressure system dragging a cold
front across the region. However, the environmental factors, such
as, the capping, instability and shear look a little underwhelming
at the moment. We shall monitor it to see if the potential improves
or not through the weekend. Despite the lacking ingredients, SPC has
introduced a 15% severe weather risk area for Tuesday (Day 4),
primarily for overnight activity going into Wednesday. The front
appears to hang up over the region, increasing our risk for
localized, urban flooding. WPC has introduced a slight risk for
excessive rainfall northwest of the Illinois River Valley because of
this. The Euro has the precip clearing out by Friday, but the GFS
shows it lingering into the weekend.

Copple

&&

.AVIATION...  (For the 00z TAFs through 00z Sunday Evening)
Issued at 606 PM CDT Sat May 31 2025

A backdoor cold front is draped over central IL this evening,
positioned approximately south of a Peoria to Lincoln to Mattoon
line as of 23Z. This will continue to drop south over the next
several hours. Winds will be variable over the next 24 hours,
starting out of the north-northeast tonight then gradually veering
to the east-southeast by Sunday morning, and then returning to a
northerly direction by Sunday afternoon as high pressure settles
southward. Mid-level clouds between 8-10k ft associated with the
aforementioned front will stick around tonight, but otherwise high
"clouds" from wildfire smoke will be in place through the period.


NMA

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$