Pierson Station, Illinois Weather Forecast Discussion

766
FXUS63 KILX 151912
AFDILX
Area Forecast Discussion
National Weather Service Lincoln IL
212 PM CDT Mon Sep 15 2025
.KEY MESSAGES...
- Hot and dry weather persists through at least Thursday, with daytime
  highs topping out in the upper 80s to low 90s.
- A slow-moving upper system will bring cooler temperatures and
  precipitation chances (20-40%) late this week through the
  weekend.
&&
.DISCUSSION...
Issued at 212 PM CDT Mon Sep 15 2025
Upper air analysis depicts an amplified ridge of high pressure over
the central US atop a closed low over the Southeast US, creating a
Rex block. Further west, a cluster of upper lows are located over
the Northwest US/Northern Plains and these will be the focus for a
much needed pattern change late this week through the weekend. At
the surface, ridging is stretched from the Great Lakes Region
southward toward the Gulf, keeping hot and dry weather on repeat.
High temperatures as of 2 pm are sitting in the upper 80s to low
90s, which is about 10 degrees warmer than normal for mid September.
Light east winds have allowed dewpoints to drop into the middle to
upper 50s over an area north of I-70 and east of the Illinois River.
Temperatures this afternoon may rise another degree or two in these
spots, with overnight lows also lowered by a couple degrees in this
same area. Expect minimum temperatures tonight to bottom out in the
upper 50s to low 60s.
A series of upper lows located to our northwest will slowly push
east the next few days, working to weaken the upper ridge. Until
then, hot and dry weather will prevail with precipitation chances
largely staying just to our west. By later this week, a closed upper
low will approach the Upper Mississippi Valley, bringing the return
of scattered shower and storm chances (20-40%) as well as cooler
temperatures as early as Friday. The last several runs of model
guidance have slowed the arrival of this feature, so timing may
still change between now and then.
A more progressive pattern characterized by cooler (yet seasonal)
temperatures and occasional precipitation chances looks to linger
into the early parts of next week as a stronger upper low/trough
pushes a cold front through the area. On the heels of this system is
yet another upper ridge, which could turn things hot again heading
into the end of September. Both the deterministic GFS and ECMWF
suggest temperatures could surge back into the upper 80s to 90s by
this time. However, their ensembles still show a large range of
possibilities. The Climate Prediction Center continues to favor
warmer than normal temperatures (60-70% chance) in their 8 to 14
day outlook, which runs from September 22-28.
NMA
&&
.AVIATION...  (For the 18z TAFs through 18z Tuesday Afternoon)
Issued at 1208 PM CDT Mon Sep 15 2025
TAFs remain one line as VFR conditions and light easterly winds
(generally less than 10 knots) will continue through the period.
Some scattered cirrus clouds will filter overhead, and a few
diurnal cumulus clouds could develop around 6-7 kft this
afternoon.
Erwin
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$

NWS ILX Office Area Forecast Discussion