340
FXUS63 KILX 061854
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
154 PM CDT Sat Jun 6 2026

.KEY MESSAGES...

- Scattered thunderstorms are possible through this evening
  north of Interstate 72. A few storms could become strong,
  posing a risk for heavy rain and damaging winds.

- An upper system slowly lifting through the Midwest states will bring
  widely scattered showers and storms Sunday through Monday.
  There is a 40 to 60% chance for total rainfall to exceed 1
  inch.

- A stronger warming trend arrives Tuesday through the end of
  the week, pushing heat index values near 100 degrees.

&&

.DISCUSSION...
Issued at 154 PM CDT Sat Jun 6 2026

Water vapor imagery early this afternoon shows a 500 mb shortwave
ridge approaching from the southwest with a closed low spinning over
the southern Plains. Surface analysis has a cold front draped over
northern Illinois with steady west-southwest winds in place south of
there across central Illinois. Temperatures as of 1 pm have
climbed into the middle to upper 80s with dewpoints in the upper
60s to low 70s, and feel-like temperatures in the low 90s. A
couple lingering outflow boundaries from overnight storms are
evident over northern and central parts of the state and will be
the focus for thunderstorm development north of I-72 through
this evening. SPC mesoanalysis shows strong instability (2-3k
J/kg) and very steep low-level lapse rates (7-8 C/km) in place.
Weak wind shear and lack of large-scale ascent should limit
overall storm organization, but collapsing updrafts could
generate locally gusty winds that may come close to severe
limits. Climatologically high PWATs, deep warm cloud depths, and
somewhat slow storm motions could also support locally heavy
rainfall especially if storms repeat over the same areas. The
12Z HREF 24 hour LPMM shows isolated pockets of QPF exceeding 2
inches near the I-74 corridor through this evening.

Upper ridging gets pushed east of here by Sunday as the previously
mentioned closed upper low becomes an open trough and lifts into the
Midwest states. The surface cold front will approach our northern
counties by Sunday morning, becoming stationary before lifting north
of here Monday. Several shortwave impulses embedded within the
main trough will promote widely scattered showers and storms
Sunday through Monday. Although the threat for severe weather
appears low, beneficial heavy rain appears increasingly likely
with high PWATs in place. There is currently a 40-60% chance of
exceeding 1 inch of rainfall across the entire area with lower
chances for exceeding 2 inches. WPC has a slight risk of
excessive rainfall in parts of the area both Sunday and Monday
for the outside chance of localized flooding.

Mid-level heights rise heading into midweek as upper ridging builds
over the east-central US, bringing a stretch of hot and humid
conditions. Air temperatures look to climb into the upper 80s to low
90s Tuesday through the end of the week, with heat indices
approaching 100 degrees. The LREF (ENS, GEFS, GEPS) shows a 20%
chance for heat indices to exceed 100 degrees during this period.
Long range guidance depicts an upper trough breaking down the
ridge and sending a cold front through the area late in the week
or early next weekend, though timing remains highly uncertain.
If this moves through sooner than later, a shorter period of
prolonged heat would be favored due to increasing precipitation
chances with the frontal passage.

&&

.AVIATION /18Z TAFS THROUGH 18Z SUNDAY/...
Issued at 1241 PM CDT Sat Jun 6 2026

MVFR ceilings in spots to start the period should lift here shortly,
with VFR conditions largely expected the remainder of the period. A
couple periods of showers and storms may impact the terminals this
afternoon (KPIA, KBMI, KCMI) and Sunday morning. Confidence in
timing and exact placement of storms remains low, so PROB30 groups
remain in place to cover this probability. West-southwest winds with
speeds between 10-15 kts will become light tonight as they back to
the south-southeast by morning.

&&

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

&&

$$

KEY MESSAGES...NMA
DISCUSSION...NMA
AVIATION...NMA