066
FXUS63 KILX 151952
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
252 PM CDT Sat Aug 15 2026

.KEY MESSAGES...

- Flooding continues across portions of central IL in a corridor
  from Fulton and southern Knox County to Vermilion County due
  to 4 to 7 inches of rain that fell overnight.

- Additional clusters of thunderstorms are likely tonight into
  Sunday morning, with isolated afternoon thunderstorms possible
  Sunday afternoon. Storms have the potential to produce locally
  damaging winds. SPC has a marginal (level 1 of 5) risk of
  severe weather.

- The heat and humidity remain a concern this weekend, with the
  hottest conditions south of I-70.

&&

.DISCUSSION...
Issued at 156 PM CDT Sat Aug 15 2026

In the wake of widespread thunderstorm activity this morning,
heat has once again been tempered over much of the area with
some late afternoon recovery expected to bring temperatures back
up to the low 90s by afternoon in a corridor from Jacksonville
to Robinson, with heat index likely to reach around 105 south of
I-70 as a warm front lifts northward through the area. Mid to
upper 80s can be expected to the north.

A few showers remain in this frontal zone, where perhaps a few
thunderstorms could develop this afternoon as diurnal
destabilization gradually takes place.

Tonight, a cold front will approach from the northwest, with
warm advection ahead of the front promoting another cluster or
two of thunderstorms. Areas of significant precipitation are
possible, although much less likely than last night. The
location of any heavy precipitation swaths remains too uncertain
for a Flood Watch at this point, but we will continue to
evaluate any corridors for potential Watch issuance. If expected
heavy precipitation corridors line up well with last night`s
heavy precipitation from Fulton to Vermilion County these would
be favorable for renewed flooding. 12Z high-res average model
guidance points to a 1.5 to 1.5 inch corridor north of Peoria
and Bloomington, although there remain considerable run-to-run
and model-to-model discrepancies. SPC continues a Marginal Risk
for locally damaging winds with thunderstorms both tonight and
Sunday as these storms move across central IL and some afternoon
thunderstorms as diurnal destabilization takes place and the
cold front lingers over the southeast half of central IL.

A couple of dry days are forecast Monday and Tuesday behind
Sunday`s front, then another cold front midweek will bring the
next chance for thunderstorms.

Temperatures will remain quite warm and humid for central IL as
2 inch precipitable water values keep dewpoints well into the
70s and highs reach the 80s, to lower 90s south of I-70. A Heat
Advisory continues for areas south of I-70 until Sunday evening
as heat index values will near 105 each afternoon until then.
Highs will be in the 80s across the area Monday through
Tuesday, then the midweek front will continue to lower
temperatures for late in the week, with some upper 70s possible.

&&

.AVIATION /18Z TAFS THROUGH 18Z SUNDAY/...
Issued at 1258 PM CDT Sat Aug 15 2026

Mostly VFR conditions can be expected until 06Z although some
brief IFR-MVFR cigs are possible at KPIA the first few hours.
Another cluster or two of thunderstorms is expected to impact
the area overnight as a cold front approaches from the NW, with
brief MVFR cigs/vsbys possible in storms. Have a tempo group
for thunderstorms at each site during 06Z-12Z timeframe.
Guidance points to widespread MVFR cigs following these storms
at KPIA and KBMI. Winds S-SW 6-10 kts this afternoon, becoming
light and variable this evening, then W 4-8 kts by 16Z.

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
Heat Advisory until 8 PM CDT Sunday for ILZ066>068-071>073.

&&

$$

KEY MESSAGES...37
DISCUSSION...37
AVIATION...37