236
FXUS63 KILX 160653
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
153 AM CDT Sun Aug 16 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 yesterday and additional
  rain moving through this morning.

- Additional clusters of thunderstorms are forecast again late
  this afternoon into the overnight hours. SPC has a slight
  risk (level 2 of 5) south of I-70 and a marginal risk for
  areas east of the IL River Valley for damaging winds.

- Cooler and less active weather is on deck after today. Monday
  will have highs in the 80s and dry weather in place.

&&

.DISCUSSION...
Issued at 153 AM CDT Sun Aug 16 2026

Tonight more showers and storms will be moving across central IL.
The main concern is the flash flooding risk. WPC has a small area of
eastern IL in a moderate risk (level 3 of 4) and near and north of I-
72 in a slight risk (level 2 of 4) for excessive rainfall for the
overnight hours (valid until 12z). The 00z sounding shows the
environment having PWATs of 2.2-2.4 inches again. Flooding is
already ongoing in many places, left over from last night`s event.
It will not take much to exacerbate the situation overnight if the
new convection decides to set up over that stripe of central IL
(Fulton Co to Vermilion Co) again. LPMM is suggesting that we could
see another localized stripe of 4-8 inches somewhere in the area
north of I-72.

There is a slight risk (level 2 of 5) south of I-70 and a marginal
risk for areas east of the IL River Valley for damaging winds again
today. The NAMNest is depicting a more widely dry, nearly no
activity, solution. The HRRR has an area of convection developing
late afternoon in west central IL, progressing eastward into the
overnight hours with the cold front. After how much rain north of I-
70 has received over the last several days, the hope is for the
drier solution, but plan for the stormier solution. With the HRRR
version of events, it is showing pockets of 2-4 inches of rainfall
from 21z-09z today into tomorrow. The good news though would be that
if this activity were to develop, it would be fairly progressive and
less of a training set up, unlike previous days.

Temperatures remain hot and humid for one more day. The heat
advisory for south of I-70 is valid through 8pm (01z) this evening.
Heat indices of 100-105 degrees are expected.

A brief break in the active weather and the heat is looking likely
for Monday into Tuesday. A high pressure center will set up over the
Upper Mississippi Valley / Great Lakes region behind a cold front
that will move through central IL during the day today. Temperatures
starting Monday into much of the next week will be mainly in the
upper 70s to 80s for highs and 60s to low 70s for lows.

More showers and thunderstorm re-enter the forecast by Tuesday
evening into Wednesday. SPC has central IL in a marginal risk for
severe weather for Tuesday west of I-55, which would be for the late
day convection. There are additional chance for rain through
Thursday before returning to a mostly dry forecast into the
late week.

&&

.AVIATION /06Z TAFS THROUGH 06Z MONDAY/...
Issued at 1208 AM CDT Sun Aug 16 2026

Another round of TSRA is expected late tonight, with the highest
probabilities shifting south to KSPI-KDEC-KCMI where TEMPO
groups are forecast and PROB30 farther north. A period of MVFR
ceilings is favored at KPIA-KBMI Sunday morning. Light southwest
winds tonight will veer west to northwest on Sunday with the
passage of a cool front.

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
Flood Watch until 10 AM CDT this morning for ILZ027>031-
036>038-043>046.
Heat Advisory until 8 PM CDT this evening for ILZ066>068-
071>073.

&&

$$

KEY MESSAGES...Copple
DISCUSSION...Copple
AVIATION...25