717
FXUS63 KILX 132324
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
624 PM CDT Thu Aug 13 2026

.KEY MESSAGES...

- Flash flooding is a concern along and north of the I-74
  corridor overnight. HREF probabilities of more than 2 inches
  of rain are 30-50% in this area, although some local totals
  over 3 inches are possible.

- Heat index values of 100 to 105 degrees will continue into the
  weekend each afternoon, in areas near and south of I-70. The
  heat is expected to spread northward across the forecast area
  by Saturday.

&&

.DISCUSSION...
Issued at 235 PM CDT Thu Aug 13 2026

MCS that tracked out of Iowa earlier today intensified again as
it crossed the Peoria metro, producing winds around 70 mph and
extensive damage in Bloomington. Cluster of storms has reached
the Champaign area this hour, with the trailing outflow
extending west through Springfield. Storms are riding along a
tight gradient of CAPE and should exit the forecast area in the
next few hours.

Next MCS is expected to begin developing this evening closer to
the warm front from Iowa to northern Indiana, then sink
southward overnight. Precipitable water values over 2 inches
persist through the night, and some of the northern parts of our
forecast area have seen a few inches of rain since yesterday.
HREF PMM precip estimates suggest 1.5-2 inches of rain in 6
hours between midnight and sunrise, and no changes are being
made to the Flood Watch at this time. South half of the forecast
area has a good chance of remaining dry until closer to
daybreak.

Heat forecasts remain a concern as well. Latest guidance
suggests 100-105 heat index could reach as far north as a
Rushville-Paris line tomorrow, but the extent of the lingering
rain/cloud shield introduces some uncertainty as to whether or
not to expand the Heat Advisory. Current inclination is to leave
it in place and allow the next shift to expand it, once the
timing and track of the MCS becomes more certain. An expansion
for the entire forecast area appears more likely for Saturday.

A quick look at the extended forecast -- upper pattern becomes
more zonal for a time as high pressure sprawls more west-east
across the southern U.S. Getting into early next week, riding
amplifies west of the Rockies as a strong upper trough swings
across the Canadian Prairies and the north central U.S. Impacts
from that in our area would be more likely toward the middle of
next week. A couple days of cooler temperatures are likely
early next week, before warming begins again.

&&

.AVIATION /00Z TAFS THROUGH 00Z SATURDAY/...
Issued at 623 PM CDT Thu Aug 13 2026

Storms from earlier this afternoon have cleared the terminals
leaving VFR conditions and east/southeast winds across central
Illinois. IFR ceilings are in place just north of PIA/BMI this
evening and expected to expand south towards the I-74 corridor
overnight while MVFR ceilings develop across the remainder of
central IL by late tonight. Meanwhile, additional showers and
storms will form tonight along a stationary front over the
region and continue into Friday morning. Confidence in
placement and timing remains low at this time but are generally
favored between I-72 and I-80.

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
Flood Watch through Friday morning for ILZ027>031-037-038-045-
046.
Heat Advisory until 8 PM CDT Sunday for ILZ066>068-071>073.

&&

$$

KEY MESSAGES...Geelhart
DISCUSSION...Geelhart
AVIATION...Deubelbeiss