931
FXUS63 KILX 041918
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
218 PM CDT Thu Jun 4 2026

.KEY MESSAGES...

- A marginal risk for severe thunderstorms on deck for tomorrow,
  with isolated damaging wind gusts serving as the primary
  risk.

- An unsettled weather pattern will bring daily chances of
  showers and thunderstorms through the middle of next week.

- Humidity builds over central and southeast Illinois this
  weekend and lingers into next week, driving peak heat index
  values into the low to mid 90s. A nonzero (10- 20%) chance for
  heat indices above 100 degrees exists for late next week.

&&

.DISCUSSION...
Issued at 218 PM CDT Thu Jun 4 2026

The high pressure center drifted off to the southeast of central IL,
shifting the flow to a more southerly direction today. This will
support increasing moisture as we go into the weekend, starting
today. Highs will increase to the upper 80s to low 90s, with
dewpoints in the mid 60s to low 70s for Friday into Monday. Heat
indices could bump north of 90 degrees by Saturday and looks to
potentially continue into the new week. The LREF shows a nonzero (10-
20%) chance for apparent temps above 100 degrees late next week. In
conclusion... summer has arrived.

A shortwave will pulse through the region tomorrow, bringing rain
chances into the forecast. The showers and thunderstorms tomorrow
into Saturday could be efficient rain producers with PWATs around
1.7-2.0 inches. The convective complex moving in from Iowa will be
decaying as it enters our western CWA. SPC has outlined a Marginal
Risk (level 1/5) of severe weather north of a Mount Sterling to
Gibson City line. The primary threat will be isolated damaging wind
gusts as a pulse or multicell storm collapses. The higher rainfall
amounts will be localized where multiple showers or thunderstorms
pass over the same area during this time. Outside of convective
activity, a tightening pressure gradient will cause southwesterly
wind gusts to exceed 25 mph at times.

There does appear to be the possibility of a few more weak rounds of
convection into Wednesday. The timing and rainfall amount forecast
remains uncertain at this time, due to weak forcing. A cutoff upper-
level low or slow-moving trough is forecast to develop and linger
around the Midwest, while a weak frontal boundary drifts around the
area. The extended forecast relies heavily on the NBM due to that
uncertainty. Looking beyond the seven-day window, the CPC 6-10 day
outlook highlights a strong signal for a persistence of above-normal
temperatures across the central U.S.

&&

.AVIATION /18Z TAFS THROUGH 18Z FRIDAY/...
Issued at 1230 PM CDT Thu Jun 4 2026

VFR conditions reign over the majority of the 18z TAF period.
However, tomorrow morning (after 14z tomorrow), showers and
thunderstorms will move into the central IL area, bringing MVFR
ceilings with it. PIA will see the <3000kft ceilings first. The
complex of showers and thunderstorms will be decaying as it
arrives, therefore the PROB30 groups were used. CMI will be the
last site to see precipitation nearing the end of the period.

Winds will be predominately out of the south-southwest gusting
to 20 knots. They will relax briefly overnight before increasing
again as the sun starts to rise ahead of the precipitation
moving in.

&&

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

&&

$$

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