853
FXUS63 KILX 290455
AFDILX

Area Forecast Discussion...Updated Aviation
National Weather Service Lincoln IL
1155 PM CDT Sat Jun 28 2025

.KEY MESSAGES...

- Very warm and humid conditions persist through Monday, then a
  cold front will usher in seasonable temperatures and humidity
  levels.

- Isolated showers and thunderstorms are possible into early
  evening south of I-72. A better chance for precip exists area-
  wide late Sunday night into Monday (50-80% chance) as a cold
  front moves in. A few strong to severe storms with gusty winds
  could occur.

&&

.UPDATE...
Issued at 617 PM CDT Sat Jun 28 2025

Only necessary change to the forecast this evening was the
addition of 15-30% PoPs along a narrow corridor extending from
roughly Decatur to Arthur where differential heating along the
remnants of an outflow boundary has led to a few showers and even
one brief thunderstorm over the past 1-2 hours. Waning surface
heating should cause this activity to weaken and eventually
dissolve, mainly after around 7pm.

Bumgardner

&&

.DISCUSSION...
Issued at 245 PM CDT Sat Jun 28 2025

A weak boundary lingered over central parts of IL/IN with isolated
convection south of I-72. Unstable airmass over central/se IL with
SB CAPES 2500-3500 j/kg south of I-74 while MLCapes were 1-2k j/kg.
PW values were 1.5-1.9 inches from Shelbyville to Paris south
where deeper tropical moisture was. More widespread convection was
over southern IN into western half of KY/TN and sw of St Louis
metro over central and south central MO into north central AR.
Very warm and humid conditions prevailed over CWA with temps
86-92F and heat indices in the 90s, with SPI, DEC, LWV and HUF
reaching 99 heat index.

Isolated convection will linger south of I-72 until sunset, though
severe storms not expected. Patchy fog is possible again later
tonight and early Sunday morning south of I-72. Muggy lows in the
lower 70s overnight across the CWA.

Isolated to scattered convection to redevelop over central IL on
Sunday from sw to ne in tropical airmass. Very warm and humid
again on Sunday with highs in the upper 80s to around 90F (warmest
I-74 north) and heat indices peaking in the mid to upper 90s. Better
coverage of convection will be during Sunday night into Monday as
cold front moves in during Monday. SPC Day2 outlook has marginal
risk of severe storms Sunday night for damaging winds over the IL
river valley in nw CWA, with slight risk over much of Iowa and
north central and nw MO. SPC Day3 has marginal risk of severe
storms for damaging winds from the IL river se on Monday as cold
front moves through. Highs Monday in the mid 80s central IL and
upper 80s in southeast IL with heat indices 90-95F. Chance of
showers and thunderstorms lingers se of I-55 Monday evening and
goes longer in the evening Monday over southeast IL.

Weak high pressure drifts into the area Tue night and Wed bringing
dry conditions with more seasonable temperatures and humidity
levels. Highs in the mid to upper 80s Tue and Wed but dewpoints
lowering from 70s Monday to 60s Tue and Wed.

Upper level ridge building back over the Eastern Plains and MS
river valley late next week to bring back some more heat and
humidity, though not quite as hot as this past week. Have isolated
convection chances Thu and Fri afternoon with 20-40% chance of
showers and thunderstorms next Saturday. Highs in the upper 80s to
near 90F Thu, around 90 Fri and lower 90s next Saturday as heat
indices climb back into the mid 90s to near 100F next Fri/Sat.

07

&&

.AVIATION...  (For the 06z TAFs through 06z Sunday Night)
Issued at 1155 PM CDT Sat Jun 28 2025

Patchy fog is expected to form late tonight, especially near the
I-72 corridor. Introduced a TEMPO for MVFR visibilities at KSPI-
KDEC-KCMI from 09-13z. Otherwise a quiet aviation forecast with
scattered diurnal cu. Calm to light/variable winds tonight will
become south by late morning under 10 kt.

25

&&

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

$$