FXUS63 KILX 201747

AFDILX



Area Forecast Discussion

National Weather Service Lincoln IL

1247 PM CDT Sat Jun 20 2026



.KEY MESSAGES...



- Widespread rain will occur across central Illinois on Sunday.

  Amounts of 1.50 to 2.50 will be common...with isolated higher

  totals west of the I-55 corridor.



- There is a Slight Risk (level 2 of 5) for severe weather along

  and south of a Jacksonville to Danville line on Sunday. 



&&



.DISCUSSION...

Issued at 1247 PM CDT Sat Jun 20 2026



*** Heavy Rainfall on Sunday ***



12z Jun 20 CAMs still display a high degree of spread 

concerning convective trends/timing for Sunday: however, the 

overall synoptic pattern remains strongly supportive of heavy

rainfall. Clusters of thunderstorms will form across Nebraska

and northern Kansas this evening, then will spread across

Iowa/Missouri overnight and into west-central Illinois toward

dawn Sunday. Based on the expected trajectory of the convection,

it appears locations north of the I-70 corridor will experience

the heaviest rainfall from Sunday morning through mid-afternoon

before it pushes further eastward into Indiana. Given a strong

low-level jet streak transporting copious moisture northward 

and precipitable water values increasing to 2.00-2.25, the 

showers/storms will be efficient rain-producers. 3-hour flash 

flood guidance ranges from 1.75 to 2.50 and am concerned the 

strongest storms will be capable of producing that much 

rainfall. Since the soil is saturated and water is still 

standing in some area fields, have expanded the Flood Watch to 

include the Peoria area northward. Storm total rainfall will 

generally range from 1.50 to 2.50: however, a few locations 

along/west of I-55 could potentially approach 3 inches.





*** Severe Weather Risk on Sunday ***



As thunderstorms spill into the Illinois River Valley Sunday

morning, they will be non-severe heavy-rain producers. However

as the atmosphere destabilizes to the east and south of the

storms, there is growing concern that some of the cells along 

the southern periphery of the rain area could become strong to 

severe during the afternoon. While the strongest instability

will remain further south from the Ozarks into the Ohio River

Valley where SBCAPEs will reach 2000-3000J/kg, increasing 

deep-layer shear with 0-6km values climbing above 40kt will

likely be sufficient to produce organized convection. While CAMs

have not yet honed in on an exact solution, am most concerned 

about locations along/south of a Jacksonville to Danville line 

where low-level shear will be maximized in the vicinity of the 

prevailing outflow boundary. Damaging wind gusts of around 60mph

and hail larger than quarters will be the primary risks:

however, a few tornadoes will also be possible. 12z HREF

Significant Tornado Parameter (STP) values range from 1-1.5

across this area from roughly 1pm to 9pm. While this event does

not appear to be close to the magnitude of June 17, all severe

hazards will be possible across the southern KILX CWA during the

afternoon and evening. Stay tuned to later forecasts for

additional details. 



&&



.AVIATION /12Z TAFS THROUGH 12Z SUNDAY/...

Issued at 543 AM CDT Sat Jun 20 2026



VFR conditions are expected through the period. A mid-level

cloud deck is in place presently, and while this will shift 

south today, additional diurnal cumulus development will keep 

skies partly cloudy. Northwest winds will be around 10 kts 

during the day. Late in the period, a system approaches from the

west, resulting in increasing mid-level cloud cover and a 

chance for showers at KPIA/KSPI after about 09z. The potential 

for rain, storms, and low ceilings increases at all terminals 

after 12z Sun.



&&



.ILX WATCHES/WARNINGS/ADVISORIES...

Flood Watch from Sunday morning through late Sunday night for 

ILZ027>031-036>038-040>057-061>063-066>068-071>073.



&&



$$



KEY MESSAGES...Barnes

DISCUSSION...Barnes

AVIATION...Erwin