374 
FXUS63 KILX 302326
AFDILX

Area Forecast Discussion...Updated Aviation
National Weather Service Lincoln IL
626 PM CDT Fri Jun 30 2023

.SYNOPSIS...
Issued at 621 PM CDT Fri Jun 30 2023

An active weather pattern will persist across Illinois through 
the holiday weekend, and bring daily chances for thunderstorms 
through Sunday evening to central and southeast Illinois. Strong 
to severe storms are possible each day through Sunday, so stay 
weather aware through this weekend. Muggy lows overnight in the 
upper 60s to near 70. Very warm and humid conditions will prevail 
again on Saturday with highs in the mid to upper 80s in central 
Illinois, and lower 90s in southeast Illinois. Heat indices could
peak at or above 100 degrees in southeast Illinois again on 
Saturday afternoon.

&&

.SHORT TERM...  (Through Late Saturday Night)
Issued at 300 PM CDT Fri Jun 30 2023

A weakening MCS/MCV over northern IL had a few showers and
isolated thunderstorms ne of I-74 and tracking eastward into west
central and nw Indiana. Outflow boundary from this system was over
central MO into southern IL and sw KY and much more unstable 
airmass there where MLCapes are 3000-4500 j/kg south of CWA and 
lower to 500-1000 j/kg over northern CWA where convection moved 
through since late morning. Tropical airmass remains in place over
central/southern IL with PW values of 1.6-1.9 inches, highest in 
southern/sw IL. Temps currently were in the lower 80s over much of
central IL with Lacon at 77F, while mid to upper 80s in southeast
IL with Flora and Lawrenceville 88-89F and heat index of 100F. 
Heat Indices were 105-115F from St Louis to Evansville where heat 
advisory in effect. 

Convection to develop near outflow boundary sw of CWA late this
afternoon and into this evening, and some of this convection could
affect our far sw CWA from Jacksonville to Effingham south. SPC
has slight risk of severe storms from Canton to Lincoln to Paris
south with a 15% or greater risk of damaging winds and large hail.
Areas from Litchfield to Effingham to Lawrenceville south have 10%
risk of wind gusts of 65 kts/75 mph or higher. The 15% risk of 2
inch or larger hail is just sw of our CWA over sw/southern IL.
CAMs still have varying solutions with evolution of convection
tonight over central/se IL, but consensus is more development of
convection during this evening into central IL and early overnight
and diminishing later tonight with stronger storms over
southern/sw CWA. WPC has marginal risk of excessive rainfall over
central and southern IL tonight with this convective complex.
Muggy lows overnight in the upper 60s and lower 70s.  

Should be a lull in convection Sat morning before airmass
destabilizes with daytime heating and ahead of a short wave/MCS
developing and tracking eastward into central MO Sat afternoon.
This MCS will likely bring more thunderstorms into central/se IL
during mid/late Sat afternoon and Sat evening and more severe wx
possible. SPC Day2 has extended enhanced risk of severe storms
northward to a Rushville to Bloomington line with slight risk as
far north as Canton to Peoria to Pontiac. There is a 30% risk of
damaging winds in the enhanced risk area with 10% or greater
probability of wind gusts 65 kts/75 mph or greater. Highs Sat
range from mid 80s northern CWA to lower 90s in southeast IL where
heat indices peak around or just above 100F Sat afternoon from 
I-70 south. PW values will be quite high on Saturday and Sat 
evening and WPC has slight chance of excessive rainfall over much 
of central and southern IL Sat afternoon into Sat night with 1-3 
inches of rainfall possible.

07

&&

.LONG TERM...  (Sunday through Next Friday)
Issued at 315 PM CDT Fri Jun 30 2023

Short wave trof to shift eastward over IL on Sunday and likely
bring more showers and thunderstorms. More unstable air mass
shifts to the se, and SPC Day3 outlook has slight risk of severe
storms south of I-72 Sunday afternoon and early Sunday evening
until sunset. WPC has marginal risk of excessive rainfall from
Wabash river se on Sunday afternoon/evening. Not as hot Sunday
with highs in the lower 80s over central IL and mid 80s in
southeast IL with upper 80s from highway 50 south. 

Quieter wx finally appear to return to CWA after sunset Sunday
night and Monday as upper level trof passes into the eastern parts
of the Great Lakes and Ohio river valley. Isolated showers and
thunderstorms could develop Mon afternoon as dewpoints still in
the mid to upper 60s. Seasonable highs Monday in the mid to upper
80s. Fair weather expected after sunset Monday into early Tue
morning, then have 20-30% chance of convection Tue mainly Tue
afternoon and early Tue evening before sunset. A cold front
pushing south/sw into the Midwest during mid week to approach nw
IL by sunset Wed and move se through central IL during Wed night
and in southeast IL early Thu morning. This will bring a better
chance of showers/thunderstorms from Wed afternoon into Thu. Very
warm and humid Tue/Wed with highs in the upper 80s to around 90F.
Temps trending cooler behind cold front Thu/Fri with highs in
upper 70s/lower 80s by next Fri. 

07

&&

.AVIATION...  (For the 00z TAFs through 00z Saturday Evening)
Issued at 625 PM CDT Fri Jun 30 2023

Main aviation concern will be with timing of convection. An arc of
developing storms from near KMCI-KSTL will make some progress
toward central Illinois toward 05-06Z. Impacts at the TAF sites
appear be most likely 06-09Z, with some brief visibility drops to
MVFR or IFR in the heavier showers. Showers will linger at times
into late morning, with more substantial thunderstorm chances
toward the end of the forecast period. 

Geelhart

&&

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

$$