871
FXUS63 KILX 262032
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
332 PM CDT Fri Jul 26 2024

.KEY MESSAGES...

- Daily chances for showers and thunderstorms from Saturday night
  through much of next week.

- Hot and humid conditions arrive Monday through Thursday with
  afternoon heat indices of 100 or higher possible west of the IL
  river Monday afternoon, and across central and southeast IL
  during the afternoon and early evening hours from Tuesday
  through Thursday.

&&

.DISCUSSION...
Issued at 330 PM CDT Fri Jul 26 2024

Mid afternoon surface analysis shows weak 1023 mb high pressure
over the central Great Lakes and ridging into central and
northeast IL. This was providing a fair amount of sunshine over
central IL while more cumulus clouds and high clouds seen over
west central and southern/southeast IL. Temperatures were mostly
in the lower 80s at 3 pm with some upper 70s from Bloomington and
Paris northeast. More comfortable dewpoints in the upper 50s and
lower 60s from Peoria, Decatur and Mattoon ne while more muggy
dewpoints in the upper 60s/lower 70s from Galesburg to Springfield
to Flora sw. Aloft a 590+ dm 500 mb skinny ridge was over the
western parts of the central and southern Plains and arching into
the upper MS river valley. 500 mb heights over IL were 588-590 dm,
highest near the Iowa border.

Fair weather expected tonight across central and southeast IL
under influence of nearby high pressure drifting slowly eastward
over the Great Lakes region. Some fog expected over southern/sw IL
mainly south of CWA overnight into early Sat morning where
dewpoints/airmass more moist. Lows tonight mostly in the lower
60s, with some upper 50s from BMI and CMI ne and near 65F from
highway 50 south where more cloud cover over and higher
dewpoints.

Developing southeast flow around back side of surface high
pressure on Saturday to bring dewpoints up into the mid to upper
60s Sat afternoon and may see an isolated shower or thunderstorms
sw of a Springfield to Effingham line by late Sat afternoon.
Clouds will also be increasing from the south during Sat afternoon
and Sat night with tropical moisture advected into the area.
Seasonable highs Saturday in the mid 80s in central IL and upper
80s se of I-70. Pops increase to 20-30% during Sat night
especially overnight Sat night as tropical plume of moisture
continues to stream northward over IL ahead of approaching weak
upper level low/trof moving into central IA/MO by Sunday morning.
Milder lows in the upper 60s to around 70F.

Have likely chances of showers and isolated thunderstorms over CWA
on Sunday, with highest pops and qpf in eastern/se IL as tropical
moisture continues to stream northward ahead of weak upper level
trof moving into the MS river valley by late Sunday afternoon.
Rainfall amounts overnight Sat night into Sunday is a quarter to
half inch with locally higher amounts especially in eastern IL and
nw of the IL river. SPC day3 outlook keeps marginal risk west of
IL for Sunday afternoon/evening. More clouds and showers on Sunday
to keep highs a bit cooler than Saturday with highs Sunday in the
low to mid 80s. More humid as dewpoints get in the low to mid 70s
with southerly flow.

Upper level ridge building into IL from Monday into Wed to bring
central/se IL a heat wave much of this work week. Highs in the mid
to upper 80s Monday with dewpoints in the 70s giving afternoon
heat indices in the mid to upper 90s east of the IL river and
around 100F west of the IL river. Tue through Thu likely see highs
in the lower 90s with dewpoints in the 70s, with afternoon heat
indices of 98-110F. We may eventually need a heat advisory for
part of our area during mid week but we are also looking at a few
more rounds of showers and thunderstorms with possible MCS
activity over top of the ridge. Monday afternoon and Monday night
looks like a high chance of convection. Another enhance chance of
convection Wed afternoon and Wed night. SPC does not have any
severe risk over central/se IL this upcoming week. But the CPU
Machine Learning has some risk from Monday through mid week. Some
upper level trof digging into IL late this week to keeping
chances of convection around along with temps getting closer to
normal with highs in the mid to upper 80s next Friday and
Saturday, though still humid with dewpoints likely in the lower
70s next Friday.


07

&&

.AVIATION...  (For the 18z TAFs through 18z Saturday Afternoon)
Issued at 1245 PM CDT Fri Jul 26 2024

VFR condtions are forecast to continue across the central IL
airports through 18Z/1 pm Saturday. Weak 1022 mb high pressure
sprawled over the Great Lakes (centered on Lake Huron) early this
afternoon will drift slowly eastward over the central and eastern
Great Lakes on Saturday morning while a frontal boundary stays sw
of central IL through midday Sat, keeping its isolated convection
sw of central IL terminals. Some diurnal driven cumulus clouds
with bases of 3.5-5k ft this afternoon (broken at SPI early this
afternoon) will diminish around dusk and redevelop after 15Z/10 am
Sat. Some passing cirrus clouds and elevated smoke layer aloft as
well. East to ENE winds around 5 kts to veer SE at 5-9 kts by
late Sat morning. CAMs show some fog over southern/sw IL later
tonight and early Sat morning in more moist atmosphere where
dewpoint in the upper 60s/lower 70s, so staying south of central
IL airports.

07

&&

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

&&

$$