783 
FXUS63 KILX 261054
AFDILX

Area Forecast Discussion...Updated Aviation
National Weather Service Lincoln IL
554 AM CDT Sat Aug 26 2023

.SYNOPSIS...
Issued at 545 AM CDT Sat Aug 26 2023

A cold front over southern IL early this morning will produce
isolated to scattered showers and thunderstorms from I-72 south
this morning, and linger isolated showers and thunderstorms south
of I-70 this afternoon. Becoming partly sunny today with highs in
the mid 80s in central IL, and upper 80s in southeast IL. Cooler 
and less humid air to arrive tonight and Sunday. Highs in the
upper 70s and lower 80s Sunday and Monday with more sunshine
expected. 

&&

.SHORT TERM...  (Through Late Sunday Afternoon)
Issued at 330 AM CDT Sat Aug 26 2023

An MCS initiated over west central IL early Friday evening with
thunderstorms with intense lightning tracking ESE into east 
central and southeast IL by early overnight and going into
far se IL, southern Indiana and nw KY past 1-2 hours. Had a few 
reports of damaging winds over parts of Fulton, Macon and DeWitt 
counties. Also had reports around 1 inch or more of rainfall over 
parts of Macon, Champaign and Douglas counties. Tropical PW values
of 1.8-2.2 inches over CWA during the night supported heavy
rainfall. Radar mosaic at 330 am shows scattered thunderstorms 
persisting south of a Rushville to Decatur to Terre Haute line and
tracking southeast. MCS had pushed the cold front south of CWA 
into southern IL near I-64 early this morning. Still muggy over 
central IL with dewpoints of 70-75. Aloft a strong 594 dm 500 mb 
subtropical high was near the AZ/NM and Mexico border and ridging 
ne into the Ozarks. An upper level trof with stronger subsidence 
was digging into the Great Lakes and putting IL in more of a WNW 
to NW upper level flow. 

The front will push further south toward the MO/AR and KY/TN
border by 18Z/1 pm today. However lingering instability north of 
the front with SB CAPES of 1500-2500 j/kg from Macomb to Lincoln 
to Robinson sw and weak short wave energy moving from MO into sw 
IL to support isolated to scattered convection this morning over 
SW CWA and lingering far sw CWA this afternoon as unstable air 
mass retreats southward. A few cells still producing moderate to 
heavy rainfall from Quincy to Springfield to Terre Haute south 
and heavy rain still a threat into mid morning over southern CWA. 
SPC day1 outlook has marginal risk of severe storms this afternoon
and evening south of I-64 over far southern IL and into southern 
MO and central/southern KY. Highs today in the mid 80s central IL 
and upper 80s from I-70 southeast. Still muggy today with 
dewpoints in the low to mid 70s, with heat indices this afternoon 
ranging from upper 80s northern CWA to mid to upper 90s in 
southeast IL. Heat advisory just south of CWA over Wayne, Edwards 
and Wabash counties until 7 pm today where heat indices around 
100F expected. 

As 1023 mb Canadian high pressure drops southward into the Great
Lakes tonight and Sunday, we will see an increase ne flow into
central IL bringing in cooler and less humid air. Lows overnight
in the upper 50s/lower 60s in central IL and mid 60s in southeast
IL. Highs Sunday in the upper 70s to near 80F in central IL and
lower 80s in southeast IL. Dewpoints dropping into the upper 50s
and lower 60s by days end on Sunday. 

07

.LONG TERM...  (Sunday Night through Friday)
Issued at 355 AM CDT Sat Aug 26 2023

Pleasant late summer weather expected over central and southeast
IL much of next work week. Surface high pressure ridge shifts se
over IL during Sunday night and Monday providing fair weather.
Lows Sunday night in the mid 50s central IL and some lower 50s ne
of I-74, and upper 50s to near 60F in southeast IL. Highs Monday
in the upper 70s and lower 80s with continued northeast flow. Lows
Mon night of 55-60F, coolest in eastern IL closer to high pressure
ridge. 

A northern stream short wave trof digs into the Great Lakes Tue
pushing a weak cold front se through IL. Blended models continue
to keep our area dry with frontal passage as better lift is to our
ne and limited moisture over IL with better moisture well se of IL
and in the Great Lakes region. Ecmwf and GEM models show some
light patchy qpf over ne CWA Tue afternoon while GFS is dry. Highs
Tue in the lower 80s and dewpoints in the upper 50s/lower 60s with
some mid 60s dewpoints over IL river valley Tue afternoon. 

A tropical system developing and lifting northward over the
eastern Gulf of Mexico on Tuesday and Tue night, projected to lift
across the Southeast states Wed/Thu with its moisture staying se
of the Ohio river. Even the further nw track of GFS model keeps 
it moisture se of Ohio river. Another surface high pressure ridge
near IL Wed/Thu to keep fair wx with lower dewpoints and
seasonably cool lows in the 50s Tue night thru Thu night. Highs
Wed in the upper 70s/lower 80s and lower 80s on Thu. 

High pressure to shift east with south to SSW flow increasing over
IL on Friday. Also have upper level ridge building into IL late
next week and supports a warming trend with temps closer to normal
next Friday with highs in the 80s, and possibly warmer going into
Labor Day weekend. The Climate Prediction Center (CPC) 8-14 Day 
outlook for Sep 2-8th has a 58-64% chance of above normal 
temperatures and a 35-40% chance of below normal precipitation. So
more summer like heat looks to return starting Labor Day weekend 
and going through the first week of September. 

07

&&

.AVIATION...  (For the 12z TAFs through 12z Sunday Morning)
Issued at 550 AM CDT Sat Aug 26 2023

Convection has mostly shifted south of the I-72 airports and only
carried VCSH at SPI for next few hours while thunderstorms appears
to be staying south/sw of SPI this morning. Fog has been common at
CMI past few hours with vsbys 3/4-3 miles past several hours and 
they also had 400-500 foot stratus decks for a time. Carried tempo
groups for MVFR vsbys at other central IL airports from 12-14Z
along with scattered stratus clouds. Otherwise VFR conditions
expected much of today and tonight with increasing subsidence
coming in from the north as high pressure builds southward into
the Great Lakes region tonight and Sunday. Light winds early this
morning to become NE at 5-10 kts today and 10-15 kts late 
afternoon and evening with few gusts 15-20 kts, and back to 6-10 
kts during overnight. Have light fog/haze with possible MVFR vsbys 
after 08-09Z overnight but feel wind strong enough tonight to 
limit widespread fog formation. 

07

&&

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

&&

$$