217
FXUS63 KILX 220843
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
343 AM CDT Sat Jun 22 2024

.KEY MESSAGES...

- Strong to severe thunderstorms are possible tonight...with the
  highest probability of damaging wind gusts and hail focused
  along and northwest of a Jacksonville to Bloomington line.

- After a brief cool-down on Sunday, temperatures will once again
  climb early next week. Heat index readings will exceed 100
  degrees by Tuesday.

- A second cold front will arrive Tuesday night into Wednesday,
  bringing another chance for much-needed rainfall.

&&

.SHORT TERM...(Today through Sunday)
Issued at 343 AM CDT Sat Jun 22 2024

Low pressure currently over Nebraska will track northeastward into
the Great Lakes, pulling a cold front into central Illinois tonight.
Given the trajectory of the low, the front will not have a strong
southward push and will instead gradually sag into the area. The
airmass ahead of the boundary across eastern/southern Iowa will
become moderately unstable/sheared this afternoon...with HREF ensemble
mean SBCAPEs of 2000-3000J/kg and 0-6km bulk shear increasing to
30-35kt. As a result, scattered thunderstorms will initiate across
this area...then congeal into a broken line as they push across
the Mississippi River into west-central Illinois this evening.
CAMs have slowed the arrival of the convection by a couple of
hours...with consensus suggesting thunderstorms reaching the far
NW KILX CWA around Galesburg between 7pm and 9pm. Given favorable
instability/shear parameters, a risk for large hail and damaging
wind gusts will initially accompany the storms. However, as the
activity drops further southeastward, the atmosphere will decouple
and become more stable with time. The severe risk will therefore
diminish later in the evening, with only a 5-10% chance of a
severe wind gust reaching the I-72 corridor around midnight. Areal
coverage of storms will continue to decrease overnight as they
push into an even less favorable environment south of I-72. Storm
total rainfall tonight will be greatest along/north of a Rushville
to Bloomington line where amounts of 0.75 to locally greater than
1 inch will be likely. Amounts will rapidly decrease further
southeast with locations along/south of a Taylorville to Paris
line only picking up 0.25 or less.

Scattered showers/thunder may linger and/or re-develop across
east-central and southeast Illinois on Sunday before the cold
front settles into the Ohio River Valley: however, am not
expecting any substantial rainfall from the few showers that
persist on Sunday. The main story will be the slightly cooler/less
humid conditions as highs drop into the upper 80s to around 90
degrees.

Barnes

.LONG TERM...(Monday through Friday)
Issued at 343 AM CDT Sat Jun 22 2024

After a warm/dry day on Monday, another cold front will drop into
the region by Tuesday. With temperatures spiking back into the
middle 90s and dewpoints climbing into the lower 70s ahead of the
boundary, peak afternoon heat index values will exceed 100 degrees.
As the front arrives, another round of scattered strong convection
will be on tap Tuesday night into Wednesday. After that, upper troughing
over the Great Lakes will bring a more substantial cool-down for
the end of next week as highs drop into the middle to upper 80s
Wednesday through Friday.

Barnes

&&

.AVIATION...  (For the 06z TAFs through 06z Saturday Night)
Issued at 1100 PM CDT Fri Jun 21 2024

Mostly clear skies will continue overnight. CU will redevelop
tomorrow morning across the area at around 5kft with some cirrus
as well...ahead of the next weather system that will approach the
area from the west and northwest. Mid clouds will begin to advect
in around the 00z time frame as storms should have developed to
the northwest of IL. Lower clouds and precip will begin to move
into the area around 03z at PIA. Some CAMs are showing the precip
diminishing as it moves toward the TAFs, but other are showing
storms arriving during the evening hours. Have decided to add a
PROB30 group starting at 03z for PIA and then 04z for SPI and BMI.
DEC and CMI would be closer to 06z. Winds will be southwest
through the forecast period. Speeds will remain light overnight
but then increase again tomorrow with gusts up to around 20kts
tomorrow morning into the afternoon. Gusty winds will continue
into the evening hours.

Auten

&&

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

$$