603
FXUS63 KILX 230354
AFDILX

Area Forecast Discussion...Updated Aviation
National Weather Service Lincoln IL
1054 PM CDT Wed May 22 2024

.KEY MESSAGES...

- There is a 70% chance for thunderstorms Friday, with a level 1
  of 5 (marginal) risk some of these storms become severe. The
  strongest storms could produce damaging wind gusts and large
  hail.

- Scattered thunderstorms are likely (70-80% chance) on Sunday
  with severe storms possible.

&&

.UPDATE...
Issued at 856 PM CDT Wed May 22 2024

Weak high pressure will be the dominant feature overnight,
promoting clear skies and light winds for much of the area,
although it still appears that a disturbance emanating from
convection over Arkansas vicinity could bring some showers and
possibly a few thunderstorms to areas near/south of I-70 late in
the night. Lows could be a touch on the cool side north of I-72
with lower 50s possible in the clear skies and low dewpoints
mainly in the 40s. Fog looks like it will be hard to develop
despite the light winds and clear skies due to the dry conditions
to the north and cloud cover developing to the south where
dewpoints in the upper 50s are more prevalent. Updates this
evening have been mainly to remove precipitation chances until
well after midnight.

37

&&

.DISCUSSION...
Issued at 314 PM CDT Wed May 22 2024

The cold front that passed through the area last night has pushed
deep into southern IL and currently lies in the OH River Valley.
Some showers and isolated thunderstorms have pushed into the
Taylorville area and may bring some light accumulations of rain
to parts of the south and eastern zones through the rest of the
afternoon hours. The upper wave associated with these showers is
expected to clear central IL by the evening hours. A strong or
marginally severe storm is possible in the far southern zones
(Crawford, Clay, Richland, Lawrence), but trends have signaled the
likelihood is decreasing. We may see a return of showers/storms
late tonight in the far south in the vicinity of the stationary
front. Otherwise, expect Thursday to be rather quiet weather-wise
with highs in the low 80s with sunny skies north and partly sunny
skies south near the stationary front.

On Friday, an upper wave will move from the Northern Rockies and
into the Northern Plains, becoming negatively tilted. The surface
low will stay in the Northern Plains, but cold front will push
east into IL. We`ll see a surge of high theta-E air north into IL
on Friday ahead of the front, but the upper support will remain to
the north. As a result, we`ll just see a Marginal Risk for severe
storms on Friday. MLCAPE will be around 3000 J/kg and deep shear
around 25-35 kts, although some models have more shear.

We`ll see a break on Saturday as high pressure moves in over the
area behind Friday`s cold front. Sunday looks to have the best
chance for severe weather in the next seven days. We`ll see better
upper support as an upper wave moves through the area. We`ll
likely have a lead shortwave Sunday morning followed by the main
wave Sunday afternoon/evening. Central IL is currently in a 15%
(Slight) risk for severe weather for Sunday given +3000 J/kg of
CAPE and 40-55 kts of deep shear. The area could see 1 to 2" of
rain with this system as well.

Northwest flow is expected for Monday and Tuesday, with some light
showers possible in the northwest flow to start the week.
Generally, expect a break from precipitation by midweek next week.

Knutsvig

&&

.AVIATION...  (For the 06z TAFs through 06z Thursday Night)
Issued at 1054 PM CDT Wed May 22 2024

VFR conditions expected across the central IL terminals over the
upcoming 24 hours as high pressure along with a relatively dry air
mass drift across the area, while showers associated with a
frontal system to the south remain confined to areas south of
the central IL terminals. Other than mid level cloud cover
affecting some of the I-72 terminals overnight, mostly clear skies
can be expected until diurnal cumulus around 5000 ft AGL develop
after 16Z. Winds light and variable overnight becoming SE 6-10
kts after 16Z.

37

&&

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

$$