811
FXUS63 KILX 031100
AFDILX

Area Forecast Discussion...Updated Aviation
National Weather Service Lincoln IL
600 AM CDT Fri May 3 2024

.KEY MESSAGES...

- Scattered showers and isolated thunderstorms diminish from the
  west during this morning, with isolated showers lingering near
  the Wabash river this afternoon. Cooler highs in the mid 70s
  today.

- Level 1 (marginal) risk of severe thunderstorms from mid
  Saturday afternoon into mid Sat evening over all but far eastern
  IL for gusty winds and hail.

- An active weather pattern re-establishes itself Monday through
  Thursday, with signals showing risk of strong to severe storms
  Tuesday and Wednesday especially during afternoon and evening
  hours.


&&

.DISCUSSION...
Issued at 400 AM CDT Fri May 3 2024

Predawn surface map shows a cold front near I-55 with scattered
showers along and east of the front and more numerous near the
Indiana border. IR Satellite loop shows clouds over much of CWA
while clearing skies just nw of Galesburg, Macomb and Quincy.
Temperatures ranged from mid to upper 50s west of the IL river, to
the mid 60s from I-70 southeast.

Cold front to push east of IL/IN border by mid morning with
scattered showers and isolated thunderstorms diminishing as cold
front passes by. Though isolated showers still possible over the
Wabash river valley this afternoon. Clouds to decrease over nw
half of CWA during today, with mostly sunny skies by mid to late
afternoon from I-55. Meanwhile skies stay cloudier over southeast
part of CWA today. Winds turning NE behind the front at 5-15 mph
so much lighter than past few days. Cooler highs today in the mid
70s, except upper 70s possible from highway 50 south in southeast
IL.

Weak high pressure ~1018 mb over western IA drifts over WI and
lower MI by sunset and ridging into central IL much of tonight and
bringing fair weather. Some fog development noted east over parts
of upper Wabash river valley of Indiana and gets close to
Vermilion county/Danville area by sunrise Sat. Will keep fog out
of forecast overnight and early Sat morning but will need to watch
areas near the Indiana border. Lows overnight range from the lower
50s west of I-55 (upper 40s by Galesburg), to the lower 60s in
southeast IL.

A short wave trof over the northern Rockies by Idaho and western
MT to track eastward into the eastern plains by midday Saturday
and push a cold front east through central IL late Sat afternoon
and evening. Air mass gets unstable Sat afternoon with CAPES
rising to 1000-1800 j/kg by mid to late Saturday afternoon while
wind shear values are 15-25 kts. Isolated to scattered
thunderstorms to develop during mid/late Sat afternoon and
continue into Sat evening. SPC introduced a marginal risk of
severe storms over all but far eastern/se IL from Watseka to
Charleston to Mt Vernon west for gusty winds and hail from mid
Sat afternoon through mid Sat evening. Highs Saturday around 80F
to lower 80s with dewpoints back up in the low to mid 60s.

Convection chances diminish overnight Saturday night and Sunday
morning and mainly 20-30% chance in southeast IL by Sunday morning.
A short wave moving ne into the Ozarks late Sunday to increase
chances of showers and isolated thunderstorms in mainly southeast
IL during Sunday afternoon with isolated showers possible late
Sunday afternoon about as far north as I-72. Instability is
weaker on Sunday so not in a threat of severe storms on Sun
afternoon and evening. Highs Sunday in the lower 70s over central
IL and 74-78 in southeast IL. The weak short wave trof lifts into
southern/sw IL by dawn Monday and into the central Ohio river
valley late Monday afternoon, and likely brings showers and chance
of thunderstorms into southeast IL Monday while lower chances
over northern CWA. SPC day4 outlook for Mon/Mon night keeps severe
risk area well west of IL over the central plains centered over
central KS. Highs Mon in the mid to upper 70s.

Forecast models continue to show a large/strong mid/upper level
trof evolving over the Rockies early next week, and ejecting
strong low pressure from CO into ND Tue night and into the upper
MS river valley Wed night. There will be periods of showers and
thunderstorms over IL from this large storm system Tue through Thu
with strong to severe storms possible Tue afternoon into Wed
evening. SPC Day5 outlook has 15% risk of severe storms over IL
Tue afternoon/evening. SPC Day5 outlook has 15% risk of severe
storms se of IL on Wed/Wed night, but would not be surprise to see
this expanded ne into parts of central and southeast IL Wed
afternoon/evening as instability is decent on Tue and Wed with
strong wind shear in place. Warm highs Tue/Wed in the lower 80s,
except upper 70s nw of the IL river on Wed. Best chances of
convection along with possible strong to severe storms shift se
of CWA on Thu though still have low pops on Thu especially se half
of CWA. Cooler and less humid air arrives on Friday and next
Saturday with seasonable highs in the upper 60s/lower 70s.

07

&&

.AVIATION...  (For the 12z TAFs through 12z Saturday Morning)
Issued at 600 AM CDT Fri May 3 2024

A cold front was pushing through central IL early this morning,
causing initially light/calm winds to go northwest/north later
this morning and then northeast this afternoon near/under 10 kt. A
narrow band of MVFR ceilings follows to front. These should
scatter out by midday, with VFR high clouds to follow through 12z.

25

&&

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

$$