647
FXUS63 KILX 171109
AFDILX

Area Forecast Discussion...Updated Aviation
National Weather Service Lincoln IL
609 AM CDT Sat May 17 2025

.KEY MESSAGES...

- Dry weather is expected through Sunday evening across central
  and southeast IL with cooler/below normal temperatures today.

- Breezy west to northwest winds with gusts of 25 to 30 mph will
  occur today, with winds diminishing during this evening after
  sunset.

- Unsettled weather returns overnight Sunday night through
  Wednesday, along with a risk of strong to severe storms Monday
  afternoon into early Tuesday evening. DESI-LREF has a 40-60%
  probability of over 2 inches of rainfall overnight Sunday night
  through Tue night over central and SE IL, highest in sw CWA.

&&

.DISCUSSION...
Issued at 410 AM CDT Sat May 17 2025

Predawn surface analysis shows strong 992 mb low pressure over
central Lake Superior with its cold front east of IL over central
Indiana into nw KY. Its convection was well southeast of IL and
even getting southeast of KY. A strong 542 dm 500 mb low over
central WI had scattered showers pivoting around it over WI and
upper MI. Patches of clouds were moving se into central IL
especially from Quincy to Bloomington north. Westerly winds were
were gusting 25-35 mph over central IL with lighter sw winds 8-16
mph in southeast IL and less gusty there. A secondary front was
pushing se toward Mattoon/Charleston. Temps were in the mid to
upper 50s nw of the IL river and mid 60s in southeast IL. Drier
dewpoints ranged from lower 40s west of I-57 with low to mid 50s
se of I-70.

The latest forecast model suite takes strong cutoff upper level
low from central WI eastward to southeast Ontario province by
sunset while central IL remains in its cyclonic circulation with
cumulus/stratocumulus clouds increasing today as skies become
partly to mostly cloudy, more clouds from I-74 north. West to NW
winds to remain breezy today with gusts 25 to 30 mph, and a few
higher gusts of 30-35 mph from I-72 north as we currently are
seeing. Cooler highs in the lower 70s today with upper 60s to near
70F from I-74 north where more clouds expected.

Winds to diminish after sunset this evening along with
stratocumulus clouds as Canadian high pressure along the northern
Saskatchewan and Manitoba province line noses down into Iowa, IL
and eastern MO overnight into Sunday morning. Nearby high pressure
ridge on Sunday to bring mostly sunny skies, lighter winds and
seasonable/pleasant temperatures with highs in the mid to upper 70s.
Dry weather should continue over most of CWA into Sunday evening
as clouds increase. A 994-996 mb low pressure system ejects out of
Colorado into central KS/NE by Monday morning lifting a warm front
slowly northeast into central MO and sw KY by Mon morning. Will
see increasing chances of showers and isolated thunderstorms from
sw to ne over CWA overnight Sunday night into Monday with highest
pops in sw CWA late Sunday night into Mon morning where likely
pops are. Highs in the upper 60s to near 70F over central IL
Monday with mid 70s from highway 50 south in far southern CWA. As
warm front slowly lifts ne across southern/sw IL during Monday
night will see increasing chances of showers and thunderstorms.
SPC day3 outlook has slight risk of severe storms late Monday
afternoon into Monday night over west central CWA with marginal
risk over rest of CWA except far ne CWA. An enhanced risk of
severe storms noted over central and northern MO not too far from
Adams, Pike and Calhoun counties IL. SPC day 3 outlook even has a
hatched area of severe over far west central IL just west of
Schuyler county. WPC Day3 ERO has marginal risk of excessive
rainfall over sw half of IL from Lincoln sw for Mon/Mon night with
slight risk of excessive rainfall across MO.

Models have trended a bit further north with low pressure track
into central Iowa Tue afternoon with warm front lifting northward
into central IL. This to likely bring more showers and
thunderstorms to the area Tue and Tue night. SPC day4 outlook has
15% risk of severe storms Tuesday and early Tue evening as far
north as a Jacksonville to Lincoln to Danville line while 30% risk
is further south over mid/western TN. WPC Day4 ERO has slight
chance of excessive rainfall over much of IL for Tue and Tue
evening. Will see a larger temp gradient over CWA Tue deepening
on how far north warm front gets. Currently we have highs in the
low to mid 60s from I-74 north and lower 70s sw CWA and mid to
upper 70s from highway 50 south.

Upper level trof/low pivots into IL during Tue night and Wed
keeping chances of showers and isolated thunderstorms going. Cool
highs in the lower 60s Wed with mid 60s by Lawrenceville. Could
even be some upper 50s for highs especially from I-74 north.
Strong mid/upper level trof just east of IL Wed night and Thu and
could be close enough to keep isolated showers around especially
eastern IL. Highs Thu in the mid to upper 60s with lows Wed and
Thu night in the low to mid 40s. Highs Fri in the upper 60s/lower
70s with dry wx expected. IL established in a nw upper level flow
pattern late next week with temps gradually modifying closer to
normal by Sunday May 25th. A weather system moving into the MO
valley late this week could bring next chance of showers and
possible thunderstorms later Fri night and Saturday.

07

&&

.AVIATION...  (For the 12z TAFs through 12z Sunday Morning)
Issued at 608 AM CDT Sat May 17 2025

Low pressure will continue to spin over the Great Lakes with
breezy west to northwesterly winds prevailing across central
Illinois. Winds will gust to around 25-30kt early this morning but
will very gradually diminish through the period. Meanwhile, cold
air stratocu is slowly inching into central Illinois early this
morning with MVFR conditions approaching PIA/BMI. There is low
confidence in MVFR ceilings spreading any further south than that,
but it will need to be monitored.

Deubelbeiss

&&

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

$$