384
FXUS63 KILX 072341
AFDILX

Area Forecast Discussion...Updated Aviation
National Weather Service Lincoln IL
641 PM CDT Sat Jun 7 2025

.KEY MESSAGES...

- There is a Marginal to Slight risk of excessive rainfall this
  evening over central and southeast IL. Model guidance has
  pockets of 1.5-3 inches from IL river east, though most areas
  should be under 1 inch of rain.

- There is a Slight Risk for severe thunderstorms west of
  I-155/I-55 Sunday afternoon and evening, and a Marginal Risk to
  the east.

- Aside of slight chance of showers in southeast IL early Monday
  morning and north of Peoria during Monday afternoon, a dry
  stretch of weather is expected over central and southeast IL
  Monday through Wednesday night. Highs in the upper 70s to around
  80 Sunday through Tuesday will warm into the mid 80s Wednesday
  and Thursday as south winds gradually increase humidity levels.

&&

.DISCUSSION...
Issued at 245 PM CDT Sat Jun 7 2025

Some showers and isolated thunderstorms were starting to track
east into areas sw of I-74 and west of I-57 and over parts of
Clay, Richland and Lawrence counties at mid afternoon. More
widespread showers and thunderstorms were further west over
central and northern MO associated with an MCV system with its
circulation centered over west central MO with 1007 mb low
pressure. Its warm front extended through central MO into
southern/sw IL near I-64. Temps over CWA were in the low to mid
70s, held back by cloud cover and also a smoke layer aloft from
Canadian wildfires. Dewpoints were in the upper 50s to mid 60s,
with lowest dewpoints from Galesburg to Peoria and Bloomington
north. Air Quality Index (AQI) was mostly in the moderate category
(yellow color) over central IL with an orange color for unhealthy
for sensitive groups sw of Lincoln around Springfield and in
northeast IL from LaSalle/Peru and Pontiac northeast to Chicago.

Remnants of MCS to track eastward into central IL by 00Z/7 pm and
surface low deepening to 1003 mb as it tracks across southern IL
late this evening. Showers likely spread over rest of CWA next few
hours with isolated thunderstorms, then diminish from the west
during mid/late evening. Best instability is south of CWA, though
far southern CWA is in marginal risk of severe for 5% chance of
damaging winds and large hail for central/southern Clay, southwest
Richland and far sw Lawrence counties. PW values peak at 1.4-1.7
inches late this afternoon and into mid evening and could see
pockets of moderate to heavy rain. LPMM shows small areas of 1.5
to 3 inches of rainfall, though most areas should be under 1 inch,
averaging around a half inch of rainfall into mid evening. A few
showers could linger in east central IL early overnight, otherwise
patchy fog likely develops overnight especially I-55 west where
clouds decrease some and lighter winds, and could be pockets of
dense fog. Lows overnight in the upper 50s to around 60F over IL
river valley and mid 60s se of I-70.

A cold front over central ND and nw SD to push se into the IL
river valley by late Sunday afternoon and into southeast IL during
late Sunday evening. This will likely bring another round of
convection to the area Sunday afternoon and evening. SPC day2
outlook has marginal risk of severe storms over area from mid
Sunday afternoon into mid Sunday evening, with slight risk over
west central CWA (west of Peoria and Springfield) where there is
a 15% risk of damaging winds, large hail and 2% to less than 5%
risk of tornadoes. Behind the cold front a new batch of Canadian
wildfire smoke moves se into the IL river valley late Sunday
afternoon and over rest of central IL during Sunday night, and se
IL late Sunday night into Monday morning. This may bring more air
quality concerns with Sunday and Sunday night having moderate air
quality levels and could linger into Monday though breezy WNW
winds expected Monday behind cold front. Highs Sunday around 80F
with lows Sunday night ranging from low to mid 50s over IL river
valley and 60-65F in southeast IL from I-70 southeast.

Small chances of showers in southeast IL during 1st half of Monday
morning until cold front clears, then a cutoff mid/upper level low
over the central Canadian Prairie Provinces dives se toward
western Lake Superior and northern WI by midday Monday. This could
produce isolated showers north of Peoria during Monday afternoon.
Highs Monday in the mid to upper 70s with breezy WNW winds.

Upper level low pulls away from the Great Lakes on Tue while weak
high pressure settles into the mid MS river valley. This to bring
fair wx to central/se IL Tue and likely remains dry through Wed
night. Highs Tue in the upper 70s to near 80F, warm into the low
to mid 80s Wed with sw winds on back side of high pressure moving
east across the Ohio and TN river valley.

Models differ with next chances of convection during 2nd half of
the upcoming week. Flat upper level ridge in place over central IL
Wed into Thu with 500 mb heights of 585-588 dm with main westerly
belt of weather system passing to our north. However tropical
moisture moving NNE from Gulf Coast States over the Ozarks on Thu
and GFS has qpf moving into central IL Thu afternoon while GEM and
Ecmwf wait until Friday for convection chances. Think GFS may be
too quickly bringing pops into central IL Thu and feel we may stay
dry and warm with more humid conditions. Highs Thu in the mid 80s
with some upper 80s possible. Blended models (NBM) has 20-30%
chance of showers and isolated thunderstorms Thu afternoon and Thu
night and increase to likely chances Fri into Saturday.

07

&&

.AVIATION...  (For the 00z TAFs through 00z Sunday Evening)
Issued at 641 PM CDT Sat Jun 7 2025

A shortwave disturbance will continue to bring showers and a few
thunderstorms to the central IL terminals through 02Z-04Z. Areas
of MVFR vsby can be expected, with isolated IFR vsby and MVFR
cigs. Once this disturbance moves to the east, low level moisture
will contribute to fog, which will likely result in continued
MVFR vsby and patches of IFR or worse developing late in the
night. Fog should dissipate by around 14Z, resulting in VFR
conditions until a cold front approaches late in the period,
bringing scattered showers and thunderstorms after 20-22Z. Winds
light and variable, becoming W 8-12 kts by 15Z.

37

&&

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

$$