909
FXUS63 KILX 221936
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
136 PM CST Wed Jan 22 2025

.KEY MESSAGES...

- Periods of light snow are forecast tonight. Any accumulations
  will be minor, mainly a dusting to half inch, north of I-72.

- Arctic air will linger over the area through Friday, before
  seasonable temperatures move in this weekend. A period of above
  normal temperatures is forecast for early next week.

&&

.DISCUSSION...
Issued at 136 PM CST Wed Jan 22 2025

12z upper air analysis and latest water vapor imagery indicated a
mid level trough axis stretched from James Bay southwest into the
central Plains. One shortwave passed just to our north this
morning, bringing light snow to northern IL. A secondary wave was
noted on w/v imagery over eastern Nebraska early this afternoon.
This disturbance will cross the CWA tonight, providing generally
weak forcing within a dry column (PWATs peak at 0.25-0.30"). Thus
a period of scattered light snow and flurries are forecast
overnight, with accumulations of a dusting to half inch north of
I-72, with the "higher" amounts favored over the far northern
CWA. Any untreated roads where snow accumulates can experience
slick spots given our frozen ground and temps below freezing.

The cold front will cross the area early Thursday morning,
veering winds around to the northwest and increasing gusts to
15-25 mph. This will usher in a fresh round of cold advection,
with most guidance showing 850 mb temps bottoming out -13 to -15 C
Thu/Fri. This chunk of Arctic air will result in a continuation
of below normal temperatures, the coldest occuring Friday morning
when lows dip into the single digits. Surface ridging will be
working across the region at that time, so light winds should
produce apparent temps only a few degrees below ambient and cold
weather headlines are not anticipated.

Mid level flow backs westerly on Saturday, and warm advection
commences in the low levels as surface ridging departs and
southwest winds take hold. Blended guidance shows highs above
freezing over the entire area, ranging from mid 30s north to lower
40s south. A brief/slight cooldown is shown for Sunday after a
dry cold frontal passage Saturday night. However, after that, both
deterministic and ensemble guidance show good agreement that
above normal temperatures will bring a "January thaw" to the
entire area for the first half of next week. This results from a
period of sustained zonal upper level flow and moderating low to
mid level temps (850 mb temps reaching a few degrees above zero
C), with the NBM offering highs in the 40s through Wed. Split flow
pattern through the extended portion of the forecast, keeping
precipitation well north and south of the local area and a dry
forecast in place after tonight.

25

&&

.AVIATION...  (For the 18z TAFs through 18z Thursday Afternoon)
Issued at 1138 AM CST Wed Jan 22 2025

Southwest winds gusting 20-30 kt will dominate the central IL
terminals this afternoon, before gusts diminish around 23-00z.
MVFR ceilings are expected to move in from the northwest tonight,
ahead of an advancing cold front. Scattered flurries or areas of
light snow are possible (30-50%) chance, mainly at KPIA-KBMI.
Ceilings are forecast to lower in MVFR category late tonight, and
model guidance shows low probability (20-40%) of IFR ceilings
developing primarily east of KBMI-KDEC into Thursday morning.
After the cold front passes early Thursday morning, winds will
veer northwest with gusts near 20 kt becoming common by mid to
late morning.

25

&&

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

$$