376
FXUS63 KILX 072341
AFDILX

Area Forecast Discussion...Updated Aviation
National Weather Service Lincoln IL
541 PM CST Fri Feb 7 2025

.KEY MESSAGES...

- A brief period of freezing drizzle may create slippery travel
  conditions along/north of a Rushville...to Lincoln...to Danville
  line Saturday morning.

- A weather system passing well south of the region will spread
  light snow into south-central Illinois Monday night into
  Tuesday. The greatest impacts will remain focused south of the
  I-70 corridor.

- Yet another wave will bring a potentially more significant
  snowfall to much of central Illinois Wednesday afternoon and
  evening.

&&

.DISCUSSION...
Issued at 1237 PM CST Fri Feb 7 2025

A sharpening baroclinic zone will lift northward across the Ohio
River Valley overnight as a mid-level shortwave and its attendant
surface low pressure slide across the central U.S. As moisture
overruns this shallow baroclinic zone, we will see the boundary
layer gradually saturate from the top-down by around sunrise.
Precip rates look light with mid-level dry air never really
eroding. Even with some 800-700mb layer FGEN present, thinking
DZ/FZDZ will be the main ptype. Further south near I-70, precip
rates look a little higher, coinciding with more favorable low-
level lift/omega.

Glancing at the thermal profiles, there remains quite a bit of
variance with the sfc wet bulb temperature at the onset of precip.
Areas along/north of a Beardstown to Lincoln to Danville line
generally have a chance (30-50%) for a thin glaze of ice, while
areas along/north of a Canton to Bloomington line have the best
chance (50-70%). Note: probabilities sourced from 12z Feb 7 HREF
joint probability of Sfc Wet Bulb < 32 AND 1-hr precip > T.

Will add that the timeframe for any accreting ice appears brief,
with the bulk of the drizzle occurring during the daytime hours.
Pavement temperatures along the I-74 corridor are forecast to warm
above freezing by 14z/8am, with ambient temperatures anticipated
to warm into the mid 30s by late morning. For these reasons, we
are holding off on a Winter Weather Advisory for now.

Cooler and drier conditions return Saturday night and extend
through Monday afternoon as an area of modified Canadian high
pressure slowly builds beneath zonal upper-level flow.

A pair of disturbances next week then threaten to bring light
wintry weather back into our region. The first of these
disturbances pushes through Monday night into Tuesday. While the
main area of low pressure looks to remain well south of us,
another overrunning precip event looks to spread as far north as
the I-70 corridor. Both blended (NBM) and ensemble (LREF) guidance
support a low (30-40%) chance for > 1" of snowfall in areas
along/south of I-70. In addition, the second of these disturbances
lifts across the region Wednesday evening into Thursday morning,
with the probabilistic guidance supporting a medium (40-60%)
chance for > 1". With the colder backdrop by midweek, thinking the
second disturbance promises greater impact than the first.

MJA

&&

.AVIATION...  (For the 00z TAFs through 00z Saturday Evening)
Issued at 540 PM CST Fri Feb 7 2025

A warm front will lift into central Illinois late tonight into
Saturday morning with MVFR then IFR ceilings developing across
central Illinois. Low pressure will track along the I-70 corridor
late morning into early afternoon. With passage of the low,
drizzle or possibly freezing drizzle are expected across portions
of central Illinois. Winds will turn NW behind the low with
modest improvement in ceilings expected behind the departing low
along with an end to the drizzle chances.

Deubelbeiss

&&

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

$$