313
FXUS63 KILX 291151
AFDILX

Area Forecast Discussion...Updated Aviation
National Weather Service Lincoln IL
551 AM CST Sat Nov 29 2025

.KEY MESSAGES...

- An early season winter storm system will create significant
  travel difficulties across much of the Midwest this weekend.

- Snow will be the primary precipitation type today...before
  mixing with rain along/south of I-70 by this evening.

- Snow accumulations will range from 1 to 3 inches south of
  I-70...to as much as 9 to 12 inches along and north of a Macomb
  to Bloomington line.

&&

.DISCUSSION...
Issued at 356 AM CST Sat Nov 29 2025

Satellite imagery early this morning shows a mid-level trough
digging across the Plains, accompanied by a deepening plume of
moisture surging northward up the Mississippi Valley. The surface
low pressure, currently centered over west-central Kansas, is
forecast to lift toward northern Illinois tonight as the
associated mid-level wave pivots across the central United States.
Radar exhibits a broad swath of precipitation wrapping around
this system, with its eastern edge just beginning to enter west-
central Illinois as of 2 AM CST.

While the 00Z sounding from last night indicated a significant
layer of dry air below 700 mb, this layer has now eroded. Regional
surface observations confirm strong warm and moist advection
developing north of the surface low, with upper-jet diffluence
contributing to an expanding area of precipitation.

Snow has been the initial precipitation type, and it is expected
to remain the dominant type through the afternoon. This is due to
the thermal profile and surface wet-bulb temperature remaining
cold enough. A notable trend across the last few model cycles is a
less aggressive push of warm air into the I-72 corridor by late
afternoon. Consequently, the potential for a rain-snow mix
(partial melting through a saturated layer) has been shunted
further south, closer to the I-70 corridor. This shift means most
of central Illinois is now likely to experience a long-duration,
all-snow event throughout the afternoon hours.

No changes were made to our winter storm headlines overnight, and
forecast snow totals largely remain intact from yesterday`s
forecast. If anything, our confidence in forecasting warning-
criteria snow across east-central Illinois has increased. We
continue to support a broad swath of 5-8 inches of snow in areas
north of I-70, with the potential for 9-12 inches in areas near
and north of a Macomb-to-Bloomington line. At this point, the
greatest uncertainty lies in areas near and south of I-70 where
there will likely be sharp cut-off in accumulating snow, owing to
the potential for a rain-snow mixture by late afternoon. In such
areas, we have maintained between a trace and 4 inches of snow.

Gusty southeast winds today will shift to the west tonight as the
surface low lifts across the forecast area. Accumulating snow,
combined with wind gusts of 25-35 mph, increases the risk of
blowing and drifting snow, occasional whiteout conditions, and
sporadic power outages.

Precipitation is expected to decrease to flurries or drizzle from
west to east after approximately 6 PM this evening as the system
dry slot moves across central Illinois. Overnight, additional snow
showers are possible near and north of I-74 where wrap-around
moisture re-enters the area, though additional snow accumulation
is unlikely to exceed one inch.

After today, we will enter a prolonged period of unseasonably
cold weather. It won`t necessarily be worthy of a Cold Weather
Advisory on any given day, but there is a legitimate chance that
temperatures do not warm above freezing at all next week as strong
surface high pressure builds in and out of the central U.S. At
this time, the coldest period appears to be Wednesday night and
Thursday night when wind chill values could fall below zero.

Aside from the cold weather impacts, we continue to monitor the
potential for a quick-hitting burst of snow Monday night as a pair
of jet streaks phase together over the region ahead of a digging
trough. At this point, much of the ensemble guidance supports at
least a few inches of snow beneath the jet streak. Fortunately,
p-type will not be a concern with this event. We will be plenty
cold, and with SLRs closer to 12-15:1.

MJA

&&

.AVIATION...  (For the 12z TAFs through 12z Sunday Morning)
Issued at 535 AM CST Sat Nov 29 2025

Flight conditions will continue to deteriorate through this
morning as an expansive winter storm system spreads periods of
heavy snow across the regional terminals. Winds will blow from the
southeast this morning, gusting up to 30 kts, then shifting west
tonight and remaining gusty as the center of low pressure lifts
across northern Illinois. Blowing snow will contribute to LIFR
visibility, while also obscuring ceilings for a brief time this
afternoon.

Heavy snow will taper to flurries or drizzle from west to east
between 23z-02z, allowing for a dramatic improvement to
visibility. Ceilings will also improve tonight, albeit briefly,
as low pressure departs toward the Great Lakes. Low stratus/MVFR
could then return late in this TAF period as moisture wraps around
the back of the system.

MJA

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
Winter Storm Warning until 6 AM CST Sunday for ILZ027>031-
036>038-040>043-047>053.

Winter Storm Warning until 6 AM CST Sunday for ILZ044>046-
054>057-061.

Winter Weather Advisory until 6 AM CST Sunday for ILZ062-063-
066>068-071>073.

&&

$$