318
FXUS63 KILX 110022
AFDILX

Area Forecast Discussion...Updated
National Weather Service Lincoln IL
722 PM CDT Thu Apr 10 2025

.KEY MESSAGES...

- Scattered showers and a few storms will continue well into the
  evening across portions of central and southeast Illinois,
  though thunder chances will steadily diminish.

- Cold air will overspread the area Friday night. There is a
  potential for sub-freezing lows, primarily east of I-57.

&&

.UPDATE...
Issued at 722 PM CDT Thu Apr 10 2025

Forecast has been updated to increase the rain chances well into
the evening.

Latest surface map shows the boundary roughly along a Monmouth to
Lawrenceville line. Afternoon convection blossomed along this
corridor and a few of the storms produce some small hail and wind
gusts 40+ mph. As we get to sunset, the thunder has been
diminishing. However, with the cold air pocket associated with the
overhead shortwave still evident on water vapor imagery, the
overall shower threat will linger for at least a few more hours.

Geelhart

&&

.DISCUSSION...
Issued at 136 PM CDT Thu Apr 10 2025

Latest water vapor imagery showed a series of shortwaves just to
our west and northwest that will track southeast across our area
through this evening. At the surface, a weak/stationary
convergence boundary was analyzed along a Galesburg-Springfield-
Flora line at 18z. Forcing ahead of these waves, and along and
south of the boundary will be a focus for scattered convection
until around 03z. Thermodynamic fields support a few strong
storms, primarily due to steep mid level lapse rates and a
pronounced near surface dry layer (inverted-v soundings below 850
mb). This would promote a few stronger downdrafts and small hail,
possibly up to quarter size. Deep layer shear is unimpressive,
generally under 25 kt, so we don`t expect much organization to
these storms and mainly a pulse strong/severe storm.

Next item of interest is a chunk of seasonably cool air sliding
into the Midwest behind this system. 850 mb temps drop to -3C
early Saturday morning, concurrent with surface ridging sliding
over our eastern CWA. Near ideal radiational cooling in place,
especially near and east of I-57 where blended guidance shows lows
30-32F. Cooler end of guidance has upper 20s lows, so sensitive
early season vegetation could again be at risk, and will be
monitoring this period for a potential Freeze Warning.

A surge of warm advection will overspread the region this weekend
as return flow sets up on the back side of the ridge, with gusty
south winds pushing highs into the lower on Sunday west of I-55.
A few showers could occur as the low level jet veers into the area
Sunday morning, but this looks brief and focused farther to the
north.

Global ensembles continue to advertise a closed 500 mb low
crossing the far upper Midwest late this weekend, and a sub 1000
mb surface low tracking through the northern Great Lakes Monday.
This will keep windy conditions going Monday, along with our next
chance of showers and storms. 12z guidance shows a progressive
frontal passage, clearing central IL by mid morning. If these
trends hold any strong/severe storms would be more likely to our
east, in line with SPC`s Day 5 outlook. Beyond this system,
cooler and dry air looks to overspread the area into midweek.

25

&&

.AVIATION...  (For the 00z TAFs through 00z Friday Evening)
Issued at 600 PM CDT Thu Apr 10 2025

An area of showers and embedded thunderstorms is expected to
continue into the evening over portions of central Illinois,
though thunder chances will be diminishing with time. These will
mainly impact KSPI and perhaps KDEC. Further north, a surface
boundary extending from KGBG-KMTO is resulting in northeast winds
at the other TAF sites. This boundary will sink south this evening,
and KSPI/KDEC should see northeast winds by 06Z, as well as
showers ending.

A band of MVFR level cloudiness is expected to drift southwest
overnight into the area. Latest ensemble guidance suggests about a
5-6 hour period where ceilings drop below 2000 feet, before
clearing moves in from the northeast later Friday morning.

Geelhart

&&

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

$$