Area Forecast Discussion
Issued by NWS Central Illinois

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418
FXUS63 KILX 071914
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
214 PM CDT Mon Jul 7 2025

.KEY MESSAGES...

- There will be daily chances (20-50% coverage) for scattered
  showers and storms, particularly during the afternoon and
  evening hours. There is a marginal risk (level 1 of 5) for
  severe storms Tuesday across portions of central Illinois.

- Seasonable heat and humidity will be in place the remainder of
  the week into this weekend with afternoon highs generally in the
  mid to upper 80s and dew points in the 70s.

&&

.DISCUSSION...
Issued at 211 PM CDT Mon Jul 7 2025

A weak area of high pressure is centered over the Great Lakes this
afternoon with ridging extending into portions of central
Illinois. This will help suppress the convective chances for the
remainder of today as well as provide brief relief from the muggy
conditions across the region with dew points generally running in
the 60s north of I-70. Some patchy fog will be possible overnight
into Tuesday morning within the weak flow, mainly over east
central and southeast Illinois.

Surface ridge axis will shift to our east Tuesday allowing
humidity to return across central Illinois with dew points
building back to around 70 degrees for most of the area.
Meanwhile, a shortwave trough is progged to move across the state
Tuesday afternoon/evening coinciding with peak heating and
allowing scattered thunderstorms to develop. Moderately strong
afternoon instability is expected to develop with MLCAPE values
advertised by the GFS expected to be around 1500-2000 J/kg.
Despite passage of the shortwave trough, deep layer shear will
remain sub-optimal for a more organized severe weather threat.
Nevertheless, a pulse severe threat will remain a concern Tuesday
afternoon and evening with downburst winds the primary concern.
Slow storm motions of 15-20 kt from west to east couple with PWats
approaching 2 inches will contribute to a localized heavy rain
threat. HREF LPMM indicates a couple very isolated pockets of
heavy rain (3-5 inches) will be possible.

Wednesday and Thursday will be characterized by weak upper level
troughing over the Great Lakes region with weak surface ridging
over much of the Midwest. Typical summer-time pop-up storms will
be possible each day within the weakly forced and modestly
unstable environment. Weak deep layer shear and more modest MLCAPE
values peaking 750-1250 J/kg both days will keep the severe
threat in check, but a brief pulse wind threat cannot be
completely ruled out along with slow moving storms that will be
capable of locally heavy rain.

Friday and Saturday will see a more notable upper wave traverse
the northern Great Plains and Upper Midwest. In response to this
wave, a warm front will lift across central Illinois Friday. A low
level jet developing Friday evening off to our west will allow
storms to develop and grow upscale and eventually track east along
the warm front into portions of Illinois late in the evening and
overnight. A severe threat will likely materialize with this
system, and depending on specific timing, could translate east
into portions of central Illinois. A cold front sweeping across
the region Saturday will result in another round of showers and
storms, again with a possible attendant severe threat depending on
timing and location of the synoptic front or effective cold front
as determined by the remnants of the Friday night storms.

Deubelbeiss

&&

.AVIATION...  (For the 18z TAFs through 18z Tuesday Afternoon)
Issued at 1135 AM CDT Mon Jul 7 2025

VFR conditions persist through the 18z TAF period. Diurnal cumulus
will develop with bases around 2k-3kft but will be scattered.
Winds shift from northerly to southerly by late tomorrow morning,
but the winds stay light (< 5 knots), so only show the shift to
easterly at this time.

Copple

&&

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

$$