858
FXUS63 KILX 182334
AFDILX

Area Forecast Discussion...Updated Aviation
National Weather Service Lincoln IL
634 PM CDT Wed Sep 18 2024

.KEY MESSAGES...

- A few more days of high temperatures close to 90 degrees are on
  tap, which is about 10 degrees above normal for this time of
  year.

- Chances of decent amounts of rain are highest early next week,
  especially across the Illinois River valley, though not enough
  to significantly impact the drought.

&&

.SHORT TERM...  (Through Friday)
Issued at 300 PM CDT Wed Sep 18 2024

Scattered high clouds continue to spread eastward across the
forecast area this afternoon, with most of the diurnal type
development off to the west. 250 mb humidity plot off the RAP
model suggests a period of mostly cloudy conditions west of I-55
this evening, though cirrus thins out as it gets further into
eastern Illinois. Behind it, another period of mostly clear skies
is expected for much of Thursday.

Not a lot of change with the first cold front that moves through
Thursday night and Friday. Forecast soundings remain on the drier
side below 7000 feet ahead of the front Thursday evening, and
several of the synoptic and high-res models show a significant
weakening of the rain after it crosses the Iowa border after
midnight. Will keep a mention of likely PoP`s across the far
northwest CWA, with rain chances quickly dropping off eastward,
but still around 30% as far east as Decatur late night.

Still a couple more very warm days ahead, with highs Thursday and
Friday again in the upper 80s to around 90 degrees.

Geelhart

.LONG TERM...  (Saturday through Next Wednesday)
Issued at 300 PM CDT Wed Sep 18 2024

Morning models continue to advertise that the persistent blocking
pattern will begin to break down this weekend. The remnant low off
to our east makes it about as far as the New England coast before
drifting south again, but this should allow the upper ridge to
break down as the low currently off the California coast swings
through the 4-corners region. The earlier cold front never truly
gets through the mid-Mississippi Valley, and will drift back
northward this weekend as the low weakens somewhat and moves into
the Plains. Most of the rain activity with this system appears to
be in the Saturday night into Monday time frame. The European
model is on the slower end of the guidance, with several of its
ensemble members lingering rain through Monday night, and even
keeps showers into mid week as a sprawling upper low forms over
the central Plains. Both the GFS and Canadian models are more
progressive and develop the midweek upper low more over Minnesota
or the Lake Superior region, but also with a potential tropical
system over the Gulf of Mexico which could complicate things. For
now, the Tuesday/Wednesday period will largely be with "silent 20"
PoP`s. In terms of amounts, time-lagged LREF ensembles show
precipitable water values peaking around 1.5-1.6 inches Sunday
afternoon, a little above the 90th percentile in climatology for
the first day of autumn. Probabilities of 24-hour rainfall over 1
inch remain in the 25% range across the Illinois River valley off
both the NBM and the time-lagged LREF. With the hard ground, the
gradual amounts would be more favorable for soaking in, though
more rainfall would be useful.

Geelhart

&&

.AVIATION...  (For the 00z TAFs through 00z Thursday Evening)
Issued at 634 PM CDT Wed Sep 18 2024

Ridge of high pressure over central Illinois today will shift to
near the IL/IN state line Thursday. Light and variable winds will
be replaced by light southerly winds along and west of I-55 midday
Thursday. VFR conditions are expected through the period.

Deubelbeiss

&&

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

$$