272
FXUS63 KILX 171945
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
245 PM CDT Tue Sep 17 2024

.KEY MESSAGES...

- Well-above normal temperatures will continue through Friday,
  with highs in the upper 80s to near 90. Some modest cooling
  takes place later in the weekend, though nothing substantial.

- Rainfall amounts are trending higher during the Saturday to
  Tuesday time frame across the Illinois River valley, though not
  likely enough to curtail the rapidly expanding drought
  conditions.

&&

.SHORT TERM...  (Through Thursday Night)
Issued at 245 PM CDT Tue Sep 17 2024

Little change in our weather is expected through mid week, with
the upper low over the western Carolinas drifting northeast and
keeping the blocking pattern in place. Like today, strong mixing
should allow for dew points to drop into the upper 40s or lower
50s Wednesday afternoon, near the NBM 10th percentile, so
temperatures in the upper 80s will not feel overly hot. Going into
Thursday, winds finally swing around to the south, as a skinny
ridge of high pressure builds northeast from Texas to Michigan in
response to an upper low in Utah lifting into Manitoba. This
should allow for some modest recovery in dew points, but with the
dry conditions over the last few weeks, the heat index should
remain below air temperatures expected to be near 90.

As the upper low moves into Canada, a trailing cold front will move
across Illinois late Thursday night into early Friday. While this
will bring the first decent rain chances in some time, they should
mainly be limited to areas west of I-55. And, with the front
battling a drier air mass, rainfall amounts should mainly be
around a tenth inch or less.

Geelhart


.LONG TERM...  (Friday through Next Tuesday)
Issued at 245 PM CDT Tue Sep 17 2024

Morning model suite continues to show a trend toward a breakdown
of the persistent blocking pattern during the second half of the
forecast period. The upper low opens up somewhat, but still hangs
around near the New England coast this weekend. Meanwhile, an
upper low developing off the West Coast mid week will swing
northeast out of the Desert Southwest. The front mentioned earlier
is expected to get hung up late in the week, while the
southwestern low moves into the central Plains. Ensemble guidance
has been trending higher with rain chances and associated amounts
for the Saturday-Tuesday time frame, with probabilities of over an
inch of rain during this period around 30-40% west of the
Illinois River valley per the time-lagged LREF. Rainfall for the
first half of the month has generally been less than 5% of normal
north of I-70 and not much better south of there. The warm and dry
weather is steering toward rapidly expanding drought conditions,
so any rainfall would be beneficial, but not likely enough in the
short term.

With this pattern shift, at least temperatures will return closer
to normal beginning late in the weekend, though nothing especially
cool. The CPC 8-14 day outlook continues to favor above normal
temperatures.

Geelhart

&&

.AVIATION...  (For the 18z TAFs through 18z Wednesday Afternoon)
Issued at 1200 PM CDT Tue Sep 17 2024

VFR conditions expected the next 24 hours. Some high-based diurnal
cumulus has formed southwest of KSPI and may produce some brief
ceilings near 8,000 feet toward the beginning of the period. Wind
flow will be out of the east, for the most part around 5 knots.

Geelhart

&&

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

$$