055
FXUS63 KILX 181701
AFDILX

Area Forecast Discussion...Updated Aviation
National Weather Service Lincoln IL
1201 PM CDT Wed Sep 18 2024

.KEY MESSAGES...

- Summer-like warmth continues through the first half of the
  weekend with daytime highs in the middle 80s to near 90.

- A more unsettled pattern arrives late this week into early next
  week as a few frontal systems bring periodic chances for showers
  and storms.

&&

.UPDATE...
Issued at 932 AM CDT Wed Sep 18 2024

About the only real difference with today vs. recent days is an
increase in cirrus clouds, which are spilling in from the
northwest. RAP 250 mb moisture analysis shows them tracking east
across the forecast area and will mainly be east of I-55 by
midnight. This is not expected to have a significant impact on
temperatures, which are still expected to reach the upper 80s to
around 90 degrees this afternoon.

Geelhart

&&

.DISCUSSION...
Issued at 247 AM CDT Wed Sep 18 2024

A rex block remains in place over the eastern CONUS with upper
ridging over the northeast US and an upper low over the southeast
CONUS. An upper trough over the western CONUS will act to break down
the rex block as a few shortwaves embedded lift through the Plains
states. Our weather will remain largely unchanged the next few days
with high temperatures through the first half of the weekend topping
out in the middle 80s to near 90 degrees. Lower dewpoints from
daytime mixing will keep overnight lows near seasonable normals this
morning and again tonight, with readings as of 2 am sitting in the
50s.

Our extended period of dry weather will be replaced by a more
unsettled pattern later this week into the start of the new week as
the aforementioned upper waves send frontal systems through the
area. The first wave will bring a cold front into western parts of
the area Thursday night into Friday morning, stalling out over
central Illinois on Friday. Most precipitation from this wave will
be near/west of I-55 through Friday morning, however some
isolated activity may develop Friday afternoon along the slow
moving front as diurnal heating kicks in. By this point in time
though the parent wave will be pretty far north of the area
suggesting low-level moisture will be rather limited. The NBM came
in with a mostly dry forecast Friday afternoon, so left that
untouched for now.

Better chances for showers and storms arrive this weekend into early
next week as a stronger upper wave lifts into the Upper Mississippi
Valley along the western periphery of the upper ridge. A strong push
of WAA along the system`s warm front will increase precipitation
chances across the area later Saturday into Sunday, with the cold
front following behind it early next week. QPF amounts over the next
7 days still looks to be beneficial, especially west of I-55 where
LREF probabilities show a 30-50% chance of amounts exceeding 1 inch.
Occasional thunderstorms may bring locally higher amounts at times.

Temperatures will be cooler to start the week with upper troughing
dives through the Midwest states. Longer range guidance suggests
upper ridging building in behind that, which would imply another
warm up. This falls in line with the Climate Prediction Center`s 8-
14 day outlook (Sep 25 to Oct 1) which favors warmer than normal
temperatures.

NMA

&&

.AVIATION...  (For the 18z TAFs through 18z Thursday Afternoon)
Issued at 1201 PM CDT Wed Sep 18 2024

VFR conditions to continue the next 24 hours, with a period of
high-based (above 20kft) ceilings through about 08-09Z. Winds will
mainly be out the south and 5 knots or less.

Geelhart

&&

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

$$