075 
FXUS63 KILX 271056
AFDILX

Area Forecast Discussion...Updated Aviation
National Weather Service Lincoln IL
556 AM CDT Wed Aug 27 2025

.KEY MESSAGES...

- Below normal temperatures will continue through the weekend,
  with daily highs ranging from the mid 70s to low 80s and lows 
  in the upper 40s to mid 50s.

- There is a around a 15% chance of a shower north of a
  Burlington, Iowa to Pontiac line this afternoon and evening, 
  and north of roughly I-74 tomorrow.

&&

.DISCUSSION...
Issued at 111 AM CDT Wed Aug 27 2025

At 1am, the Midwest finds itself in a stable, northwesterly flow 
regime between an expansive upper level ridge across the West and a 
trough centered in the Hudson Bay. Light winds and clear skies 
continue across central and southeast IL, where temperatures are 
generally in the low 50s and dropping. At this rate, we'll kick off 
the day with temperatures once again in the mid 40s to around 50 
degrees (coolest in low-lying areas) around sunrise. Despite the 
cool start to the day, though, temperatures should top out in the 
mid to upper 70s (several degrees warmer than yesterday) as 
temperatures aloft warm slightly and also winds veer to 
southwesterly with the surface high shifting east.

***** SMALL SHOWER CHANCES NORTH THIS EVENING, TOMORROW *****

A pair of northern stream shortwaves will drift across IA, WI, and 
northern IL - the first this afternoon, and the second tomorrow. 
Each one will bring an increase in cloud cover, but only slight 
(15%) rain chances across our northern counties as moisture return 
is limited by convection further south. Weak isentropic upglide 
driving this afternoon-evening's rain chances suggests precip rates 
will be low and hence we will struggle to saturate the dry 
(dewpoints in the low-mid 50s) subcloud layer. Tomorrow, surface 
dewpoints may climb a little higher (perhaps to around 60) ahead of 
the front and unsurprisingly forecast soundings show a little more 
in the way of surface based instability for shallow afternoon 
showers. Nonetheless, we're only looking at a couple hundred J/kg 
SBCAPE, and with both (1) only weak forcing along the front and (2) 
a relatively dry column (PWATs only around 1 inch) it seems coverage 
of any showers would be limited to less than 15% of our area, with 
the highest chances near and north of I-74. With little, if any, of 
that instability poking into the hail growth zone, we also wouldn't 
expect any thunder with this activity. Ahead of the back door front 
tomorrow, temperatures are slated to rise into the low 80s.

***** WEEKEND LOOKING COOL AND DRY, WARMING NEXT WEEK *****

In the wake of the front and attendant shortwave disturbance, 
northwest flow will maintain below normal temperatures through the 
weekend with daily highs confined to the 70s and lows in the 50s. 
The expansive troughing across the Hudson Bay/Northeast Regions 
should begin to shift east late in the weekend into early next work 
week, allowing temperatures to moderate with highs returning to the 
80s Monday into Tuesday. Deterministic guidance is no longer 
depicting any shortwaves rippling through the area and resulting in 
shower chances this weekend, and NBM probabilities for rain are now 
5% or less into Monday. Current thinking is the best chance for 
precip will arrive with the next trough around mid-late next week, 
when 60-70% of raw and EPS AI guidance has measurable precip in the 
area.

Bumgardner

&&

.AVIATION...  (For the 12z TAFs through 12z Thursday Morning)
Issued at 556 AM CDT Wed Aug 27 2025

VFR conditions should prevail throughout the forecast period, 
with the one caveat being a small (10-15%) chance for patchy fog 
to develop this morning. HREF guidance suggests the highest 
probability is at SPI where it made a brief cameo yesterday 
morning, so the TEMPO group was extended through 13z there. Winds 
will blow from the southwest today, peaking around 7-9 kt this 
afternoon and diminishing after 23z/6pm. Isolated and light 
showers upstream across central IA may hold together and impact 
PIA or BMI this afternoon; the highest chance being at PIA, VCSH 
was added there. Impacts to visibility and ceilings would be 
minimal.

Bumgardner

&&

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

$$