885 
FXUS63 KILX 261111
AFDILX

Area Forecast Discussion...Updated Aviation
National Weather Service Lincoln IL
611 AM CDT Fri Sep 26 2025

.KEY MESSAGES...

- Patchy shallow fog near the Indiana border and river valleys
  will lift by mid morning. HREF has a 30-40% chance of
  visibilities restricted below 1/2 mile in eastern Vermilion
  county from Danville eastward early this morning until 8 am. 

- A stretch of dry weather will likely continue through next week
  across central and southeast IL. This will likely exacerbate  
  ongoing drought conditions.

- Unseasonably warm weather will develop late this week over IL.
  Highs will reach the lower 80s today, mid 80s Saturday and mid
  to upper 80s Sunday through Tuesday. Highs are still expected to
  reach the low to mid 80s Wednesday through Friday of next week.
  

&&

.DISCUSSION...
Issued at 345 AM CDT Fri Sep 26 2025

The 08Z/3 am surface analysis shows a weak 1015 mb high pressure
over central Texas and ridging northeast across central MO and 
into central IL. Aloft a 500 mb 570 decameter low was near 
Cleveland, Ohio and a 575 decameter low was in west TN. These were
embedded in a mid/upper level trof from the eastern Great Lakes sw
into the mid/lower MS river valley. Upper level subtropical
ridge over western Mexico was ridging into NM and west Texas and
into the Central Plains (NE/KS). Nearly clear skies and light to
calm winds across IL. Patchy shallow ground fog near river 
valleys and lakes. Danville's vsby has been 1-3 miles past few 
hours. Fog is more widespread with lower vsbys in northern Indiana
where a dense fog advisory is in effect for Warren county IN 
until 9 am EDT (13Z). Vsbys down to 1/2 mile at Lafayette and
Crawfordsville, IN and 1/4 miles at Rennsselaer in nw IN. Temps 
had cooled into the low to mid 50s at 330 am, with NWS Lincoln 
down to 49F and Pontiac on the Vermilion river at 47F. 

Have a few more hours to see more patchy shallow fog develop near
the Indiana border and by river valleys and lakes before
dissipating by around 9 am (14Z). Weak surface high pressure 
ridge to stay near IL through tonight maintaining fair wx and
light winds, while upper level trof slowly shifts further east 
with 500 mb ridge building into the Eastern Plains (IA/MO) this 
afternoon. 500 mb heights rise to 578-580 decameters over central 
IL during this afternoon. Should be less cumulus clouds developing
later this morning than what we saw yesterday with best chances 
of scattered cu over southern IL from highway 50 south and MS 
river valley south of Quincy. So a fair amount of sunshine 
expected today over central IL with milder highs in the lower 80s 
(warmest over IL river valley with Peoria near 84F). 

Patchy shallow fog could develop overnight into early Sat morning
near river valleys but appears less likely than what is occuring
early this morning. Lows in the mid 50s, with some lower 50s in 
southeast IL. 

Strong upper level ridge continue to build into IL during this
weekend with 500 mb heights of 588-590 decameters by Sunday and
Monday. A fair amount of sunshine with highs in the mid 80s Sat
and mid to upper 80s Sunday and Monday and likely again on Tue. A
few spots from I-72 north could be approaching 90F Sunday and Monday.

A developing tropical system between Cuba and Hispaniola to track
toward the Carolinas Mon night/Tue and an omega blocking pattern
over the US to likely keep its moisture se of CWA into the middle
of next week. GFS does show light qpf getting into southeast IL
Tue night but other models are keeping qpf se of the Ohio river
which is preferred due to strong upper level high pressure ridge
near IL. A strong 1032-1034 mb Canadian high pressure settling
into James Bay, eastern Ontario and western Quebec by Wed to bring
some cooler air especially into areas ne of CWA. We have highs in
the low to mid 80s Wed and lower 80s next Thu/Fri but could trend
cooler if high pressure ridge gets further south into the Great
Lakes region.  

Nearby high pressure ridge at surface and aloft will suppress 
rain chances across the region resulting in another prolonged 
period of dry weather that could exacerbate ongoing drought 
conditions. Most of CWA (excluding Knox, Stark and Marshall 
counties) are in a moderate to severe drought according to the
U.S. Drought Monitor update on Thu/Sep 25. 

The Climate Prediction Center (CPC) 8-14 Day Outlook for Oct 3-9th
has 55-60% chance of above normal temperatures in southeast IL and
60-65% chance of above normal temps in central IL. Precipitation
is trending near or slightly below normal over CWA during this
time frame. 

07

&&

.AVIATION...  (For the 12z TAFs through 12z Saturday Morning)
Issued at 611 AM CDT Fri Sep 26 2025

VFR conditions will prevail at all central IL TAF sites next 24 
hours, with clear skies and light and variable winds.

Auten

&&

.CLIMATE...  
Issued at 147 PM CDT Thu Sep 25 2025

Record high temperatures for Sunday through Tuesday:

Location        Sunday      Monday     Tuesday
--------      ---------  ----------  ----------
Bloomington   94 (1953)  100 (1953)   98 (1953)
Champaign     94 (1953)   99 (1953)   91 (1971)
Charleston    94 (1953)   99 (1953)   92 (1933)
Decatur       96 (1953)  100 (1953)   94 (1922)
Lincoln       96 (1953)  101 (1953)   93 (1952)
Olney         97 (1939)  101 (1953)   93 (1952)
Peoria        92 (1939)   98 (1953)   91 (1933)
Springfield   94 (1953)  100 (1953)   92 (1971)


&&

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

$$