223
FXUS63 KILX 092255
AFDILX

Area Forecast Discussion...Updated Aviation
National Weather Service Lincoln IL
555 PM CDT Tue Sep 9 2025

.KEY MESSAGES...

- An extended period of well above normal temperatures is
  expected, especially late week into early next week. However,
  longer range ensembles would suggest the warmth continuing
  several more days after that.

- The heat, and associated lack of rain, will result in a risk of
  flash drought conditions through mid month.

&&

.DISCUSSION...
Issued at 215 PM CDT Tue Sep 9 2025

The warmup has begun, as temperatures have reached the mid to
upper 70s early this afternoon, albeit still with comfortably low
dew points in the 45-50 degree range. A fair amount of mid and
high level cloudiness is accompanying an upper wave, which
currently extends from central Minnesota southward down the length
of the Mississippi Valley. Skies will remain partly cloudy through
the night, as the wave passes through, and temperatures will
remain comfortable with lows in the lower to mid 50s.

No significant changes are in the forecast through the weekend.
Upper level ridging builds across the central U.S. through mid
week, gradually edging eastward. Synoptic models are trending
toward an omega block pattern developing over the Mississippi
Valley this weekend, anchored by lows over the Rockies and New
England. This is more of a shift from this time yesterday, when
the eastern low was favored more over lower Michigan, and would
result in the warmer conditions persisting well into next week. As
for the actual temperatures, the straight NBM guidance appears to
be running too warm, likely due to the ongoing issue with GFS
guidance overmixing the airmass and bringing in triple digit
temperatures. Will lean more toward the NBM 50th percentile, which
brings more uniform lower 90s to the forecast area. Record
temperatures from the longer term climate stations in the area are
in the upper 90s to around 100 degrees for the weekend.

While a few ensemble members, along with the deterministic models,
trying to bring in a few showers/storms Saturday night into early
next week, placement of the ridge and associated capping would
tend to suppress much convective activity. Will keep any rain
chances around 20% or less at this time.

Geelhart

&&

.AVIATION...  (For the 00z TAFs through 00z Wednesday Evening)
Issued at 555 PM CDT Tue Sep 9 2025

Another VFR cycle with SCT/BKN mid to high level clouds and light
southeast to south winds.

25

&&

.HYDROLOGY...
Issued at 215 PM CDT Tue Sep 9 2025

Rainfall over the last 30 days in most of the forecast area is
running less than 50% of normal. Analysis from the Midwestern
Regional Climate Center is showing a widespread area from about
Macomb to Mattoon southward at 10% or less, with less than a
tenth inch of rain in south central Illinois. Streamflow
conditions along the Sangamon, Mackinaw and Vermilion Rivers are
much below normal. Significant concern exists that the extended
heat, along with soil moisture rankings below the 20th percentile
and the meager rain prospects over the next week or two, will
trigger flash drought conditions. CPC 8-14 day hazards outlook is
highlighting a large area south of I-72 as being at risk of rapid
onset drought, with much of this region already at D0/D1 level
drought conditions. Longer range ensembles suggest the above
normal temperatures will continue through the remainder of
astronomical summer, and CPC 8-14 day temperature outlooks show a
greater than 50% chance of above normal temperatures from
September 16-22nd.

Geelhart


&&

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

$$