436
FXUS63 KILX 101034
AFDILX

Area Forecast Discussion...Updated Aviation
National Weather Service Lincoln IL
534 AM CDT Thu Oct 10 2024

.KEY MESSAGES...

- The stretch of warm weather will end this weekend as a sharp
  front cuts through the region and ushers in the coldest air so
  far this season. Monday night and Tuesday night both exhibit a
  high probability (greater than 60% chance) for widespread frost.

&&

.DISCUSSION...
Issued at 1229 AM CDT Thu Oct 10 2024

Surface high pressure will begin to depart this afternoon as an
upper-level disturbance digs toward the Upper Mississippi Valley,
helping push the predominant ridge axis through our area. As
southerly flow returns Friday afternoon, temperatures will jump a
few degrees warmer with mid 80s heat anticipated across west
central Illinois. This will put Peoria near record territory, with
a forecast high of 85 degF against its record high of 87 degF set
back in 1928.

Saturday will be another warm day with temperatures in the lower-
to-mid 80s once again ahead of a surface cold front. Nevertheless,
a strong upper-level disturbance will dig toward the Great Lakes
region Saturday night, helping drive a sharp 850mb front southward
across Illinois by Sunday morning as the polar jet stream buckles.
The net effect will be a cooler and breezy Sunday with temps
perhaps staying steady or even falling during the daytime hours.
Depending on the timing of the front, we could see a large
temperature gradient across our area, with mid 60s at Galesburg
and near 80 at Lawrenceville.

Overall, model guidance took a bit of a step back on forecast
wind gusts associated with the frontal passage on Sunday, likely
owing to a slight eastern shift in the upper low and ultimately a
weaker and less organized surface low tracking through our area.
Model statistics from the NBM, GEFS and EPS all exhibit a mean
gust between 30-35 mph. But, depending on how dry and deep the
boundary layer becomes behind the front, we could still see a few
gusts creep up over 40 mph. The probability is currently low
(20-40% chance), but we`re curious to see how some of the hi-res
guidance begins to resolve the pattern once it trickles in later
Friday.

With the pattern change forthcoming, we continue to monitor the
greatest impact of the next week: frost. Our probabilistic data
sets support frost blanketing the region both Monday night and
Tuesday night (greater than 60% chance), though the potential for
our first freeze has decreased slightly from the previous
forecast cycle -- again owing to a slight eastward shift in the
core of the upper low. If we do get our first freeze of the
season, it is more likely to occur Tuesday night when the surface
high builds overtop of us, but the NBM is only offering middling
probabilities for this to occur (40-60% chance).

After the brief cold snap, temperatures look to rebound by later
next week as an upper ridge quickly builds across the Plains and
Midwest regions, bringing forth deep southwest flow and a return
to the 70s.

MJA

&&

.AVIATION...  (For the 12z TAFs through 12z Friday Morning)
Issued at 529 AM CDT Thu Oct 10 2024

VFR conditions will persist through this TAF cycle as surface high
pressure lingers over the regional terminals, keeping skies clear
and winds light and variable. By tonight, winds will become
uniformly from the south as high pressure begins to depart.

MJA

&&

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

$$