920
FXUS63 KILX 212324
AFDILX

Area Forecast Discussion...Updated Aviation
National Weather Service Lincoln IL
524 PM CST Thu Nov 21 2024

.KEY MESSAGES...

- Snow will continue across portions of central and east central
  Illinois before tapering off late this evening. 1-3 inches of
  snow (80 percent confidence) will fall over portions of northern
  Vermilion County with amounts tapering off to just a dusting
  along and north of a Bloomington to Paris line.

- A Wind Advisory remains in effect through midnight tonight.
  Winds of 20-30 mph will gust to 40-50 mph through the evening.

&&

.DISCUSSION...
Issued at 131 PM CST Thu Nov 21 2024

This afternoon, an upper low is centered over the Great Lakes with
strong mid level warm air advection occurring on the southwest
quadrant of the low over portions of northern and central
Illinois. This has been driving light to moderate snow across
those parts of the state today. Forcing will continue across
portions of east-central Illinois through around 00Z this evening
before settling off to our southeast over southern Indiana into
the Ohio Valley. Latest suite of hi-res guidance continues to
paint the highest snow totals near the IL/IN state line near/north
of I-74, especially across the northern half of Vermilion County
where 1-3 inches of snow appears likely. HREF 10th-90th percentile
snow amounts has a fairly small range of 1-3 inches near
Hoopeston with the mean snow amount near 2 inches. Amounts taper
off quickly to the southwest with a dusting expected from roughly
a Bloomington to Paris line. There may be a transition back to
liquid precip before precip ends altogether late this evening
owing to loss of ice crystals aloft and a very slowly warming
boundary layer.

For the wind advisory, HREF probabilities of exceeding 45 mph
gusts drop off dramatically between 7pm and 10pm this evening,
with the entire CWA solidly at or below 50 percent by 9pm. Have
trimmed the back end of the wind advisory accordingly. In the
meantime, have already experienced a few sporadic gusts of 45-50
mph with the potential continuing through much of the evening.

Friday, upper low will continue to dig southeast to the mid
Atlantic Coast while upper ridging spreads east across the mid
Mississippi Valley with strong mid level heights rises/subsidence
centered over much of the Midwest. Subsidence will strengthen a
low level inversion across central Illinois while lingering weak
low level cyclonic flow should help to keep cloud cover locked in
over the region through the day Friday. At the surface, an
elongated ridge will be in place across the Great Plains with a
moderate pressure gradient and steep low level lapse rates in the
northwest flow continuing to allow gusty conditions over central
Illinois, though winds should gradually subside through the day
as the ridge axis approaches the Mississippi River Valley. NBM
90th percentile wind gusts, which indicate a reasonable high end
gust potential, generally fall in the 25-30 mph range through late
Friday afternoon before tapering off during the evening.

Surface ridge axis will gradually translate east across the
Mississippi Valley over the weekend resulting in fair weather
conditions across central Illinois along with a gradual warming
trend. 925mb flow will gradually become more neutral to slightly
anti-cyclonic through the day Saturday allowing low level cloud
cover to finally clear. Seasonable temps in the upper 40s to lower
50s Saturday will warm into the mid to upper 50s Sunday as the
ridge axis shifts to our east allowing southerly flow back across
central Illinois.

Deubelbeiss

&&

.AVIATION...  (For the 00z TAFs through 00z Friday Evening)
Issued at 524 PM CST Thu Nov 21 2024

SN has changed to -RA over the past couple hours, and the area of
rain will diminish over central IL over the next few hours. MVFR
ceilings will be common through the remainder of the forecast,
with IFR most favored at KBMI-KCMI tonight. Northwest winds
gusting over 30 kt this afternoon, will gradually lower this
evening, though gusts will continue around 20 kt through Thursday
afternoon.

25

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
Wind Advisory until 9 PM CST this evening for ILZ027>031-036>038-
040>057-061>063-066>068-071>073.

&&

$$