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000
FXUS63 KILX 172030
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
330 PM CDT Wed Apr 17 2024

.KEY MESSAGES...

- Severe weather risk has increased for Thursday...particularly
  along/south of a Taylorville to Robinson line.

- Much cooler weather is on tap for the weekend...with potential
  frost/freeze conditions.

&&

.SHORT TERM...(Tonight through Thursday)
Issued at 330 PM CDT Wed Apr 17 2024

Low pressure currently developing in the lee of the Rockies across
eastern Colorado will track eastward over the next 24 hours...spreading
clouds and precipitation back into central Illinois late tonight
into Thursday. With an initially dry boundary layer characterized
by surface dewpoints in the middle to upper 40s in place, precip
associated with this system will be slow to arrive. While a few
CAMs are a bit more aggressive, have limited PoPs to locations
west of the Illinois River after 09z/4am. Otherwise it will be a
cool/dry night with low temperatures in the upper 40s and lower
50s.

Showers will spread as far east as the I-55 corridor by midday
Thursday...with areas further east remaining dry until the
afternoon. The latest Day 2 Convective Outlook from SPC has
increased the probability of severe weather into the Enhanced Risk
category along/south of a Taylorville to Robinson line for Thursday
afternoon and evening. Models indicate a modestly unstable/sheared
environment along/south of the low track...with the 12z Apr 17 HREF
featuring a high probability (greater than 60% chance) of SBCAPEs
exceeding 500J/kg and 0-6km bulk shear more than 30kt along/south
of a Litchfield to Paris line. HRRR/RAP have been consistently
showing cells developing across eastern Missouri toward midday,
then spreading E/NE into south-central Illinois during the
afternoon. Given relatively skinny SBCAPE profiles with values of
only 1000-1500J/kg, do not think very large hail is a serious
threat with the storms. It appears the main hazards will be
damaging wind gusts of 60-70mph and isolated tornadoes as the main
storm mode will be QLCS. Most likely time for severe will be noon
to 8pm.

Barnes

.LONG TERM...(Friday through Next Wednesday)
Issued at 330 PM CDT Wed Apr 17 2024

Once the low tracks into the Ohio River Valley, much cooler/drier
air will filter into the region for next weekend. As has been
advertised for quite some time, it appears frost/freeze conditions
will be possible across parts of central Illinois beginning as
early as Friday night and continuing through Sunday night. The
coldest night will be Saturday night when the 00z Apr 17 LREF
indicates a low probability (20-40% chance) of low temperatures
dropping below 32F along/north of I-72. Those with sensitive
newly-planted vegetation outside will need to keep an eye on
future forecasts and be prepared to protect their plants from the
cold this weekend. The chill will be short-lived however, as highs
rebound into the 60s and lows climb back into the 40s to around 50
by Monday-Wednesday.

Barnes

&&

.AVIATION...  (For the 18z TAFs through 18z Thursday Afternoon)
Issued at 1251 PM CDT Wed Apr 17 2024

A large area of clouds continues to blanket locations along/north
of I-72 early this afternoon. VFR ceilings have been prevalent:
however, MVFR cloud bases across Iowa continue to pivot E/NE and
will stay just N/NW of KPIA over the next couple of hours. The
entire cloud shield will lift N/NE and gradually dissipate later
today...with clear skies anticipated at all terminals by late
afternoon/early evening. The next storm system will quickly
approach from the west tonight, with latest CAMs spreading clouds
and a few showers into west-central Illinois toward dawn. Based on
NAM/HRRR consensus, have introduced VCSH at KPIA by 11z...with
predominant -SHRA after 16z. Dry conditions will persist at the
remaining TAF sites until closer to 18z. Westerly winds will
initially gust 25-35kt, then will begin to subside before sunset.
Think winds will decrease to less than 10kt at all sites after
01z/02z.

Barnes

&&

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

$$