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000
FXUS63 KILX 211947
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
247 PM CDT Sun Apr 21 2024

.KEY MESSAGES...

- A Frost Advisory is in effect for all of central and southeast
  IL tonight with lows in the mid 30s expected.

- Shower and isolated thunderstorm chances increase for Monday
  night into Tuesday with 0.10 to 0.25" of rainfall likely.

- Thunderstorms return for Fri-Sun with an early concern for
  severe weather all three days.

&&

.DISCUSSION...
Issued at 247 PM CDT Sun Apr 21 2024

The central U.S. is currently dominated by dry and cool high
pressure, which is centered over the southern High Plains as of
19Z. This high will slide southeast through Monday while an upper
low dives southeast from the prairie provinces across the upper
Midwest and into Illinois by Tuesday. This low opens up and we`ll
see a surface low track east across southern Ontario and through
the Great Lakes on Tuesday.

With the high pressure in place tonight, expect nearly all of
central IL to see frost with low temperatures generally in the mid
30s, clear skies, and light winds. A Frost Advisory remains in
effect for the entire area tonight. Southerly winds will increase
and become breezy on Monday in response to the low moving east
from MB into ON. A lead shortwave will bring some showers to the
area Monday night, with the cold front not coming through the area
until Tuesday afternoon and evening. We`ll see showers remain in
the forecast until the front and main upper wave come through the
area on Tuesday evening. Thunder is not looking favorable with
this system as instability looks rather meager. Precipitation also
looks to be rather limited, with amounts generally between 0.10
and 0.25".

After seeing Mon/Tue in the low to mid 60s, we`ll see highs dip a
bit for Wed behind the cold front. An upper ridge will then build
over the central U.S. for Thursday, with an upper low following
quickly on it`s heels. This wave will move southwest to northeast
and through the central Plains/Upper Midwest on Friday, ushering
in some warmth (highs in the low to mid 70s) and chances for
showers and thunderstorms for Friday. The area stays in southwest
flow aloft over the weekend with a second wave likely moving
through the region on Sunday night. Highs will warm to around 80
for Sat/Sun. Thunderstorms look to be possible all three days
(Fri-Sun), with the grand ensemble having a mean CAPE of around
1000 J/kg and mean shear of 30-40 kts each day. The SPC has west-
central IL outlooked for 15% probability of severe storms for
Friday, while Saturday/Sunday are starting to look more favorable
for severe weather as well. The ballpark precipitation estimate
for the Fri-Sun period is around 0.5 to 1.5" for central IL.

Knutsvig

&&

.AVIATION...  (For the 18z TAFs through 18z Monday Afternoon)
Issued at 1210 PM CDT Sun Apr 21 2024

VFR conditions are expected for the period.

Knutsvig

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
Frost Advisory from 2 AM to 8 AM CDT Monday for ILZ027>031-
036>038-040>057-061>063-066>068-071>073.

&&

$$