Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 240442
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
1142 PM CDT Mon May 23 2022

.SYNOPSIS...
Issued at 228 PM CDT Mon May 23 2022

With high pressure bringing dry easterly winds into our area, the
arrival of rain with a storm system to our southwest looks to hold
off until Tuesday night, when a warm front lifts into our area.
Expect showers and scattered thunderstorms during the middle of
the week, lingering through Thursday.

&&

.UPDATE...
Issued at 920 PM CDT Mon May 23 2022

High pressure centered in the Great Lakes will continue to provide
dry weather for central IL overnight and likely for much of the
day on Tuesday. High clouds are streaming into Illinois on SW flow
ahead of a developing low pressure system in the southern Plains.
The cloud cover will help keep low temps about 7 to 10 degrees
warmer than last night. Steady E-NE winds at 10-15 mph will also
keep temps from dropping as far as under calm wind conditions.

The low pressure system will eject toward the mid- Mississippi
River Valley on Tuesday, with radar returns likely approaching
western Illinois through the day. However, the dry low level E-NE
flow will aid in keeping the lower boundary layer dewpoints from
increasing quickly. That will help delay the onset of rainfall in
our CWA until Tuesday later evening.

The only adjustments to the forecast tonight was to increase sky
cover in our western counties commensurate with satellite trends.

&&

.SHORT TERM...(This evening through Tuesday)
ISSUED AT 228 PM CDT Mon May 23 2022

Diurnal cumulus is generally limited to areas near and west of the
Illinois River early this afternoon, with clear skies elsewhere.
Some mid and high level clouds continue to edge in from the
southwest, and layer humidity plots indicate these will spread in
overnight, though skies will mainly be partly cloudy.

Morning model guidance continues the trend of the last few runs,
of slowing down the arrival of the rain from the next storm
system. None of the synoptic models get the rain any closer than
the Mississippi River before early Tuesday evening, so the
lingering rain in the forecast during the day has been removed.
Temperatures should be a bit warmer than today, though, mainly
reaching the lower 70s over the majority of the forecast area.

.LONG TERM...(Tuesday night through Monday)
ISSUED AT 228 PM CDT Mon May 23 2022

Continuing with the theme from the previous paragraph, the new
forecast will keep the dry conditions into Tuesday evening, but
some significant moistening of the atmosphere takes place
overnight as a warm front lifts into the area. While PoP`s were
cut back a bit, rain still appears likely after midnight. Some
elevated convection will accompany the warm front, but better
thunder chances are expected Wednesday as we get fully into the
warm sector. SPC Day3 outlook has areas near/east of I-57 in a
marginal severe weather risk, though we should be on the edge of
the better instability so we`ll have to keep an eye on this
potential.

The upper low with this system will not be breaking any speed
records, though the GFS is slowest with it not getting through
Illinois until late Friday night. That solution would keep
scattered showers around into early Saturday. Will be going with
the slightly faster progression of the international models, which
keeps a slight chance of showers going into Friday over eastern
Illinois.

The holiday weekend still appears to be significantly warmer, as
an upper low over the western U.S. forces a southwest flow into
the Mississippi Valley. With an upper high developing over the
southeast states, we will be on the periphery of the storm track,
keeping our area dry overall.

&&

.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
Issued at 1142 PM CDT Mon May 23 2022

Winds will remain on the gusty side for the first 3-6 hrs of the
06z TAFs, as boundary layer mixing drags a weaker LLJ toward the
surface. A few gusts around 20KT will be possible. A diminishing
trend in peak gusts is expected toward sunrise, but winds will
increase again by mid-morning on Tuesday.

Despite the approach of a storm system from the southern Plains
tomorrow, we still expect enough influence from slowly departing
high pressure to keep VFR conditions through 06z Tuesday night.
Ceilings will begin to lower in response to virga gradually
saturating the boundary layer. No precip will be included in this
TAF set through 06z Tues night, but rain chances should increase
for PIA and SPI just beyond this TAF period.

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

UPDATE...Shimon
SYNOPSIS...Geelhart
SHORT TERM...Geelhart
LONG TERM...Geelhart
AVIATION...Shimon


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