Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 140445

Area Forecast Discussion
National Weather Service Lincoln IL
1145 PM CDT Thu May 13 2021

Issued at 250 PM CDT Thu May 13 2021

While quiet weather continues through much of Friday, the arrival
of a storm system this weekend will bring scattered showers
Saturday and Sunday. A few thunderstorms will be possible by
Sunday as well, mainly south from Springfield and Champaign. While
temperatures briefly cool off on Saturday with the more widespread
clouds and rain, in general, a warming trend will be taking place
over the next several days.


Issued at 831 PM CDT Thu May 13 2021

Another quiet weather night is in store across central Illinois.
High pressure is centered over northern Indiana this evening with
ridging extending back across central Illinois. High based diurnal
cumulus has begun to dissipate with sunset leaving mostly clear
skies and very light or calm winds. Expect overnight lows in the
lower to mid 40s.


.SHORT TERM...(This evening through Friday)
ISSUED AT 250 PM CDT Thu May 13 2021

Diurnal development began shortly before midday, but has been on
the high side, generally around 8,000 feet. The area from Quincy
to Kankakee has been the slowest to see any clouds develop, but
has started to fill in a bit as of late. Temperatures have reached
the mid 60s in most areas, while humidity levels remain on the dry

While the diurnal clouds will fade with sunset, a steady increase
in high clouds is expected on Friday ahead of the shortwave
currently moving through the Dakotas. While several of the high-
res models try to get some rain in here during the afternoon,
forecast soundings show quite a bit of dry air lingering below
6,000 feet, so most of the afternoon appears dry. Temperatures are
expected to edge up a few degrees as southerly flow finally kicks
in behind the departing high, with most of the CWA reaching the
upper 60s to around 70 degrees.

.LONG TERM...(Friday night through Thursday)
ISSUED AT 250 PM CDT Thu May 13 2021

Have increased rain chances across the northwest forecast area
late Friday night as the upper wave gets closer, but it may take
until later on Saturday before the rain threat makes it as far as
I-70. With instability limited, will only mention showers through
early Sunday.

Still some struggle with the longer range models on the placement
of the weekend frontal boundary, with the GFS and Canadian models
having more of a placement near or just north of I-70 on Sunday
and the European model shifting back north to I-80. Consequently,
the ensembles from the latter scenario show the heavy rain axis
west-east across the heart of Illinois, and the GFS focused more
toward the lower Ohio Valley into eastern Kansas. Will limit
thunder mention to mainly the southern 2/3 of the forecast area
for now, with the highest rain chances Sunday night, though some
uncertainty remains in this period.

With the mid week system, there is reasonable agreement in
placement of a surface front north of us, favoring warmer
conditions with highs getting to around 80 Wednesday and Thursday.


.AVIATION...(For the 06Z TAFS through 06Z Friday night)
Issued at 1144 PM CDT Thu May 13 2021

High pressure is in place over the Midwest and will provide light
and variable or calm winds overnight and VFR conditions. As the
high shifts east Friday, expect increasing mid and high clouds and
a modest south wind to develop.




SHORT TERM...Geelhart
LONG TERM...Geelhart
AVIATION...Deubelbeiss is the U.S. government's official web portal to all federal, state and local government web resources and services.