Decatur, Illinois 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

284
FXUS63 KILX 111721
AFDILX

Area Forecast Discussion...Updated Aviation
National Weather Service Lincoln IL
1221 PM CDT Fri Apr 11 2025

.KEY MESSAGES...

- Freeze Warning in effect overnight until mid morning Saturday in
  eastern IL with lows 30-32F. HREF has 40-70% chance of
  temperatures at or below freezing east of highway 51 at 6 am
  Saturday.

- Breezy south winds Sunday will bring warmer highs in the upper
  60s to mid 70s (warmest in west central IL). LREF has a 35-55%
  chance of over 35 mph wind gusts southeast of the IL river and
  northwest of I-70 around 1 pm Sunday.

&&

.DISCUSSION...
Issued at 400 AM CDT Fri Apr 11 2025

Early morning surface map shows a surface trof extending from
central KY northwest to near the MO/IL border and into central
Iowa. 1025-1027 mb high pressure was over eastern SD/NE and into
central KS. Aloft a deep mid/upper level trof was over eastern
Canada/US with 552 dm 500 mb low along the eastern KY/TN border
and 548 dm 500 mb low in southeast Ontario Province east of
Georgian Bay. A short wave was in southeast Iowa near the IL
Border while stronger short wave was in eastern KY. A few
isolated showers lingered near Quincy, Litchfield and near and
east of Effingham and have been diminishing as they track SSE.
Broken to overcast low clouds cover much of the CWA early this
morning. NE winds 7-12 mph brought in cooler temps in the lower
40s in central IL and mid to upper 40s in southeast IL from I-70
south.

Latest CAMs take surface trof southward today while high pressure
settles into central IL this evening. Isolated showers in
southeast IL should diminish/end in next hour or so while mostly
cloudy skies this morning to decrease from the ne during the
afternoon and early evening. NE winds gusting 18-25 mph today to
turn more northerly during the afternoon and diminish this
evening as high pressure moves in. Highs in the 60s yesterday will
be in the mid 50s today with some lower 50s in east central IL.
High pressure over IL tonight to bring clear skies and light winds
and colder lows in the low to mid 30s. Issued a freeze warning
from 2-9 am Saturday in eastern IL where HREF has 40-70% chance of
temps at or below 32F at 6 am Sat east of highway 51. May also need
a frost advisory over rest of CWA overnight and early Sat
morning where lows are in the mid 30s.

High pressure to slowly drift east of IL by Saturday afternoon as
light winds become southerly around 10 mph or less. Some increase
in clouds Sat afternoon northern CWA otherwise a fair amount of
sunshine and highs in the lower 60s (around 60F in eastern IL).

Upper level ridge shifts into IL Sat night and Sunday while
surface low pressure over eastern CO Sat afternoon approaches nw
IL by sunset Sunday. Most of the forecast models keep qpf north of
CWA on Sunday with our area remaining dry on Sunday night. Breezy
to even windy on Sunday with winds gusting 25-35 mph. LREF has
35-55% chance of over 35 mph wind gusts se of the IL river and nw
of I-70 early Sunday afternoon. This brings in warmer air with
highs in the upper 60s to around 70F in eastern IL and low to mid
70s over central and western CWA, warmest in west central IL where
upper 70s possible just west of Schuyler and Scott counties in
Quincy and Pittsfield area.

Cold front to push se into the IL river valley during Sunday
evening, central IL overnight Sunday night and passes through
southeast IL during Monday morning. The front initially does not
have as much moisture to work with and best instability is to our
se on Monday afternoon where SPC Day4 outlook has slight risk in
northern KY, southeast Indiana into central/se Ohio. We carried
20-30% chance of showers and isolated thunderstorms in central and
southeast IL on Monday morning and then shifts east of IL on Mon
afternoon. Highs Monday in the lower 60s nw of the IL river, mid
60s heart of CWA and upper 60s in southeast IL. Breezy WNW winds
behind the front Monday with gusts 25-30 mph in central IL and
gusts 20-25 mph in southeast IL.

Another deep mid/upper level trof into the eastern US Monday night
and Tue with breezy NW winds gusting 25-30 mph on Tue brings in
cooler temps with highs in the upper 50s to near 60F Tue.
1023-1025 mb high pressure settles into the MS river valley by
dawn Wed and lows in the mid 30s Tue night could bring more frost
overnight Tue night/early Wed morning to parts of central/eastern
IL. Lighter winds Tue night and Wed with increasing clouds from
the west during Wed. Seasonable highs Wed in the low to mid 60s
with upper 60s over west central IL.

Low pressure forms over the lee of the Rockies Tue night and Wed
morning and tracks to near IL late Wed night into Thu morning.
This to bring chance of showers and isolated thunderstorms Wed
night and Thu with another upper level trof digging into the
eastern US Thu into next Friday with upper level ridging from the
SW US into the Great Plains. Upper level ridge appears to shift
east into IL by Easter Sunday and if true, would bring a milder
and hopefully dry easter weekend. CPC 8-14 Day outlook for Apr
18-24 has 40-50% chance of above normal temperatures across IL and
50-60% chance of above normal temps over far west central IL.
Near normal precipitation over central/northern IL and 33-40%
chance below normal precipitation in southern IL.

07

&&

.AVIATION...  (For the 18z TAFs through 18z Saturday Afternoon)
Issued at 1221 PM CDT Fri Apr 11 2025

VFR conditions will prevail through the 18z TAF period. Northerly
winds will be breezy (10-15 knots) could occasionally gust up to 20-
25 knots this afternoon. By the evening (00-04z), winds will become
light and variable. They are forecast to remain that way late in the
morning tomorrow. A lower deck of cumulus will push south from Lake
Michigan mainly impacting CMI and BMI, but remaining VFR ceilings.

Copple

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
Freeze Warning from 2 AM to 9 AM CDT Saturday for ILZ044>046-
054>057-061>063-066>068-071>073.

&&

$$