Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 092017
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
317 PM CDT Sun May 9 2021

.SYNOPSIS...
Issued at 317 PM CDT Sun May 9 2021

A cold and frosty night is in store across central and southeast
Illinois as low temperatures drop into the middle to upper 30s.

&&

.SHORT TERM...(This evening through Monday)
ISSUED AT 317 PM CDT Sun May 9 2021

Overcast continues to erode across north-central Illinois this
afternoon, with 20z/3pm satellite imagery showing partial clearing
from the Peoria area northward. The clearing will accelerate
southward toward sunset as diurnal cloudiness on the periphery of
the main cloud area rapidly dissipates. End result will be mostly
clear skies along/north of I-72 by early this evening...with
clearing further south by mid-evening. High clouds will increase
from the west late tonight: however, these will do little to
mitigate the radiational cooling that develops once the atmosphere
decouples and the strong/gusty northerly winds diminish. With
overnight lows dipping into the middle to upper 30s, think frost
will be a threat across a good portion of the area. With planting
season well under way, decided to issue a Frost Advisory across
nearly the entire KILX CWA...except the far west where increasing
clouds may keep temps a degree or two warmer overnight.

After a cold/frosty morning, partial sunshine will help boost
Monday afternoon highs into the lower to middle 60s. A short-wave
trough evident on latest water vapor imagery over South Dakota
will track into the region during the day, triggering scattered
showers during peak heating. All CAMs depict precip developing
along/north of a Rushville to Bloomington line by early afternoon,
with the showers settling south of I-72 before dissipating by
early evening. Despite decent mid-level lapse rates, forecast
soundings exhibit little to no instability. As a result, will not
mention thunder.

&&

.LONG TERM...(Monday night through Sunday)
ISSUED AT 317 PM CDT Sun May 9 2021

The unseasonably cool weather will persist for a few more
days...as daytime highs remain in the 60s and overnight lows dip
into the 30s and lower 40s through Wednesday. Depending upon exact
wind/sky conditions, additional frost headlines may be required
both Monday and Tuesday night. After that, the blocking upper
pattern will break down and heights will begin to rise by the end
of the week. As WAA commences, rain chances will return perhaps as
early as Friday...but more likely Saturday/Sunday as temps
gradually climb back to near normal in the lower to middle 70s by
next weekend.

&&

.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
Issued at 1245 PM CDT Sun May 9 2021

Low overcast continues to blanket central Illinois early this
afternoon: however, skies are clearing upstream along and north of
the I-80 corridor...and this clearing will work southward later
this afternoon and evening. Based on satellite timing tools and
HRRR/NAM RH fields, have raised ceilings to VFR at KPIA by
20z...then further south to the I-72 terminals by 23z/00z. Skies
will be mostly clear this evening, followed by increasing high
clouds overnight. A weak front approaching from the north will
trigger scattered showers across the area by around midday Monday.
Will introduce a mid-level cloud deck at all sites by mid-morning,
but will not mention showers at this time. Winds will initially be
N/NE with gusts to 25-30kt this afternoon, then will rapidly
decrease to less than 10kt after sunset.


&&

.ILX WATCHES/WARNINGS/ADVISORIES...
Frost Advisory from 1 AM to 7 AM CDT Monday for ILZ029>031-037-
038-041>057-061>063-066>068.

&&

$$

SYNOPSIS...Barnes
SHORT TERM...Barnes
LONG TERM...Barnes
AVIATION...Barnes


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