Peotone Weather
National Weather Service Forecast for: Peotone, IL
Issued by: National Weather Service Chicago/Romeoville, IL
Updated: Wed, 22-Jan-2020 1:16pm CST

Peotone, IL
This Afternoon: Cloudy

Thursday: Light Snow
Light Snow

Friday: Light Rain then Rain And Snow
Light Rain then Rain And Snow

Saturday: Chance Light Snow then Cloudy
Chance Light Snow then Cloudy

Sunday: Mostly Cloudy
Mostly Cloudy

Monday: Mostly Cloudy
Mostly Cloudy

Tuesday: Mostly Cloudy
Mostly Cloudy
Hi 33 °F ↓ Hi 34 °F ↓ Hi 36 °F Hi 35 °F Hi 35 °F Hi 38 °F Hi 43 °F  

Tonight: Light Snow
Light Snow
Thursday Night: Light Snow
Light Snow
Friday Night: Rain And Snow
Rain And Snow
Saturday Night: Cloudy
Sunday Night: Mostly Cloudy
Mostly Cloudy
Monday Night: Mostly Cloudy
Mostly Cloudy
Tuesday Night: Mostly Cloudy
Mostly Cloudy
Lo 28 °F Lo 31 °F Lo 31 °F Lo 27 °F Lo 27 °F Lo 29 °F Lo 32 °F  


This Afternoon
Cloudy. High near 33, with temperatures falling to around 31 in the afternoon. South wind around 15 mph.
Snow after 11pm. Cloudy, with a low around 28. South wind around 10 mph, with gusts as high as 20 mph. Chance of precipitation is 80%. New snow accumulation of less than half an inch possible.
Snow. Cloudy. High near 34, with temperatures falling to around 32 in the afternoon. South southeast wind around 10 mph, with gusts as high as 20 mph. Chance of precipitation is 80%. New snow accumulation of less than one inch possible.
Thursday Night
Snow. Cloudy, with a low around 31. East southeast wind 5 to 10 mph. Chance of precipitation is 80%. New snow accumulation of 1 to 2 inches possible.
Rain before 2pm, then rain and snow. Cloudy, with a high near 36. East wind 5 to 10 mph. Chance of precipitation is 80%. Little or no snow accumulation expected.
Friday Night
Rain and snow. Cloudy, with a low around 31. Chance of precipitation is 60%. New snow accumulation of less than one inch possible.
A chance of snow before noon. Cloudy, with a high near 35. Chance of precipitation is 40%.
Saturday Night
Cloudy, with a low around 27.
Mostly cloudy, with a high near 35.
Sunday Night
Mostly cloudy, with a low around 27.
Mostly cloudy, with a high near 38.
Monday Night
Mostly cloudy, with a low around 29.
Mostly cloudy, with a high near 43.
Tuesday Night
Mostly cloudy, with a low around 32.


Forecast from NOAA-NWS for Peotone, IL.

FXUS63 KLOT 222138

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
338 PM CST Wed Jan 22 2020

213 PM CST

Through Tonight...

The primary forecast message for this prolonged light wintry
event had only slight refinement with honing in on details
especially through Thursday. The confidence remains fairly high
that impacts will be limited through all of Thursday and into
Friday morning with this event. There likely will be lulls or
even periods of mixing with drizzle or a brief light rain, which
will prevent much for any accumulation during that time. For the
second portion of this event, Friday afternoon into early
Saturday, there remains greater uncertainty on some of the
specifics but moderate snow rates and more efficient accumulation
remain plausible. All in all this does not look like a winter
storm by either definition or by impacts, but with light snow
fairly frequent for portions of the CWA over the upcoming 60
hours, there will be at least some impacts and some challenges to

Focus through tonight has been on the onset time of light snow.
Satellite water vapor imagery indicates multiple short waves
across the central United States. These are all part of a
developing larger trough (eventual closed low) forced by a digging
jet stream maximum now moving into the Pacific northwest. A
fairly large area of wintry precipitation extends across Missouri
and Iowa and into Wisconsin. This is slowly inching eastward and
various satellite bands show clouds starting to thicken just west
of the region, indicative of more ascent and saturation. The
multiple waves right now have resulted in pockets of ascent and
broader snow to the west, with some freezing drizzle in-between.
As the forcing improves for a broader area of moisture transport
and isentropic ascent at the low-level jet height, would expect
that light snow will become prevailing upstream, possibly with
some pockets of moderate snow. This will creep into north central
Illinois this evening before a more rapid expansion across the
rest of the Illinois CWA into overnight, as forecast on RAP and
NAM isentropic surfaces. Northwest Indiana will be on the edge of
the deeper saturation, thanks to marginally moist air upstream
from that area, so light snow looks to onset there closer to
sunrise or even a little after.

This snow looks to be primarily minimal in impact, not only
because of timing but because of intensity being primarily light.
That said, precipitable waters of 0.6 inches and the broad forcing
should keep snow consistently falling once it starts into
Thursday morning. With it onsetting during the night and following
the recent cold, untreated pavement temperatures will be cold
enough for the light snow to accumulate. This will lead to some
impacts to the morning commute, with snow totals through mid-
morning forecast to be one half inch to one and a half inches
(highest north and west).



330 PM CST

Thursday through Wednesday...

Thursday through Saturday:

Stepping forward from the short term discussion, confidence is
high in falling precipitation for most of the CWA except perhaps
the far southeast through mid day Thursday, with aforementioned
generally broad WAA/isentropic ascent. Thermal profiles support
snow as p-type during this time, though of the lower ration/wetter
type. Temperatures will inch upward slightly amidst modest
southerly boundary layer flow to within a degree or two of 32F.
Additional snow amounts on colder surfaces Thursday morning of a
few tenths to locally near one inch are forecast.

Continue to suspect that road impacts through early Thursday PM
will be mitigated by temperatures being near to slightly above
freezing and the primarily light snowfall rates, with slick spots
more likely on untreated, elevated, or less traveled roads. During
Thursday afternoon, and possibly bridging the early evening with
northward extent, there is a signal (12z HREF 1-hr QPF as a proxy)
for a weakening of forcing that could yield a lull from already
light precip rates. Depending on surface temps, could potentially
see light rain mixing in with the snow, and overall minimal if any
additional snow. Consensus of model forecast soundings suggest
that saturation of ice nucleation layer should remain sufficient
to preclude any drizzle becoming a prevalent p-type. While impacts
to the Thursday morning commute are not expected to be significant,
latest trends suggest that Thursday PM commute will be even less
so, as additional snow would be a dusting/coating to perhaps a few
tenths, if that.

Focus Thursday night through Friday night and possibly into
Saturday morning centers on the additional rounds of light to
occasionally moderate precipitation from closed upper level low
pressure gradually tracking east-northeastward. With persistent
low clouds and rounds of precipitation, the diurnal temperature
range through Saturday will be exceptionally low (2-4F or less).
Favored precipitation type for a good chunk of the CWA much of
this time is wet snow, however a flip to rain is a decent
possibility southeast of I-55 on Friday. Finally, depending on the
exact position and strength of the closed mid-upper low and
associated 850 mb and 925 mb lows, there may be enough warm air
aloft for melting while 2m temps are near freezing for a chance
for spotty freezing rain south of IL and Kankakee Rivers late
Thursday night into Friday morning.

There was a slight northward and a bit stronger trend with the
closed low among the 12z guidance, and a bit farther north with
associated weak surface low through Friday night. That said, 12km
NAM was a notably stronger and farther northwest with key
features, including 925 mb low center, resulting in much warmer
air aloft at 925 mb advecting in from the southeast Thursday night
into Friday. This forecast was leaned toward the ECMWF (and
similar 12z CMC thermal profiles), which has had good run to run
consistency and strong ensemble clustering. Regarding thermal
profiles, the uniformly just above freezing layer at 925 mb over
the CWA repeated on multiple runs of the operational GFS has had
minimal support from the rest of the guidance, including the GEFS.
Therefore, have continued to lean away from this idea.

The next round of more steady precipitation rates will evolve
mid-late Thursday evening into Friday morning as the closed low
and surface low approach and cross the MS River near or south of
STL. Increase in large scale ascent and developing trowal feature
will blossom area of precip northward, all snow CWA at least
initially, with strength of mass fields determining whether a warm
layer aloft spreads into southern CWA and introduces any chance
for light freezing rain. Confidence in this aspect of the forecast
is low. Message for the Friday morning commute is similar to that
of Thursday morning`s, with ongoing snow and additional light
accumulations of up to 1-2", except an inch or less far southeast.
Wet snow, primarily light rates, and near to a bit above freezing
temps again seem to point toward road impacts being more likely
on untreated, elevated, or less traveled roads.

Uncertainty increases the rest of Friday into Saturday morning,
owing to the inherent uncertainty in correctly modeling the
strength, exact track, and timing of a large closed low
circulation. In short, a stronger and farther north track would
bring warm air farther northwest into the CWA, and also possible
loss of ice presence in DGZ from mid-level dry-slot impingement.
At still about two days out, deferred any potential for transition
to drizzle as p-type, especially south, for later updates. Leaned
toward colder guidance for temperatures in anticipation of
extremely small diurnal range. Precipitation type could oscillate
between rain and snow at times of lighter precip (and flip to rain
at least southeast of I-55 depending on how mild it gets).

Main time period of interest for a potentially more impactful
round of snow is later Friday afternoon through Friday night. The
closed low and surface low may actually slow its forward progress
just to our east, putting portions of northern Illinois in line
for several hours of deformation area snow with more sustained
steady light to moderate rates. Additional snow amounts of up to
2-4" will be possible, with current official gridded forecast
placing this zone near and north of I-88. Depending on how this
all plays out, Friday PM through early Saturday AM may have best
chance for portions of our area needing a winter weather advisory.
With possibility of further slowing of the system, light snow may
continue deeper into Saturday morning, if not the afternoon
hours. We continue to message this event in multiple parts, as the
incremental snowfall accumulations over the next few days will
likely be a good bit higher than the net accums when accounting
for melting, compaction and any mix or transition to rain.


Saturday Night through Wednesday:

For the remainder of the weekend into the middle of next
week a very gradual warming trend appears likely, with highs each
day in the 35 to 40 degree range for most locations, maybe a bit
warmer south, and lows about ten degrees above seasonal norms.
Winds also will be relatively light through this period.
Considering this falls in the latter half of our climatologically
coldest part of the year, the situation could be much worse.

On the heels of the departing low, with continued cloudiness plus
northwesterly flow at the surface and aloft, Sunday looks to be the
coolest day of the period.  Flow off the lake may support some
slight rain or snow chances Saturday night in Indiana but otherwise
precip chances appear very low at least through Tuesday afternoon or
evening.  Models do show a sheared out upper wave sliding through
sometime on Monday ahead of an approaching ridge, along with a weak
surface frontal zone, but moisture presently appears too limited to
support more than ongoing cloudiness.

By Tuesday, models are in reasonable agreement in pushing the upper
ridge axis to our east and developing a well organized low over the
southern Plains.  Warm advection precip ahead of this system could
reach the area by late Tuesday, and surface temperature trends as
well as the track of the low will determine whether this falls as
rain, snow, or a transition.

By Wednesday there is considerable disagreement on the eventual
speed and direction of the low track.  This is reflected in the
deterministic runs but also in the ensembles where there is enough
disagreement that the surface and upper lows are not even diagnosed
as areas of focused circulation. Confidence is therefore low on
the potential significance for this area.



For the 18Z TAFs...

Concerns with TAFs through the daytime Thursday are:

- Winds becoming due south this evening with occasional gusts to
  over 15 kt

- Snow moving in overnight and continuing into Thursday morning,
  likely tapering in intensity, with the potential for mixing
  with drizzle or ending for a period in the afternoon

- IFR ceilings Thursday with fair potential to drop to LIFR
  especially if drizzle does develop

A quiet afternoon across the area before snow spreads in tonight.
This spread in will occur from west-to-east across RFD later this
evening and the Chicago area between 06Z and 09Z. Visibility will
likely vary some in the snow and this has the character of a 1
1/2 SM to 2 1/2 SM type event through that time with medium
confidence. Snow will be a wetter ratio with marginal temperatures
with respect to freezing, and so forecast snow accumulation is
under an inch at ORD and MDW through 18Z Thursday.

Regarding winds through Thursday morning, the direction should
back slightly this evening to 180 degrees. The frequency of gusts
tonight is with low confidence but they should be mainly 16-20 kt.
Winds will ease into Thursday morning and high confidence in
backing in direction gradually through the afternoon.

For Thursday afternoon, snow will taper in intensity with medium-high
confidence, however whether it will continue precipitating and
what type it will be is with lower confidence. Forecast
atmospheric profiles do indicate some potential for drizzle
especially with the low clouds in place. If the drizzle
materializes, LIFR ceilings (500 ft or less) are more probable.





Visit us at

Follow us on Facebook, Twitter, and YouTube at:

NWS LOT Office Area Forecast Discussion