Cicero, Illinois 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

299
FXUS63 KLOT 202007
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
307 PM CDT Sun Jul 20 2025

.KEY MESSAGES...

- Thunderstorms capable of producing torrential rainfall and
  damaging winds toward central Illinois late this afternoon and
  evening. May impact areas as far north as a Pontiac to Fowler
  line.

- Dangerous swimming conditions for Lake Michigan beaches
  through Monday morning.

- Dangerous heat and humidity expected Wednesday and Thursday.

&&

.DISCUSSION...
Issued at 307 PM CDT Sun Jul 20 2025

Through Tonight:

Following a rainy morning around the area, only widely
scattered showers remain into the early afternoon. The low-mid
level shortwave impulse responsible for the widespread rain
moved across and out of the area late this morning and drier,
more stable air feeding in behind has chipped away at most of
the precip coverage. A quasi-stationary front remains draped
over our CWA following that wave. The leftover shower coverage
that we`re seeing is coincident with the front and a counterpart
low level convergent axis just north of the surface boundary.
On the map, this very roughly equates to areas near and south of
I-80.

Expectations are that the front will drift south into central
IL through the rest of the afternoon, and the precip coverage
should mostly follow suit. Through the middle of the afternoon,
we could see spotty showers as far north as a Rochelle to Joliet
line. Thereafter, coverage should trend farther south toward
central IL as it continues to favor areas near and south of that
front. A second midlevel impulse moving over IL will feed
additional moisture into the environment later today, and
efficient moist upglide will take place through the low levels
south of the front. As a result, latest RAP guidance resolves
over 2.25" of PWAT this evening immediately south of the front.
Deep westerly shear vectors oriented roughly parallel to the
front with tall, skinny CAPE profiles amid such rich moisture
will lead to a potential for training convection near and south
of the front and spells trouble from a flooding perspective.
Conditions do look to dry out and stabilize very quickly as you
move north of the boundary though, which will hinder any
flooding concerns across a big majority, if not all, of our CWA.
While confidence is rather high that the surface boundary
should push south of the CWA this evening, a couple of CAMs
suggest that front will remain close enough where parts of our
far southern CWA may get in on some of that training convection.
This potential may extend as far north as a Pontiac to Fowler
line, but is much greater closer to the I-74 corridor just
outside of our area. A few showers and possibly a couple of
shallow thunderstorms may manage to go up north of the front
too, especially along any outflow boundary moving across, but
this potential should also be confined to the southern reaches
of the local warning area and not present any more than a
localized heavy rain/flooding threat.

If the front does manage to get hung up farther north than
expected, a marginal damaging wind threat will exist with
thunderstorms this evening. This is represented by a Marginal
Risk across our far south on SPC`s day 1 outlook. We recently
received a report of a funnel cloud in McLean County. A few
funnel clouds or even a brief landspout tornado will remain
possible amid the locally backed surface winds and uncapped
SBCAPE near and south of the front. And wherever the front does
decide to setup, model camps are in good agreement that a long
swath of at least 1-2" rain totals will likely coincide through
this evening. The expectation for now though is that this should
be found just outside of our CWA. Additional heavy training
precipitation will be possible overnight as another embedded
circulation moves across central IL, but this potential should
be even farther south than this evening`s and is not of much
concern in our local area.

Expanded the beach hazard statement into northwest IN as waves
have come up into the 3-5 foot range there was well. With a
steady northeasterly wind expected tonight, these waves will
continue through mid morning Monday before slowly subsiding.
Winds turn more easterly on Monday so its possible the beach
hazard statement may need to be extended longer in time for the
IL Lake Michigan shore.

Doom/cms

Monday through Sunday:

Primary forecast concern is dangerous heat and humidity expected
Wednesday and Thursday.

There remains very low chances for thunderstorms through Tuesday
night but the dry trend among guidance and the ensembles
continues, to the point now where the blended pops are now dry
from Monday night through Thursday morning. The upper ridge will
be steadily building into the region Tuesday and then solidly in
place through at least Wednesday night. While there could be a
few storms during this transition, there is very little support
or focus for development. If anything were to develop, perhaps
the best timing would be early Tuesday morning as the warm air
advection is strongest but given the dry model trends/consensus,
dry conditions may persist until the end of the week.

Still no significant changes to the high temps and dewpoints as
the models have been in good agreement for several days now.
High temps into the mid 90s on Wednesday with dewpoints in the
upper 70s/near 80 look on track. These conditions will yield
peak heat indices in the 110-115 range Wednesday afternoon. Its
possible a few locations may reach upper 90s for high temps on
Wednesday. Southwest winds will be strong enough to prevent any
lake breeze, with these temps/heat indices expected all the way
to the lakeshore. Low temps may only drop into the mid/upper 70s
by Thursday morning, with lows perhaps only around 80 in the
immediate Chicago metro area. These warm temps will allow for a
fast rise in temps Thursday morning. High temps may be similar
on Thursday, in the mid 90s along with dewpoints once again in
the upper 70s/near 80 with peak heat indices in the 105-115
range.

A cold front will be moving south across the upper midwest on
Thursday and into the Western Great Lakes Thursday night into
Friday. Thus, thunderstorm chances return Thursday afternoon
into Thursday evening and will continue through end of the week
with this boundary expected to be in/near the area. Should
thunderstorms develop Thursday afternoon/evening, severe storms
would be possible given the expected instability. While temps
are expected to be at least a few degrees cooler by Friday and
Saturday, the hot and humid conditions may continue depending on
precip chances. cms

&&

.AVIATION /18Z TAFS THROUGH 00Z TUESDAY/...
Issued at 1252 PM CDT Sun Jul 20 2025

Key Messages:

- MVFR ceilings are expected across the area over the next few
  hours, however cannot rule out sporadic VFR conditions.

- Northeasterly winds 10-12kts this afternoon will weaken into
  the overnight turning more northerly, then become easterly and
  increase Monday morning.

Precipitation chances continue to diminish heading into the
afternoon. Some light precipitation bands, elongated west to
east, continue south of the I-80 corridor, with a better axis
for additional development further south from the Kankakee River
Valley through central Illinois. Current conditions around much
of the region feature MVFR BKN ceilings, in the 1,200-2,000 ft
range, however sporadic reports of SCT in that height range have
been noticed...but not expected to be the rule until after
21-23z depending on terminal location, north to south.
Northeasterly winds continue this afternoon with a weakening
trend forecast heading into the overnight. Winds turn northerly
overnight, before increasing again Monday morning (near
10-12kts) and turning easterly.

Baker/cms

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...Beach Hazards Statement through Monday morning for ILZ006-
     ILZ103-ILZ104.

IN...Beach Hazards Statement through Monday morning for INZ001-
     INZ002.

LM...None.

&&

$$

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