Arlington Heights, Illinois 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

310
FXUS63 KLOT 111947
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
247 PM CDT Fri Apr 11 2025

.KEY MESSAGES...

- Quiet conditions are expected through at least Saturday before
  some lower end chances (20-30%) for precipitation are
  forecasted late Saturday night through Monday.

&&

.DISCUSSION...
Issued at 247 PM CDT Fri Apr 11 2025

Through Saturday:

Light winds and mainly clear skies are expected tonight as a
surface high shifts overhead. This will result in a chilly night,
with temperatures expected to bottom out in the upper 20s to the
lower 30s outside the Chicago urban heat island. This surface high
slides east of the area and allows for a wind shift out of the
south on Saturday. The associated influx of a warmer airmass will
thus result in a warm temperatures Saturday afternoon.
Accordingly, we are anticipating temperatures topping out in the
lower 60s across inland sections of northern IL and IN. However,
conditions along the northeast Illinois Lake Michigan shore will
remain several degrees cooler due to a continued onshore
wind component through the afternoon.

Saturday Night through Friday:

Warm air advection will ramp up across the region Saturday night
into Sunday along an increasing southwesterly low-level jet
developing in advance of low pressure setting up over the central
Plains. Ultimately, this will set the stage for a rather breezy
and mild day across our area on Sunday as a low-level thermal
ridge advects overhead. In spite of the fact that there will be
a decent amount of cloud cover around during the day,
temperatures in this air mass should have no problem warming into
the mid to upper 60s (possibly low 70s in western areas) Sunday
afternoon. Slightly cooler conditions may once again persist
right along the the far northeastern IL lakeshore for Sunday, as
it appears an offshore wind component may not develop until after
sunset Sunday evening.

The threat of showers Saturday night into Sunday remains low
(~20%). Nevertheless, I would not be surprised to see a few
showers (maybe even a storm or two given some steeper mid-level
lapse rates) late Saturday night into Sunday morning as the nose
of the low-level jet and better moisture transport shifts
overhead. Some additional showers (and maybe a thunderstorm)
could develop across far northern IL Sunday afternoon as a weak
impulse moves into southern WI. The better threat for these
showers looks to be north into southern WI where slightly better
moisture looks to reside. However, at this time see no reason to
pull the low (~20%) chances offered up by the NBM. Most areas and
much of the day should be rain free.

Sunday night into Monday, an upper-level trough will shift
eastward across the Upper Midwest into the Upper Great Lakes. As
it does, surface low pressure will redevelop northeastward over
Lake Superior. An accompanying cold front will shift
east-southeastward across our area late Sunday night into early
Monday morning. Given the early passage of this front, and most
of the low-level moisture quickly be shunted off to our
southeast, the main threat for storms with the front will likely
end up largely east-Southeast of the area on Monday. In spite
of this, a chance (20-30%) for some light rain/showers continues
in the wake of the frontal passage Monday morning, particularly
for areas south of I-80.

Otherwise, expect winds to turn westerly and become rather gusty
(40+ mph) in the wake of this cold front on Monday. In spite of
the early morning cold frontal passage, the colder airmass is
expected to lag behind the front across the Upper Midwest.
Accordingly, conditions across our area on Monday are expected to
remain seasonably mild, with highs in the low to mid 60s.

We should see a better push a colder airmass occur into our area
Monday night into Tuesday morning as a secondary upper-level
impulse quickly dives southeastward into the Midwest. Our current
forecast remains dry Monday night into Tuesday, but would not be
surprised if we see another period of light rain showers as this
impulse dives into the area. If any rain materializes this
period, it looks to be mainly through mid to late Tuesday morning,
with the afternoon looking to be drying out. Will continue to
monitor this potential to see if this needs to be added to the
forecast. Otherwise, expect breezy northwest winds through the day
Tuesday with cooler temperatures in the 50s.

Conditions look to warm again into the mid-week period in advance
of another area of low pressure likely to develop across the
Plains. This weather system will result in our next decent potential
for showers and thunderstorms as it moves into the central CONUS
later in the week.

KJB

&&

.AVIATION /18Z TAFS THROUGH 00Z SUNDAY/...
Issued at 1230 PM CDT Fri Apr 11 2025

No significant aviation impacts for the current TAF period.

Winds remain out of the northeast around or just over 10 knots
with FEW/SCT clouds around 5000 ft AGL. Sky cover is expected to
diminish overnight as winds become light and variable, if not
calm entirely. Winds will remain mostly light Saturday morning
out of the west-southwest. As the pressure gradient strengthens
to the west, winds will become southeasterly in the afternoon
increasing once again to 10 to 15 knots. Some mid to upper level
clouds may move into the region in the late morning/afternoon,
but not impacting the VFR conditions.

DK

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...None.

&&

$$

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