Arlington Heights, Illinois 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

756
FXUS63 KLOT 260834
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
334 AM CDT Tue May 26 2026

.KEY MESSAGES...

- Generally above normal temperatures (highs in the 80s) and
  dry conditions are expected through early next week. Onshore
  winds will keep temperatures cooler near Lake Michigan each
  day (60s-70s).

- Backdoor cold fronts will lead to cooler conditions (60s and
  70s) extending farther inland late Wednesday into Thursday
  and potentially again over the weekend.

&&

.DISCUSSION...
Issued at 334 AM CDT Tue May 26 2026

An expansive area of thin cirrus remains overhead early this
morning associated with a mid-level cut-off low and associated
surface reflection currently over the Lower Mississippi Valley.
This cloud layer will likely remain overhead through the day
(perhaps with varying coverage at times). It is unclear how much
of an influence this will have on temperatures today but opted
to cap high temperatures in the low to mid 80s with some of the
warmer guidance (upper 80s to near 90) potentially too warm
unless skies fully clear out. Either way, dewpoints in the
upper 40s and 50s should help keep heat indices in check. Winds
will be light out of the south and southeast today with an
afternoon lake breeze dropping temperatures back into the 60s
and lower 70s near the lakeshore.

Thunderstorms are expected to develop to our northwest over
portions of Minnesota and Wisconsin today associated with a
stalled frontal boundary intersecting with a residual unstable
airmass. Model guidance continues to depict these storms
dissipating with southward extent as they propagate toward
Illinois overnight into early Wednesday, with not much more than
a sprinkle possible here locally. There is the potential that
outflow boundaries associated with these storms manage to hold
together into Illinois, turning winds northerly in their wake
late tonight. This could allow for an earlier arrival of an
expected backdoor cold front which is currently forecast to move
inland late Wednesday afternoon through the evening. There is a
narrow window where additional isolated storms from Wisconsin
manage to persist into far northern/northwest Illinois late
Wednesday afternoon ahead of the front. The potential remains
very low (20% chance) given storms will be encountering a much
drier airmass into Illinois.

We will also have to keep an eye on the northern periphery of
any showers associated with the aforementioned cut-off low to
our south which is expected to gradually lift northeast through
tonight into Wednesday as it elongates and merges into the
broader upper level flow. There remains a low (20%) chance that
showers graze the far southern forecast area (south of a Gibson
City, IL to Fowler, IN line). There will likely also be a very
sharp gradient in PWATs (from 0.7" to 1.8"+) very near the area.
Any showers that reside within the deeper moist airmass would
be capable of efficient rainfall rates. However, dry conditions
are still favored this far north.

With all that said, dry conditions are expected for most of, if
not the entire, area on Wednesday with highs in the low to mid
80s inland and lower 70s near the lakeshore. Temperatures then
steadily fall late afternoon/evening in the wake of the backdoor
front with continued onshore flow keeping temperatures cooler
into Thursday, potentially much farther inland (highs in the mid
60s to upper 70s).

An expansive 1020+ mb Hudson Bay surface high is then expected
to translate south and stall out across the western Great Lakes
region mid to late week as a pseudo-Omega blocking pattern
becomes established across the broader CONUS and Canada.
Accordingly, above normal temperatures are expected for inland
areas most days with highs in the upper 70s to lower 80s.
Onshore winds and daily lake breezes will lead to continued
cooler conditions near the Lake Michigan shore (highs in the 60s
to near 70). There is lower confidence on temperature trends
over the weekend into early next week owing to differences in
timing for any potential additional backdoor cold fronts.
Suspect that high temperatures could end up trending cooler
(potentially by as much as 10+ degrees!) as the timing of these
features gets refined.

Petr

&&

.AVIATION /06Z TAFS THROUGH 12Z WEDNESDAY/...
Issued at 1228 AM CDT Tue May 26 2026

Key Aviation Messages for the current TAF period:

VFR conditions are expected through the current TAF window, as
well as no precipitation. Winds will be light and out of the
southwest through mid morning. Winds will likely flop over to
the southeast prior to 18Z, but remain less than 8 knots.
However, a lake breeze with winds up to 10 knots is expected in
the early afternoon, and thus it was chosen to highlight that
feature in the TAFs. Winds at Chicago terminals may turn to the
north after 06Z depending on if outflow from showers/storms in
Wisconsin move southward into Illinois. But confidence was too
low so it was kept out of the TAF presently.

DK

&&

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

&&

$$

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