Grayslake, Illinois Weather Forecast Discussion

367
FXUS63 KLOT 011703
AFDLOT
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
1203 PM CDT Wed Oct 1 2025
.KEY MESSAGES...
- Dry and unseasonably warm daytime conditions through the
  weekend.
&&
.DISCUSSION...
Issued at 200 AM CDT Wed Oct 1 2025
Quiet and dry conditions continue. Temperatures will be several
degrees cooler today compared to Tuesday, particularly near the
lake, although highs will still remain some 5 to 10 degrees above
climatological normals. An elongated shortwave to our west will
end up throwing some increased high-level moisture our way
through the day. Based on the current satellite appearance, this
cloud cover (above 20 kft) doesn`t look like it`ll be
particularly dense, at least until later this evening and
overnight, so have generally limited things to "partly cloudy to
partly sunny" today in the gridded forecast.
We`ll warm back up again to close out the week as deeper south to
southwesterly flow returns to the region. Highs Thursday will
push back solidly into the mid to locally upper 80s, except at
the immediate Illinois lakeshore where lake cooling will
continue. On Friday, offshore flow will develop everywhere, with
highs possibly pushing 90 F in spots. Deeper mixing both days
will probably yield a bit more of a diurnal cumulus field than
we`ve seen of late, particularly on Friday when some guidance
even develops a hint of surface-based CAPE in spots. Little/no
forcing and a very dry PBL and warming around 500 mb will
continue to limit precip chances to near nil, however.
Still no real signs of precip chances this weekend with general
neutral mid-level height tendencies overhead and broad
southwesterly flow guiding disturbances off to our north and
west. The main focus will be on wind and RH trends as we`ll
begin to pick up a bit more boundary layer flow, especially on
Sunday west of the Fox Valley, where gusts could near 30 mph
based on the latest guidance. If dewpoint/RH trends of late are
any indication, these may mix out a bit more than the current
NBM values indicate, leading to RH values falling under 30
percent in spots. With several additional days of dry weather,
we`ll need to keep an eye on a heightened field and grass fire
threat, with latest ERC values climbing rapidly.
A strong cold front will eventually work its way into the region
sometime early next week in the Monday morning to Tuesday
timeframe. Unfortunately, this doesn`t look like a big rain
maker with the bulk of the upper forcing and jet dynamics
forecast to remain to our north. By the middle of next week,
it`s looking increasingly likely we`ll see some morning lows
back in the mid to perhaps low 40s in spots.
Carlaw
&&
.AVIATION /18Z TAFS THROUGH 00Z FRIDAY/...
Issued at 1203 PM CDT Wed Oct 1 2025
Expect VFR conditions with cirrus and perhaps a few diurnal
cumulus through Thursday. Winds will favor ENE/E around 10 knots
through this evening and ESE/SE under 10 knots overnight and
Thursday.
Kluber
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...None.
&&
$$
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NWS LOT Office Area Forecast Discussion