Ancona, Illinois Weather Forecast Discussion

278
FXUS63 KLOT 282327
AFDLOT
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
627 PM CDT Sun Sep 28 2025
.KEY MESSAGES...
-  Dry and unseasonably warm daytime conditions through next
   weekend will lead to worsening drought.
&&
.DISCUSSION...
Issued at 152 PM CDT Sun Sep 28 2025
It will continue to be just about as quiet as it can be weather
wise for us, along with summer-like daytime warmth away from
Lake Michigan. Amplified mid-upper ridging (500 mb heights near
590 DaM) forced by the relatively close proximity of the
tropical systems off the southeast coast through midweek will
transition to broader eastern CONUS ridging later in the week
into next weekend. Surface ridging from expansive high pressure
setting up over eastern Canada will expand southwestward through
midweek and then the surface high will center over the northeast
and Mid Atlantic into next weekend.
The result will be very little change in our weather, though
some variability in terms of just how warm it will be and the
inland extent of lake cooling from Lake Michigan. Monday will
likely be the warmest day of the work week for the area as a
whole, followed by very modest cooling for a few days (most
pronounced near the lake and several miles inland) and then
back into the 80s for the whole area next weekend (summer
weekend in early October). Dew points mixing out by day, and
calm winds at night will keep the overnights comfortably cool,
however.
In the near term, the setup may be a bit more favorable for
patchy shallow ground fog outside of Chicago later tonight into
early Monday due to dew points being a bit higher this
afternoon. It may be a bit too dry for any truly impactful fog,
but opted to include patchy fog mention in the gridded
forecast outside of Chicago. The other exception to this may be
roughly the Pontiac to Paxton corridor in central IL where the
burgeoning drought has been supporting upper 40s afternoon Td.
Castro
&&
.AVIATION /00Z TAFS THROUGH 06Z TUESDAY/...
Issued at 627 PM CDT Sun Sep 28 2025
Forecast concerns include...
Patchy fog overnight/early Monday morning.
Lake breeze/easterly wind shift Monday afternoon.
Easterly winds will slowly diminish this evening and are
expected to become light and variable or calm overnight. After
daybreak Monday morning, wind directions may become southwest
through early afternoon, though speeds will be light. And these
light winds will allow a lake breeze to develop and move inland
through all of the Chicago terminals, shifting winds easterly.
Patchy fog will be possible overnight into early Monday morning,
especially in the usual rural locations. However, some of the
short term/hi-res guidance is showing the potential for fog at
both ORD/MDW at sunrise. Confidence is very low and have not
included any fog mention with this forecast, but trends will
need to be monitored tonight. cms
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...None.
&&
$$
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NWS LOT Office Area Forecast Discussion