714
FXUS63 KLOT 080742
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
242 AM CDT Sun Sep 8 2024

.KEY MESSAGES...

- One more seasonably cool afternoon before temperatures turn
  more summer-like Monday through much of next week.

&&

.DISCUSSION...
Issued at 242 AM CDT Sun Sep 8 2024

Through Tonight:

An upper-level low continues to progress eastward across
southern Ontario and Quebec this morning with the back edge of
its associated trough over the western Great Lakes. Within the
western edge is a shortwave trough that has manifested some mid-
level stratus and higher level cirrus across the upper Midwest
and northern Great Lakes. While these clouds (namely the cirrus)
are expected to drift into northern IL this morning, their thin
nature should do little aside from creating some filtered
sunshine for our Sunday. Thus after a chilly start to the day,
temperatures will rebound into the low to mid-70s this
afternoon.

The aforementioned clouds are expected to erode this evening
which will set up another night favorable for diurnal cooling.
While overnight low temperatures will once again be on the
seasonably cool side, they will be more modest compared to this
morning`s with readings in the mid-40s to lower 50s (mid-50s in
the urban core of Chicago).

Monday through Saturday:

Mid-level ridging will begin to build into the Great Lakes and
eastern CONUS on Monday and is expected to persist through the
majority of the upcoming work week. At the same time, a broad
surface high is progged to remain in place beneath the ridge
which looks to limit the return of any appreciable moisture from
the Gulf of Mexico and thus keep rain chances near zero. So
while temperatures will become more summer-like through the week
(highs in the upper 80s to near 90), humidity values are
expected to remain rather low at least through midweek. In fact,
depending on the degree of mixing each afternoon, there is the
potential for afternoon RH values to dip into the sub-20% range
especially during the Monday to Wednesday timeframe. Relatively
light winds (speeds generally in the 10 to 15 mph range) should
temper the overall fire weather threat, although drying fine
fuels may become receptive to increased grass/brush fire starts
through the end of the week.

The only notable potential (albeit low) for any rain looks to
be towards the end of the week into next weekend as guidance is
hinting at the possibility for a remnant tropical system to be
moving into the Ohio River Valley. While there is surprisingly
decent agreement at nearly 7 days out on this solution, it
should be noted that the tropical system of interest has yet to
even develop. Therefore, there is far too much uncertainty to
know where the system may track and what if any impacts it could
bring to northern IL and northwest IN. The NBM did offer some
20% POPs across portions of the area for Friday into next
weekend, but given the aforementioned uncertainty I caution
getting too excited just yet as the forecast may change as we
get closer.

Yack

&&

.AVIATION /06Z TAFS THROUGH 12Z MONDAY/...
Issued at 1207 AM CDT Sun Sep 8 2024

There are no significant aviation weather concerns. Light and
variable winds will become westerly with time overnight and
through Sunday morning before becoming southwesterly and
diminishing Sunday evening. VFR conditions will prevail.

Carlaw

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...Beach Hazards Statement until 4 AM CDT early this morning for
     ILZ006-ILZ103-ILZ104.

IN...Beach Hazards Statement until 4 AM CDT early this morning for
     INZ001-INZ002.

LM...Small Craft Advisory until 4 AM CDT early this morning for the
     IN nearshore waters.

&&

$$

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