865
FXUS63 KLOT 142323
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
623 PM CDT Sun Sep 14 2025

.KEY MESSAGES...

- Warm and dry conditions are expected through midweek.

- Periodic shower and storm chances return toward the end of
  the work week.

- Temperatures turn more seasonable into next weekend.

&&

.DISCUSSION...
Issued at 142 PM CDT Sun Sep 14 2025

Recent GOES-19 vapor imagery shows an area of low pressure
spinning cyclonically over SW Nebraska/NE Colorado, as another
area of low pressure spins off coast of Florida an SE Georgia.
Sandwiched between the two is an area of high pressure with
clear skies, as seen (or maybe not seen?) on visible satellite
imagery. Surface winds are light and out of the east, but will
become more northeasterly through the evening. Dry conditions
will prevail through this evening and overnight.

Over the next several days, some slight shifting will happen to
the overall synoptic pattern. The upper level low over the
southeastern CONUS will slowly move over the mainland. An upper
level low, currently over the Pacific Northwest, will help kick
the Northern Plains low back into movement. The strength of the
high over the western Great Lakes will help forces this low
northward toward Manitoba, though pushing the high slightly
north over the Great Lakes setting up a pseudo-Rex Block
patterned east of the Mississippi. An area of convergence is
expected to develop between the high and the Northern Plains low
that can allow for some showers and storms to develop over Iowa
and southern Minnesota. A few CAMs have the showers moving
slightly into western Illinois, but the higher pressure over
area area will help keep temperatures above normal with drier
conditions through at least mid-week.

By Wednesday, the blocking pattern is expected to break down,
with ensembles showing fairly decent agreement in the next upper
level low moving eastward over the Northern Plains toward the
Great Lakes. But there are some discrepancies as the GEFS has a
more southerly track to the low, where the Euro ensemble have
it ever so slightly more north. This low will help bring back
the chances for showers and storms to northern Illinois and
northwest Indiana, likely sometime between Thursday PM into
Friday. With it still 5 days out, timing can be adjusted and
felt no reason to change the provided 20% to 40% chance PoPs
from the NBM. But it will also come with a cooler air mass.
Models are suggesting 850 mb temps will drop down to around 10C
behind its passage. NBM temps are still running a little too
warm for Saturday, so max values were lowered slightly.
Nevertheless, more seasonable temps in the 70s with lows in the
50s are expected next weekend, with drier conditions.

DK

&&

.AVIATION /00Z TAFS THROUGH 06Z MONDAY/...
Issued at 623 PM CDT Sun Sep 14 2025

Quiet flying conditions are expected. The only minor item of
note is a small potential for patchy/shallow BR tonight into
Monday morning. However, chances appear lower than last night
with ~20 kts of flow just off the surface, coupled with a less
favorable vertical RH profile. As a result, VFR prevails in the
outgoing TAFs, but trends will be monitored. Winds will vary
from SE to NE around 5-10 knots through the period.

Carlaw

&&

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

&&

$$

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