FXUS63 KLOT 111119

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
519 AM CST Mon Dec 11 2023

Issued at 235 AM CST Mon Dec 11 2023

Through Tuesday night...

Key Message

* Stratus clears out from the west and southwest today

Seasonably symbolic stubborn stratus sticking around this
morning, though gradual clearing is expected today as low level
flow backs and becomes anticyclonic. With stratus probably
lingering into the early afternoon hours over the eastern CWA,
did trim a couple degrees off of forecast highs today, but still
in the ballpark of seasonal norms.

A south to southwesterly breeze will lock in tonight as the pressure
gradient tightens a bit in advance of a cold front trailing south
from a low over Canada. Despite mostly clear skies tonight, the
south winds should temper the temperature fall a bit with lows
mostly in the mid-upper 20s.

Cold front will move across the area Tuesday morning with very
little fanfare, just a wind shift to the west-northwest. Brunt of
the cold air should stay north of our CWA, so shouldn't see much
of a temp drop with the front.

Temps Tuesday night will be a bit tricky. Assuming the encroaching
mid-high level cloudiness doesn't put too big of a kibosh on
temp fall, then the light/variable winds and ambient cold air mass
would support lows in the teens across interior northern IL away
from the Chicago metro urban heat island. Assuming those low temps
verify, this will probably end up being the coldest night over the
next 7-10+ days.

- Izzi


Issued at 235 AM CST Mon Dec 11 2023

Wednesday through Sunday...

Key Message

* Return to warmer than average temps later this week through next
  weekend with minimal chances of precipitation

Wednesday will be one last cold (temps near average) day before
mild Pacific air mass floods east across the country. Still seeing
hints of potentially some small scale northern stream disturbance
impacting the region this weekend, but guidance continues to vary
from run to run and NBM pops are below mentionable, which is fine
for now. Thursday through Sunday highs look to be in the 40s,
with 50F not out of the question.

- Izzi


For the 12Z TAFs...

Long duration MVFR stratus is expected to persist through early
afternoon then gradually clear out from west to east. Winds will
be light W to SW today then turning SSW to S after sunset. A cold
front moves through early Tuesday morning turning winds NW with
increasing gustiness to near 20kt.





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