968
FXUS63 KLOT 131734
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
1234 PM CDT Wed May 13 2026

.KEY MESSAGES...

- After a relatively cool Wednesday, temperatures will trend
  upward through the weekend and into early next week.

- Chances for periodic showers and storms will return to the
  area Thursday night and last through early next week. Some
  storms may be severe, particularly Saturday through Tuesday.

&&

.DISCUSSION...
Issued at 1234 PM CDT Wed May 13 2026

Regional satellite imagery early this afternoon shows expansive
cyclonic flow across the Great Lakes associated with a surface
low pressure system moving across southern Ontario. The passage
of an upper-level shortwave embedded within the parent trough
over southern Lake Michigan allowed for a lake breeze to shift
well inland this afternoon, which is leading to a gradient int
temperatures ranging from the lower 60s west of I-39 to upper
40s along the shore. When combined with blustery north to
northwesterly winds, it feels more like March than May outside
(though the largely sunny skies are welcome).

Tonight, a surface high pressure system will quickly move into
the region causing surface winds to become nearly calm and skies
to clear. Temperatures will hence be poised to plummet
overnight with lows expected to bottom out in the upper 30s to
lower 40s. Patchy frost may develop in the typical cold spots by
daybreak.

The surface high pressure system will only slowly shift away
from the region throughout the day on Thursday, leading to
fairly calm winds. Mostly sunny skies and a gradual increase in
low-level warm air advection will help highs rise into the upper
60s to lower 70s. The exception will be along the Lake Michigan
shoreline where a lake breeze will hold temperatures in the low
to mid 50s.

Thursday night onward:

Toward the end of the week, the upper-level pattern will
transition from predominantly upper-level cyclonic flow across
the northern Untied States to zonal and eventually southwesterly
flow. The net result will be a gradual warming and moistening
trend leading to more seasonable to above-average temperatures
and periodic shots of showers and storms. Note that some storms
could be severe in the general region, particularly Saturday
through Tuesday. Ensemble guidance suggests a break in the warm
and stormy pattern toward the middle of next week.

Borchardt

&&

.AVIATION /18Z TAFS THROUGH 00Z FRIDAY/...
Issued at 1220 PM CDT Wed May 13 2026

There are no key concerns for the 18Z TAF period.

Winds have turned NE 10 to 12 kt in Chicago and at GYY in the
wake of an early lake breeze push. Farther inland ahead of the
front, NNW winds are gusting to 20 to 25 kt. DPA will also go NE
at 10 to 12 kt by around 19Z, if not sooner, while RFD will
maintain the gusty NNW winds through the afternoon. Winds will
go light and variable for this evening into Thursday. Anticipate
NE winds below 10 kt at ORD, MDW, and GYY by late morning while
light and variable will persist into the afternoon at DPA and
RFD. Expect VFR throughout the period.

Doom

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...Small Craft Advisory until 7 PM CDT this evening for the IL
     nearshore waters.

     Small Craft Advisory until 1 AM CDT Thursday for the IN
     nearshore waters.

&&

$$

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