917
FXUS63 KLOT 262316
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
616 PM CDT Fri Jul 26 2024

.KEY MESSAGES...

- Very warm to hot, humid, and at times stormy pattern returning
  Sunday into next week. A few strong storms possible Monday.

&&

.DISCUSSION...
Issued at 228 PM CDT Fri Jul 26 2024

High pressure remains centered over the Great Lakes this
afternoon, resulting in sunny skies and temps slightly below
normal for late July. The high will gradually shift east on
Saturday, with max temps into the mid 80s under increasing high-
level clouds.

An elongated upper-level trough extending from southeast Texas
through the Lower Mississippi River Valley will drift northward
toward the Upper Mississippi River Valley through Sunday while
drawing a moisture-rich airmass into the region. Scattered
showers and diurnally enhanced thunderstorms are expected to
spread across much of the area Sunday amid weak to modest mid-
level lapse rates and minimal low-level capping. Locally
enhanced forcing within a coupled weakly upper-jet structure
combined with the higher PWAT airmass could support a narrow
swath of 1"+ rainfall Sunday afternoon.

A weak trough over the central Great Plains will phase with the
aforementioned trough on Monday. By this time, increasing lapse
rates and low-level moisture will yield another window of
scattered and diurnally enhanced showers and storms Monday
afternoon and evening. While severe convection is not currently
expected, favorable thermodynamic profiles within a weakly
sheared environment could support pulsing convection with strong
wind gusts.

Guidance remains generally in agreement with a broad, low-
amplitude ridge building across the central CONUS Monday through
Thursday, though there has been a weakening trend with the
ridge over the past couple days. A weak cold front may stall
over or just south and west of the forecast area late Tuesday
into Thursday on the periphery of persistent steep mid-level
lapse rates over the region. This puts the area in the vicinity
of a weak ring-of-fire pattern with at least a couple periods of
convection expected during the week. However, timing out these
episodes can be difficult to impossible this far out. Either
way, seasonably warm and humid conditions with heat index values
well into the 90s to perhaps locally 100F appear likely mid to
late week.

Kluber

&&

.AVIATION /00Z TAFS THROUGH 06Z SATURDAY/...
Issued at 614 PM CDT Fri Jul 26 2024

Light easterly winds at press time will tend to turn more
southerly with time, and settle between 180 and 160 degrees by
sunrise tomorrow. The direction may sneak west of south for a
few hours during the morning hours, though speeds should remain
light (around or less than 5 kt). A lake breeze will work toward
ORD/MDW during the afternoon allowing for winds to turn
easterly once again, before they return to southeasterly
tomorrow night.

Upper-level clouds will stream overhead toward the end of the
TAF period.

Borchardt

&&

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

&&

$$

Visit us at weather.gov/chicago