364
FXUS63 KLOT 062019
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
319 PM CDT Sat Jul 6 2024

.KEY MESSAGES...

- Mostly dry conditions are expected, but cannot completely rule out
a brief pop-up shower early this evening.

- Chance (25-45 percent) of showers and thunderstorms Sunday, mainly
northwest of a La Salle to Lake County line.  Slight chance (15-25
percent) southeast of that line.

- Continued periods of unsettled weather Sunday night-Tuesday
afternoon with periodic showers and thunderstorms, highest
chance/coverage on Monday.

- Seasonable temperatures will continue for the coming week.

&&

.DISCUSSION...
Issued at 316 PM CDT Sat Jul 6 2024

Through Sunday...

Overcast skies have kept most locations in the upper 70s to around
80 early this afternoon, and a lake breeze pushing west through the
metro area has supported some even slightly cooler temperatures.
Sunday, with more sunshine expected, looks to be several degrees
warmer with a bit more humidity as well.  The exception would be
toward the Rockford area where shortwave energy exiting the base of
a shallow upper trough would support increased cloudiness and
scattered showers or thunderstorms.  It is possible that some of
these showers could also work east toward the Chicago metro during
the afternoon or evening. Elected to maintain just a slight chance
mention in that region for now.  However, more favorable mid-level
lapse rates and low level moisture profiles do spread across the
area later in the day as southerly surface winds turn southwesterly
for a while and tap into the better moisture to our west.

Sunday Night through Saturday...

The weakly forced and seasonably mild pattern...at least by July
standards...continues into the early part of the coming week.  On
Monday a frontal zone to our west makes very slow progress toward
our area but increases the overall low level moisture convergence.
Lapse rates don`t look overly impressive but should be enough to
support scattered thunderstorms, especially by the afternoon.  The
lack of strong forcing along with generally unidirectional SW wind
profiles would not appear to pose a severe threat, but the
possibility of flooding may need to be monitored if storms manage to
track repeatedly across the same area.  As with Sunday, the greatest
concern would be for the northwest half of the forecast area.

The weak front...maybe more of a surface trough...moves through the
area Tuesday.  Surface winds turn west then northwest but copious
low level moisture remains in place, which in conjunction with the
upper trough trailing the front will support ongoing chances (25-45
percent) of thunderstorms into Tuesday evening.

Wednesday presently looks quieter with subtle height rises aloft in
the wake of the passing trough, but Thursday into next weekend are
more of a question.  The path of Beryl remnants may play some part
in how the rest of the week evolves.  Models suggest the low center
passes to our south, which could provide the primary focus for
convection late in the week. A different track might allow more
of the moisture to work farther north. For now will maintain
slight chance mentions of precip, with highs very gradually
warming toward the upper 80s.

Lenning

&&

.AVIATION /18Z TAFS THROUGH 00Z MONDAY/...
Issued at 1211 PM CDT Sat Jul 6 2024

Current satellite imagery shows a broad field of diurnal cumulus
across the area creating scattered CIGs around 040. A lake
breeze has been pushing inland through the late morning and will
be across KMDW and KORD by 18Z bringing NE/E winds. Winds will
shift to southeasterly tonight before becoming southwesterly
tomorrow. Another lake breeze is expected to move across KORD
and KMDW tomorrow afternoon. VFR conditions are expected at all
terminals through the end of the TAF period although a shower
can`t be ruled out tomorrow morning, especially for the Illinois
terminals.

Carothers

&&

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

&&

$$

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