-- Discussion containing changed information from previous version are highlighted. --
548
FXUS63 KLOT 071716
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
1216 PM CDT Fri Jun 7 2024

.KEY MESSAGES...

- West/northwest winds will gust to 35-40 mph today.

- Chance (40%) for showers Saturday with small chance (20%) for
  a few thunderstorms.

- Hot and humid conditions return toward the end of next week.

&&

.DISCUSSION...
Issued at 220 AM CDT Fri Jun 7 2024

Through Saturday:

Westerly winds are expected to quickly increase just after
sunrise and will peak in the 35-40 mph range this morning. Winds
will turn more to the northwest by early afternoon with gusts
slowly diminishing into the 30-35 mph range. Speeds and gusts
will rapidly diminish with sunset this evening. Mainly sunny
skies this morning should allow temps to quickly warm into the
mid/upper 70s with a few locations possibly tagging 80 for highs
this afternoon. Increasing high clouds are expected by late
afternoon and into the early evening.

There will be a chance of showers Saturday morning, mainly
across the southern cwa as an upper wave moves across central
IL. Its possible that most of the area will remain dry through
midday. A cold front will then move south into northern IL late
Saturday afternoon into Saturday evening. There will be chances
for showers along/ahead of this front Saturday afternoon, mainly
across the northern cwa. Instability is rather limited, but an
isolated thunderstorm is possible. High temps on Saturday will
be tricky. If the cloud cover is thick enough, that may hold
temps in the upper 60s/lower 70s, regardless of precip
coverage. Though sunshine for just a few hours may push temps in
the mid, possibly upper 70s. cms


Saturday Night through Thursday:

As mentioned above a few showers may linger into Saturday
evening as the cold front gradually makes its way across the
area. In spite of the frontal passage and continued northwest
surface winds through the day on Sunday, the combination of
deep mixing and ample sunshine should allow for temperatures to
warm back into the mid-upper 70s for areas inland from the
immediate lakeshore.

Generally cooler conditions are then on tap for the start of the
workweek with highs in the low-mid 70s as an expansive surface
high moves over the region beneath a southward sagging upper jet.
There continues to be variability in the evolution of the upper
level pattern and the handling of a potential cut-off upper
low and subsequent embedded shortwaves. This variability as
well as the broader influence of the surface high have resulted
in reduced precipitation chances with this update, less than
20% for any given 6 hourly period through midweek. A stray
shower certainly can`t be ruled out at times though most areas
could remain dry.

Ensemble guidance for late next week continues to point toward a
return toward summer-like conditions as the western CONUS ridge
begins to build east toward the region with highs back into the
upper 80s to even lower 90s.

Petr

&&

.AVIATION /18Z TAFS THROUGH 00Z SUNDAY/...
-- Changed Discussion --
Issued at 1215 PM CDT Fri Jun 7 2024

Gusty northwest winds at press time will gradually ease
throughout the afternoon as a surface high pressure system
approaches from the west. Rather than carrying multiple lines
for downward-trending gusts, will simply lower prevailing speeds
with the scheduled 21Z AMD. After sunset, winds will become
light and variable.

Tomorrow, a pair of storm systems will move through the general
region. Winds will slowly become southerly toward daybreak and
southwesterly throughout the morning as each move overhead. In
addition, upper-level (VFR) clouds will gradually thicken from
daybreak onward. A few rain showers may start as early as
tomorrow morning with the first system (10-20% chance), and
will increase (to 30 to 40%) after 18Z as warm-air advection
moves overhead with the second system. In addition, cigs may dip
into MVFR during the afternoon, as well. For now, opted to
group together MVFR and VCSH to start at 20Z at ORD/MDW in
favor of refinements in later TAF packages. Chances for thunder
appear less than 20% tomorrow.

Borchardt
-- End Changed Discussion --

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...Beach Hazards Statement until 4 PM CDT this afternoon for
     INZ002.

LM...Small Craft Advisory until 7 PM CDT this evening for the IL
     nearshore waters.

     Small Craft Advisory until 3 PM CDT this afternoon for the IN
     nearshore waters.

&&

$$

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