582
FXUS63 KLOT 080731
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
231 AM CDT Sat Jun 8 2024

.KEY MESSAGES...

- Scattered showers with a few rumbles of thunder today.

- Northeast wind shift with a cold front this afternoon,
  bringing cooler temps and a short period of choppy 2-4 foot
  waves to Lake Michigan beaches.

- Northwest winds gusting to 30 mph Sunday.

- A shift toward warmer temperatures and higher humidity remains
  on track for the third week of June

&&

.DISCUSSION...
Issued at 230 AM CDT Sat Jun 8 2024

Through Sunday:

Scattered showers are expected later this morning and into the
afternoon and there has been an overall trend upward in coverage
with the 00z guidance. Given current precip coverage with this
wave across MN, this upward shift looks reasonable and have
raised pops to likely for areas along and north of I-80. Still
some timing uncertainty which may need later refinement. There
will likely still be some dry hours, but after mid/late morning,
difficult to pin down when those would be. Areas south of I-80
may stay mainly dry this morning and then as the activity across
the northern cwa shifts southeast, best precip chances will be
in the late afternoon and early evening. Instability remains
quite limited with perhaps the best chance for thunder southeast
of I-57 later this afternoon into this evening but maintained
slight chance (15-20%) for thunder areawide this afternoon.

This expected precipitation and mainly cloudy skies will likely
keep high temps only in the lower to mid 70s and once the
showers begin, temps may drop back into the upper 60s. A cold
front will be moving south down Lake Michigan today and all of
the guidance has sped up the arrival of this front, likely
moving through northeast IL during the mid afternoon hours and
then into northwest IN by late afternoon. Winds will shift to
the northeast and depending on where temps are at, they will
likely fall further into the lower/mid 60s behind the front.
While it may be brief, an increase in winds over southern Lake
Michigan will likely lead to a period of increased waves of 2-4
feet and a moderate risk for rip currents.

Lows tonight are expected to dip into the mid 50s for most of
the area with clouds slowly clearing. Mostly sunny to start
Sunday with increasing clouds later in the afternoon. Winds
will steadily increase during the morning with gusts into the
30 mph range during the afternoon, especially north of I-80.
cms

Sunday Night through Friday:

Pleasant conditions are forecast through the first half of the
upcoming week. An expansive surface high will remain to our
northwest at the start of the workweek resulting in northerly
surface flow across the area. This will result in notably cooler
temperatures on Monday with highs only in the 60s to lower 70s.
Overnight lows Monday night could even dip into the 40s outside
of Chicago.

Long range guidance is beginning to come into a bit better
agreement with the handling of the upper level pattern though
there remain timing differences. The general trend is toward
drier conditions through midweek due to dry low levels amidst
an expansive area of surface high pressure limiting precip
potential as weak disturbances move within the upper jet. It is
possible portions of northern Illinois are grazed by showers
moving across Wisconsin toward midweek.

Temperatures very gradually through midweek with highs back
into the 80s by Wednesday and near 90 on Thursday. A frontal
passage Thursday night into Friday could bring our next chance
of showers and storms (currently at 20%). There continues to be
a longer range signal for above normal temperatures and higher
humidity across the region for the third full week of June as
upper level ridging builds across the eastern half of the CONUS.

Petr

&&

.AVIATION /06Z TAFS THROUGH 12Z SUNDAY/...
Issued at 1255 AM CDT Sat Jun 8 2024

Key Messages:

- SHRA potential mid-late morning through early evening with
  associated MVFR CIGS/VSBYS

- Northeast wind shift with cold front mid-late afternoon

A pair of disturbances moving across the region are still on
track to bring periods of showers to the area today. Have sped
up the SHRA arrival time with this update based on the latest
hi-res guidance trends. Also opted to convert the prevailing
VCSH to -SHRA due to an anticipated broader time window for
scattered showers across the area. Ceilings will also gradually
trend down to MVFR as shower coverage increases along with
associated reductions in  visibility to MVFR in the steadiest
showers. IFR cigs/vsbys are not out of the question though
confidence is not high enough to include with this update.
While no TS is officially included in the TAF a few embedded
lightning strikes cannot be fully ruled out at the terminals.
The better potential remains mainly south of I-80.

Light and variable winds are expected early this morning,
eventually prevailing SSW after daybreak. A cold front will move
across the area mid-late afternoon. As it does so, a strong
northeast wind shift may occur across the Chicago area
terminals. Accordingly have introduced an 020 direction with
this update at ORD/MDW at 22Z. The timing of this wind shift
will be refined with later updates. Winds then gradually ease
and settle back into a NW direction after sunset.

Petr

&&

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

&&

$$

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