773
FXUS63 KGRB 182305
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
605 PM CDT Thu Jul 18 2024

Updated aviation portion for 00Z TAF issuance

.KEY MESSAGES...

- Mainly dry weather is expected through Saturday morning.

 - Isolated to scattered showers and/or thunderstorms are likely to
   develop each afternoon from Saturday through the middle of
   next next. Severe thunderstorm potential is low.

 - Temperatures will be near-normal for the next week.

&&

.DISCUSSION...
Issued at 221 PM CDT Thu Jul 18 2024

Short Term...Tonight and Friday

Skies were partly cloudy away from the bay and Lake Michigan this
afternoon. Temperatures were in the 70s away from Lake Michigan,
which was a few degrees below normal for this time of year.

For tonight, skies will become clear early this evening and then
continue overnight. Some patchy fog is possible across north-
central and far northeast Wisconsin. The fog is not expected to
impactful at this time. Did lower temperatures a few degrees,
especially across the north in our typical cold spots. On Friday,
fair weather cumulus are expected to develop in the late morning
and continue through the afternoon. High temperatures should climb
into the middle 70s to lower 80s.

Long Term...Friday Night Through Thursday

The region will generally be caught between a high amplitude
ridge building over the western CONUS and trough developing over
the eastern Great Lakes through the long-term forecast period.
This synoptic set-up will likely lead to a minimally impactful,
yet tricky forecast, as diurnally driven showers and thunderstorms
will be possible each afternoon.

As the aforementioned trough develops over the eastern Great
Lakes the related surface low pressure system will drop a cold
front south across the area Saturday. Guidance generally shows
this boundary then lingering over Wisconsin through the early to
middle part of next week. The boundary will likely shift slightly
to the north or south each day, but at this time it`s difficult
to pin down exactly where it will set up from one day to another.
With this persistent pattern in place each day, Saturday through
Wednesday, will likely follow a similar pattern: dry and sunny to
start the day with clouds developing late in the morning/afternoon
along with isolated to scatted showers and a few thunderstorms,
then skies will likely clear out during the evening to overnight
hours leading to areas of patchy fog development. The location of
showers and storms each day will be dependent on the location of
the frontal boundary. Not every location will see rain each day,
but there is a chance of rain (25-50%) at most locations daily.

The severe weather potential with any thunderstorms that do
develop is low at this point. Forecast soundings Saturday through
Wednesday show SBCAPE peaking around 1000 J/kg each day with very
little effective layer wind shear (10-20kt). Additionally, PWATS
look fairly modest during this period generally raging from 1-
1.5". With this environment and a lack of more robust forcing any
severe storms that do develop should be short-lived. Main threats
would be small hail, locally strong wind gusts, and brief heavy
downpours.

Near normal temperatures are expected during this period with
daily highs in the upper 70s to low 80s and overnight lows in the
middle 50s to low 60s.

&&

.AVIATION...for 00Z TAF Issuance
Issued at 605 PM CDT Thu Jul 18 2024

Expect VFR conditions to prevail through the TAF period as high
pressure settles over the Great Lakes region. A fair weather
cumulus field will dissipate early this evening with the loss of
daytime heating. Mostly clear skies are then expected for the rest
of tonight into Friday morning. Another VFR cumulus deck is
expected to develop Friday afternoon, with bases of 3500 to 5k ft.
These clouds should then dissipate Friday evening with the loss of
daytime heating.

.OSH...SCT cumulus clouds are expected to dissipate by 01-02z this
evening, with mostly clear skies expected the rest of tonight into
Friday morning. Another VFR cumulus deck, with bases of 4-5k ft,
is expected to develop around 16Z. These clouds are then expected
to dissipate by Friday evening. Surface winds should be fairly
light, remaining under 10 knots.

&&

.GRB WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$

DISCUSSION.....Eckberg/Kruk
AVIATION.......Kurimski