NWS-Green Bay Forecast Discussion

						FXUS63 KGRB 270935
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
435 AM CDT Sat Jul 27 2024

Forecast discussion for routine morning forecast issuance

.KEY MESSAGES...

- There is a chance of thunderstorms Sunday afternoon through Tuesday.
  The severe weather potential is low.

- Warmer and more humid weather is expected for much of next week.

&&

.DISCUSSION...
Issued at 434 AM CDT Sat Jul 27 2024

Short Term...Today...Tonight...and Sunday

Southerly winds will bring warmer temperatures into
Wisconsin today, but humidity levels will be low enough for it to
be pleasant enough, especially across the Fox Valley and lakeshore
counties where dewpoints should be lowest. Low level warm advection
and increasing moisture will produce increasing clouds across
central and northcentral WIsconsin today, with skies remaining
mostly sunny further east. Highs today will be a few degrees above
normal in most areas.

Dry air circulating around the surface high across the Lower Great
lakes, and mostly clear skies will allow temperatures to fall to
near or just above normal levels tonight.

Sunday will be mostly cloudy and there is a chance of thunderstorms
across central and east central Wisconsin as a weak upper trough
approaches from the Central Plains. It will feel much more humid
with dewpoints climbing through the 60s during the day. Temperatures
will be a few degrees above normal.

Long Term...Sunday Night Through Friday

Main highlights from this forecast period revolve around multiple
chances for showers and thunderstorms throughout the work week,
paired with above normal temperatures and humid conditions.

Precipitation...Showers and thunderstorms will likely be ongoing
into Sunday evening as a weakening shortwave lifts northeast across
the state. However, this precip will come to an end rather quickly
into the evening/night, as forecast soundings indicate low to mid-
level dry air moving into the area. A brief break in the precip
looks to occur through Monday morning before the next shortwave
phases with its predecessor. This phasing has resulted in models
generating areas of convection in different locations across the
Upper Midwest. Where and how these areas of convection evolve and
progress eastward for the remainder of Monday will be the main
challenge to iron out over the next few days. Despite these
discrepancies, it does still appear the forecast area will see
showers and thunderstorms sometime between Monday afternoon and
night, but the finer details of who will see the greatest amount of
rain, when it will occur, and the severity of the thunderstorms
remains uncertain. Guidance is indicating the main shortwave will
linger over the western Great Lakes on Tuesday, which may generate
some diurnally driven showers and storms in far eastern WI.

Broad upper-level ridging will attempt to build over the area
Tuesday night, but won't last long as models are showing signs of
multiple shortwaves riding the ridge throughout the rest of the work
week. However, there are large discrepancies in the timing and
placement of these shortwaves. Anticipate the forecast area will see
precip at some point between midweek and the end of the week, but it
is too difficult to determine any further details at this time.

Temperatures...Despite the several chances for precip throughout
this forecast period, the warm, moist airmass producing this precip
will also result in above normal temperatures and humid conditions.
Anticipate highs to mainly top out in the middle to upper 80s each
day, with a few spots potentially reaching 90 degrees. Dew points
will generally be in the middle to upper 60s, with low 70s on some
days. While heat index values will be in the upper 80s to low 90s,
the risk for excessive heat remains low.

&&

.AVIATION...for 06Z TAF Issuance
Issued at 1046 PM CDT Fri Jul 26 2024

Precipitation: None.

Clear skies will continue until around 15z Saturday. Increasing
low level moisture will result in stratocumulus clouds developing
between 15z and 18z Saturday and continue through Saturday
afternoon. A broken deck with CIGS developing between 2500 and
3000 feet during the morning should rise to around 3500 feet
during the afternoon is expected at KRHI/KAUW/KCWA/KMFI/KISW. A
few to scattered deck is expected across northeast Wisconsin
around 3000 feet.

VSBY trends: Could see patchy ground fog in river valleys of far
northeast and east central WI late tonight into early Saturday
morning, but confidence remains too low to include at GRB/ATW/OSH/MTW.
Low level winds increase tonight across north-central Wisconsin
which should prevent any fog from forming.

Smoke Trends: Elevated smoke to remain across the forecast area
through the TAF period, but little or no surface impacts are
expected.

Winds: Light S-SE winds expected tonight, with S winds gusting to
15-20 kts by late Saturday morning and then continue through
Saturday afternoon.

.OSH...VFR conditions expected through the TAF period, with only a
very low (10%) probability of MVFR vsbys in fog late tonight.
Clear skies will prevail through 15z Saturday, then stratocumulus
should develop around 3000 feet between 15z and 18z, rising to
3500 feet Saturday afternoon. South winds around 5 knots should
prevail tonight, then increase to around 10 knots with gusts to
around 17 knots late Saturday morning and afternoon.

&&

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

&&

$$

DISCUSSION.....RDM/Kruk
AVIATION.......Eckberg