311
FXUS63 KGRB 150807
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
207 AM CST Fri Nov 15 2024

Forecast discussion for routine morning forecast issuance

.KEY MESSAGES...

- High temperatures will range from 5 to 10 degrees above normal
through early next week.

- Next potentially impactful weather system is forecast to arrive
  on Monday night and Tuesday with widespread rain and breezy
  conditions. Wet and cool conditions are expected through the
  middle part of next week.

&&

.DISCUSSION...
Issued at 207 AM CST Fri Nov 15 2024

Short Term...Today...Tonight...and Saturday

Despite high pressure building in across the western Great Lakes
region, the area remains entrenched in low stratus as low level
moisture is trapped underneath a subsidence inversion. This has
actually kept temperatures rather warm early this morning, with
temperatures generally in the 40s. There are signs of clearing
slowly making its way into Wisconsin from Minnesota, which is
expected to make its way through Wisconsin this afternoon. Before
then, cloudy skies will remain across the region for much of the
day. The extensive cloud cover will limit the diurnal range
today, with highs this afternoon expected to range from around 50
across the north, to the lower 50s across central and east-central
Wisconsin.

Any clearing that occurs this afternoon is expected to fill back
in tonight as a combination of high clouds stream in and lingering
low level moisture develops low stratus once again due to the
subsidence inversion. Some ground fog will be possible later
tonight with lingering low level moisture, especially across areas
that clear out longer. Lows tonight are expected to range from
around 30 across the north, to the middle 30s across east-central
Wisconsin.

The ridge of high pressure will shift east on Saturday, shifting
surface winds to the south-southeast as a low pressure system
develops across the northern Plains. Despite some models
generating light rain showers across eastern Wisconsin Saturday
afternoon, model soundings indicate abundant mid level dry air.
Therefore, conditions should stay dry on Saturday; however,
clouds will linger across the area in the form of high and low
clouds as indicated by model soundings. Highs on Saturday are
expected to range from the upper 40s across the north, to the
lower 50s across central and east-central Wisconsin.

Long Term...Saturday Night Through Thursday

Forecast concerns through the extended period revolve mainly around a
synoptic scale cyclone that is forecast to impact the region late
Monday through the end of next week.

Saturday night through Monday...A digging upper level trough and
surface low system are progged to move across the northern Plains
and into southwestern Ontario Saturday night into Sunday. This will
drag a cold front across WI bringing a 50-75% chance of rain to much
of the region Sunday morning. However, forecast soundings show dry
air ahead of the front preventing profiles from becoming deeply
saturated. This will limit overall rain amounts with much of the the
area only having a 20-25% chance for greater than 0.1" of rain
through Sunday morning. A brief period of high pressure should bring
dry conditions back to the region Sunday afternoon through the
daylight hours Monday.

Attentions then turn to a likely more impactful system as a well
developed cyclone lifts northeastward out of the central Plains and
toward the western Great Lakes. Ensemble members are in generally
good agreement that light to moderate rain will arrive from south to
north late Monday night into Tuesday morning with rain expected to
linger much of Tuesday. In addition to the rain breezy winds with
gusts of 25-30mph are expected Tuesday. Beyond this ensemble members
become more variable hence introducing more forecast uncertainty.
The uncertainty is in part being driving by the possibility for
phasing system during the middle part of the week, as well as, the
development of a potential dry slot. With that said there are signs
that as the backside of this system moves over the region the
possibility for snow related impacts will increase Wednesday and
Thursday, mainly during the overnight hours as surface temperatures
cool near or just below freezing across much of northern and central
WI.

&&

.AVIATION...for 06Z TAF Issuance
Issued at 1049 PM CST Thu Nov 14 2024

Lingering sprinkles and drizzle will end across far eastern WI
late this evening, with dry conditions expected the rest of the
TAF period. Plenty of low-level moisture will keep IFR/MVFR
ceilings in place tonight into at least Friday morning, with some
lower visibilities possible at times as well overnight,
especially if any breaks in the clouds can develop. Then, as high
pressure builds into the region, skies will begin to at least
partially clear out Friday afternoon and evening, but some lower
clouds could remain as surface low turns to the southeast. Fog
will be possible late Friday evening into Friday night, mainly
after 06z Saturday. Some higher clouds will also spread into the
region later on Friday as well. Winds will remain under 10 kts.

&&

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

&&

$$

DISCUSSION.....Kurimski/GK
AVIATION.......Bersch