Wausau, Wisconsin 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

012
FXUS63 KGRB 022355
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
655 PM CDT Mon Jun 2 2025

Updated aviation portion for 00Z TAF issuance

.KEY MESSAGES...

- Elevated wildfire smoke will lead to hazy skies at times through
  Wednesday. Surface impacts are expected to be minimal until Tuesday
  night, when smoke may mix to the surface over north central and
  parts of central and far northeast WI.

- Increasing south winds and building waves will result in
  hazardous conditions for small craft on Lake Michigan starting
  late this afternoon and continuing through Tuesday evening.
  Dangerous swimming conditions will also develop on Lake Michigan
  beaches from late this afternoon through Tuesday evening.
  Hazardous conditions for small craft are also expected from late
  Tuesday morning through early Tuesday evening.

- Showers and thunderstorms are expected Tuesday into Tuesday
  night. There is a marginal risk of excessive rainfall (urban
  flooding) and severe thunderstorms (damaging winds).

&&

.DISCUSSION...
Issued at 146 PM CDT Mon Jun 2 2025

Short Term...Tonight and Tuesday

The latest RAP analysis and satellite/radar imagery show surface
high pressure over the mid-Atlantic states while a cold front is
draped from northern Minnesota to eastern Colorado. Hazy skies
remain present over Wisconsin thanks to rather thick elevated
wildfire smoke. No signs of any smoke reaching the surface nearby.
The closest indications of surface smoke is over northern
Minnesota. The cold front remains largely inactive so far today as
deeper Gulf moisture has been slow to advect northeast ahead of
the front. Weak shortwave impulses are moving northeast over the
eastern Dakotas, which are producing clusters of showers and
storms, and are the closest precip activity to the region. As the
cold front moves across the region, forecast concerns revolve
around thunderstorm and severe weather chances to go along with
surface smoke potential.

Thunderstorm Potential: The shortwave impulses over the Dakotas
are on track to move into western Lake Superior this evening.
Guidance depicts a decent push of mid-level thetae with the
shortwave that leads credence to the chance of elevated showers
over north-central WI like the HRRR depicts. Instability of
200-400 j/kg is forecast to arrive by this time, but the CAMS show
this first push of showers decaying, so left thunder out of the
forecast.

Showers and thunderstorms are forecast to become more widespread
by late Tue morning as the cold front moves across northwest
Wisconsin.  Decent moisture convergence, mid-level fgen, and high
precipitable water values 200% of normal will accompany the front,
which will lead to a high chance of rain (greater than 90%)
across the region. While not excessive, widespread instability of
500 to 1000 j/kg will lead to a chance of thunderstorms. Most
guidance paints a picture of the heaviest precip would lie post-
frontal. Therefore expect precip to arrive by late in the morning
over north-central WI and end of northeast WI by late Tue night.

Severe Weather and Heavy Rain Potential: Concern for severe
weather remains highest over eastern WI where surface-based
instability has time to develop ahead of the front on Tuesday. How
much heating occurs remains uncertain due to the thickness of the
smoke aloft and coverage of cloud cover or shower activity ahead
of the front. Forecast high temperatures have decreased over the
past 24-48 hours and appear to peak early in the afternoon.
Modifying a 18z forecast sounding with a surface parcel of 81/65
generates around 1200 of surface based instability. Like
yesterday, this looks like the upper limit of what to expect for
instability.  With convective temps in the low 80s, think storm
coverage will increase early in the afternoon over northeast WI.

Deep layer shear of 30-40 kts is expected for any convection that
develops ahead of the front. With lengthening hodographs and
veering winds in the 0-2 km layer, an isolated severe threat
remains possible. High freezing levels (13.9 kft) and -20C (24.2
kft) along with poor mid-level lapse rates (5.5 C/km) should make
the hail threat take a back seat to a damaging wind threat should
surface based storms develop. Timing of the highest chances for
severe weather would be from 12-6 pm.

Conditions will also be favorable for heavy rainfall on Tuesday
and Tuesday night. High freezing levels around 14 kft,
precipitable water values 200% of normal, low level winds
parallel to the front, and skinny instability profiles support
potential for heavy rainfall. Probabilities indicate widespread
precip from 0.75" to 1.75" is most likely (25-75 percentiles),
which is a little higher than yesterday. Flooding concerns
increase if precip amounts could reach above 1.50". Considering
that probabilities for 1.50" ranges from 30-60% across the
region, could see localized and urban flooding develop where the
heaviest rain falls. The recent dry weather decreases the
probability of flooding, particularly over north-central WI where
precipitation has been running 25-50% of normal over the past 30
days.

Surface Smoke Potential: There has been no indications of surface
smoke across Wisconsin so far today. The closest area of surface
smoke is over northern Minnesota. Confidence is low whether
surface smoke will occur prior to frontal passage, but there
appears to be enough evidence to support an Air Quality Advisory
from midnight tonight through noon Tuesday. A statewide advisory
is expected from noon Tuesday through noon Wednesday. Confidence
increases behind the front for Tue afternoon and night, primarily
over north- central WI.

Temperatures: Warm temperatures are expected over the next 36
hours. Lows will not fall much tonight due to breezy conditions,
warm advection, and increasing cloud cover. Highs will be the
warmest over eastern WI (near 80) away from Lake Michigan on Tue.
Then temps fall off closer to normal behind the front for Tue
night.

Long Term...Tuesday Night Through Monday

Relatively low impact weather is forecast for much of this period.
The lone exception could be on Sunday into Monday when a large
upper low digs across the northern Plains and south-central
Canada. The front associated with this low looks quite potent and
some instability is forecast to be present ahead of the front.
This period looks to be the next chance of widespread rainfall a
thunderstorm chances.

Otherwise, flattened troughing on the southern periphery of an
upper trough will be moving across the region from Wednesday
through Saturday. Embedded shortwaves within this flattened
troughing will bring occasional periods of light rain showers.
Timing and coverage remains relatively uncertainty, but the latest
guidance indicates the highest chances (30-40%) of rain will
occur on Thursday night into Friday.

Temperatures will be near normal over the period.

&&

.AVIATION...for 00Z TAF Issuance
Issued at 654 PM CDT Mon Jun 2 2025

VFR conditions will prevail until at least daybreak on Tuesday.
A few showers leftover from storms over central MN could cross
north-central WI by late evening. Additional showers then work
in from the west as cold front approaches on Tuesday morning. All
terminals will see showers with a chance of thunder through the
day. Greatest risk of showers and storms will be 17z-21z AUW, CWA
and RHI and from 20z-24z at GRB, ATW and MTW. If strong storms
form, then wind gusts over 40 kts would occur over east-central
terminals mid to late afternoon. Showers will diminish and end
from west to east on Tuesday evening as the cold front finishes
crossing the area.

Flight conditions will deteriorate steadily from VFR late tonight
to IFR/MVFR central and north-central WI on Tuesday morning, and
to MVFR over east-central and northeast WI on Tuesday afternoon.

Winds will strengthen aloft tonight, resulting in low-level wind
shear from 35-45 kts at all terminals. With daytime mixing on
Tuesday, gusty southwest surface winds 20-25 kts will develop
after 15z over east-central WI.

Finally, elevated wildfire smoke will continue to be present
aloft. The greatest potential for surface impacts will be in
wake of the cold front late Tuesday afternoon into Tuesday night,
especially over northern WI (RHI).

&&

.GRB WATCHES/WARNINGS/ADVISORIES...
Beach Hazards Statement through late Tuesday night for WIZ022-
040-050.
&&

$$

DISCUSSION.....MPC/MPC
AVIATION.......JLA