Appleton, Wisconsin 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

501
FXUS63 KGRB 031156
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
656 AM CDT Tue Jun 3 2025

Updated aviation portion for 12Z TAF issuance

.KEY MESSAGES...

- Rain and thunderstorms are expected today and tonight. There is
  a marginal risk of excessive rainfall (urban flooding) and
  severe thunderstorms (damaging winds).

- Elevated wildfire smoke will lead to hazy skies at times through
  Wednesday. Smoke may mix to the surface, particularly late
  tonight and Wednesday, and cause air quality issues for sensitive
  groups.

- Conditions hazardous conditions for small craft and dangerous
  swimming conditions are expected through this evening.

&&

.DISCUSSION...
Issued at 427 AM CDT Tue Jun 3 2025

Short Term...Today...Tonight...and Wednesday

Focus is on heavy rain and thunderstorm potential as a cold
front slides across the state today; along with wildfire smoke and
its potential to have surface impacts.

Overnight, a few diminishing showers moved across central WI, and
one little shower across north-central WI produced a few lightning
strikes. Otherwise, conditions were quiet and mild, as
temperatures at 3:00 AM were still in a the 60s and low 70s. A sfc
cold front was just entering far northwest WI, and behind it sfc
visibility reductions were noticed from smoke, with vsbys from
3-7SM.

For today, the cold front will gradually make its way across the
state, entering central and north-central WI late this morning and
early afternoon, and reaching far east-central WI early this
evening. Proximity to the RRQ of the upper jet, mid-level
shortwave, and low level fgen, will all aid in providing a
prolonged period of lift, and therefore rain and thunderstorms
from midday through this evening. Precip will arrive from the SW
as the moisture surges northward along the front, but sweep across
WI from west to east through the day. With max pwats ranging
from 1.5-2.0 in (around 200% of normal for early June) heavy rain
will be possible. The NBM probabilities for getting at 1.5" of
rain ranges from 40-75%; and the probabilities for getting 2.0"
even ranging from 5-50%. Therefore, the entire area is highlighted
in the Day1 Marginal Risk (level 1 or 3) of excessive rainfall,
with some localized urban or small stream flooding possible today.

Initially, there isn`t much instability to work with, but as this
builds through the day thunderstorms will also be in the mix. Most
of the forecast area, aside from north-central WI, is also in a
Marginal Risk (level 1 of 5) for isolated severe thunderstorms
today. Severe storms are most likely across the Fox Valley/east-
central WI where instability has a longer time to build prior to
the arrival of the front. Peak forecast instability ranges from
800-1500 J/kg, with sfc-6km shear of 40-50 kts, and some modest
inverted-v soundings at times. However, freezing levels are high,
lapse rates remain low around 5.5 C/km, and CAPE is long/skinny.
Therefore, wind still appears to be the primary severe threat.
There is uncertainty with how smoke aloft may inhibit heating
and/or convective initiation. CAMs are in relatively good
agreement with the general precip trend for the day as rain and
thunderstorms sweep across, with the development of stronger cells
across central/east-central WI from approximately Noon-8PM.

This evening, front moves east of WI, but lingering upper level
energy continues a rain/isolated thunder chance overnight,
especially across eastern WI. Severe threat will be low by this
time. Drying and clearing clouds on Wednesday, although the smoke
will likely make it appear hazy or overcast much of the day.

Smoke...Forecast models show the current surface smoke across NW
Wisconsin well, and keep the thickest of the surface smoke in
this area today. For central and northeast WI, smoke is still
expected overhead, and some may reach the surface at times, but
it appears this is more likely to occur after the front on
Wednesday. An Air Quality Advisory from the WI DNR remains in
effect until noon Today for the northwest half the state, with a
statewide Advisory likely to begin after noon.

Marine/Beach...Gusty winds and high waves will create hazardous
conditions for both small craft and beach goers through this
evening. See further details in associated products.

Long Term...Wednesday Night Through Monday

Although weather will be largely low impact in the extended
period, active weather will still be around the area at multiple
points in the forecast period. Temperatures will hold fairly
steady near normal during this period.

Precipitation...
Some isolated showers are possible late in the day Thursday and
overnight as weak warm air advection arrives in the mid-levels and
a more organized surface system moves into Illinois to our south.
Some vorticity advection will accompany this period, so some
isolated precipitation is in the forecast. Overall, most of the
area will be dry during this period still, with only around 15-20%
chance of rain at any one location. A better chance for rain then
follows Friday afternoon, as another upper shortwave crosses the
region. Diurnal heating may allow for just enough instability to
allow for better shower coverage on Friday. In either case, any
active weather is expected to be fairly low impact.

The best chance for widespread and possible Sunday evening into
Monday. Long range guidance shows broad upper low that will cross
north of the region and bring a cold front through the region.
This could bring some rain to most of the area but thunder remains
a little more in question at this time. The timing is not the most
favorable and soundings show diminishing instability as the rain
approaches the area. As a result, thunder does leave the forecast
early in the overnight period Sunday. This system may move slowly
enough to bring additional precipitation from wrap around moisture
on Monday as well, but thunder chances remain minimal then as
well.

Temperatures...
High temperatures will be near normal through the period, which is
to say in the 70s through the weekend.

&&

.AVIATION...for 12Z TAF Issuance
Issued at 655 AM CDT Tue Jun 3 2025

Starting with VFR conditions area-wide early this morning, but as
a cold front approaches from the northwest today expect
MVFR/occasional IFR conditions to develop from west to east
through the morning and early afternoon.

As lower clouds arrive, so do scattered showers with embedded
thunderstorms, along with the chance for surface smoke to reduce
vsbys at times. Once showers begin, they will continue off and on
through mid- evening in central and north- central WI (KRHI, KAUW,
KCWA TAF sites), and through the night farther east (KGRB, KATW,
KMTW TAF sites). The showers are noted in the prevailing weather
conditions, with the most likely window for thunderstorms in TEMPO
groups. Models have been somewhat consistent, so have medium
confidence on timing. Widespread severe storms are not expected,
but localized strong/severe storms with heavy rain and sudden,
strong wind gusts could accompany any thunderstorms this
afternoon.

S/SW surface winds will gust up to 25kts this afternoon, and then
veer to the NW after the passage of a cold front. There is also a
small window of LLWS in the eastern WI TAF sites late this
evening.

&&

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

$$

DISCUSSION.....KLJ/Uhlmann
AVIATION.......KLJ