Waukesha, Wisconsin 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

796
FXUS63 KMKX 072016
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
316 PM CDT Sun Jun 7 2026

.KEY MESSAGES...

- A very humid airmass will return Monday and Monday night ahead
  of approaching low pressure with widespread showers and
  scattered thunderstorms forecast.

- Showers and storms tomorrow will be slow moving and capable of
  heavy rainfall. Localized flooding is possible. General
  rainfall totals will be between 0.5 and 1.5 inches, but
  locally higher amounts will be possible where thunderstorms
  set up on Monday. A brief, isolated, spin-up tornado also
  can`t be ruled out with some of the storms tomorrow.

- Hot and humid conditions expected mid to late week, with some
  potential for Heat Advisory conditions and additional chances
  for showers and storms.

&&

.SHORT TERM...
Issued 248 PM CDT Sun Jun 7 2026

Tonight through Monday night:

Surface high pressure will slowly begin to retreat east
overnight, allowing for a broad moist axis ahead of a large lee
trough over the High Plains to shift east into our area. As the
moist axis shifts into our area, surface dew points will rise
into the low 70s and PWATs will rise to between 1.7 to 2 inches.

Overnight, convection to our south will generally see a downward
turn in coverage as instability wanes after sunset, but some
showers may begin to move into southwest and south central WI
between midnight and dawn on Monday as the moisture surges
northward.

Tomorrow, instability is expected to increase after sunrise and
1500 to 2000 J/kg of CAPE will be realized from the late morning
into the early afternoon. Shower and storm coverage will
increase, and scattered storms capable of locally heavy rain
will occur. Given the high PWATs, very efficient rainfall is
expected. Generally 0.5 to 1.5 inches of rainfall is expected
over the area, but with the ample moisture, any locations that
get stuck beneath the expected slow moving, training storms
tomorrow may see locally higher amounts that could eclipse 2-3
inches. SPC HREF 3 HR PMM corroborates this, showing potential
for rainfall in the 2-3 inch range in scattered pockets over
central WI during the afternoon.

Another added layer to tomorrow`s storms will be the presence
of an MCV left over from today`s convection. This MCV is likely
to be located over NE IA tomorrow, and may cause some local
enhancements to shear over southwest and south central WI. This
localized shear enhancement, coupled with very good low level
stretching potential (3CAPE >150 J/kg) and low LCLs around 400m
may allow for a short window for an isolated, brief spin-up
tornado tomorrow afternoon, similar to what was seen in Illinois
earlier today.

Showers and storms will continue into Monday evening until
instability wanes again after sunset, with some widely scattered
rain lingering overnight.

CMiller

&&

.LONG TERM...
Issued 255 PM CDT Sun Jun 7 2026

Tuesday through Sunday:

Hot, humid and mostly quiet on Tuesday as subsidence takes hold
behind a departing upper trough. Highs will be in the mid to
upper 80s, with head indices in the low 90s. There will be
chances (~20 to 30 %) for a lake breeze driven shower or storm
Tuesday afternoon, though these may not materialize owing a
sturdy cap aloft of 13 C at 700mb that will build in behind a
push of warm advection during the morning into the afternoon.

Warmth builds Wednesday with highs pushing 90. The combination
of the heat and humidity may cause heat indices near 100. We`ll
have to monitor Wednesday in particular for a Heat Advisory.
Wednesday afternoon and evening strong trough is expected to
kick off convection over northern WI which will then track
southeast Wednesday night into our area. Still a bit too early
to pin down the particulars but GFS soundings suggest a highly
unstable environment with 4000 j/kg of SBCAPE, appreciable low
level turning in the hodographs, and effective shear around 25
knots which would support all modes of severe weather.

Another wave may propagate northeast along a baroclinic zone on
Thursday, causing another chance for severe weather on Thursday
before a cold front comes crashing through Thursday night.

Temperatures and humidity briefly moderate on Friday, with
additional shower and storm chances Saturday and Sunday.

CMiller

&&

.AVIATION...
Issued 221 PM CDT Sun Jun 7 2026

VFR conditions are expected to persist this afternoon and into
tonight, save for Far SW WI, where rain may cause lower flight
categories. Overnight, VFR conditions slowly give way to MVFR
and IFR conditions from west to east around dawn on Monday as a
more humid airmass and rain showers/storms move into southern
WI. Scattered rain showers/storms will then continue through
Monday, with a mixture of flight categories through the day.

Southeast winds will persist through the TAF period with
moderate gusts from 15 to 20 knots tomorrow.

CMiller

&&

.MARINE...
Issued 254 PM CDT Sun Jun 7 2026

High pressure over the Upper Great Lakes will gradually begin
to shift east through the rest of today and into Monday morning.
Warm and humid air lingering over the relatively cool waters of
Lake Michigan has caused marine dense fog over the northern
half of the lake into the early part of the afternoon. Recent
satellite trends have shown this area of fog dissipating, so the
Marine Dense Fog Advisory may be cancelled before 7PM CDT this
evening.

Otherwise, broad low pressure over the Great Plains and high
pressure over the northeastern states will lead to moderate
southeast winds over the lake into Tuesday morning. Winds then
become southerly during the day on Tuesday as a warm front lifts
north over the lake.

Occasional chances for showers and thunderstorms are in the
forecast, particularly late Monday through Monday night.
Additional chances later in the week.

CMiller

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...Beach Hazards Statement...WIZ052-WIZ060-WIZ066-
     WIZ071...midnight Monday to 7 PM Monday.

LM...Dense Fog Advisory...LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565-
     LMZ567-LMZ643-LMZ868 until 7 PM Sunday.

     Small Craft Advisory...LMZ643-LMZ644...4 AM Monday to 4 PM
     Monday.

&&

$$

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