NWS-Milwaukee/Sullivan Forecast Discussion

						FXUS63 KMKX 061844
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
144 PM CDT Sat Jun 6 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.

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

&&

.SHORT TERM...
Issued 145 PM CDT Sat Jun 6 2026

Tonight through Monday night:

Upper level ridging settling into the region tonight with
strengthening high pressure developing over the Great Lakes
region. This will keep the region dry tonight and into Sunday
morning. However, models appear to indicating that storms that
will have developed south and west of the CWA Sunday, primarily
off of a trailing front that had become stationary, will lift
north into the CWA due to an embedded shortwave lifting through
the ridge. This likely to be limited spatially in terms of
impact due to significant dry air further north and east as the
high continues to strengthen as it pivots southeast. A few CAMs
show some of this activity entering southwest portions of the
CWA before rapidly dying out. The high pressure and drier air
will likely hold most of the precip and storms to the west of
the CWA through Sunday night but as the upper shortwave
continues shifting northeast and high slides further east this
will allow for the rain/storms to push in.

Looks likely that Monday could be on the wet side with strong
PVA, plenty of moisture with access to the Gulf, and PWATs
rising to around 2 inches. Any rain/storms would likely be quite
efficient. How much rain we get from this will generally come
down to whether we get more or less storm activity. There will
definitely be some storm activity but the question really
becomes how convoluted are storms and do we end up with more
stratiform type rainfall. Either case is good because the rain
is needed, however the storm potential will help determine
whether there may be a risk for flash flooding rains. In
addition, corfidi vectors suggest precip would likely be fairly
slow moving and if we can manage some backbuilding or training
there will be some flash flooding concerns. It should also be
mentioned that storms are not expected to be severe given fairly
limited deep layer shear around 20-30kts and frankly not
overwhelming instability either (up to ~1000J/kg or so).
However, that could change if we see a situation where a
lingering MCV pushes overhead. In any case expect the shortwave
to push out by late Monday night allowing for at least a brief
period of drier air behind it by Tuesday morning.

Kuroski

&&

.LONG TERM...
Issued 145 PM CDT Sat Jun 6 2026

Tuesday through Saturday:

Latest model guidance is still showing that southern Wisconsin
will remain on the northwest side of upper ridging Tuesday through
at least Thursday. This is expected to result in a persistent
stretch of warm and humid conditions through this period.
Precipitable water values are forecast to be 1.5" to 2.0", with
dewpoints anywhere from 65 to 75. Above normal high temps in the
mid to upper 80s may crack the low 90s at times (mainly Wed and
Thu), with 925 mb temps upwards of 25C expected. By Friday
morning, a cold front is expected to move through, bringing in a
drier and more stable airmass along with somewhat cooler
conditions. The GFS keeps the high and quiet weather in place
through Saturday, while the latest ECMWF has the moisture
returning Saturday along with more shower/storm chances.

Given the warm and humid conditions through at least mid-week next
week, plenty of instability is expected each day. Since southern
Wisconsin will be on the northwest side of the upper ridge, the
door will be open for a couple shortwaves to move through during
this period, bringing a chance for showers and storms at times.
The best chance for storms currently looks like Wednesday and
Thursday, as precipitable water values are trending a bit lower
for Tuesday behind the Monday shortwave, and the cold front may be
through by daybreak Friday. May see a the potential for some
strong to severe storms Wed/Thu as well, given somewhat stronger
shear and decent lapse rates.

It still looks like there will be the potential to approach or
reach Heat Advisory levels Wednesday and/or Thursday. This will
largely depend on the timing of clouds and showers/storms. Given
enough sunshine during the day, heat index values will likely
approach the 100 degree mark due to the warm temps and humid
conditions.

DDV

&&

.AVIATION...
Issued 145 PM CDT Sat Jun 6 2026

The lake breeze has pushed across the nearshore areas and
continues inland this afternoon with mostly east winds behind
it. Otherwise brief periods of VFR diurnal cu today with quiet
and calm conditions tonight. Into Sunday there will be a chance
for showers and even storms across parts of southwest WI but
will likely stay south and west of the TAF sites. Better chances
for MVFR CIGS and more widespread storm activity possibly
impacting VSBYs will move in Sunday night but more specifically
on Monday which is the next period to focus on for impacts to
aviation.

Kuroski

&&

.MARINE...
Issued 145 PM CDT Sat Jun 6 2026

High pressure of 29.9 inches builds into the Upper Great Lakes
and strengthening to 30.1 inches overnight. Warm and humid air
will linger over the relatively cool waters of Lake Michigan
with a light wind regime and cause areas of fog into Sunday
morning. Marine Dense Fog Advisory remains in effect until 18z
Sunday for the northern 2/3 of Lake Michigan. Low pressure
develops in the Great Plains Monday, bringing south-
southeasterly winds through at least midweek. Additional chances
for thunderstorms develop Monday with more chances throughout
the week.

Kuroski

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...None.
LM...Dense Fog Advisory...LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565-
     LMZ567-LMZ669-LMZ671-LMZ868-LMZ870-LMZ872 until 1 PM
     Sunday.

&&

$$

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