National Weather Service Weather Forecast Office

• Home
• Site Map
• News
• Organization
• Search for: NWS All NOAA 

000
FXUS63 KMKX 260851
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
351 AM CDT Fri Apr 26 2024

.KEY MESSAGES...

- Multiple rounds of showers and thunderstorms are expected
  later today through the weekend, with storms possibly
  lingering into early Monday. Locally heavy rainfall will be
  possible.

- A few thunderstorms may be severe during this active pattern,
  particularly later Saturday through Sunday.

- Additional chances for showers and storms mid to late week
  next week.

&&

.SHORT TERM...
Issued 350 AM CDT Fri Apr 26 2024

Today through Saturday:

Persistent moisture and warm air advection will bring rounds of
showers to Wisconsin this afternoon into tonight. The first
round this afternoon into early evening should be thunder free,
but round 2 later evening into tonight should have at least a
few rumbles of thunder. Bumped up precip chances, as latest HREF
probabilities of 6 hr measurable precip are 80-100 percent as
the stronger forcing moves through.

Temps will be coolest east today under persistent onshore
winds, with highs also a bit cooler in the southwest as the
thicker clouds and rain move in this afternoon. Central portions
of the forecast area should see temps near normal, topping out
at around 60. Temps will stay on the mild side tonight due to
the persistent warm air advection, elevated winds, and cloudy
conditions.

Showers/storms should wind down by sunrise Saturday, with mainly
dry weather then expected through the daytime hours as the
deeper moisture and stronger forcing move on to the
east/northeast. By late afternoon, a few showers and storms
could develop mainly northwest of Madison, as a weak low level
frontal boundary sags into the area from the northwest.

Though clouds may linger through Saturday morning, models
suggest enough mixing for some breaks in the clouds by mid-
afternoon. Given the warm southwest low level flow, went on the
warmer side of models for high temps at 75 to 80 degrees. If
the clouds hang on longer into the afternoon though, these
forecast highs may be several degrees too mild.

DDV

&&

.LONG TERM...
Issued 350 AM CDT Fri Apr 26 2024

Saturday night through Thursday:

As the first low pressure ejects northeastward from the Great Lakes
region Saturday evening, a second (deeper) low pressure drifts
northeastward from the central plains. The cool sector from the
first low (over northwestern WI) collides with the warm sector of
the second low, producing a SW to NE oriented frontal boundary
drifting into our CWA Saturday evening / night. The exact timing
of this front remains uncertain, but an increase in shower /
thunderstorm coverage is expected Saturday evening into Saturday
night as the front draws closer. The ECMWF and the GFS both show
MUCAPE of roughly 1000 to 2000 Saturday evening south of the
front, decreasing to 500 to 900 j/kg south of the front by 1 AM
Sunday as we lose daytime heating, suggesting that convection
may transfer from surface based to elevated, increasing in
coverage and weakening in intensity overnight. Severe hail and
thunderstorm wind gusts will be possible Saturday evening, with
the hail threat potentially lingering with the elevated
convection overnight.

A surge in the southwesterly low-level jet arrives Sunday morning,
rapidly boosting 850-700mb RH. A corresponding northward push of the
surface warm front (ahead of the approaching low) is expected,
though the exact timing / positioning of this front (and the surface
based instability behind it) remains uncertain. Early Sunday,
accelerating northeasterlies off of Lake Michigan are progged to
halt the warm front`s advance in our northeast CWA, while the front
makes more progress in the west. The front then fully overruns the
CWA later that evening / overnight. Rain / thunderstorms with
localized heavy rainfall and potentially some severe storms remain
possible throughout this period.

Showers and thunderstorms then linger into Monday as as the cold
front from the second low pressure finally pushes through. Next
week`s weather pattern then features two additional chances for rain
as smaller amplitude troughs pass by.

Sheppard

&&

.AVIATION...
Issued 350 AM CDT Fri Apr 26 2024

High level clouds will continue this morning, with lowering
bases from the southwest this afternoon and evening as a round
of showers moves into the area. Ceilings are expected to drop to
the 5-10 hft range. Additional showers are expected this evening
into tonight, with some thunder also possible. Precip is
expected to wind down 09-12Z early Saturday, with mainly dry
weather then during the day Saturday. Scattered showers/storms
may eventually develop northwest of Madison by late Sat
afternoon. Ceilings should gradually improve Saturday, with a
return to VFR by mid-afternoon.

Breezy southeast winds are expected today and tonight, becoming
south to southwest on Sunday. A period of low level wind shear
is likely this evening and overnight as the low level jet moves
overhead.

DDV

&&

.MARINE...
Issued 350 AM CDT Fri Apr 26 2024

Breezy southeast winds are expected today into tonight as low
pressure lifts from the Central Plains into Minnesota. Winds
will remain elevated Saturday from the south as the low
continues to lift northward west of the area. Winds will then
flip to northerly from the north Saturday night through at least
central portions of the lake, with a frontal boundary likely
remaining draped across the southern lake on Sunday. Winds will
be southerly south of the front and east to northeast north of
the front. A Small Craft Advisory is in effect for today through
Monday, through winds and waves may drop below criteria for a
time on Sunday. Multiple rounds of showers and storms are
expected this evening through the weekend.

DDV

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...None.
LM...Small Craft Advisory...LMZ643-LMZ644-LMZ645-LMZ646...7 AM
     Friday to 7 PM Monday.

&&

$$

Visit us at weather.gov/milwaukee

Follow us on Facebook, Twitter, and YouTube at:
www.facebook.com/NWSMilwaukee
www.twitter.com/NWSMilwaukee
www.youtube.com/NWSMilwaukee