NWS-Milwaukee/Sullivan Forecast Discussion

						FXUS63 KMKX 142049
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
349 PM CDT Sat Mar 14 2026

.KEY MESSAGES...

- A Winter Weather Advisory north of I-94 corridor for 1-3
  inches of snow and up to an tenth of an inch of ice
  accumulation tonight into Sunday morning. This advisory will
  then continue into the afternoon over central Wisconsin for
  continued light freezing rain potential.

- Thunderstorms capable of hail are possible Sunday late
  morning into the afternoon, mainly along and south of a Lone
  Rock to Mequon line.

- A Winter Storm Watch remains in effect from late Sunday afternoon
  through Monday. Snow accumulations between 5 to 9 inches and
  locally higher may occur along with a light glaze of ice. Wind
  gusts to 45 mph will cause blowing snow and visibility
  restrictions.

- Gale Warning, Storm Watch, and Heavy Freezing Spray Watch are
  now in effect for varying periods from Saturday night through
  Tuesday morning.

&&

.SHORT TERM...
Issued 342 PM CDT Sat Mar 14 2026

Tonight through Monday:

Light echoes have been appearing on radar through the day as
warm advection aloft touches off attempts at precipitation. The
precipitation has been sporadically reported at the surface,
though most of it has been evaporated by low level dry air.
Some scattered light snow can't be ruled out as this band lifts
northeast through the rest of the afternoon.

The precipitation mentioned above is in association with a
baroclinic zone draped from the Dakotas into northern Illinois.
As we head into tonight, low pressure will move into the high
plains over Nebraska and increase 850-700mb WAA and
frontogenesis over the upper Midwest. More substantial snow
will then begin over the area, starting our expected prolonged
winter weather event.

This afternoon, we are still confident in the storm unfolding in
3 phases, though the details of phase 2 and 3 still continue to
shift this afternoon.

Phase 1:
Confidence is high in the evolution of this phase and not much
has changed since yesterday. Snow is expected to begin over east
central Wisconsin after 7pm tonight and generally spread in
coverage to as far south as a line from Milwaukee to Lone Rock.
With time, warm advection aloft and at the surface will change
this band of snow to mixed precipitation, and then rain over the
area. Temperature profiles overnight will favor an overlap of
snow and freezing rain mainly for counties north of the I-94
corridor. Little, if any wintry precip is expected from
Milwaukee to Madison. The overlap of precip types will lead to 1
to 3 inches of snow accumulation and then ice accumulations up
to a tenth of an inch tonight into Sunday morning. A Winter
Weather Advisory remains in effect tonight into Sunday morning
for counties north of I-94 for this phase.

Phase 2:
The low is then still expected to approach from the west and
pass along the southern border of Wisconsin Sunday afternoon
into Sunday evening. As the low approaches, warm air at the
surface will advect northward and generally stall just north of
I-94 during the late morning and into the afternoon, creating a
sharp frontal boundary and sharp temperature gradient.
Temperatures in the 50s will exist south of the boundary and 30s
north. Temperatures over central Wisconsin will still be around
freezing, which will support a more prolonged period of freezing
drizzle and freezing rain. With this more prolonged period of
freezing precip potential, we have extended the Winter Weather
Advisory for central Wisconsin into the afternoon to run up
against the Winter Storm Watch, which starts at 4pm. Ozaukee and
Washington Counties will still drop from the WW Advisory at
10AM, as they will likely transition to all rain with surface
temperatures near 40, ending the freezing precipitation
potential.

Thunderstorms are also possible, potentially starting as early
as 8AM in southwestern WI, as MUCAPE of 500 to 1000 J/kg moves
into the areas along with a prefrontal trough feature. A line of
thunderstorms extending from Lone Rock south toward the WI/IL
border is expected to then move from west to east over the area
through 1PM. Models do generally show MUCAPE decreasing as
storms move toward the lakeshore, but given mid level lapse
rates around 7 C/km, some hail may occur. Following this first
round, additional thunderstorms may occur as the cold front or
triple point of the low move through later in the afternoon, but
the CAPE profile is expected to be much skinnier and weaker,
diminishing any potential for stronger storms.

Phase 3:
Snow is still expected with phase 3 but the end time of impacts
and snow amounts remain variable with the morning and afternoon
model runs. Synoptically, as the surface low moves southeast of
the area Sunday afternoon, cold air will wrap in behind the low
pressure system and into the deformation zone of the low. This
will support rain changing back over to freezing rain and mixed
precip Sunday afternoon, and then over to all snow Sunday night.
Wind is also expected to become very gusty, up to 45 mph as a
sharp pressure gradient moves over the area.

From here models diverge, showing differences in snow totals
overnight Sunday into Monday as well as differences in end
timing. Some models like the HRRR and RRFS would end snow over
the region as early as 6 to 9am, which would leave most of
Monday windy, but dry. This would decrease potential winter
impacts for Monday and lead to less of a need for local closures
during the day. Models like the ECMWF and GFS however would
linger snow into the early afternoon, which would change the
flavor of local impacts.

Models have also trended lower with snow in recent runs. The
Euro ensemble currently only features a 30 to 50% chance of snow
greater than or equal to 6 inches over southwest Wisconsin.
More alarming still, the GFS ensemble features only a 10 to 30%
chance of snow greater than/equal to 6 inches in this area.
HRRR and RRFS runs also corroborate this trend. With the
deformation zone of the storm featuring the lion's share of the
expected snowfall for this winter event, the decreasing
probabilities 6+ inches of snow in the GFS and ECMWF ensembles
and CAM trends for a good chunk of our CWA gives us pause. We
have elected to maintain the Winter Storm Watch until these
details get ironed out in further forecast model runs. We
envision some part of our CWA getting upgraded to a Winter Storm
Warning heading into tomorrow (more likely toward central WI
where higher snow totals and high winds will overlap) while the
rest may only need a Winter Weather Advisory.

CMiller

&&

.LONG TERM...
Issued 342 PM CDT Sat Mar 14 2026

Monday Night through Saturday:

High pressure will build in from the northwest Monday night and
Tuesday behind the departing low pressure system. Additionally,
a colder airmass will continue to move in through Monday night,
with the coldest temps of the month likely. Lingering moderate
winds will add an extra chill to the air, with wind chills
dropping to -5 to -15 later Monday night into early Tuesday
morning. Despite a fair amount of sunshine under the high Tuesday
morning into at least early afternoon, high temps will remain
well below normal, only topping out in the low to mid 20s.

Low level winds will become southerly later Tuesday into Tuesday
night as high pressure departs ahead of an approaching shortwave.
Models are showing a decent amount of warm air advection aloft
along and ahead of the wave Tuesday night into early Wednesday.
Moisture will increase as well ahead of this wave, with a round of
snow likely per latest models. Latest guidance would suggest snow
would arrive from the west late evening, winding down west to east
early Wednesday morning. Models range from 1-2" to about 2-4" with
totals. These potential amounts and timing could result in
impacts to the Wednesday morning commute. Plenty of time left for
the details of this system to change though, given it's still a
few days out.

Milder temperatures are expected to gradually build in during the
second half of the week in response to upper ridging nudging in
from the southwest. Mainly dry weather is expected during this
period.

DDV

&&

.AVIATION...
Issued 342 PM CDT Sat Mar 14 2026

Southeast winds will become easterly overnight and then modestly
breezing into tomorrow ahead of low pressure. Tomorrow late
morning into the afternoon, winds will then become southerly to
light and variable for a time as the low pressure approaches and
passes overhead, before winds come around to north and
northwesterly following the low. Strong wind gusts are then
expected Sunday night.

With the increasing moisture over the region, ceilings will
decrease to MVFR to IFR overnight over most of southern WI save
for near the WI/IL border. Snow and mixed precip is expected
with the low ceilings.

Tomorrow ceilings will decrease to IFR everywhere, and some
thunderstorms may occur through the daytime hours. A changeover
to freezing rain and then snow is expected across the area late
Sunday afternoon into Sunday night.

Southerly LLWS to 50 knots is also possible Sunday morning ahead
of the low pressure. This will be possible along and south of
a line from KMSN to KMKE.

CMiller

&&

.MARINE...
Issued 342 PM CDT Sat Mar 14 2026

High pressure of 30.2 inches will slide east later today and
easterly winds will steadily increase tonight through Sunday, as
a low pressure system around 29.3 inches forms in the central
Great Plains. A Small Craft Advisory may be needed for a few hours
this evening prior to the start of Gale Warning. The low will
progress over far southern Lake Michigan Sunday evening as it
deepens to around 29.1 inches, resulting in strong northerly winds
developing.

Strong winds will shift out of the northwest Monday, as the
strong low continues to move into Ontario. Expect another
prolonged period of gales and storm force gusts early Sunday
morning through Monday night as the low progresses through the
region. The best chance for storm force gusts will be across the
northern two-thirds of the lake.

Prolonged snow is expected Saturday night through
Monday, some of which could be heavy over northern portions of the
lake. Sleet or freezing rain should mix in with rain and snow
over central and parts of northern Lake Michigan Saturday night
into Sunday, with mainly rain and perhaps a few thunderstorms in
the far southern portions of the lake Sunday into Sunday evening.
Snow is then expected over southern portions of the lake Sunday
night into Monday night.

Freezing spray potential will increase Monday and linger into
Tuesday behind the departing low, with areas of moderate to heavy
freezing spray possible. The Heavy Freezing Spray Watch continues.

DDV

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...Winter Weather Advisory...WIZ046-WIZ047-WIZ051-WIZ052-WIZ056-
     WIZ057-WIZ058...7 PM Saturday to 4 PM Sunday.

     Winter Storm Watch...WIZ046-WIZ047-WIZ051-WIZ052-WIZ056-WIZ057-
     WIZ058-WIZ059-WIZ060-WIZ062-WIZ063-WIZ064-WIZ065-WIZ066-
     WIZ067-WIZ068-WIZ069-WIZ070-WIZ071-WIZ072...4 PM Sunday
     to 7 PM Monday.

     Winter Weather Advisory...WIZ059-WIZ060...7 PM Saturday to 10
     AM Sunday.

LM...Gale Watch...LMZ080-LMZ673-LMZ675-LMZ777-LMZ779-LMZ874-LMZ876-
     LMZ878...1 AM Sunday to 7 AM Tuesday.

     Heavy Freezing Spray Watch...LMZ080-LMZ261-LMZ362-LMZ364-
     LMZ366-LMZ563-LMZ565-LMZ567-LMZ643-LMZ644-LMZ645-LMZ646-
     LMZ669-LMZ671-LMZ673-LMZ675-LMZ777-LMZ779-LMZ868-LMZ870-
     LMZ872-LMZ874-LMZ876-LMZ878...4 AM Monday to 1 PM Tuesday.

     Gale Watch...LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565-LMZ567-
     LMZ669-LMZ671-LMZ868-LMZ870-LMZ872...1 AM Sunday to 7 PM
     Sunday.

     Storm Watch...LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565-LMZ567-
     LMZ669-LMZ671-LMZ868-LMZ870-LMZ872...7 PM Sunday to 1 AM
     Tuesday.

     Gale Watch...LMZ643-LMZ644-LMZ645-LMZ646...4 AM Sunday to 1 AM
     Tuesday.

&&

$$

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