NWS-Milwaukee/Sullivan Forecast Discussion
FXUS63 KMKX 140456
AFDMKX
Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
1156 PM CDT Fri Mar 13 2026
.KEY MESSAGES...
- A Winter Weather Advisory has been issued north of the
Interstate 94 corridor for snow accumulation of 1 to 3 inches
and around a tenth of an inch of ice accumulation Saturday
night into Sunday morning.
- Thunderstorms may occur Sunday morning into the afternoon.
These thunderstorms may feature hail.
- A Winter Storm Watch is then in effect from late Sunday
afternoon through Monday. Snow accumulation between 5 to 9
inches may occur along with a light glaze of ice. Wind gusts
to 45 mph will cause blowing snow and visibility restrictions.
- Gale Watch, Storm Watch, and Heavy Freezing Spray Watch are
now in effect for varying periods from Saturday night through
Tuesday morning.
&&
.SHORT TERM...
Issued 1145 PM CDT Fri Mar 13 2026
Tonight through Monday Night:
Quiet conditions tonight into Saturday as high pressure has
moved in overhead. This will only persist for a short period
before we start to see the signs of the next system beginning to
push in. This event appears likely to feature multiple
transition phases from Saturday through Monday.
Phase 1:
A low pressure system will develop over southeast Wyoming later
Saturday morning into Saturday afternoon. As it develops expect
a tongue of moisture and WAA at 700-850mb to swing in to
southwest WI to begin seeding the atmosphere with moisture.
Saturation may not be fully expected Saturday afternoon given
the dry lower levels but toward the late afternoon there may be
enough saturation down to the surface to allow for some initial
snow chances. However, saturation isn't truly expected until
Saturday evening when a significant increase in 700-850 Fgen
moves in. This will bring a significant boost to the snow, which
at that time would be expected to be the predominant p-type with
potential for heavier snow toward central WI. Then because we
will be warm advecting, a warm nose in the temperature profile
aloft will develop with gradually increasing surface
temperatures. This will cause a transition from snow, to mixed
precip/freezing rain, and then all rain across southern WI by
around midnight. The warm nose mentioned may also bring
significant midlevel dry air where this could significantly
undercut precip chances in general, possibly clearing out precip
for upwards of 2/3 of the CWA overnight Saturday into early Sunday
morning. A Winter Weather Advisory has been issued to capture
this first phase. Snow accumulation will range from 1 to 3
inches in the advisory area along with around a tenth of ice
accumulation from freezing rain (up to quarter inch of ice
possible in a worse case scenario where freezing rain sits over
the same area for hours). Highest icing and snow amounts will be
over central WI.
Phase 2:
The low is then expected to approach from the west and pass
along the southern border of Wisconsin through the day on
Sunday. There may be a continued gap in our area from dry air
where warmer temperatures begin nudging in significantly with
breezy southerly winds and WAA where winter weather is
minimalized across most of the CWA. There may very well be a
very sharp temperature gradient over the northern portions of
the CWA where snow/mixed precip remains a concern but is far
more uncertain. The rest of the CWA would see some drizzle risk
with the low but largely remaining dry (perhaps even seeing some
clearing?). With CAMs and long term models bringing in warm
temperatures, primarily along and south of I-94 at this time,
MUCAPE is expected to increase to around 500 to 1000 J/kg across
primarily south central and southeast WI. This will bring
potential for some thunderstorms, especially as either the cold
front or the triple point of the low moves through Sunday
afternoon. Some of these thunderstorms may have small hail, few
stones up to an inch possible but storms will be elevated.
However, it is worth mentioning that the newest CAMs suggest
some potential for storms even Sunday morning out ahead of the
front as well. Still a lot of uncertainty in how this time
period plays out.
Phase 3:
Banded snow is then expected late Sunday afternoon into Monday
as the deformation zone of the low moves in and cold air wraps
into the area behind the front. There may be some freezing
drizzle at the onset of this deformation band, but it should be
transitory as snow pushes in directly behind it. The Sunday
afternoon through Monday time period will feature the majority
of the snow accumulation for southern Wisconsin with generally 5
to 9 inches expected, with the most in this range over central
to east central Wisconsin. Along with the deformation zone, a
very tight pressure gradient is expected to move over the region
and winds will gust to 45 mph, leading to blowing snow and
reduced visibility. Snow character is expected to be wet at the
onset of the snow Sunday, but should change to a drier snow with
time as cold air wraps into the area, especially Monday. For
now, a Winter Storm Watch remains over the area from 4pm Sunday
to 7pm Monday, given some remaining shifts in the snow band and
some uncertainty regarding totals through that time period.
Blizzard-like conditions will be possible with the backside of
this system.
Kuroski
&&
.LONG TERM...
Issued 1145 PM CDT Fri Mar 13 2026
Tuesday through Friday:
Looking further into the work week, there will be a few chances for
additional precipitation. As the robust troughing from Sunday/Monday
pulls east, the 500mb heights will slowly be rising. There will be a
few shortwave troughs moving through the flow as a near stationary
ridge remains parked over the western CONUS, which will bring us
those precip chances. The first opportunity will be with a quick
moving shortwave Tuesday night into Wednesday morning with a (40-55%
chance). Ensembles seem to be handling this system well with the
upper level and mid level troughing. The one thing to keep an eye on
will be the winds and dewpoints. Until winds become southerly and we
get some moisture advection the dewpoints depressions look to be
pretty large, which may whittle away any incoming snow (virga
likely until the low level moisten up). There is a signal that
this will happen overtime. Snow will be the predominate precip
type with temperature well below freezing.
The next potential for some precipitation is at the end of the
extended for Friday. There is a lot of uncertainty with this next
round which you can easily see in the deterministic guidance (GFS =
shortwave, Euro = ridge, CAN = trough to east). This pattern
continues when you look at the ensembles and is reflected well in
the split among the cluster analysis. The EOF 1 and 2 show this well
for days 6 and 7 with one having a monopole and the other a dipole
distribution. All to say significant uncertainty in location,
timing and strength in the 500 mb flow.
Beside this the only other item worth mentioning for the extended is
the period of cold temperatures Monday night through Tuesday
night. Monday night looks to be the coldest of the two nights with
temperatures in the single digits, but Tuesday night brings temps
in the teens. Thankfully this period of chilly temps seems short
lived as temperatures should rise back to normal for Wednesday
afternoon. near normal temps continue through the rest of the
extended (highs in the 40s and overnight lows in the low 30s).
Patterson
&&
.AVIATION...
Issued 1145 PM CDT Fri Mar 13 2026
VFR to MVFR conditions are expected through the period. VFR
ceilings and visibilites will persist through Saturday afternoon.
A scattered to broken mid level cloud deck that is overhead will
be moving east southeast out of the area tonight with additional
mid to high level clouds moving in from the west-northwest through
Saturday. A few terminals may have a period of clear skies as
these two cloud decks move through Wisconsin. The clouds will
increase to a broken to overcast deck throughout the day Saturday.
Heading into Saturday evening/night MVFR clouds around 1-3 kft
will start to move in with incoming snow and mixed precipitation.
Central and southwestern Wisconsin will have the best potential
for those MVFR ceilings at the end of the period. Ceilings
should continue to fall heading into Sunday night with MVFR to
IFR conditions expected with both low ceilings and visibilities.
These lower conditions should expand across southern Wisconsin
Sunday.
Gusty northwest winds this evening are slowly diminishing. Winds
will become light and variable early Saturday morning as a quick
moving high pressure system passes through northern Wisconsin.
East to southeast winds will set up behind the exiting high
Saturday late morning. By Saturday afternoon east southeast winds
will increase becoming breezy again. Winds will remain strong
ahead of an incoming low pressure system through Saturday night.
As the low pressure system tracks overhead there will be a quickly
changing wind direction Sunday afternoon and brief lull in the
gusts. Gusty northwest winds resume behind the low Sunday night.
Patterson
&&
.MARINE...
Issued 1145 PM CDT Fri Mar 13 2026
Strong low pressure is pushing into southern Ontario tonight.
Strong northwest winds continue this evening. Gusts have largely
weakened below gale force as higher pressure nudges in from the
west. Gales Warning will expire in the next hour.
East northeast winds will steadily increase Saturday night
through Sunday, as a second low pressure system forms in the
central Great Plains. The low will progress over far southern
Lake Michigan Sunday night as it deepens, 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, across all of the open waters and
nearshore waters late Saturday night through Monday night at
various directions as the low progresses through the region.
Gale Watches have been issued for much of Lake Michigan from
Saturday night through Monday night. Where gale watches are not
in effect is where a Storm Watch is in effect. The potential for
storm force gusts is primarily for Sunday night and Monday for
the northern two thirds of the lake. This is largely transitory
but the potential for storm force gusts is fairly high at least
at some point during this timeframe.
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
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 late Sunday night and
linger into Tuesday behind the departing low, with areas of
moderate to heavy freezing spray possible. Thus we have issued a
Heavy Freezing Spray Watch as well.
Kuroski
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...Winter Weather Advisory...WIZ046-WIZ047-WIZ051-WIZ052-WIZ056-
WIZ057-WIZ058-WIZ059-WIZ060...7 PM Saturday to 10 AM
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.
LM...Gale Warning...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-
LMZ565-LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ777-LMZ779-
LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878 until 1 AM
Saturday.
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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