NWS-Milwaukee/Sullivan Forecast Discussion

						FXUS63 KMKX 171056
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
456 AM CST Sat Jan 17 2026

.KEY MESSAGES...

- A Winter Weather Advisory remains in effect until 9 AM CST
  this morning for the Highway 18 and Interstate 94 corridor
  area, for a narrow band of moderate to heavy snow. Snowfall
  rates of one half to one inch per hour are possible in this
  band. This band should shift slowly southward later today and
  exit to the southeast this evening. Snow covered and slippery
  roads are expected.

- Light snow is expected Sunday afternoon, exiting to the
  southeast Sunday night.

- Below normal temperatures are expected this weekend through
  the early part of next week. The coldest temperatures and wind
  chills are expected Sunday night through Tuesday. Cold Weather
  Advisory criteria (wind chills 20 degrees below zero) may be
  met or exceeded Sunday night into Monday morning.

- A Gale Watch is in effect for Lake Michigan later Sunday
  night into Monday. Building waves and cold temperatures will
  bring freezing spray Sunday night into Tuesday, with some
  heavy freezing spray possible.

&&

.SHORT TERM...
Issued 456 AM CST Sat Jan 17 2026

Today through Sunday night:

The narrow band moderate to heavy snow continues to meander and
morph slowly over the Highway 18 and Interstate 94 corridor
early this morning. The heaviest snow is currently over
northern Milwaukee and northeast Waukesha Counties, with mainly
light snow elsewhere in the Winter Weather Advisory area. Snow
rates of one half to one inch per hour are expected with this
narrow band, with rates of one quarter inch per hour or less
elsewhere. 1 to 2 inches of additional snow accumulation is
forecast for the advisory area at this time.

This band has been driven by 850 mb to 700 mb frontogenesis
response from a slowly moving trough in this layer. The narrow
snow band has been essentially quasi-stationary this evening
into the overnight hours, though it has recently been reduced to
the current affected area. Forecast soundings are also showing
a deep and saturated dendrite snow growth zone from overnight
lingering into today. This snow band has been quite difficult to
forecast, and there is some uncertainty with what may occur
with this band into today.

CAMs and other models suggest that this band may linger across
the advisory area into this morning, before slowly shifting
southward this afternoon and southeast of the area by early to
middle evening. Continued monitoring will be needed to see if
this narrow heavy snow band will redevelop or will become more
light snow into this morning, and if the current advisory needs
any extension in time and/or expansion to the south.

Another Arctic cold front shifting southeast through the region
this evening would help shift this snow out of the area. Thus,
have kept light snow in the forecast with high probabilities (80
to 100 percent) today before exiting southeast by middle
evening. CAMs have some possible convective snow showers
shifting southeast but missing northeast parts of the forecast
area this evening. This may need some watching, as the snow
squall parameter is over one to the northeast of the area.
Again, most of this activity should remain to the northeast.

Another period of light snow is expected Sunday afternoon,
exiting to the southeast Sunday night, with warm air advection
and deep moisture combining with a cold frontal passage and some
differential CVA passing through. Forecast soundings show steep
low level lapse rates with saturation in the dendrite snow
growth zone during this period.

For now, have another period of high probabilities for light
snow (70 to 90 percent) Sunday afternoon. Snow rates should
generally be around one quarter inch per hour or less, with
light QPF and high snow to liquid ratios allowing for snow
accumulations of 1 to perhaps up to 2 inches possible.

Cold lows in the single digits above zero are expected tonight,
with wind chills in the single digits below zero. Wind chills
should dip to or below 20 below zero Sunday night into Monday
morning, and a Cold Weather Advisory may be needed for the
entire area. Lows Sunday night should drop below zero for most
of the area with the fresh snow cover.

Wood

&&

.LONG TERM...
Issued 456 AM CST Sat Jan 17 2026

Monday through Friday:

Bitterly cold conditions will continue through the day Monday,
with temperatures struggling to get much above zero.
Additionally, winds gusting 25 to 30 MPH will result in the wind
chills of 20 below to 25 below zero early morning, only
improving to 10 below to 20 below zero by the afternoon. Though
below zero temps are expected Monday night, winds will be
lighter as high pressure slides by to the southwest, resulting
in wind chills remaining in the 10 below to 20 below zero range.

Dry weather is likely Monday into Tuesday, with a shortwave
possibly brining snow chances back to the area Tuesday night
into Wednesday. Temperatures will be a little milder mid-week,
though likely remaining below normal. Colder conditions are then
expected to return late week into the weekend, along with light
snow chances.

DDV

&&

.AVIATION...
Issued 456 AM CST Sat Jan 17 2026

The narrow band moderate to heavy snow continues to meander and
morph slowly over the Highway 18 and Interstate 94 corridor
early this morning. The heaviest snow is currently over
northern Milwaukee and northeast Waukesha Counties, with mainly
light snow elsewhere in this area. Snow rates of one half to
one inch per hour are expected with this narrow band, with rates
of one quarter inch per hour or less elsewhere. 1 to 2 inches
of additional snow accumulation is forecast for the Madison,
Waukesha and Milwaukee terminals.

This snow band has been quite difficult to forecast, and there
is some uncertainty with what may occur with this band into
today. It may linger this morning, before slowly shifting
southward this afternoon and southeast of the area by early to
middle evening. Continued monitoring will be needed to see if
this narrow heavy snow band will redevelop or will become more
light snow into this morning.

Ceilings have been varying widely between VFR and around 1000
feet AGL, and should generally become 1000 to 2000 feet AGL
today into tonight, before rising above 3000 feet AGL later
tonight. Visibility has also varied widely, from 6 miles or more
in light snow or snow free areas to 1/2 to 3/4 mile in the
heavier snow bands. A general 2 to 5 mile visibility in light
snow is anticipated into today, before improving tonight as the
snow exits the area. Locally lower values may occur with heavier
snow bands. Gusty west winds are generally expected today into
tonight.

Some snow showers shifting southeast should miss the Sheboygan
terminals this evening, but may need some watching.

Wood

&&

.MARINE...
Issued 456 AM CST Sat Jan 17 2026

Low pressure around 29.3 inches will move into eastern Ontario
today. Gusty west winds are expected over southern portions of
the lake, with lighter winds to the north. Winds should become
more northwest tonight, as a cold front shifts southeast across
the lake.

A Small Craft Advisory has been extended through today south of
Port Washington, for gusty west winds.

Another low pressure system around 29.7 inches will track from
northwest Minnesota into Lake Superior Sunday afternoon and
evening. Winds will turn to southwest to west and increase ahead
of this system. A few gusts may approach gale force Sunday
afternoon and evening.

A cold front will move across the lake late Sunday evening,
causing winds to become west to northwest and strengthen. High
pressure around 30.5 inches will move into the central Plains
Monday, helping sustain the strong winds.

Gales are likely later Sunday night into Monday, with a Gale
Watch in effect for all of Lake Michigan. Building waves and
cold air moving into the region will bring a period of freezing
spray Sunday night into Tuesday. Some heavy freezing spray is
possible during this period.

The Gale Watch is in effect for the nearshore waters of Lake
Michigan as well later Sunday night into Monday morning. A Small
Craft Advisory will be needed Sunday afternoon into Sunday
evening, with another Monday into Monday evening, for gusty
winds. Freezing spray may occur.

Winds will weaken and shift west to southwest Monday night into
Tuesday night, ahead of another low pressure system around 29.9
inches shifting from Alberta towards the Great Lakes.

Wood

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...Winter Weather Advisory...WIZ056-WIZ057-WIZ058-WIZ059-WIZ060-
     WIZ062-WIZ063-WIZ064-WIZ065-WIZ066 until 9 AM Saturday.

LM...Gale Watch...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565-
     LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ777-LMZ779-LMZ868-
     LMZ870-LMZ872-LMZ874-LMZ876-LMZ878...midnight Monday to 6
     PM Monday.

     Gale Watch...LMZ643-LMZ644-LMZ645-LMZ646...midnight Monday to
     noon Monday.

     Small Craft Advisory...LMZ644-LMZ645-LMZ646 until 6 PM
     Saturday.

&&

$$

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