NWS-Milwaukee/Sullivan Forecast Discussion

						FXUS63 KMKX 060026 AAA
AFDMKX

Area Forecast Discussion...UPDATED
National Weather Service Milwaukee/Sullivan WI
626 PM CST Thu Mar 5 2026

.KEY MESSAGES...

- Dense Fog Advisory until 6 AM CST Friday for Lakeshore
  Counties. The dense fog may spread north and west tonight as
  winds remain light and low level moisture increases.

- Moderate to briefly heavy rainfall rates are possible Friday
  into Friday night, with embedded thunderstorms expected.
  Strong to potentially severe storms are expected Friday
  afternoon into Friday night. All hazards will be possible at
  times from Friday morning through Friday night.

- Rain with perhaps a few embedded thunderstorms Tuesday into
  Tuesday night, with snow developing Tuesday night into
  Wednesday.

- Very mild Friday and again Monday and Tuesday.

&&

.UPDATE...
Issued 625 PM CST Thu Mar 5 2026

The primary concern through this evening and overnight remains
the fog potential. Fog (dense at times) will likely persist for
lakeshore counties through the overnight hours, with a
progression westward possible. A blend of the latest mesoscale
models suggests that dense fog may spread westward a row or two
of counties mid to late evening, then persist there through the
rest of tonight. Will continue to monitor conditions and expand
the Dense Fog Advisory if needed.

DDV

&&

.SHORT TERM...
Issued 1241 PM CST Thu Mar 5 2026

Tonight through Saturday:

Light winds, overcast skies and fog is the name of the game for the
afternoon through tonight for southern Wisconsin. Low level moisture
is high, light rain fell overnight further adding to that moisture
and winds are light, the perfect recipe for lingering fog and
stratus. The fog will slowly rise bringing visibilities above 1/4
mile but many areas may not see it completely clear. Visibilites are
likely to remain around 2-4 SM miles through the evening. Under this
pattern, widespread dense fog will likely (60% chance or higher)
return again tonight. Counties along and south of I-94 and along
Lake Michigan are the most likely to see dense fog return tonight.
Those counties away from the lake and north of 94 wont get off scot-
free but its more of a question on how dense it will be and how
widespread. As winds turn southerly tonight and warmer air moves in
the likelihood that all of southern Wisconsin sees dense fog
grows.

Friday will be a fun peak at a high shear low CAPE severe day.
Kicking things off early with a push of WAA Friday morning,
widespread rain and thunderstorms will move into the state (POPs 80%
or higher). Rain and storms will move in from the southwest to the
northeast during the morning. Shear in the predawn hours will be
around 200 m^2/s^2 and quickly increase to around 400 m^2/s^2 (or
higher in some areas). The primary threat in the morning hours will
be predominately hail, lightning and brief heavy rain.
Dewpoints will still be a bit low as the breezy south winds kick
in and storms are likely to be mostly elevated. By far the
better environment for this early morning convection will be to
our south, but in these high shear environments any CAPE we get
will only enhance storms further. The primary area under the
gun for stronger to severe storms in the morning hours will be
far southern and southwestern Wisconsin.

Heading into the afternoon hours this is where storms become more
scattered to isolated. For some this may be no storms again until
the evening while other may wonder if there was ever a break in the
rain/storms. The storm mode will slowly shift to supercellular
during this time as shear remains high, dewpoints are on the
rise with steady WAA and the sfc low starts to move into the
state. This expands the threat area to all of southern Wisconsin
overtime. The immediate lakeshore areas will be the last ones
to see this flip over strong/severe storm chances as winds will
need to shift to southerly or southwest. Any easterly component
will undercut storm development until the winds shifts away from
Lake Michigan. Once the sfc low and warm front start to move
into the state mid to late afternoon, thats when storm coverage
increases again and hazards increase. With any of the scattered
convection that develop in the afternoon all hazards will be on
the table including strong winds, hail and tornadoes. Storms
that latch onto the warm front will be be the primary concern.
With the strong shear, these storms are likely to be low topped
so hail will become a secondary concern to winds and tornadoes.
Again these storms are likely to be more isolated to scattered
during this time frame. Brief heavy rain is possible.

Heading into this evening into the overnight hours the LLJ starts to
kick in and Wisconsin will be in the warm sector. With the warm
front continuing to push onward into northern Michigan, we will have
high shear, low CAPE and a cold front barreling down on the CWA. All
hazards will remain on the table as a line of thunderstorms develops
along the cold front. This will make storms widespread again along a
southwest to northeast line along the front. Right now the timing of
the cold front has it moving in during the late evening hours around
8 to 10 PM in our west then progressing east with time. QLCS
tornadoes (quick hitting smaller tors) will be mostly likely along
the front, but can't rule out some slightly stronger or longer
lived ones. Any segment of the line that starts to bow out will
pose a high wind threat. Hail by far will be the smaller threat
by this time in the day. Immediate lakeshore areas will again be
battling the more stable air, but southwest winds should be
strong enough to combat that cooler lake air. The cold front is
not expected to clear the state until early Saturday morning
around 3 to 5 AM.

With a frozen ground and chances for heavy rain all day there
will be some nuisance ponding occuring as well. All rain is
likely to be run off as the frozen ground fails to absorb it.
River, creeks and lakes have room to take in the extra water
will little concerns, but areas where the rain would normally
soak in could have some ponding at times. Given all of this with
multiple rounds of severe weather, this is a great time to
review any safety plans you have and make sure you stay up to
date with the forecast. Early season systems tend to catch
people off guard. Make sure you have multiple ways to receive
warnings especially options that will wake you up at night.

Once the cold front has cleared Saturday morning, there may be some
light rain lingering on the back side. These will be very light
showers and should exit to the east quickly. Lakeshore counties
could see these light showers linger into the early afternoon. High
pressure then builds in for some quiet after the storms.

Patterson

&&

.LONG TERM...
Issued 1241 PM CST Thu Mar 5 2026

Saturday Night through Thursday:

Clear skies with light winds and lows down to the lower 30s are
expected Saturday night due to high pressure briefly taking hold
as it expands from the Plains. The northern stream upper level jet
will set up across the southern Canadian provinces and a couple
waves along it will drive our weather for early next week.

Weak low pressure crossing Ontario on Sunday will drop the
associated cold front into northern WI by the afternoon. Southern
WI will get sunny skies and gusty southwest winds Sunday afternoon.
High temperatures Sunday will likely reach 60, and potentially 63
to 64 along the southeast lakeshore due to downsloping off the
Kettle Moraine.

The next low crossing Ontario and the associated cold front may or
may not dip into southern WI. The GFS and its ensembles maintain a
stronger surface low and a push of the colder air briefly into srn
WI, compared to the ECMWF. The only (minor) operational impacts
of where this front actually goes are our wind directions and our
high temps for Monday. The NBM model blend has highs in the upper
60s, which is right around the record high for Madison and
Milwaukee. The frontal placement will create a more definite
yes/no for breaking a record, especially for Milwaukee (possible
onshore wind direction).

Yet another low will cross the Northern Plains and northern WI
Tuesday. Ahead of it, expect our temps to remain mild, with over
a 40 percent chance of exceeding the record high of 67 at MSN. There
is a separate shortwave trough crossing the center of the country
that may try to phase with the northern system as it crosses the
Great Lakes. Rain chances increase over southern WI Tuesday
afternoon and evening along the front, with greater than 75% south
of a Port Washington to Janesville line. Slight chance of thunder
with this in far southeast WI, with better chances over IL and IN.

Cooler temperatures and dry weather will return Wed-Thu, but temps
will continue to be above normal.

&&

.AVIATION...
Issued 625 PM CST Thu Mar 5 2026

Low ceilings (mainly IFR and lower) are expected through
tonight, with fog also a concern under light east to southeast
winds. A blend of the latest mesoscale models suggests that
dense fog currently over the lakeshore counties may spread
westward a row or two of counties mid to late evening, then
persist across the eastern half of the forecast area through
the rest of tonight. Could see locally dense fog in the west as
well. Will continue to monitor conditions and update TAFs as
needed.

Attention then turns to the potential for showers and storms
tomorrow morning into tomorrow night. Widespread showers with
some embedded thunder are expected to move in from the southwest
early to mid morning, lasting into at least early afternoon as a
warm front lifts into the area. Fog will probably linger at
least toward the lake tomorrow morning as east/southwest winds
persist. Low clouds will hang around through the morning as
well. There should be some improvement in ceilings and
visibilities by later afternoon into the evening with the warm
front positioned north of the area and increasing southerly
winds expected.

There will likely be a lull in the shower/storm activity
mid/late afternoon into early evening, before the next round
ahead of the cold front arrives mid/late evening from the west.
This round could contain a few strong to severe thunderstorms,
with the activity expected to wind down west to east between
06Z and 09Z Fri night.

DDV

&&

.MARINE...
Issued 1241 PM CST Thu Mar 5 2026

East to northeast winds will continue through much of today, as
weak low pressure around 29.9 inches passes across the northern
Ohio River Valley. Rain and drizzle are possible across the
southern half of the lake into today, while marine dense fog with
visibilities of 1 nautical mile or less continues across the
southern third of the open waters today into tonight. Its
possible that fog could start to expand further north this
evening into tonight as southerly winds develop across the Lake.

Low pressure around 29.5 inches will develop in the central
Plains Thursday night, and track toward the Upper Mississippi
River Valley by Friday evening. This low will move near or just
north of Lake Michigan later Friday night into Saturday morning,
quickly moving into Quebec by Saturday evening.

As the low passes to the north, breezy southerly winds will
develop for Friday afternoon and night, then shifting west to
northwest on Saturday, with the passage of the cold front.
Widespread rain and embedded thunderstorms will accompany the
approaching and passing low Friday into Friday night. Breezy
southwest winds are then forecast for Sunday into Monday.

Patterson

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...Dense Fog Advisory...WIZ052-WIZ060-WIZ066-WIZ071-WIZ072 until
     6 AM Friday.

LM...Dense Fog Advisory...LMZ080-LMZ643-LMZ644-LMZ645-LMZ646-LMZ669-
     LMZ671-LMZ673-LMZ675-LMZ777-LMZ779-LMZ870-LMZ872-LMZ874-
     LMZ876-LMZ878 until 6 AM Friday.

&&

$$

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