NWS-Milwaukee/Sullivan Forecast Discussion

						FXUS63 KMKX 082048
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
248 PM CST Thu Jan 8 2026

.KEY MESSAGES...

- Rain is beginning to spread from the southwest to the
  northeast through the afternoon/evening. Heaviest rainfall
  will be between 3 PM to 9 PM tonight.

- The mild temps and rain today into Friday will allow for ice
  to break up along rivers, with potential for ice jams.
  Isolated minor river flooding and ponding of water in poor
  drainage areas will also be possible as the rain falls on
  partially frozen soil. A Flood Watch in effect for northwestern
  counties of the CWA.

- Could see a few thunderstorms for southeastern WI this
  evening and cannot rule out some small hail or gustier winds
  with any taller thunderstorms.

- Downward trend in snowfall for Saturday given a weaker system,
  but still a potential for some minor accumulations across our
  region. Uncertainty remains quite high at this time.

&&

.SHORT TERM...
Issued 245 PM CST Thu Jan 8 2026

Tonight and Friday:

Forecast remains on track as low pressure centered over the
MO/IA border lifts northeastward through the evening bringing a
bout of moderate to heavy rain to southern WI. Will see rain
start to creep in from southwest WI through 21z and spread
northeastward through the evening. Overall there is ample
dynamics and synoptic forcing with this system given the
coupling of the upper-level jets left exit and right entrance
regions paired with mid-level dCVA, sub- 1000mb surface low and
accompanying 700mb frontogenesis band, and 850mb WAA all
aligning with unseasonable high PWATs around or exceeding 1".
The highest rain rates and heaviest rainfall looks to occur
between onset and 03z. The 12z CAMs have shifted the band of
heaviest rain a bit more northwest of HWY-151 where there is the
highest probability (>70%) of seeing over half an inch and even
pockets of 1 inch or more across the Wisconsin River Valley
(40- 50%).

Main impacts with the rain this afternoon and evening will be
the moderate to heavy rainfall falling over frozen grounds that
may result in localized ponding/minor flooding for low-lying
areas and roadways. Additionally the well above average temps in
the 40s and even 50s paired with the rainfall will also
contribute to ice on area rivers breaking up and potentially
jamming under bridges or around river bends resulting in minor
river flooding. Thus paired with 12z HREF LPMM exceeding 1 inch
will continue the Flood Watch for northwestern counties of the
CWA.

Meanwhile areas southeast of HWY-151 where the center of the
low is progged to track is looking to see lighter rainfall
amounts this afternoon and evening generally less than half an
inch. However, given the latest low track a smidge further north
as well, 12z models are pinging a bit more instability (250-500
J/kg) building into southeastern WI through the early evening
and cannot rule out seeing a few isolated thunderstorms. Main
area for this isolated activity will be in the warm sector of
the low where the favorable upper-level dynamics and nose of
50-60kt LLJ align with the higher moisture and instability into
the evening. Thus localized pockets of heavier rain associated
with any of this convective activity will be possible. Also
cannot completely rule out some small hail or even some of the
gustier winds mixing down to the surface this evening with the
elevated convection. So will need to keep an eye on how things
evolve over the next few hours.

The heaviest rain looks to wrap up later this evening over
southern WI as the low lifts northeast across the Straits of
Mackinac, but light rain looks to linger on the backside through
early Friday morning. Given a push of CAA also cannot rule out
see rain transition to a wintry mix through early Friday morning
before the drier airmass settles in. Otherwise, conditions will
be drying out through the morning/afternoon as weak high
pressure builds across the region with cooler, drier air, but
still looking at low 40s highs.

Wagner

&&

.LONG TERM...
Issued 245 PM CST Thu Jan 8 2026

Friday night through Thursday:

The models have changed in unison with a weaker scenario and less
expected snowfall for Sat-Sat nt. It is certainly possible the
models could return to greater cyclogenesis but for now going
with less QPF and snow.

A shortwave trough will be located over the srn Great Plains at 00Z
Sat while a stronger upper wave will be over srn Manitoba
extending swd through the Dakotas into NE. At the surface, weak
low pressure will track from the lower MS River Valley to the srn Ohio
River Valley by 12Z Sat, with an inverted trough extending to the
nw into WI and wrn Lake Superior where another weak low will be
situated near the approaching upper wave.

For Sat, the srn shortwave trough will track into srn WI ahead of
the amplifying wave from the nw. PVA and 850-700 mb frontogenesis
should result in widespread (70-80% ern WI and 40-60% south
central WI) light to moderate snowfall at least over ern WI.
Subsidence behind the initial shortwave trough and a dry slot
will slow the snowfall for the early afternoon, but wly winds and
cold advection will be increasing through the afternoon with
steepening low level lapse rates and the potential for snow
showers. Another vorticity maximum will arrive later in the
afternoon and evening, providing additional support for snow
showers. For Sat nt, a sfc trough and warm front, extending from
the consolidated low over srn Ontario and the lower Great Lakes,
will shift swd through srn WI, while the closed 500 mb low passes.
This will likely bring a return of a steadier light snow. QPF
values are ranging from 0.05 inches west of Madison to 0.20 inches
for far ern WI with 1-3 inches of snow possible. The light snow
will end Sun AM but brisk nwly winds and cold advection will
continue through the day.

At least a couple waves of low pressure tracking to the north,
and several shortwave troughs in nwly flow aloft are then expected
from Mon-Wed. The end result will be a deepening upper trough
over the central USA by Wed. Swly winds and warm advection will
initially occur with relatively mild temps returning for Mon-Tue
then a stronger cold front for Tue nt-Wed. 20-40 percent chances
for rain and snow trending to all snow are forecast during this
time. Polar air will be back in place for Wed-Thu.

Gehring

&&

.AVIATION...
Issued 245 PM CST Thu Jan 8 2026

VFR conditions will gradually diminish through the afternoon as
the low pressure lifts into southern WI later through the
evening. Seeing a mix of MVFR and IFR ceilings and visibility
upstream accompanying the rain shield. Will see even lower
ceilings and visibilities with the heaviest rainfall, which
continues to look to occur northwest of HWY-151 through 03z.
Meanwhile areas southeast may see less overall rain as the dry
slot air moves in with the low, but there is a growing potential
for a few thunderstorms to develop into the evening for
southeastern terminals. If any thunderstorms develop and move
over a terminal, expect to see a brief drop in visibility and
ceilings. Expect the bulk of the heavier rain to move out of
the area by 06z with fog and drizzle persisting into early
Friday morning keeping those lower flight conditions around
longer. Still looks to be another swath of light showers and
even some wintry mix swings through by daybreak on the backside
of the departing low. Will see conditions improve through Friday
morning as high pressure builds in and a return of VFR
conditions.

Otherwise will see winds vary counter-clockwise across southern
WI as the low lifts through this evening with gustiest
southerly flow for southeastern WI. Then winds shift more west-
northwesterly behind the departing low overnight remaining gusty
into early Friday morning before gradually easing through
Friday afternoon.

Wagner

&&

.MARINE...
Issued 245 PM CST Thu Jan 8 2026

Southerly winds across Lake Michigan will gradually turn as low
pressure lifts from the MO/IA border into the northern half of
Lake Michigan overnight. Will see gusty south to southeasterly
winds over the southern half of Lake Michigan this evening as
the low approaches then veering to southwest overnight. Lighter
more easterly winds are expected for the north half of the lake,
but gradually weaken as the low pushes northeastward into
Friday morning. Behind the low, expect more north to
northwesterly winds pick up into Friday morning. Given the tight
pressure gradient on the backside of this departing system,
will see gusts of 30 knots and a few brief gale force gusts
through late Friday morning, especially along the eastern
lakeshore. Winds will gradually weaken Friday afternoon as high
pressure works its way across the Lake Michigan through Friday
night. Then looking at two areas of low pressure one coming up
from the southern Plains and another digging down across the
Upper Midwest merging over the Great Lakes for Saturday. Expect
west-northwesterly winds over Lake Michigan to increase on the
backside of this deepening low pressure as it lift into eastern
Ontario/Quebec. Will be a potential for gales across the open
water, but still some uncertainty on the overall strength of
the low pressure. Then another high pressure will build across
the region for Sunday before another system traverses the
region early next week.

Wagner

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...Flood Watch...WIZ046-WIZ047-WIZ056-WIZ057 until midnight
     Friday.

LM...Small Craft Advisory...LMZ643-LMZ644-LMZ645-LMZ646...6 PM
     Thursday to 8 AM Friday.

&&

$$

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