NWS-Milwaukee/Sullivan Forecast Discussion
FXUS63 KMKX 141209
AFDMKX
Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
709 AM CDT Tue Apr 14 2026
.KEY MESSAGES...
- Significant severe weather event remains forecast this
afternoon & evening (peak intensity 3-10 PM). All severe
weather hazards, including very large hail greater than golf
ball size and tornadoes, are possible. Seek immediate shelter
if a warning is issued for your area later today.
- Additional severe storms possible Wednesday afternoon if a
front remains stalled across the area. If the front sets up
south of the area, severe potential will greatly decrease.
- Heavy rainfall could lead to additional periods of flooding
this afternoon into Wednesday. Additional Flood Watches are
possible.
- Additional windows for heavy rainfall, flooding, and severe
thunderstorms Friday into Saturday. All severe hazards will
be possible later Tuesday afternoon into the evening.
&&
.UPDATE...
Issued 710 AM CDT Tue Apr 14 2026
Quiet weather and sunny weather prevails through this morning,
which unfortunately bodes poorly for severe weather potential
later today. Expecting an abundance of sunshine to allow a warm
front to return back into the area by mid-day, which will be
further ushered northward by a broad area of low pressure over
northeast Iowa/southeastern Minnesota. Northward return of the
front, in addition to an abundance of sunshine, will allow for
ample instability to build back into the area by late afternoon.
Guidance suggests that rapid convective initiation will occur
by mid-late afternoon as falling surface pressures begin to
encroach upon an uncapping boundary layer. Extent of initiation
appears to be at least scattered in coverage, with more numerous
development possible if the lake breeze also gets active. Shear
profiles will be supportive for initially discrete/supercellular
development as storms form, with very unstable conditions aloft
being supportive for large to very large hail exceeding the size
of golf balls. Straight line wind threat & some tornado
potential will also accompany the discrete storm development,
although modest low level flow through mid-late afternoon (~2-6
PM) & shorter hodographs pose some uncertainty as to how
widespread any tornado potential will be through the beginning
phases of the event. How long a discrete mode will be able to
maintain will depend upon the extent of convective development,
with more widespread initiation making cell mergers & upscale
growth increasingly favored by early evening. In the event
initiation stays more scattered & storms remain well-separated
from one another, discrete modes will remain favored into early
evening.
A potentially concerning phase of the event then begins
near/after 6 PM, and will continue into at least the middle
portions of the evening hours (~9-10 PM). A southwesterly low
level jet will be steadily increasing to & through 40 kts during
this time period, which will act to enhance previously modest
low level hodograph curvature in advance of thunderstorms. This
will create an increasingly favorable environment for low level
rotation & potential tornadoes in storms. Have concerns for this
potential even if storms have upscaled into one or more
clusters, as low level thermodynamics and wind shear will be
plenty conducive for QLCS-type tornadoes. Additional wind and
hail potential will accompany the tornado threat. Storms then
look to push out over Lake Michigan between 11 PM and 2 AM.
Above set-up aside, the last trend to monitor will be the
evolution of the returning warm sector as it comes back toward
the area from Iowa & western Illinois this afternoon. Majority
of available guidance suggests that unstable air will make it
into the area uncontaminated, putting the entirety of the region
in line for storm development by late afternoon. If, however,
storms fire earlier in the day in the returning warm/moist air
mass over eastern Iowa & northwest Illinois, the northern
extent of severe potential could be curbed in our area. This
scenario is currently a strong minority in available guidance,
and is thus being treated as outlier for the time-being, but is
one to be aware of nonetheless.
Will be monitoring trends regarding all of the above very
closely through today. Given the potential for widespread severe
weather, have multiple ways of receiving warning information,
including methods that will be available in the event of power
outages. Move to shelter immediately if a warning is issued for
your area.
Quigley
&&
.SHORT TERM...
Issued 1220 AM CDT Tue Apr 14 2026
Tonight through Tuesday night:
A line of thunderstorms will roll through the forecast area over
the next few hours, as low pressure approaches along a stalled
frontal boundary. The main threat through 2-4 am will be
damaging winds, though an isolated tornado will be possible.
Given sustained instability overnight along with WSW 0-3 km
shear around 40 knots, any storm line segments that become more
north/south oriented could bow out increasing the wind threat
and also producing a QLCS tornado threat. The flooding concern
remains overnight as well, as the line of storms across the
northern forecast area slowly sags southward tonight, with some
back building currently evident over southeast MN and northeast
IA.
Storms may linger in the southeast forecast area towards around
daybreak, with dry weather then likely through the morning
hours. Attention then turns to another severe storm threat
during the afternoon and evening hours. The stalled frontal
boundary will be set up around the far northern forecast area in
the afternoon, as another weak surface low and shortwave
approach from the west. Plenty of instability is expected
across at least the south half of the forecast area, with
surface based CAPE of at least 3000 J/KG. Additionally, wind
profiles look more than sufficient for severe storms as a 45 kt
LLJ noses from the south by late afternoon. All severe hazards
will be possible as storms initialize between 3 and 6 pm, with a
decent chance for supercell development. Storms will likely
eventually organize into line or two, with the severe threat
leaning more towards wind and QLCS tornado at that point.
Locally heavy rainfall and flooding will be a concern as well,
especially if storms roll through the same areas that received
the heavier rainfall the last couple days. Adding to this
concern as that some of the latest models do show that a line of
storms may set up west to east across the southern half of the
forecast area tomorrow night, with some training possible.
DDV
&&
.LONG TERM...
Issued 1220 AM CDT Tue Apr 14 2026
Wednesday through Sunday:
It is still looking like the frontal boundary could remain far
enough north on Wednesday for another severe storm threat. This
will somewhat depend on what happens Tuesday/Tuesday night and
where the effective front ends up because of that round of
storms. Overall though, there is enough confidence to continue
to message a severe threat, with locally heavy rainfall also a
concern again.
Storms may linger Wednesday night into early Thursday, with a
break in activity then likely Thu afternoon into at least Friday
morning. Yet another round of storms is then possible Friday
evening into Saturday morning as a cold front finally pushes
through the region. The later timing of this front may somewhat
diminish the severe threat, due to the better interaction with
peak daytime heating Friday remaining to the west. Plenty of
time though for timing to change, so this period remains worth
keeping an eye on.
Much cooler conditions are expected to settle into the area this
weekend behind the departing low and cold front. Highs will
likely struggle to get out of the 40s by Sunday. It looks mainly
dry Sat afternoon through Sunday, though not out of the question
for a few snowflakes in the north Sat night as a shortwave rolls
through.
DDV
&&
.AVIATION...
Issued 710 AM CDT Tue Apr 14 2026
VFR flight categories continue through this morning, with strong
to severe storm development this afternoon. Reduced CIGs and VIS
readings will accompany the storms.
Quigley
&&
.MARINE...
Issued 1220 AM CDT Tue Apr 14 2026
Shower and thunderstorm activity is expected across lake
Michigan late into tonight as low pressure of 29.6 inches over
southeast Minnesota continues to head northeast. Winds will be
easterly north of a frontal boundary across roughly the northern
half of the lake, with southerly winds expected in the south.
Then expecting another a couple passing low pressure system to
develop in the Plains and track across Lake Michigan again on
Tuesday and Wednesday. Each system will bring a chance for
showers and thunderstorms through the middle of the week. Areas
of dense fog will likely occur at times due to a relatively mild
and humid airmass over the cold waters paired with lighter
winds.
DDV
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...Flood Watch...WIZ046-WIZ047-WIZ051-WIZ052-WIZ056-WIZ057-WIZ058-
WIZ059-WIZ060 until 7 AM Tuesday.
LM...Dense Fog Advisory...LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565-
LMZ567-LMZ643-LMZ644-LMZ645-LMZ646-LMZ669-LMZ671-LMZ673-
LMZ675-LMZ868-LMZ870-LMZ872-LMZ874-LMZ876 until 7 AM
Wednesday.
&&
$$
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