New Berlin, Wisconsin 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

800
FXUS63 KMKX 260628
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
128 AM CDT Sun Jul 26 2026

.KEY MESSAGES...


- Hot and humid conditions Sunday and Monday are likely. A Heat
  Advisory is in effect from noon to 9 PM CDT Sunday. Additional
  Heat Advisories may be needed Monday.

- A line of storms may impact far southwestern Wisconsin early
  Sunday morning.

- Isolated to scattered storms may develop Sunday afternoon and
  evening. Large hail and damaging winds would be possible with
  this activity. Sunday night, a line of storms with damaging
  winds and hail is expected to develop and progress
  southeastward.

- Monday, a cold front will bring final chances for storms to
  southern Wisconsin. All hazards are possible with this
  activity, but confidence in exact timing and placement remains
  dependent on Sunday night storms.

&&

.SHORT TERM...
Issued 128 AM CDT Sun Jul 26 2026

Today through Monday:

Currently keeping an eye on Minnesota as convection has
blossomed over the central portions of the state. Rapid refresh
CAMs suggest a dying MCS may clip the southwestern portions of
our CWA near daybreak on Sunday. If this were to occur, gusty
winds and hail would be the main hazards.

Subsidence is then expected following this morning convection
and skies should clear. Dew points are expected to rise into
the mid 70s tomorrow, amid daytime highs in the low 90s. This
will lead to heat indices in the 100 to 103 range over much of
the area tomorrow. The weak pressure gradient will promote a
lake breeze which may keep the immediate lakeshore cooler for
tomorrow. A Heat Advisory has been issued for much of southern
WI from Noon to 9PM today.

It looks increasing likely that storms will hold off until
either the evening or overnight hours tonight into Monday. One
constant among the CAMs is that an MCS will fire closer to the
500mb trough over northern WI/UP of Michigan and propagate
south-southeast into central WI. However, CAMs vary regarding
timing/positioning, as some have this complex further east over
Lake Michigan, while others have this MCS tracking south into
our CWA around midnight. In either scenario, it does look like
convection may linger through the night following the main MCS
as the low level jet triggers new storms along an outflow
boundary. With whatever MCS gets going, gusty winds and hail
will be the main threats, as DCAPE will be near 1100 J/kg, mid
level lapse rates will be near 8 C/km, and effective bulk shear
will approach 70 knots. A conditional boundary interaction with
the remnants of the lake breeze may lead to a sneaky QLCS
tornado threat on an isolated basis, provided the boundary
doesn`t wash out quickly after dark.

Weak convection then may linger into Monday with some potential
for storms to reinvigorate ahead of a cold front with daytime
heating late Monday. Given the potential for convection and
cloud cover to linger during the day, have held off on hoisting
a Heat Advisory for Monday at this time until details about
Monday`s convection become clearer.

CMiller

&&

.LONG TERM...
Issued 105 AM CDT Sun Jul 26 2026

Tuesday through Saturday:

Mid week looks quiet as a sfc high pressure ridge builds into
the upper Great Lakes region. Northeast sfc flow Tuesday and
Wednesday should promote more manageable dew points in the low
60s and daytime highs in the low to mid 80s. Precip chances then
return late week as a warm front lifts northward into the
region and humidity mildly increases.

CMiller

&&

.AVIATION...
Issued 1237 AM CDT Sun Jul 26 2026

Expect a continuing mix of marginal MVFR and VFR ceilings
overnight with chances for fog near daybreak from KMSN on
westward toward the MS valley. Winds will be light and
southwesterly. Expect breaks in the MVFR and VFR ceilings
tomorrow morning and for broad VFR conditions to take hold by
Sunday afternoon. Some isolated to scattered thunderstorm
activity is possible on a conditional basis Sunday afternoon,
but forecast model agreement is poor regarding coverage and
when/where/if storms will form.

CMiller

&&

.MARINE...
Issued 1237 AM CDT Sun Jul 26 2026

No major changes to the going forecast

A weak low pressure trough will stall along the Wisconsin-
Upper Michigan border this evening. It will remain over
Wisconsin and Lake Michigan through most of Monday which will
result in increasing thunderstorm chances with severe storms
possible. Very warm, moist and unstable air flowing over the
relatively cool waters may cause patchy dense fog over the lake
through Monday as well.

Northerly winds will develop Monday night through Wednesday as
high pressure builds over the Upper Great Lakes and the front
pushes southward. A few gale force gusts are possible Tuesday
afternoon. Look for southerly winds and more unsettled weather
to resume Thursday into next weekend.


CMiller

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...Heat Advisory...WIZ046-WIZ047-WIZ051-WIZ056-WIZ057-WIZ058-
     WIZ059-WIZ062-WIZ063-WIZ064-WIZ065-WIZ066-WIZ067-WIZ068-
     WIZ069-WIZ070-WIZ071-WIZ072...noon Sunday to 9 PM Sunday.

LM...None.
&&

$$

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