898
FXUS63 KMKX 080821
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
321 AM CDT Tue Jul 8 2025

.KEY MESSAGES...

- Periods of showers and thunderstorms anticipated this morning into
this evening, though an all-day washout is not expected.

- Warm & largely dry conditions expected Wednesday through Thursday.

- Heat and humidity ramp up Friday into Saturday, accompanied by
periods of showers and thunderstorms.

- Drier and more comfortable conditions forecast Sunday into the
  beginning of next week.

&&

.SHORT TERM...
Issued 323 AM CDT Tue Jul 8 2025

Today and Tonight:

Synopsis/Mesoanalysis: Early morning surface charts show an area of
low pressure centered across the Minnesota Boundary Waters. The
surface low is positioned beneath an upper trough axis, which
extends from southwestern Ontario into the Missouri River Valley. A
cold front extends from the surface low into northern South Dakota.
A diffuse warm front is also attached to the low, and has been
analyzed along an approximate St. Cloud - Rochester - Dubuque axis.
Apparent in VWPs from DVN and MKX, weak warm advection is ongoing
within the 1000-925 mb layer along & northeast of the warm front,
providing sufficient lift for the scattered showers currently
ongoing across south-central and southeast Wisconsin. The
aforementioned upper trough & warm front will advance east into the
western Great Lakes today, providing support for additional periods
of showers and thunderstorms across southern Wisconsin. The Boundary
Waters low will advance east into Lower Michigan tonight, dragging
its affiliated cold front across the area in the process. Additional
scattered showers and thundershowers will be possible along the
front tonight, gradually becoming confined to southeast and south-
central Wisconsin after midnight. Organized severe weather is not
expected in any of today/tonight`s precip, though storms could
produce brief gusty winds, heavy downpours, and cloud to ground
lightning. Keep an eye on the sky if planning to be outdoors today
into this evening, and move indoors if a storm approaches your area.

Rest Of Overnight: With winds having decoupled, localized areas of
patchy fog are possible in the Wisconsin River Valley over the next
couple hours. Anticipate that conditions will start to improve
closer to daybreak, when winds will begin to pick up ahead of
approaching low pressure & the sun starts to rise. Further east,
widely scattered showers and thundershowers will continue within a
weak area of 1000-925 mb isentropic ascent. Apart from a brief heavy
downpour---MSN recorded 0.20 inches of rain in thundershower between
2:20 and 2:35 AM---and a clap of thunder, don`t anticipate any
appreciable impacts in this activity.

Today: Daytime heating and broad synoptic ascent from the
encroaching trough will support scattered shower/storm development
from late morning through the afternoon. Expect that activity will
be overall benign, though increasing southwest flow aloft will
support effective shear values in the 15-25 kt range by early
afternoon. Combined with deep boundary layers progged in forecast
soundings, could thus a see a few isolated storms that produce brief
gusty winds to ~30-45 MPH. Anticipate hazards to otherwise remain
confined to cloud to ground lightning and brief heavy downpours.
Despite the largely garden variety nature to today`s showers &
storms, those with outdoor plans should keep tabs on the radar &
move indoors if a storm approaches.

Tonight: Shower and thundershower chances will continue along a
passing cold front. Given current frontal timing progs, expect that
precip will end near/just after midnight north of US-151 & hang on
to near sunrise over far south-central and southeastern Wisconsin.
With the low levels stabilizing post-sunset, don`t anticipate any
brief gusty winds in tonight`s activity, with a few claps of
thunder and brief heavy downpours being the primary impacts.

Quigley

&&

.LONG TERM...
Issued 323 AM CDT Tue Jul 8 2025

Wednesday through Monday:

Mid-level trough axis continues to slide east for Wednesday, but the
western side may linger around the Lake Michigan through the
morning. Model still hint at the backside of the surface low to
linger around the area as well, thus cannot rule out a stray shower
or two through Wednesday. However, drier airmass, northerly winds
and broad surface pressure building into the Lake Superior region
should lend itself to a predominately dry forecast. The upper-level
ridge continues to build across the Canadian PLains into Ontario for
Thursday, however, mid-range models have come into better agreement
of a mid-level shortwave trough potentially under-cutting the area
of subsidence and may be enough for another chance at some stray
shower activity. Midweek temps will be near normal with highs in the
lower 80s and overnight lows in the 60s, but Thursday is looking a
few degrees warmer given the return of southerly flow.

Friday into Saturday looks to the next active period with increased
shower and thunderstorm chances as the upper-level ridge pushes east
as a pair of troughs digs across the Plains and into the Upper
Midwest. This pattern looks to establish southern WI in the warm
sector of the end of the week system, which paired with the upper-
level forcing may be conducive for convective development later on
Friday. Will see southerly flow advect warmer temps and dewpoints
with model progging PWAT values trending above 1.5 inches and even
exceeding 2.0 inches. Instability will also increase for Friday
afternoon with LREF members generally agreeing on MUCAPE to exceed
1000-1500 J/kg. On the flip side, long range models do vary in the
location of the first of the mid-level shortwave trough and surface
low feature and the timing of it.

So while there is higher confidence to see thunderstorms with this
round of activity, questions remain on exact timing, strength, and
areas with the best chances. Overall deep layer shear looks fairly
meager (<35kt), so while stronger storms cannot be ruled out
especially if the surface low track further north, chances remain on
the lower side at this time. The first wave looks to lift out of the
area overnight, but the second upper- level trough is progged to
quickly follow right behind it for Saturday. Thus additional shower
and storms will be possible into the start of weekend. A bit more
uncertainty as we head toward the later half of the weekend with the
backside of the trough lingering before zonal to slight ridge
returns for the start of next week.

Wagner

&&

.AVIATION...
Issued 323 AM CDT Tue Jul 8 2025

Mostly VFR conditions prevail across southern Wisconsin early this
morning. Isolated -SHRA and -TSRA are lingering over south-central
and southeastern Wisconsin, with recent obs from Madison showing
brief VIS and CIG reductions. Given the widely scattered nature to
precip, have accounted for ongoing trends with PROB30 groups at all
fields through sunrise. Will continue to monitor trends over the
next few hours and insert prevailing mentions if conditions warrant.
Additional scattered -SHRA and -TSRA are anticipated today into this
evening as an upper disturbance crosses southern Wisconsin. Similar
to the ongoing activity, low forecast confidence in the precise
locations of storm development has precluded any prevailing mentions
in the 06/09Z updates, with potential being covered by PROB30
groups. Will plan to insert prevailing mentions based on radar
trends throughout the day. Brief VIS and CIG reductions will
accompany any -TSRA or -SHRA that impact terminals. Anticipate
precipitation to gradually taper from northwest to southeast
tonight.

Quigley

&&

.MARINE...
Issued 323 AM CDT Tue Jul 8 2025

1020 mb high pressure is centered along the Ontario-Quebec border
early this morning, encouraging continued light and variable winds
across the open waters. Winds will shift out of the southeast today
as 1014 mb low pressure moves east along the Wisconsin-Upper
Michigan border. The low will advance into Lower Michigan tonight,
dragging a cold front across Lake Michigan in the process. The
front`s passage will result in a northerly wind shift across the
open waters by Wednesday morning. Periods of showers and
thunderstorms are anticipated today through tonight, with severe
weather not expected. Northerly winds will persist into Thursday
morning, becoming light and variable Thursday afternoon as 1016 mb
high pressure moves across Lake Michigan. South to southeast winds
will re-establish on Friday as a broad area of 1004 mb low pressure
moves into the northern Great Plains. Additional showers and
thunderstorms are forecast Friday through Saturday.

Winds will turn southerly in nearshore zones today as low pressure
moves into the western Great Lakes. The low`s approach, combined
with a cold frontal passage this evening, will bring chances for
scattered showers and thunderstorms today and tonight. Severe
weather is not expected. Quiet conditions are forecast Wednesday
through Thursday. The next chances for showers and storms arrive
Friday into Saturday.

Quigley

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...None.
LM...None.
&&

$$

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