473
FXUS63 KMKX 301523
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
1023 AM CDT Sun Jun 30 2024

.KEY MESSAGES...

- River flooding and high water levels remain elevated this
  week. Additional rises will be possible with any heavier
  rainfall (late Monday night through Tuesday night).

- A moderate swim risk is in effect for Lake Michigan beaches in
  Milwaukee County today. A high swim risk is in effect for
  Racine and Kenosha County beaches until 3 PM today, downgrading
  to a moderate risk through the evening hours.

- Patchy fog may develop tonight, with some patches of denser
  fog possible exclusively in low lying areas, marshes, and
  river valleys.

- Next chances for thunderstorms is late Monday night through
  Tuesday night.

&&

.UPDATE...
Issued 1015 AM CDT Sun Jun 30 2024

The forecast remains on track for today through Monday. Breezy north
winds will gradually subside throughout the day today, with winds
veering slightly northeasterly near Lake Michigan this afternoon,
holding lakeshore county temps to the upper 60s to low 70s despite
ample sunshine. Until these winds slow down and waves subside, a
High Swim Risk is in effect for Racine and Kenosha county beaches,
and a Moderate Risk for Milwaukee county beaches. By 3 PM CDT this
afternoon, winds and waves are expected to be low enough to
downgrade to a Moderate Swim Risk for all 3 of those counties.

Continuing to monitor the potential for radiation fog tonight
underneath the centroid of the high pressure system. The clear skies
and nearly calm winds will allow surface temps to fall to the upper
40s to around 50 for inland areas, approaching (or reaching)
the dewpoint temps. The dewpoint field is relatively homogeneous
between land areas and Lake Michigan, though air temps are
forecast to be warmer (closer to 60) at night over the lake,
hence the effect of the lake will be to inhibit fog formation.
Weak northeasterly flow off Lake Michigan (indicated by most
model guidance) in Milwaukee, Racine, and Kenosha counties is
likely to completely inhibit fog formation (particularly right
along the shoreline and over the waters). The rest of the CWA
still has radiation fog potential. With only a weak signal for
fog development present in model / MOS guidance at this time,
fog is expected to be patchy at best, with the possibility for
patches of dense fog exclusively in low- lying areas,
marshlands, and river valleys (especially the Wisconsin and Rock
river valleys). Sunshine will burn off this fog (if applicable)
within a few hours after sunrise Monday, with no synoptic cloud
cover to slow that process down.

Sheppard

&&

.SHORT TERM...
Issued 410 AM CDT Sun Jun 30 2024

Today through Monday:

High pressure will continue to build into the Great Lakes Region
from the Northern Plains today. The surface high pressure center
is expected to be overhead of the state tonight into Monday
morning. By Monday, night this high pressure will be exiting to
the east and the synoptic scale subsidence will be clearing out
of the state. With the high pressure overhead tonight, there
will be a chance for some radiation fog development. Winds will
be light and variable with clear skies. Not anticipating fog to
become dense at this time, but low lying areas such as river
valleys and marsh lands will have the best potential for any
patchy dense fog.

Breezy winds are expected over Lake Michigan into this afternoon
due to the tighter pressure gradient between a low pressure
system in eastern Michigan and the incoming high pressure from
the Northern Plains. While the northerly winds over the lake
will be able to be largely ignored by most people. Far southern
Wisconsin lakeshore areas will have some impacts to their
beaches. In particular, Racine county will be especially
susceptible to high swim risk conditions because the geography of
the lakeshore juts out to the east. Beach hazard statements are
in effect for both Kenosha and Racine counties through this
afternoon. Use extra caution today if you will be on Lake
Michigan.

Patterson

&&

.LONG TERM...
Issued 410 AM CDT Sun Jun 30 2024

Monday night through Saturday:

As high pressure exits to the east Monday night, an incoming
trough will bring a return to precipitation chances late Monday
night into Tuesday. WAA will have been underway since mid Monday
with the south to southeasterly winds. The moisture advection
will prep the low and mid levels for storm development within
and ahead of the warm sector for Tuesday. Guidance suggests the
low level jet setting up across Wisconsin Tuesday
morning/afternoon, which will provide some forcing for rain and
storm development. With guidance being pretty consistent on the
cold front moving through Tuesday night into Wednesday, there
could be a potential for two "rounds" of precipitation. One
within the warm sector and a second with the passage of the cold
front. Its still a bit to early to really get into the
specifics of timing, but if things begin to line up well and
southern Wisconsin gets clearing skies there could be a good
potential for some stronger storms. Instability will be the key
player to keep an eye on.

Behind the cold front Wednesday has the best potential for a
brief period of dry weather, but timing and duration on this is
uncertain. Another trough is expected to be right on the heels
of the first, which will quickly bring additional chances for
rain and storms. Guidance has this second trough holding off
until Thursday. There is quiet a bit of variability in the
timing and location of this low pressure system. The sfc low
fluctuates locations between far northern Wisconsin to southern
Wisconsin which would play a big roll in the anticipated rain
potential. As things stands now there is a moderate potential
for rain (around 40-50%) Thursday evening when sticking to the
average among guidance. The holiday is by no means a wash out at
this point, but its definitely a time where everyone will be
looking at the forecast. So make sure to keep up to date with
the forecast through the week.

Beyond the holiday, the pattern continues to look active with
additional troughs and shortwaves on the horizon. Long range
guidance has quiet a bit of variability which has allowed some
broad brush low chance POPs of 20-25 percent or less to be in
place for Friday through Sunday. This will likely continue until
guidance start to solidify and coverage toward a singular point
later on.

As mentioned a few times above there will be periods of ongoing
WAA through the extended forecast. Ensembles pick up on this
well and thus temperatures climb back up in the low to mid 80s
for much of the extended.

Patterson

&&

.AVIATION...
Issued 1015 AM CDT Sun Jun 30 2024

Diurnal cumulus clouds have achieved scattered to broken
coverage recently, around 2500 to 3000 ft AGL. These should
continue to lift as solar heating continues, generally 3000 to
4000 ft in the afternoon. These will rapidly erode as the sun
goes down, leaving clear skies tonight. Breezy north winds
decelerate this afternoon, with light and variable winds
expected overnight underneath a high pressure system. Patchy fog
may develop overnight, with the potential for some denser fog
exclusively in low lying / marshy / river valley areas (KLNR and
possibly KJVL). This may merit a PROB30 group in the KJVL TAF
for fog late tonight, confidence is too low for inclusion in
other TAFs at this time. Any fog that does develop should burn
off quickly after sunrise Monday given the lack of synoptic
cloud cover.

Dry weather continues into Monday, with ~30 kft and some 10 kft
VFR cloud ceilings gradually developing. Rain and thunder
chances hold off until late Monday night.

Sheppard

&&

.MARINE...
Issued 410 AM CDT Sun Jun 30 2024

Gusty north to northwest winds are expected today due to a
tighter pressure gradient over the lake. This tighter pressure
gradient between a low pressure system in eastern Michigan and
the incoming high pressure from the west will shift easterly
overtime today. A Small Craft Advisory is in effect through this
afternoon for all nearshore waters. A beach hazard statement is
in effect for Racine and Kenosha areas due to the breeze
northerly winds.

Winds will weaken tonight into Monday and become predominately
easterly as high pressure around 30.3 inches builds in from the
Northern Plains. High pressure will advect east of the Lake
Monday night, causing winds to become southeasterly and
increase. South to southeast will linger into Tuesday night,
before a cold front moves east across the region.

Patterson

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...Beach Hazards Statement...WIZ071-WIZ072 until 3 PM Sunday.

LM...Small Craft Advisory...LMZ645-LMZ646 until 3 PM Sunday.

&&

$$

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