NWS-Milwaukee/Sullivan Forecast Discussion

						FXUS63 KMKX 191039
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
539 AM CDT Fri Jun 19 2026

.KEY MESSAGES...

- Chance for showers and thunderstorms for this evening (40-75%).
  Cannot rule out a stronger storm or two for areas along and
  west of I-39, but potential remains low.

- Chance of showers in far southern WI Sunday, then again for
  the entire region toward the middle of next week.

- Warm but slightly below normal temps expected this weekend
  through early next week.

&&

.UPDATE...
Issued 540 AM CDT Fri Jun 19 2026

No major changes to the going forecast. The latest CAM guidance
continues to show dry and pleasant weather between now and 5:00
PM in southern WI, with the scattered showers and thunderstorms
pushing in thereafter. Modeled MUCAPE fields remain at or below
750 joules later today for the most part, hence the potential
for stronger thunderstorms remains low. Main point to get across
is that there is still a threat for lightning, and with lots of
outdoor activities scheduled for today, we're encouraging folks
to stay weather aware.

Sheppard

&&

.SHORT TERM...
Issued 1235 AM CDT Fri Jun 19 2026

Today and Tonight:

High pressure will track to south and east of the area early
this morning. This will bring clear, calm, and dry conditions
with temps dipping down into the mid to lower 50s for the rest
of tonight.

High pressure with continue to push eastward through this
morning with light winds picking up through the afternoon and
evening as weak low pressure track southeastward across WI
through the evening along with a mid-level shortwave trough
traversing across the Upper Midwest. Accompanying this wave
will be a slug of Pacific moisture moving across the region and
will allow for PWAT values to increase to around and even exceed
1 inch by this evening. Pair the moisture with mid-level dCVA
and a 30-40 LLJ rounding the base of the trough and looks to be
enough forcing to support shower development.

Main window for this activity will be late this afternoon
through the evening. While there is ample synoptic forcing,
there remains some questions on the instability as well as how
quickly the moisture advects back into the area as most model
prog only mid-50s dewpoints and 00z CAMs are suggesting below
500 J/kg of SBCAPE. However, still enough for a few rumbles of
thunder, especially for areas along and west of the I-39
corridor. While mainly expecting showers and thunderstorms
(30-60%), the latest CAMs are picking up on some 40-50 kt of
deep layer shear and there are a few models that are more
bullish with 500-1000 J/kg SBCAPE. If the more aggressive
scenario pans out, then could see a few stronger storms develop
with this system, which any taller/stronger storm will be
capable of producing hail and gusty winds. Overall, the stronger
storm potential remains on the lower side for our area as
uncertainty on the moisture return, instability, along with all
these factors aligning with the synoptic forcing will determine
stronger convective development or not.

Wagner

&&

.LONG TERM...
Issued 1235 AM CDT Fri Jun 19 2026

Saturday through Thursday:

Overall, extended period looks fairly mild with slightly below
(5- 10F) normal temps. Will be a few opportunities for
additional shower and thunderstorms for the end of the weekend
and again toward the middle of next week.

Behind this evening's system will see drier airmass settle over
southern WI as high pressure builds into the area through the
weekend. Expect daytime temps in the mid to upper 70s for
Saturday with mostly sunny conditions as the high pressure
tracks across the Upper Great Lakes region.

Sunday will be our next chance for showers as models prog a
surface low to track across central IL/IN. This looks to bring
easterly flow off of Lake Michigan through the day and keep
temps on the cooler side in the lower 70s. Given the latest
model trends in the low track, this will keep southern WI on the
cooler side of the system is likely to limit much of any
instability to develop along with thunderstorms. Thus, Sunday is
trending toward more of a widespread rainy day especially for
the southern half of the CWA, while ares north may still see
some rain and cloudy skies, there is a potential for drier air
to the north limit shower development toward Central WI for
Sunday, especially if we continue to the see the low track
slightly farther south. Also could see elevated swim risk
conditions with the easterly onshore flow for southern WI
beaches on Sunday.

The start of the work week is looking to be dominated by high
pressure build across the region with gradually warming temps.
Then looking at another another shortwave trough to develop and
dig across the Upper Midwest toward the middle of the week
bringing additional shower and thunderstorm chances. Then for
the later half of next week, upper-level ridging looks to build
across the region toward next weekend.

Wagner

&&

.AVIATION...
Issued 540 AM CDT Fri Jun 19 2026

Sunny and VFR conditions through this morning and early
afternoon. A light west to northwest breeze. VFR-altitude
altocumulus and cumulus clouds (over the 5,000 ft mark)
gradually increase in coverage later today, with scattered
showers and thunderstorms then expected to push in from west to
east late this afternoon through this evening. Lightning will be
a concern with these as they cross the region; there is a level
1 out of 5 threat for an isolated stronger storm for airports
north and west of Madison with some gusty winds in addition to
the lightning.

Clouds scatter apart tonight into Saturday, with predominantly
dry weather expected after midnight tonight.

Sheppard

&&

.MARINE...
Issued 1235 AM CDT Fri Jun 19 2026

High tracking across the area this morning will bring lighter,
westerly winds, but expect the winds to gradually pick up
through the day as low pressure works its way southeastward
across WI through the evening bring more southerly winds.
Another High pressure and lighter winds expected for Saturday
before another low pressure tacks across central IL/IN and
turning winds more easterly. The strengthening onshore flow may
see waves and winds build to small craft levels for Sunday along
with showers across the southern half of the Lake and linger
into the start of next week. Then lighter winds return as high
pressure moves through for the start of next week.

Wagner

&&

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

$$

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