NWS-Milwaukee/Sullivan Forecast Discussion

						FXUS63 KMKX 311752
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
1252 PM CDT Sun May 31 2026

.KEY MESSAGES...

- Chances (~15-30%) for a few showers tonight mainly west of I-39.

- Watching for areas of elevated fire weather conditions through
  the first half of this week.

- Trending warm & humid Thursday into next weekend with multiple
  chances for showers & storms.

&&

.SHORT TERM...
Issued 1255 PM CDT Sun May 31 2026

Rest of Today through Monday night:

Synopsis/Mesoanalysis: High pressure will remain entrenched from the
Hudson Bay south toward Lake Michigan through the duration of the
short term period, keeping temperatures warm and humidity low.
Evident in current water vapor imagery, an upper trough will
continue to swing north through the Upper Mississippi Valley through
tonight, bringing increasing cloud cover to southern Wisconsin this
afternoon & evening. Ascent tied to the trough & broad warm
advection in the lower portions of the atmosphere could trigger a
few scattered showers primarily west of I-39 this evening/tonight,
though most locations will stay dry. Persisting warm and dry
conditions could lead to some fire weather concerns Monday into the
middle of the week. Refer to the Fire Weather section below for
additional details regarding this potential.

This Afternoon through Tonight: Will be watching the radar for some
scattered showers & sprinkles across the western half of the area.
Already apparent in current radar & surface obs trends, activity
will struggle to reach the surface with the northeastward extent
given lingering high pressure & very dry conditions in the lower
portions of the column. Thus thinking that any shower activity will
hold off until this evening/tonight & remain focused across the
west, where large scale lift will be greatest/has the highest
potential to overcome dry low level conditions. Meager to nill
elevated instability leaves thunder chances very low in this
activity. Not expecting much in the way of measurable precip in any
showers.

Quigley

&&

.LONG TERM...
Issued 1255 PM CDT Sun May 31 2026

Tuesday through Sunday:

Synopsis: Upper ridging will gradually break down across the western
Great Lakes Tuesday into Wednesday, allowing surface high pressure
to gradually shift from Lake Michigan toward the Ohio River Valley.
With subsidence remaining prevalent through the column, conditions
will remain rain-free through the middle of the week. Temperatures
will stay warm under a mix of sun and clouds. A belt of enhanced
upper level westerlies will sag into the western Great Lakes from
the Canadian Prairies Thursday night through Saturday, with trailing
surface cyclogenesis occurring from Saskatchewan into Ontario.
Placement of low pressure to the north/west of the region & high
pressure to the south/east of the region will allow Gulf moisture to
return to the area late week into next weekend, resulting in
noticeably more humid conditions areawide. A surface front will
slowly drop through the region Thursday night into the weekend,
bringing multiple chances for showers and thunderstorms. Trends will
be monitored over coming updates for possible hazards in late
week/weekend shower & storm activity.

Thursday Night through Sunday: A transition to a more active pattern
is still anticipated as a slow-moving surface front moves into the
Upper Midwest, triggering multiple rounds of afternoon/evening
shower & storm development as it interacts with a seasonably moist
air mass. Precise timing for shower/storm windows will be refined
over coming updates, though it appears that an initial round of
storm development will occur to the northwest of the region Thursday
evening, with activity gradually dropping into southern Wisconsin
during the overnight hours/early Friday morning. How subsequent
rounds of storm development play out will then be highly dependent
on the positioning of outflow boundaries/the effective front & any
smaller scale perturbations passing overhead. Initial forecast
soundings suggest that ~20-30 kts of shear & 1-1.5"+ precipitable
water values will be present during this time frame, so will be
watching trends & providing additional details regarding more
organized storm & heavy downpour potential as this portion of the
period draws closer.

Quigley

&&

.AVIATION...
Issued 1255 PM CDT Sun May 31 2026

VFR flight categories are expected to prevail through the entirety
of the period at southern Wisconsin terminals. Already building in
from the southwest, BKN to OVC mid-level clouds based between FL100
and FL150 will settle in across the region by early this evening. An
upper disturbance will continue to migrate north through the Upper
Mississippi Valley this afternoon & evening, bringing chances for
SHRA & a few embedded CB over southwest Wisconsin and northeast
Iowa. While probabilities remain too low to carry any PROB30
mentions, will be watching trends to see if some precip attempts to
work toward the vicinity of KMSN or KJVL through the evening and
overnight hours tonight. Should confidence in SHRA increase, TEMPO
groups may be needed in later updates. CIGs will gradually rise back
toward FL200 - FL250 during the day Monday. Lake breezes will bring
east-northeast wind shifts during the afternoon/evening periods both
today and tomorrow at the Lake Michigan terminals.

Quigley

&&

.MARINE...
Issued 1255 PM CDT Sun May 31 2026

Widespread gales are not anticipated through the period across the
open waters of Lake Michigan. 1030 mb high pressure will remain
entrenched across the Hudson Bay through Monday, resulting in
generally north to northeasterly breezes. The center of the high
will build south over Lake Michigan Tuesday and Tuesday night,
leading to generally north-northeast winds over southern Lake
Michigan and light westerlies further north. Said high will
gradually shift east on Wednesday, allowing winds to trend southerly
across the entirety of the lake. 1006 mb low pressure will shift
from the Canadian Great Plains into Ontario Wednesday night through
Thursday, resulting in increasing southwesterly winds across the
waters. Gusts between 20-25 knots will be possible over the northern
third of the lake during this time frame. Trends will need to be
monitored for isolated gale force gusts, though the need for
headlines is not anticipated at this time.

The weather pattern will trend more active regionally Thursday night
into next weekend, with multiple chances for showers and storms
returning to the open waters. Strong storm potential remains
uncertain at this time, with trends being monitored over coming
forecasts.

Widespread Small Craft Advisory conditions are not anticipated
through the period in nearshore zones. Southwest winds will increase
Thursday afternoon as low pressure moves into Ontario, with a few
gusts approaching Small Craft Advisory thresholds possible. While
conditions aren't expected to be widespread enough to warrant
headlines, trends will continue to be monitored over coming forecast
updates. Multiple rounds of showers and thunderstorms are expected
Thursday night into next weekend as the weather pattern trends more
active across the western Great Lakes.

Quigley

&&

.FIRE WEATHER...
Issued 1255 PM CDT Sun May 31 2026

With little measurable rainfall anticipated overnight tonight, a
continued combination of warm & dry air will lead to widespread
relative humidities in the 20 percents on Monday afternoon. Light
winds are expected to keep fire weather conditions well below Red
Flag Warning thresholds, though trends will need to be monitored for
possible Special Weather Statements. Exercise caution if planning to
be burn tomorrow afternoon.

With precip-free conditions continuing & a dry air mass lingering
across the area, will need to be monitoring for additional periods
of fire weather concerns Tuesday through Wednesday. If current
forecasts verify, winds will likely be a touch too low to realize
critical fire weather/Red Flag Warning thresholds, though afternoon
humidities as low as the low-mid 20 percents would still be
supportive for areas of elevated to near-critical conditions. Will
thus need to monitor trends for additional Special Weather
Statements during this portion of the period.

Quigley

&&

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

$$

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