textproduct: Milwaukee/Sullivan

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.