Sunrise 5:48 AM   Sunset 7:50 PM Moonrise 12:00 AM   Moonset 7:39 AM

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LMZ644 Port Washington To North Point Light Wi- 505 Am Cdt Sat Apr 27 2024
.small craft advisory in effect through Monday evening - .
Today - South wind 15 to 20 knots becoming 10 to 20 knots late in the morning, then becoming southwest 15 to 25 knots early in the afternoon easing to 10 to 20 knots late in the afternoon. Gusts up to 30 knots. Slight chance of showers and Thunderstorms late in the afternoon. Waves 4 to 6 feet subsiding to 3 to 4 feet. Tonight - Southwest wind 10 to 20 knots becoming 10 to 15 knots late in the evening, then easing to 5 to 10 knots after midnight veering north early in the morning. Rain showers likely and a chance of Thunderstorms. Waves 2 to 4 feet subsiding to 1 to 2 feet in the late evening and overnight. Sunday - Northeast wind 10 to 15 knots rising to 15 to 20 knots in the late morning and afternoon. Chance of Thunderstorms in the morning. Rain showers through the day. Slight chance of Thunderstorms in the afternoon. Waves 1 to 2 feet building to 3 to 4 feet in the late morning and afternoon. Sunday night - Northeast wind 10 to 15 knots veering south early in the morning. Rain showers and a chance of Thunderstorms. Waves 3 to 4 feet.

LMZ600
No data

FXUS63 KMKX 270930 AFDMKX

Area Forecast Discussion National Weather Service Milwaukee/Sullivan WI 430 AM CDT Sat Apr 27 2024

KEY MESSAGES

- Multiple rounds of showers and thunderstorms are expected through the weekend, with storms possibly lingering into early Monday. Locally heavy rainfall will be possible, especially along and south of the I-94 corridor.

- A few thunderstorms may be severe during this active pattern.
Hail, damaging wind gusts, and isolated tornadoes are all possible, especially late this afternoon into this evening.

- Additional chances for showers and storms mid to late week next week.

SHORT TERM
Issued 415 AM CDT Sat Apr 27 2024

Today through Sunday:

Early today: Except for a band of light rainshowers currently passing close to Sauk and Marquette counties, dry weather is expected to prevail until this afternoon, with gusty southwest winds rapidly building after sunrise. The strongest wind gusts are expected near Sheboygan and Fond du Lac counties, upwards of 40 mph. Roughly 30 to 40 mph gusts elsewhere.

This afternoon / evening: Storms are expected to develop along a southwest to northeast oriented frontal boundary, perhaps as early as 1 PM or as late as 7 PM today. CAMs currently depict the position of convective initiation as a line from Monroe WI to Sheboygan WI, with roughly one or two counties distance east/west disagreement in positioning. Forecast soundings indicate southwest winds throughout the column, with unidirectional shear, yet impressive helicity integrals. HRRR Mean MUCAPE south of the boundary exceeds 2000 j/kg, with a surface-based effective inflow layer. HRRR mean STP exceeds 2.0, with some models (esp. the Nam NEST) pushing 3.0. This parameter space would suggest an environment capable of all SVR hazards (hail, damaging winds, and possibly tornados). Localized heavy rainfall is a concern, especially if storms along the front affect the same area multiple times. The best agreement in model QPF is positioned along and south / southwest of the I-94 corridor.

Late tonight through Sunday: Instability is progged to decline late tonight. Some models depict a lull in shower / storm activity late tonight, while others depict wider storm coverage with weaker intensity. Severe wx potential does continue into Sunday, but with HRRR mean MUCAPE less than 1000 j/kg (even with the compliment of daytime heating), this is looking like the less active day of the two. That said, the positioning of the warm front leaves much in question in the way of instability.
Regardless of severe wx potential, localized heavy rainfall seems equally probable on Sunday, with model QPF evenly split between the two rounds of activity.

Sheppard

LONG TERM
Issued 415 AM CDT Sat Apr 27 2024

Sunday night through Friday:

Synopsis: The upper trough ejecting into the Northern Plains on Sunday afternoon/the conclusion of the short term period will progress toward the Canadian border Sunday night into early Monday morning. The advancement of the upper wave will support surface low placement along the MN-WI border vicinity by sunrise Monday, with a cold front forecast to be extending southwest into the Central Plains. The upper trough will progress across Lake Superior during the day on Monday, gaining separation from its attendant surface cyclone in the process. This will promote gradual filling of the surface low over northern WI and the Upper Peninsula of MI Monday afternoon, with the associated cold front crossing & ultimately exiting the region during the evening hours. The advancing upper wave & surface front will support additional periods of showers and embedded thunderstorms from Sunday night through Monday afternoon.
Westerly surface flow will usher a drier/Canadian air mass into the state Monday night, with winds quickly turning back out of the south from Tuesday into the middle portions of next week. Occurring in response to an upper jet/trough pairing approaching from the Northern Plains, said southerly flow will allow moisture to return to the area on Tuesday afternoon. Additional showers and storms will be possible Tuesday night through Wednesday as a surface low related to the upper trough/jet tracks across Ontario & pulls a cold front across the state. The boundary is likely to stall out somewhere to our south & east during the Thursday/Friday timeframe, with considerable spread in placement evident in current deterministic & ensemble-based guidance.

Sunday Night & Monday: Anticipate periods of showers and embedded thunderstorms. While depicting plenty of shear through the column, available forecast soundings show only weak (<500 J/kg) MUCAPE through the majority of this timeframe, suggesting low overall strong/severe storm potential in this activity. Will nevertheless monitor trends over the coming cycles, as a slower FROPA on Monday PM would allow for instability & isolated strong/severe potential to trend up.

Tuesday Night & Wednesday: Expect another round of rainfall during this portion of the period. Early progs show some signal for CAPE to work into the area, which has justified continued mentions of thunder in the overnight weather grids. It remains too early to comment on any stronger storm potential, though trends will continue to be monitored.

Thursday & Friday: Forecast uncertainty jumps up considerably during this portion of the period, as area weather is likely to be influenced by where the mid-week frontal boundary ultimately stalls.
Additional rainfall chances would be possible in the scenario that the feature lingers further north than currently progged. Will continue to adjust the late week forecast as boundary placement clarifies.

Quigley

AVIATION
Issued 415 AM CDT Sat Apr 27 2024

2000 ft Low Level Wind Shear is expected to remain a threat until an hour or two after sunrise today, when faster winds aloft mix down to the surface, causing southwest gusts upwards of 30 kts by this afternoon. An arc of MVFR / Fuel-Alt cloud ceilings currently overspreads southwestern WI, expected to spread eastward later this morning. Broken clouds gradually lift to roughly 4000 ft this afternoon. A slight chance for thunderstorms begins in the mid afternoon (30 pct chance), ramping up to a 50 to 80 pct chance this evening into tonight.
Some of the stronger storm cells / lines may be capable of producing localized damaging wind gusts, hail, and frequent lightning. A southwest to northeast oriented frontal boundary is expected to approach from the northwest this evening (roughly 00z to 06z tonight). Gusty southwest winds will decline and thunderstorm coverage will increase as this boundary approaches, then gentle northeast winds develop behind the boundary late tonight. Model guidance suggests rain from these thunderstorms will lower cloud ceilings late tonight, with areas of IFR likely.

Sheppard

MARINE
Issued 415 AM CDT Sat Apr 27 2024

Low pressure around 29.3 inches over southern Minnesota continues to drift northeastward this morning, reaching Lake Superior around noon today. Gusty south winds are expected across Lake Michigan today, with a few gusts approaching gale force, especially in the northern half of the lake. Winds will then become light and northeasterly tonight into Sunday morning as the low exits and a weak cold front drapes across central portions of the lake. Sunday into Sunday night, winds will become breezy and southerly south of the front and will become breezy and easterly to northeasterly north of the front.

A few thunderstorms are expected to cross southern Lake Michigan early this morning. Additional rounds of showers and thunderstorms are expected this afternoon through Sunday. A few storms this afternoon and evening could produce locally gusty winds and hail.

Sheppard

MKX WATCHES/WARNINGS/ADVISORIES
WI...None.
LM
Small Craft Advisory
LMZ643-LMZ644-LMZ645-LMZ646 until 7 PM Monday.

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