Sunrise 5:36 AM   Sunset 7:58 PM Moonrise 3:31 AM   Moonset 2:31 PM

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LMZ366 Expires:202405032130;;549442 Fzus63 Kmkx 031402 Glflm
open lake forecast for lake michigan national weather service milwaukee/sullivan wi 902 am cdt Fri may 3 2024
for waters beyond five nautical miles of shore on lake michigan.
waves are provided as a range of significant wave heights, which is the average of the highest 1/3 of the wave, along with the average height of the highest 10% of the waves which will occasionally be encountered.
Synopsis -
high pressure of 30.1 inches and lighter surface winds are expected later this afternoon and tonight. Some low level moisture returns on Saturday ahead of a cold front. This front will move across lake michigan on Saturday evening, before high pressure around 30.1 inches again moves into the region for Sunday. No precipitation for Saturday night and Sunday. Winds are expected to be light to breezy across lake michigan through the upcoming weekend.
lmz261-362-364-366-563-565-567-868-032130- lake michigan from seul choix point to rock island passage 5 nm offshore to mid lake- lake michigan south of a line from seul choix point to the mackinac bridge and north of a line from charlevoix mi to south fox island 5 nm offshore- lake michigan from charlevoix to point betsie mi 5 nm offshore to mid lake- lake michigan from point betsie to manistee mi 5 nm offshore to mid lake- lake michigan from rock island passage to sturgeon bay wi- lake michigan from sturgeon bay to two rivers wi 5 nm offshore to mid lake- lake michigan from two rivers to sheboygan wi 5 nm offshore to mid lake- lake michigan from pentwater to manistee mi 5 nm offshore to mid lake- 902 am cdt Fri may 3 2024
sheboygan wi to pentwater mi north - .
Rest of today - West winds 10 to 15 kt becoming south. Waves 1 to 3 ft. Tonight - South winds 10 to 15 kt becoming southeast 5 to 10 kt. Waves 1 to 2 ft. Saturday - Southeast winds 5 to 10 kt becoming northeast 10 to 15 kt. Waves 1 to 3 ft. Saturday night - West winds 10 to 15 kt becoming northwest. Chance of rain showers in the evening. Waves 1 to 3 ft. Sunday - Northwest winds 10 to 15 kt increasing to 10 to 20 kt. Waves 1 to 3 ft. Sunday night - East winds 10 to 15 kt diminishing to 5 to 10 kt. Waves 1 to 2 ft. Monday - East winds 10 to 15 kt becoming northeast. Waves 1 to 2 ft. Tuesday - Southeast winds 15 to 25 kt. Showers likely with a chance of Thunderstorms. Waves 3 to 5 ft.

LMZ300
No data

FXUS63 KGRB 031155 AFDGRB

Area Forecast Discussion National Weather Service Green Bay WI 655 AM CDT Fri May 3 2024

Updated aviation portion for 12Z TAF issuance

KEY MESSAGES

- Scattered showers and isolated thunderstorms are possible Saturday into Saturday evening with more showers and thunderstorms Monday night through Wednesday.

- Slightly elevated fire weather conditions, mainly across northern WI, this afternoon and again Sunday and Monday afternoons due to RHs dropping into the 20-35 percent range.

- A few rivers will remain at or reach bankfull stage into the weekend.

DISCUSSION
Issued at 352 AM CDT Fri May 3 2024

Short Term
Today
Tonight...and Saturday

Main forecast issues will be dealing with lingering low clouds/fog early today, relative humidities in the 20/30s this afternoon and any fire weather issues, and shower/thunder chances Saturday afternoon.

Today...rain showers associated with a shortwave trough and weak low pressure/front will exit east of the area early this morning, with only some patchy fog/drizzle/sprinkles left around sunrise across mainly northern/eastern WI. As drier air advects in from the west, look for any light precip to end/exit, with the fog and low clouds mixing out through the morning hours. Plenty of sunshine is expected in the late morning and afternoon as high pressure builds across the western Great Lakes. Mixing to at least 4000-5000 ft will support warmer temperatures, with highs climbing into the upper 60s to middle 70s, and west winds gusting to 20 to 30 mph (strongest in northern WI) and low relative humidity (20-35 percent) in the sandy soil areas. If we can mix closer to 7000 ft, as the RAP suggests, wind gusts would be a little higher and RH's a little lower. The recent rainfall, along with the continued green-up, will limit the overall fire weather concern. However, locations across northern WI may see slightly elevated fire weather conditions as green-up has been the slowest, the deepest mixing is expected and winds will be the highest this afternoon.

Tonight...dry conditions continue as high pressure slides east of the region. Mostly clear skies are expected during the evening, with mid and high clouds spreading east across the area overnight.
Lows look to mainly be in the 40s with a light south/southeast wind.

Saturday...a dry start to the day is expected, but skies look to become cloudy through the morning. An area of rain showers will spread west to east across the area during the morning, as another shortwave trough and frontal boundary approach from the west.
This first area looks to be weakening as it traverses the area, but additional showers look to develop later in the morning and afternoon ahead of the front. Rain amounts look to remain under a quarter inch for most spots. As for thunder chances, assuming the front pushes through in the afternoon, should get at least 500 J/kg of CAPE across eastern WI by early-mid afternoon. This would be enough to support a few storms, but severe weather is not expected. Will carry a slight chance for thunder in the afternoon across parts of central and eastern WI. Light south/southeast winds will increase in the morning ahead of the front, then shift to the west/northwest behind the front in the afternoon. Winds could get a little gusty, up to around 35 mph ahead of the front, but will be difficult to break into the inversion to mix down the stronger winds. Will hold gusts closer to 20-25 mph for now. As CAA arrives behind the front, better mixing will promote gusts to ~25 mph.

Long Term...Saturday Night Through Thursday

Main focus of the extended period revolves around a well organized cyclone that is forecast to bring showers and thunderstorms to the region early to middle of next week.

Scattered showers and an isolated thunderstorm or two may linger Saturday night into early Sunday morning across far eastern WI as an upper-level trough and surface cold front depart from the region. A ridge of high pressure is forecast to build over area Sunday returning dry and calm conditions to the region through at least Monday afternoon. The ridge will also ushering in a drier air mass which may lower RHs to around 30 percent Sunday and Monday afternoons. These lower RHs and warmer temperatures in the low 60s to around 70 degrees may bring slightly elevated fire weather conditions to far northern WI, where vegetation has yet to green up, Sunday and Monday afternoons.

While there are still slight differences in timing and intensity, ensemble models are in decent agreement that a near vertically stacked low pressure system will eject out of the Great Basin toward the norther Plains late Monday into Tuesday. An initial wave of warm air advection out in front of the low along with diffluent flow aloft may bring a round scatter showers and storms Monday night into Tuesday. Perhaps the best chance for strong to potential severe storms comes Tuesday afternoon and evening as much of the CWA may reside in the warm sector allowing for an increase in instability, however, the question remains if there will be a forcing mechanism present for thunderstorm initiation.

Periods of rain and thunderstorms will remain possible through Wednesday and Thursday as the cyclone brings several pieces of jet energy across the region. With several area rivers and streams already at or near bankfull the active pattern for next week may create some minor flooding concerns particularly in low laying and flood prone areas.

AVIATION
for 12Z TAF Issuance Issued at 641 AM CDT Fri May 3 2024

Lingering MVFR/IFR conditions, with some briefly lower VSBYs possible in central and north central WI, will continue early this morning, then will improve to VFR by mid to late morning as high pressure and drier air build into the region. VFR conditions are expected this afternoon into tonight, with some mid high clouds arriving overnight.

West winds will gust up to 25 kts today, then decrease late this afternoon. Light south to southeast winds are expected tonight.
LLWS will be possible overnight as southeast winds increase to 30-35 kts at 2000 ft.

GRB WATCHES/WARNINGS/ADVISORIES
None.

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