Sunrise 5:36 AM   Sunset 7:59 PM Moonrise 3:53 AM   Moonset 3:53 PM

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LMZ669 Expires:202405041515;;601406 Fzus63 Kmkx 041100 Glflm
open lake forecast for lake michigan national weather service milwaukee/sullivan wi 600 am cdt Sat may 4 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 -
areas of low clouds and patchy fog are moving into the open waters from lower michigan this morning. While not expected to be widespread, visibilities could briefly drop to and below a mile in spots over the southern half of the lake. Dense fog advisories are not planned at this time, though trends will continue to be Monitored.
a weak, 29.9 inch low pressure center will approach from the west today, dragging a cold front across the open waters in the process. Scattered showers and Thunderstorms will be possible along the front. Most activity is expected to remain sub-severe, though an isolated strong storm with small hail and gusty winds can't be ruled out. A 30.1 inch high pressure will approach from the northern great plains on Sunday, resulting in light & variable surface winds. Winds will begin to shift out of the east-southeast Monday afternoon & evening as a 29.1 inch low pressure center develops over the northern great plains. Winds will pivot between southeasterly and southwesterly through mid- week, prior to turning out of the north and northwest on Thursday & Friday as a 29.6 inch low pressure center moves east of the open waters. Periods of showers and Thunderstorms are forecast from early to mid week, with conditions drying out by the end of the week & beginning of next weekend.
lmz080-669-671-673-675-777-779-870-872-874-876-878-041515- lake michigan from michigan city in to st. Joseph mi 5 nm offshore to mid lake- lake michigan from sheboygan to port washington wi 5 nm offshore to mid lake- lake michigan from port washington to north point light wi 5 nm offshore to mid lake- lake michigan from north point light to wind point wi 5 nm offshore to mid lake- lake michigan from wind point wi to winthrop harbor il 5 nm offshore to mid lake- lake michigan from winthrop harbor to wilmette harbor il 5 nm offshore to mid lake- lake michigan from wilmette harbor il to michigan city in 5 nm offshore to mid lake- lake michigan from whitehall to pentwater mi 5 nm offshore to mid lake- lake michigan from grand haven to whitehall mi 5 nm offshore to mid lake- lake michigan from holland to grand haven mi 5 nm offshore to mid lake- lake michigan from south haven to holland mi 5 nm offshore to mid lake- lake michigan from st. Joseph to south haven mi 5 nm offshore to mid lake- 600 am cdt Sat may 4 2024
sheboygan wi to pentwater mi south - .
Today - East winds 10 to 20 kt becoming southeast. Waves 1 to 2 ft. Tonight - South winds 10 to 15 kt veering to west 10 to 20 kt late in the evening, then becoming northwest after midnight increasing to 15 to 25 kt late. Chance of rain showers and Thunderstorms in the evening, then slight chance of rain showers and Thunderstorms overnight. Waves 1 to 3 ft building to 2 to 4 ft. Sunday - Northwest winds 15 to 25 kt becoming north 10 to 20 kt. Waves 3 to 5 ft. Sunday night - Northeast winds 10 to 20 kt diminishing to 5 to 10 kt overnight. Waves 2 to 4 ft subsiding to 1 to 3 ft. Monday - East winds 10 to 15 kt increasing to 10 to 20 kt. Waves 2 to 4 ft. Monday night - East winds 10 to 15 kt becoming southeast 10 to 20 kt. Waves 2 to 4 ft building to 3 to 5 ft. Tuesday - Southeast winds 15 to 25 kt becoming south. Showers with a chance of Thunderstorms. Waves 4 to 6 ft occasionally to 8 ft. Wednesday - Southwest winds 10 to 20 kt becoming south. Waves 1 to 3 ft.

LMZ600
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FXUS63 KMKX 040904 AFDMKX

Area Forecast Discussion National Weather Service Milwaukee/Sullivan WI 404 AM CDT Sat May 4 2024

KEY MESSAGES

- A few strong thunderstorms with hail and gusty winds are possible near & east of I-39 this afternoon.

- Additional showers and thunderstorms are expected during the middle portions of next week.

SHORT TERM
Issued 401 AM CDT Sat May 4 2024

Today through Sunday:

Synopsis/Mesoanalysis: Early morning surface observations place a surface cold front along an approximate Wichita, KS to Omaha, NE to Rochester, MN axis. Regional radar mosaics show a line of convection extending from southwest IA to northeast KS, with light to moderate rainfall covering much of northwest IA and southwestern MN. This activity has developed thanks to frontogenetic forcing from the aforementioned surface front, as well as upper divergence within an upper jet streak currently analyzed from the Northern Plains to Lake Superior. This area of precip will continue to pivot northeast toward the Mississippi River through sunrise, gradually weakening as it drifts off the most favorable upper jet dynamics & encounters a more stable air mass with eastward extent. A weak surface low will organize over central IA this morning, dragging the previously mentioned cold front across southern Wisconsin later this afternoon and evening. Scattered shower and thunderstorm redevelopment is anticipated along the advancing surface boundary, with the bulk of activity expected to focus near and east of the Interstate 39 Corridor. While widespread severe weather chances are low, an isolated strong to severe thunderstorm can't be ruled out. Precip chances will quickly shift east with the departing surface front this evening. Shortwave ridging will become established in the mid- levels over the Northern Plains on Sunday, with weak high pressure moving across the state at the surface. This will translate to pleasant & quiet weather tomorrow.

Today: Anticipate that at least some of the rainfall currently ongoing to our west will survive to our western zones later this morning/early this afternoon. Given well-established weakening trends, don't envision any of this activity amounting to much more than scattered showers and perhaps an isolated thundershower. With the surface front discussed above pushing in from the west, and peak heating of the day beginning to be realized, anticipate scattered redevelopment of showers and thunderstorms moving into the mid to late afternoon hours. Given frontal positioning near or just east of the I-39 Corridor, most 00Z and 06Z CAM guidance suggests that said redevelopment will focus over the eastern half of the area. While widespread severe weather is not expected, an isolated strong to severe storm can't be ruled out given the presence of ~500-1000 J/kg of surface-based CAPE in a warm sector bounded by the advancing front and the westward-mixing lake breeze. A sampling of forecast hodographs depict modest & largely unidirectional shear profiles, with shear vectors oriented predominantly parallel to the approaching cold front. Thus expect a clustered/messy mode in any redeveloping storms, with hail and gusty winds being the primary hazards in any isolated strong/severe activity given the mid-level lapse rates and deeply-mixed boundary layers sampled in area forecast soundings. Keep an eye on the sky if planning to be outdoors this afternoon, and be sure to move inside if a thunderstorm approaches your area.

Tonight: Precip chances will taper quickly this evening as the cold front pushes east of the region. Some patchy fog is possible near daybreak, particularly over the Wisconsin River Valley.

Quigley

LONG TERM
Issued 401 AM CDT Sat May 4 2024

Sunday night through Friday:

High pressure is anticipated to expand over the Upper Great Lakes Sunday night ahead of approaching ridging from the Central Plains. This should keep Sunday night through Monday mostly dry, as rain from a weak shortwave in the middle Mississippi Valley will likely stay south, owing to dry air from the high pressure center.

By Monday Night, rain chances will begin to increase as WAA and a weak frontal boundary bring a dying line of storms toward southern Wisconsin. Overnight into Tuesday morning, this line will pass from west to east, with models depicting coverage becoming spotty by the time the line hits the Lake Michigan shoreline.

Through the day on Tuesday, a secondary warm front is then expected to lift north, with another round of thunderstorms forming Tuesday afternoon as a strong 500mb wave and intensifying 850mb jet provides lift over the region. ECMWF and GFS solutions show favorable shear for this event with modeled sfc to 500mb shear around 50 knots, but both models depict differing positions for the secondary warm front Tuesday afternoon. The ECMWF brings it north through most of WI, while the GFS keeps it parked over northern IL, owing to differing evolutions of the formation of a sfc low during that time period. The positioning of this warm front will determine the area of better instability and mode of potential severe weather hazards on Tuesday. For what its worth, 00z CIPS analogs based on the GEFS favor a hail threat (10% chance) mainly along and south of I-94, with no signals in the GEFS for a wind or tornado threat at the moment.

Whatever convection develops over the middle to upper Mississippi Valley on Tuesday is expected to push the effective warm front farther south into central IL. At this time, models depict thunderstorm activity staying south of the Wisconsin-Illinois boarder, though some benign showers and a rumble of thunder may occur Wednesday evening as an inverted trough/cold front sinks south over the upper Midwest. This could all change by Wednesday, however, if that warm front isn't pushed as far south as models currently anticipate.

Beyond, details get fuzzy, with the NBM painting broad slight chance to chance PoPs (15% to 35%) into Friday evening, as long range models diverge in their handling of an upper level trough going into the upcoming weekend.

CMiller

AVIATION
Issued 401 AM CDT Sat May 4 2024

Expect primarily VFR conditions to prevail through the remainder of the overnight and AM hours today. East-southeast winds will begin to increase ahead of an approaching surface low near/just prior to daybreak, allowing moisture to begin increasing across the region.
Given the timing of the wind shift/onset of moisture returns, will be closely monitoring obs for any possible CIG/VIS reductions, particularly at SBM where surface temp & dew point spreads are approaching zero. Anticipate improvements in any isolated categorical reductions by mid-late morning. Chances for SHRA and TSRA will increase this afternoon along and ahead of an approaching cold front. Mentions of said chances have been maintained in the 06 and 09Z updates. Expect a period of prevailing MVFR behind the departing frontal boundary early this evening, with improvements occurring closer to midnight as west-northwest winds pick up regionally.|

Quigley

MARINE
Issued 401 AM CDT Sat May 4 2024

Areas of patchy fog are possible from predawn through the morning hours today over the open waters, though confidence regarding the precise placement of any development remains low. Will monitor trends over the next several hours and make forecast adjustments as necessary. A weak, 1012 mb low pressure center will approach from the west today, dragging a cold front across the open waters in the process. Scattered showers and thunderstorms will be possible along and ahead of the front. Most activity is expected to remain sub- severe, though an isolated strong storm with small hail and gusty winds can't be ruled out. A 1020 mb high pressure will approach from the northern Great Plains on Sunday, resulting in light & variable surface winds across the open waters. Winds will begin to shift out of the east-southeast Monday afternoon & evening as a 984 mb low pressure center develops over the northern Great Plains. Winds will pivot between southeasterly and southwesterly through mid-week, prior to turning out of the north and northwest on Thursday & Friday as a 1002 mb low pressure center moves east of the open waters.
Periods of showers and thunderstorms are forecast from early to mid week, with conditions drying out by the end of the week & beginning of next weekend.

Quigley

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

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