Sunrise 5:46 AM   Sunset 7:43 PM Moonrise 12:00 AM   Moonset 7:41 AM

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LMZ779 Expires:202404280315;;480859 Fzus63 Kmkx 271958 Glflm
open lake forecast for lake michigan national weather service milwaukee/sullivan wi 258 pm cdt Sat apr 27 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 -
low pressure around 29.5 inches over lake superior will continue to gradually weaken as it moves into ontario this evening. Gusty south winds are expected across lake michigan this afternoon, with a few gusts approaching or reaching gale force, especially in the northeast portion of the lake. Areas of dense fog may redevelop this evening over the northern portion of the lake as the winds become lighter, while dense fog may form over the southern portion of the lake late tonight into Sunday.
winds will then gradually shift from southwest to northerly tonight as a cold front tracks south, but southerly winds will continue over far southern lake michigan as the front stalls. Brisk northeast winds will then prevail over central lake michigan on Sunday with lighter winds in the north, and variable winds in the south where the stalled front remains. Modest east to southeast winds will then develop over all of the lake Sunday night as the stalled front moves north as a warm front. Brisk east winds, possibly reaching gale force, are expected over the northern tip of the lake late Sunday night into Monday morning. Breezy south winds will develop over the remainder of the lake on Monday.
rounds of showers and Thunderstorms are expected tonight into Monday morning. A few of these storms could produce locally gusty winds and hail.
lmz080-669-671-673-675-777-779-870-872-874-876-878-280315- 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- 258 pm cdt Sat apr 27 2024
sheboygan wi to pentwater mi south - .
Tonight - South winds to 30 kt diminishing to 10 to 20 kt. Chance of rain showers and Thunderstorms. Patchy dense fog overnight. Waves 4 to 7 ft occasionally to 9 ft subsiding to 2 to 4 ft. Sunday - Southeast winds 15 to 25 kt backing to northeast. Patchy dense fog in the morning, then patchy fog in the afternoon. Rain showers likely with a chance of Thunderstorms in the morning, then rain showers and slight chance of Thunderstorms in the afternoon. Waves 1 to 3 ft building to 4 to 7 ft occasionally to 9 ft. Sunday night - Northeast winds 10 to 20 kt veering to southeast. Patchy fog. Chance of rain showers and Thunderstorms in the evening, then rain showers with a chance of Thunderstorms overnight. Waves 4 to 6 ft occasionally to 8 ft subsiding to 3 to 5 ft. Monday - South winds 10 to 20 kt increasing to 15 to 25 kt. Chance of showers. Waves 4 to 6 ft occasionally to 8 ft building to 4 to 7 ft occasionally to 9 ft. Monday night - Southwest winds 10 to 20 kt becoming west 10 to 15 kt. Chance of showers in the evening. Waves 4 to 7 ft occasionally to 9 ft subsiding to 3 to 5 ft. Tuesday - West winds 10 to 15 kt becoming south 10 to 20 kt. Waves 1 to 3 ft. Tuesday night - Southeast winds 10 to 20 kt becoming south. Chance of showers. Waves 2 to 4 ft. Wednesday - Southwest winds 10 to 20 kt increasing to 15 to 25 kt. Waves 2 to 4 ft. Thursday - Southeast winds 10 to 20 kt becoming east. Chance of showers and Thunderstorms. Waves 1 to 3 ft.

LMZ700
No data

FXUS63 KLOT 272350 AFDLOT

Area Forecast Discussion National Weather Service Chicago/Romeoville, IL 650 PM CDT Sat Apr 27 2024

KEY MESSAGES

- Several waves of showers and thunderstorms are expected over the next 48 hours. A few storms may produce localized flooding and severe weather (mainly tonight).

- After a break on Tuesday, a stormy pattern will return toward the middle of next week.

- Above average temperatures will prevail through at least the middle of next week.

DISCUSSION
Issued at 251 PM CDT Sat Apr 27 2024

Through Sunday Night:

A stout upper-level shortwave continues to dig into the Southern Plains in the wake of a departing shortwave now lifting into Canada.
The resulting broad region of southwesterly flow across much of the Mississippi River Valley has led to a summer-like day with partly cloudy skies, temperatures in the mid to upper 70s, dew points in the lower 60s, and breezy southwest winds gusting over 35 mph.

We are watching two areas for the development of thunderstorms this evening. The first area is along a zone of low-level confluence extending from near Topeka, KS to Milwaukee, WI, ahead of locally pooling low-level moisture across northern Illinois.
Early attempts at the initiation of sustained convection have thus far failed across Iowa and far northwestern Illinois, likely owing to a strong cap sampled by an 18Z DVN RAOB based near 850mb. While a storm or two may develop within the confluence axis across eastern Iowa, northwestern Illinois, and southern Wisconsin over the next few hours, a rapid expansion of ongoing convection across northern Kansas into northern Missouri and southern Iowa toward sunset appears to be more likely as the aforementioned upper-level shortwave currently in the Southern Plains lifts northeastward and lifts/cools the cap.

The second area we are watching for thunderstorm development is across central Illinois, that is, south of US-24, within a gradually destabilizing open warm sector. With nebulous forcing (e.g. offset from the low-level confluence axis), the development of thunderstorms in the second area will depend entirely the erosion of a cap via warming and moistening of the boundary layer. Based on AMDAR soundings from aircrafts ascending/descending from ORD, temperatures around 78-79F and dew points near 65-66F are needed for free convection to take place. With that in mind, it may be several hours yet before sustained convective attempts can take place, or at least until the leading influence of the upper-level shortwave arrives.
Given impressively steep mid-level lapse rates across the warm sector (>8 K/km from the base of the cap to around 500mb as sampled by the 18Z DVN RAOB), convection will likely intensify rapidly once the cap is breached in either area and pose a threat for locally damaging wind gusts and hail. Note it's possible much of our area is completely dry through at least sunset if the cap holds tight.

This evening, the expectation is for convection across northern Missouri and southern Iowa to grow upscale and "meet" developing free convection across the open warm sector across central Illinois in tandem with the intensifying low-level jet. While the pattern does not resemble more typical regimes for warm season flash flooding, the prolonged forcing of the 925-850mb jet, availability of PWATs of 1.25-1.5", and weak upper-level jet diffluence may support a band of training convection across central Illinois through the overnight hours. If convection can repeatedly train over the same area tonight, 6-hour rainfall amounts of 2-4" may fall supporting a threat for flash flooding of low lying areas such as ditches, farm fields, and low-lying roadways. The past two runs of the HRRR and most recent available HRRR/RAP/RRFS guidance continues to suggest the threat zone for training convection will be near US-24, though operational experience suggests it may end up just to the north or (more likely) south of the advertised axis.

Now, for the fly in the ointment. Assuming the forthcoming MO/IA convection does meet developing convection across central Illinois this evening, any convection developing along the Wisconsin state line would become "choked" off from the low- level jet. However, if the central Illinois convection fails to develop and meet the MO/IA convection, the confluence axis across far northern Illinois would be the "hotpot" for storms this evening and overnight given the replenishing low-level jet will be able to lift much further northward. In such a scenario, an axis of 2-4 inches of rain would be displaced closer to the Wisconsin state line. Moreover, any upscale growth out of MO/IA would support at least decaying complex of gusty thunderstorms to move across most of our area after dark. At this point, it's not clear which scenario (axis across central IL or near the Wisconsin state line), is most likely.

Toward daybreak Sunday, the MUCAPE reservoir feeding the overnight convection (wherever it is) will become exhausted, allowing the low- level jet (e.g. the "advective" component offsetting any southward propagation via consolidated outflows) to push activity northeastward away from our area. Meanwhile, the remnants of what will likely become an expansive squall line across the Southern Plains will northeastward into northern Illinois after daybreak in the form of thicker cloud cover or decaying showers. Tomorrow will accordingly start out wet and cloudy. Ongoing isentropic ascent may support isolated to scattered showers throughout the day, but overall, there should be dry hours tomorrow. A few breaks in clouds should nevertheless allow for highs to reach the low to mid 70s, especially southeast of I-55.

The next wave of showers and storms will arrive tomorrow night as the well-advertised upper-level shortwave trough finally lifts into the Upper Mississippi River Valley. Compared to tonight, instability tomorrow night looks far more meager in spite of favorable kinematics for severe weather. For this reason, we favor a broken band of showers and storms (perhaps with gusty winds) to move through the region during the overnight hours.

Borchardt

Monday through Saturday:

The upper trough currently ejecting into the southern Plains is forecast to be lifting into the upper Midwest as an upper low in conjunction with a surface low on Monday which will force a cold front through northeast IL and northwest IN. Thus, shower and thunderstorm chances are expected to persist through Monday afternoon. While instability continues to look rather modest, the trajectory of the upper low into Wisconsin will position a stout 500 mb jet streak over the area generating around 30 to 35 kts of shear. Therefore, if the warm-moist advection ahead of the front can destabilize the atmosphere I would not be surprised to see some of the thunderstorms try to become better organized Monday afternoon, especially east of I-55. However, the progressive nature of the front does look to limit the window for ample instability and shear to overlap in our area and therefore confidence on any severe threat occurring is low at this time. Regardless, showers and storms are expected to end from west to east Monday evening as the front exits.

Heading into Tuesday, modest upper-level height rises are expected in the wake of the aforementioned front which will promote a period of dry weather for Tuesday. Though, the reprieve looks to be short lived as a series of shortwave troughs are forecast to develop and traverse across the north- central CONUS. This will result in periods of showers and thunderstorms beginning Tuesday night and persisting through at least the end of next week. While details on exact timing and intensity of storms remains fluid, the area is expected to remain under in an unseasonably warm pattern with afternoon highs forecast to be in the mid to upper 70s through Thursday.

Yack

AVIATION /00Z TAFS THROUGH 06Z MONDAY/
Issued at 650 PM CDT Sat Apr 27 2024

Key Aviation Messages: - Area of TS shifting across the Chicago terminals overnight.
- NE wind shift from TS outflow sometime mid-morning to early afternoon Sunday - Potential retreat of the outflow boundary and return toward S/SSE winds Sunday evening.
- Another round of possible TS late Sunday evening and overnight.

An enhanced mid-level disturbance near Kansas City will lift northeast toward northern Illinois overnight and interact with currently developing convection across eastern Iowa and southern Wisconsin. This should shift a somewhat organized area of TSRA eastward over the terminals generally in the 06-10Z window, with some lingering TS possible through sunrise Sunday. Outflow from this convection will then drift south into northern Illinois, turning winds NE at ORD and possibly MDW for much of Sunday afternoon. The onset time as well as the longevity of NE winds will depend heavily on the amount of convection over/near the region overnight. The current forecast depicts a NE wind shift by around noon, followed by a quickly veering SSE direction Sunday evening as a warm front surges back northward. If convection become rather robust overnight, ORD and possibly MDW may shift NE Sunday morning and remain NE or E through the remainder of the period. Additionally, MVFR ceilings north of the boundary/wind shift may lower in IFR levels at time.

The next round of potential convection will arrive late Sunday evening and especially after midnight Sunday night. A PROB30 for TS was included for 03-06Z (end of TAF period) to account for the potential for an earlier arrival of TS or scattered TS developing ahead of the main TS period.

Kluber

LOT WATCHES/WARNINGS/ADVISORIES
IL...None.
IN...None.
LM...Small Craft Advisory until 10 PM CDT this evening for the IL and IN nearshore waters.

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