Chicago, IL Marine Weather and Tide Forecast
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Marine Weather and Tide Forecast for Chicago, IL

June 20, 2024 7:03 AM CDT (12:03 UTC) Change Location
Sunrise 5:13 AM   Sunset 8:30 PM
Moonrise 7:47 PM   Moonset 3:35 AM 
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NOTE: Some of the data on this page has not been verified and should be used with that in mind. It may and occasionally will, be wrong. The tide reports are by xtide and are NOT FOR NAVIGATION.

Marine Forecasts
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LMZ742 Expires:202406201515;;345465 Fzus53 Klot 201047 Nshlot
nearshore marine forecast national weather service chicago/romeoville il 547 am cdt Thu jun 20 2024
for waters within 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 waves, along with the average height of the highest 10 percent of the waves which will occasionally be encountered.
lmz740>742-201515- winthrop harbor to wilmette harbor il- wilmette harbor to northerly island il- northerly island to calumet harbor il- 547 am cdt Thu jun 20 2024

.dense fog advisory in effect until noon cdt today - .

Today - North winds 10 to 15 kt. Areas of dense fog this morning. Patchy fog in the afternoon. Slight chance of showers and Thunderstorms. Waves 1 to 3 ft.

Tonight - North winds 10 to 15 kt diminishing to 5 to 10 kt. Patchy fog in the evening. Slight chance of showers and Thunderstorms in the evening. Waves 1 to 3 ft.

Friday - North winds 5 to 10 kt becoming east in the afternoon. Slight chance of showers and Thunderstorms. Waves 1 to 2 ft.

Friday night - East winds 10 to 15 kt becoming south 5 to 10 kt overnight. Partly cloudy. Waves around 1 ft.

No data

7 Day Forecast for Marine Location Near Chicago, IL
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Area Discussion for - Chicago, IL
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Area Forecast Discussion National Weather Service Chicago/Romeoville, IL 337 AM CDT Thu Jun 20 2024


- Isolated to scattered storms are possible today along and north of I-80. Gusty winds will be possible, but organized severe weather is not expected.

- Hot and muggy conditions will prevail through Saturday, although cooler conditions are expected near Lake Michigan today and on Friday.

- Periodic chances for thunderstorms will continue, though most hours will remain dry.

Issued at 337 AM CDT Thu Jun 20 2024

Through Friday:

A cold front has moved into the CWA and brought light northerly winds to the northwest half of the area. Through the morning hours this front will retreat back to the north, setting up along the IL/WI state line. A backdoor cold front is also expected to advance down Lake Michigan and approach the area this morning. The backdoor front/lake breeze will likely be held up just inland, but will surge southward across northwest IL and northern IN early this afternoon into this evening.
Temperatures behind the backdoor front/lake breeze are much cooler than out ahead of it, so the timing of the front could impact high temperatures today. Areas that are unaffected by the backdoor front/lake breeze through roughly 18Z will see temperatures climb into the low 90s, bringing maximum heat indices into the mid 90s.

Behind the backdoor front/lake breeze, conditions appear favorable for marine fog to form this morning. This will decrease visibility over the lake and may seep slightly inland through the morning, but is not expected to persist inland into the afternoon.

The presence of both of these fronts brings a chance of showers and storms across the area this afternoon. Highest coverage will likely be along and north of I-80 where a band of 1000-1500 J/kg of MLCAPE is expected to build. Where all of these boundaries converge may also serve as a prime location for convective development. Any storms that are able to form here will likely move into the Metro area. Organized severe weather is not expected, although some storms may be able to produce gusty downburst winds. Coverage will be highest through the afternoon with some storms lingering into the evening hours, however, the overnight hours are expected to be dry.

Friday looks to be a fairly quiet day. A shortwave will move across Wisconsin bringing a chance of showers and storms into the far northern portion of the CWA, however, most areas should remain dry. Temperatures will return to the low-to-mid 90s except along the lakeshore where a lake breeze will keep things cooler. This will create heat indices in the mid-to-upper 90s away from the lake.


Friday Night through Wednesday:

A developing surface low to our west/northwest on Saturday will yield a tighter surface pressure gradient across the region.
This will afford us breezy southwesterly winds that will help facilitate warm air advection and push the warmth all the way up to the lakeshore for the first time in a few days. Saturday's highs are currently pegged to top out in the low to mid 90s across the area, and with dew points generally expected to span from the mid 60s to near 70F, this will translate to another day of heat indices peaking in the 95-100 degree range at most locations.

The cold front associated with the aforementioned surface low will press southeastward on Saturday as the low center approaches Lake Superior, and thunderstorms will likely develop along it as it does so. These storms will enter our forecast area from the northwest as early as the mid-late afternoon, but more likely during the evening, and continue southeastward into the night, likely weakening and diminishing in coverage with time as diurnal instability is lost. Deep-layer shear will be better than it has been the past several days given the presence of enhanced flow through the tropospheric column on the southeastern periphery of the deepening low pressure system, and with pre-frontal MLCAPE potentially pushing 2000-2500 J/kg, the overall kinematic and thermodynamic parameter space will likely allow for some of the frontal convection to become severe.
Whether any severe thunderstorms occur in our forecast area will largely hinge on the timing of the cold frontal passage.
An earlier frontal passage while diurnal instability is still plentiful would be more favorable for severe weather prospects here, while a later frontal passage would see convection arrive as the boundary layer stabilizes and our supply of instability has been depleted to some degree, thus keeping the potential for severe weather minimal. The Marginal (level 1/5) Risk introduced into the northwest half or so of our CWA in SPC's Day 3 Convective Outlook seems appropriate for now given the current distribution of frontal passage timing in the latest available deterministic and ensemble guidance.

A slow frontal passage could also see showers linger around into Sunday morning in our southeastern counties, but otherwise, no additional precipitation is expected on both Sunday and Monday as surface high pressure and a drier post-frontal air mass settle into the region. Averaged across our forecast area, both days should generally be cooler and less humid than the past few days, but high temperatures on both days still look like they'll end up being slightly above normal for late June.
Towards mid-week, a flattened ridge should build back into the southern Great Lakes and allow for 90+ degree air temperatures to make a return to the area on Tuesday. The presence of a baroclinic zone in the region could also present us an additional opportunity or two to see showers and storms mid-week next week.


Issued at 129 AM CDT Thu Jun 20 2024

Key Messages:

- Potential for low clouds and mist/fog early this morning and again early tomorrow (Friday) morning.

- Scattered showers and isolated thunderstorms expected this afternoon.

Fog is expected to develop along the Lake Michigan shoreline overnight and may then creep inland and affect ORD, MDW, and/or GYY -- most likely as low stratus, though some visibility reductions can't be ruled out from this either. Confidence in MVFR or lower conditions prevailing from this is currently low, so have continued to carry prevailing VFR conditions in the TAFs for now and will continue to monitor how things evolve. In addition, with the light winds, mostly clear skies, and moist boundary layer, patches of radiation fog may also develop inland and produce visibility reductions at DPA, GYY, and/or RFD before dissipating after sunrise.

Slightly better large-scale forcing for ascent today will likely lead to a greater coverage of showers and storms this afternoon compared to yesterday. In particular, a frontal boundary that is expected to stall out in the area today may serve as a focus for convective development near the terminals. Thunderstorm coverage may still only be isolated, though, due to a mid-level warm nose inhibiting vertical cumulus growth, and the hit-or-miss nature of these "pulse"-like storms lends low confidence to any one TAF site being impacted by a storm as well, so have continued to keep any TSRA mentions confined to PROB30 groups for now.
Needless to say, any deeper convection that develops this afternoon will likely produce sub-VFR visibilities and gusty winds. Shower and storm coverage will then dwindle this evening with the loss of diurnal instability.

Similar to early this morning, the overnight into early Friday morning time period should also be characterized by light winds, mostly clear skies, and a moist boundary layer in the wake of this afternoon's and evening's showers. Thus, it is possible that patches of fog may develop near DPA, GYY, and/or RFD once again and that marine-induced fog and/or low clouds may also ooze inland and affect ORD, MDW, and/or GYY once again.
Confidence in sub-VFR conditions being observed early tomorrow morning is currently low, though think that whatever happens this morning could be a harbinger for what might happen tomorrow morning.


Issued at 337 AM CDT Wed Jun 19 2024

After breaking a couple of temperature records this week, the high and warmest low temperature records for both today and Friday are unlikely to be broken, though Saturday's temperature records for both Chicago and Rockford could potentially be threatened.

Here are the daily high and warmest low temperature records for Chicago and Rockford for each day through Saturday, June 22nd:

Chicago ----------------------------- Day: 6/20 6/21 6/22 ----------------------------- Record High: 104 101 97 Record Warm Low: 78 74 76

Rockford ----------------------------- Day: 6/20 6/21 6/22 ----------------------------- Record High: 101 100 97 Record Warm Low: 73 71 73


IN...Air Quality Alert until midnight CDT /1 AM EDT/ tonight for INZ001-INZ002-INZ010-INZ011-INZ019.


Weather Reporting Stations
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Stations Dist Age Wind AirWater WavesinHgDewPt
CNII2 1 mi18 minN 7G11 69°F 64°F
45198 4 mi33 minN 12G14 66°F 65°F1 ft30.29
OKSI2 4 mi123 minN 5.1G7 69°F
CHII2 - Chicago, IL 5 mi43 minNNW 14G16 69°F 69°F
CMTI2 - 9087044 - Calumet, IL 9 mi45 minNW 5.1G9.9 67°F 30.2466°F
45174 20 mi43 minNW 7.8G9.7 65°F 64°F1 ft30.2465°F
BHRI3 - Burns Harbor, IN 28 mi83 minWSW 2.9G5.1 70°F 30.26
45170 34 mi43 min0G1.9 73°F 0 ft30.27
45186 37 mi33 minSSW 12G14 60°F 60°F1 ft
MCYI3 - Michigan City, IN 37 mi43 minESE 4.1G4.1 73°F 30.2269°F
45187 45 mi33 minN 12G16 58°F 57°F1 ft

Wind History for Calumet Harbor, IL
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