Lake Forest, IL Marine Weather and Tide Forecast
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Marine Weather and Tide Forecast for Lake Forest, IL

June 16, 2024 6:01 AM CDT (11:01 UTC) Change Location
Sunrise 5:12 AM   Sunset 8:31 PM
Moonrise 3:20 PM   Moonset 1:49 AM 
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Marine Forecasts
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LMZ740 Winthrop Harbor To Wilmette Harbor Il- Wilmette Harbor To Northerly Island Il- Northerly Island To Calumet Harbor Il- 410 Am Cdt Sun Jun 16 2024

Today - South winds 15 to 20 kt. Slight chance of showers and Thunderstorms. Waves 2 to 4 ft.

Tonight - South winds 15 to 20 kt becoming southwest 10 to 15 kt. Slight chance of showers and Thunderstorms in the evening. Waves 2 to 4 ft subsiding to 1 to 2 ft.

Monday - South winds 10 to 15 kt increasing to 15 to 20 kt. Slight chance of showers and Thunderstorms in the afternoon. Waves 1 to 2 ft.

Monday night - South winds 15 to 20 kt. Mostly clear. Waves 1 to 3 ft.

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7 Day Forecast for Marine Location Near Lake Forest, IL
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Area Discussion for - Chicago, IL
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Area Forecast Discussion...CORRECTED National Weather Service Chicago/Romeoville, IL 346 AM CDT Sun Jun 16 2024


- A stretch of unseasonably warm and humid conditions will begin today and continue through the end of the week. Heat indices will be in the upper 90s to around 100 degrees at times.

- There is a 20-30% chance for a few thunderstorms today, mainly across northern Illinois.

- Chances for showers and storms from Monday onward are relatively low (30% or less), with expected limited coverage.

Issued at 339 AM CDT Sun Jun 16 2024

Through Monday:

Convection is ongoing early this morning from northeast Kansas through Iowa and into western/central Wisconsin as a shortwave trough tracks northeastward across the region. The current trajectory of the closest precipitation in eastern Iowa should keep the bulk of it west and north of our forecast area, though as an associated outflow boundary propagates eastward and isentropic ascent continues, additional cells may pop up south of the existing convective activity and track into the northern half or third of our CWA this morning. Therefore, have continued to carry chance and slight chance PoPs in the gridded forecast for this possibility, with the highest probabilities centered near/over the Rockford metro.

One thing that should not be overlooked as it pertains to today's forecast is the possibility of the convection currently in northeast Kansas evolving into an MCV that tracks into or near our forecast area this afternoon. Some model guidance had been hinting at this possibility yesterday, but the signal for this has been inconsistent from run to run in the models that have depicted such a scenario, which has lent low confidence to this solution verifying. Notably though, the 05Z HRRR jumped back onto the idea of an MCV tracking into northern Illinois this afternoon, and the 06Z run doubled down on that idea. The 06Z RAP advertises a similar outcome, albeit with a weaker MCV.
It's hard to put much stock into any one of these model runs when they have been bouncing back and forth on this like they have been, but if these latest HRRR and RAP runs are the beginning of a trend, then significant adjustments may need to be made to this afternoon and evening's forecast and to our messaging as if a relatively robust MCV makes it into northern Illinois, then part of the area would likely see thunderstorms this afternoon and/or evening, and these storms would have a decent chance at becoming strong to severe given that there should be plenty of instability (about 2000-2500 J/kg worth of MLCAPE)
around during this time. For now, just added some slight chance PoPs for this afternoon and evening to account for this low confidence possibility.

Regardless of how today plays out precipitation-wise, today will mark the beginning of a stretch of hot and muggy weather as the axis of a strong upper-level ridge stalls to our east and increasingly breezy southerly flow serves to advect warmth and moisture of Gulf origin into our CWA Dew points will climb from comfortable 50-55 degree readings this morning to much more humid values in the mid 60s to about 70 by mid-afternoon, while temperatures rise into the upper 80s and low 90s across the area. Peak heat indices are thus expected to top out in the mid 90s at most locations this afternoon.

Going into Monday, the upper-level ridge will remain locked in place, allowing for ample sunshine to further warm the newly arrived air mass. High temperatures are thus likely to end up being a few degrees warmer on Monday than they will be today.
There's still some uncertainty as to how much dew points will mix out on Monday, with HRRR forecast soundings suggesting that the 850-700 mb layer will be quite a bit drier than it will be today, possibly allowing for more efficient mixing to take place and scour out dew points more readily. Nevertheless, continued warm/moist advection off of southerly winds and evapotranspiration should offset this mixing to some degree and keep dew points from plummeting lower than the mid 60s, affording us another humid day. The degree of mixing that occurs shouldn't have a substantial effect on heat indices as lower dew points would mean that air temperatures would likely end up being a little higher, but our latest forecast grids have peak heat indices getting to about as high as 100 degrees, with some potential for them to end up being as high as 105 degrees if dew points struggle to mix out. Either way, it looks like we will fall shy of meeting Heat Advisory criteria.

Lastly, it remains possible that isolated to scattered pulse-type thunderstorms could be seen tomorrow afternoon. Most CAMs are quite bullish on thunderstorms developing and expanding in coverage as new convection bubbles along the outflow that they spit out. However, large-scale forcing for ascent looks pretty nebulous tomorrow, and it appears that we will see slight geopotential height rises as well, so the thinking is that the CAMs are a little overcooked with their output, and have continued to carry just slight chance PoPs for now with the expectation that their coverage should remain isolated to widely scattered at best in our CWA Nevertheless, wherever storms do develop, their rain-cooled outflow will provide temporary local relief from the heat and humidity, but there will also be some potential for strong to perhaps locally damaging downburst winds to occur as deep updraft cores collapse in an environment characterized by meager deep layer shear.


Monday Night through Saturday:

The northern fringes of a deeper moist plume advecting off the Gulf of Mexico will arrive in the area on Tuesday, and PWATs look to build towards 1.75-2 inches through the day. At least some increase in mid-level cloud cover looks to accompany this advancing moist plume, and this may curtail mixing a bit compared to Monday. This should result in slightly higher dewpoints and lower high temperatures, driving peak heat indices in the mid to upper 90s. Somewhat gustier southerly winds may help take some of the edge off though, and this is reflected with slightly lower wet bulb globe values compared to Monday. Large scale forcing still won't be significant, but low-amplitude vort lobes within the southwesterly steering flow will likely continue parading around the periphery of the sprawling east coast high. Isolated to widely scattered mainly afternoon shower/storm chances will continue, as a result.

Through Tuesday night, a southward-advancing cold front to our north looks to be pretty active across Iowa, Minnesota, and parts of Wisconsin with widespread convection. While it's possible some of this activity tries to ooze into our northwest into Wednesday morning, thickness gradients and LLJ orientations seem to point to any upwind propagating portions of MCSs building preferentially into southern Iowa, while the forward propagating components scoot across central/northern Wisconsin.

On Wednesday, the aforementioned cold front will have sagged further southward into southern Wisconsin as outflow from overnight activity pushes closer to our region. With diurnal thunderstorm activity igniting in a bit closer proximity, higher- end chance PoPs across northwest Illinois seem appropriate during the afternoon. The thermodynamic/kinematic parameter space suggests pulse convection will be the norm, with heavy rain (due to slow cell motions) and gusty winds as the main threats, if activity manages to sneak south of the Wisconsin state line. With the core of the parent upper ridge expected to be situated near Long Island, highs on Wednesday will probably be near where they were on Tuesday although there is a decent spread across the guidance suite. The latest gridded forecast shows heat indices generally in the mid and upper 90s again.

On Thursday, guidance suggests the east coast high may attempt to build farther west which would increase thicknesses locally and support a higher ceiling on air temperatures compared to the previous two days. However, it's possible the portion of the quasistationary boundary/cold front across southern Wisconsin starts to move southward, with some acceleration as a lake breeze/lake-enhanced boundary. Latest indications are this probably wouldn't occur until later in the day and for a small part of our forecast area across northeast and northern Illinois, but there's quite a bit of uncertainty regarding this evolution.
Ahead of wherever the front ends up during the afternoon, eyeing a potential for temperatures to surge a bit within the thickness bump ahead of the synoptic front, along with dewpoints to locally pool which could result in a corridor of notably higher peak heat indices. Pinpointing where (and if) this will set up remains too unclear to try to paint this in the grids for Thursday, but something we'll be keeping an eye on.

Looks like another toasty day on Friday as the front lifts back northward, but we'll eventually push a reinforcing front through here on Saturday or Sunday. This will bring increased chances for thunderstorms to the area along with a cool down into early next week.

Regarding heat headlines: while this continues to look like an extended stretch of anomalously warm and humid conditions, it still looks like we'll end up largely under local Heat Advisory criteria with peak heat indices generally near or under 100 degrees. However, if these values creep up a bit more, particularly Wednesday and Thursday, there could be an argument for an advisory due to the extended nature of 100+ values. We're not seeing a strong enough signal for this right now, however.


Issued at 1200 AM CDT Sun Jun 16 2024

- Threat for a few showers and TS after daybreak, mainly INVOF RFD, but can't discount the potential at the Chicago-area terminals

- Gusty SSW winds developing through Sunday

Southeast winds around 10 knots will slowly veer to the south and eventually southwest through mid-late morning today. Gusts will increase towards 25 knots during the afternoon before easing through the evening.

The potential for showers and a few embedded TS remains as a disturbance in Iowa tracks northeastward. Still not seeing enough to commit to TEMPO TSRA at RFD, so have maintained the PROB30 group 14-16z for the time being. Chances for showers and TS are a bit lower farther east at the Chicago-area terminals during the 14-17z time frame, but look too low to introduce anything at ORD, MDW, and GYY at this point. Will continue to monitor upstream trends tonight.


IN...Air Quality Alert until 1 AM EDT Monday for INZ019.


Weather Reporting Stations
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Stations Dist Age Wind AirWater WavesinHgDewPt
45186 9 mi32 minE 12G16 64°F 62°F2 ft
45174 13 mi42 minESE 14G16 66°F 63°F2 ft29.9360°F
45187 18 mi32 minSE 16G19 65°F 62°F3 ft
KNSW3 - Kenosha, WI 24 mi62 minSSE 8G8.9 64°F 29.94
OKSI2 26 mi122 minESE 4.1G6 72°F
CHII2 - Chicago, IL 27 mi42 minS 18G20 73°F 65°F
45198 29 mi32 minESE 9.7G14 68°F 65°F2 ft29.99
CNII2 30 mi32 minS 8.9G12 69°F 49°F
45199 34 mi62 minSE 19 61°F 60°F3 ft29.98
CMTI2 - 9087044 - Calumet, IL 39 mi44 minSSE 8G11 69°F 29.9553°F

Wind History for Calumet Harbor, IL
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Airport Reports
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AirportDistAgeWind ktVisSkyWeatherAirDewPtRHinHg
KPWK CHICAGO EXECUTIVE,IL 9 sm69 minS 0910 smClear70°F52°F53%29.96
KUGN WAUKEGAN NATIONAL,IL 12 sm70 minSSE 08G1910 smClear66°F57°F73%29.94
KORD CHICAGO O'HARE INTL,IL 19 sm70 minS 0910 smMostly Cloudy72°F52°F50%29.95
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Wind History graph: PWK
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