Monday, April19, 2021
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Marine Weather and Tides
Lake Forest, IL

Version 3.4
NOTICE
1/26/2021 -- The West Coast Satellite images havd been updated. They now use GEOS-17.
1/1/2021 -- The 7 day forecast are now working well. Thank you NOAA for your support.

Sunrise 6:01AMSunset 7:38PM Monday April 19, 2021 5:40 PM CDT (22:40 UTC) Moonrise 11:01AMMoonset 2:01AM Illumination 55% Phase: First Quarter Moon; Moon at 8 days in cycle
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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LMZ740 Winthrop Harbor To Wilmette Harbor- Wilmette Harbor To Northerly Island- Northerly Island To Calumet Harbor- 401 Pm Cdt Mon Apr 19 2021
Tonight..Northwest winds 10 to 20 kt easing to 10 to 15 kt this evening, then becoming north late. Slight chance of rain in the evening. Waves 1 to 3 ft.
Tuesday..North winds 10 to 15 kt becoming northeast in the afternoon. Chance of rain and snow. Waves 1 to 3 ft.
Tuesday night..Northeast winds 5 to 10 kt becoming north after midnight. Slight chance of rain in the evening. Slight chance of snow through the night. Waves 1 to 3 ft.
Wednesday..North winds 5 to 10 kt. Chance of rain and snow showers. Waves 1 to 3 ft.
LMZ740 Expires:202104200330;;811573 FZUS53 KLOT 192101 NSHLOT NEARSHORE MARINE FORECAST National Weather Service Chicago/Romeoville IL 401 PM CDT Mon Apr 19 2021 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>742-200330-


7 Day Forecast for Marine Location Near Lake Forest, IL
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location: 42.24, -87.86     debug


Area Discussion for - Chicago, IL
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FXUS63 KLOT 192029 AFDLOT

Area Forecast Discussion National Weather Service Chicago/Romeoville, IL 329 PM CDT Mon Apr 19 2021

SHORT TERM. 329 PM CDT

Through Tuesday night .

The threat of a late season snow on Tuesday, followed by freezing conditions Tuesday night, continue to be the primary focus during the short term period. Headline wise, we have transitioned the freeze watch to a warning for Tuesday night due to high confidence in freezing conditions.

A potent cold front pushed across much of far northern IL this morning. Currently this cold front is beginning to shift into central parts of the state. A strong temperature gradient is associated with this front. For example, as of the 2 PM hour, Pontiac (KPNT) was 45 degrees in the wake of the front, while Champaign (KCMI) was 68 degrees ahead of the front.

For the rest of this afternoon into early this evening expect a band of rain to continue near and south of the I-80 corridor. This is being driven by a band of low to mid-level frontogenesis to the north of the southward sagging surface boundary. The rain will end over much of northern IL (north of I-80) early this evening, though a few areas of rain may persist over my southern counties through the evening. Thereafter, we will await our next period of precipitation expected on Tuesday.

Water Vapor imagery this afternoon depicts the mid/upper level trough, and its associated upper level speed max in place over the northern Plains eastward into the Upper Midwest. Of main interest, however, is the embedded impulse currently digging southeastward over the Northern Rockies and High Plains. This feature will drive a developing storm system to our south near the surface frontal boundary on Tuesday as it digs into the Mid- Mississippi Valley. While this storm system does look to drive some snow and rain into most of the area beginning mid to late morning through the afternoon.

Trends in forecast guidance continue to support the heavier precipitation remaining to our southeast. For this reason, snow accumulations look to remain rather limited due to the marginal surface air temperatures and the warm ground surface during the daylight hours. With this being said, there is still the possibility for some minor slushy accumulations on grassy and elevated surfaces. This would especially be the case with any local enhancements to the snow that may occur. The best potential area for an inch or two of wet snow continues to be over my southeastern counties in closer proximately to some possible heavier rates.

While the widespread precipitation will begin to wane across the area early Tuesday evening, there are some signs that a lingering weak surface trough may linger into parts of northeastern IL Tuesday night and Wednesday. This could in turn act as the focus for some continued snow shower activity as low to mid-level lapse rates look to remain steep under the upper trough overhead. Otherwise, expect widespread freezing conditions Tuesday night. Since this looks to occur in spite of possible cloud cover and lingering snow shower activity we have opted to transition the freeze watch to a warning.

KJB

LONG TERM. 248 PM CDT

Wednesday through Monday .

Surface low pressure will be moving northeast into the Pennsylvania Wednesday morning with one upper trough axis exiting to our east with another moving into Iowa. Between the associated ascent inherent with the upper trough axis and cold air aloft leading to steep mid level lapse rates and instability, expect isolated to scattered convective showers. Given the forecast temp profiles, expect at least a mix of rain and snow/graupel with the more ominous and unstable soundings suggesting bursts of all snow possible as mixing would be quite deep into to the 600-700 mb range. May see a situation where air temps are well above freezing but wet bulb cooling associated with the showers pulls temps down. The concern is that this, combined with any more intense bursts of precip/snow, could lead to a very brief accumulation along with sharp visibility reductions under any more intense showers. With early morning temps in the upper 20s, more surfaces may be below freezing than we will see tomorrow but air temps will warm above freezing into midday. Still many details to work out but for now have gone with high temps lower than blended guidance and raised pops into the chance range for many areas. Expect to have to raise pops on upcoming shifts and possibly lower high temps. Will also need to keep an eye out for the need to add a mention of isolated thunder should instability trends continue or look more impressive.

By Thursday, upper ridging will approach and surface high pressure will pass to the south. Another nigh of lows around or below freezing is expected Wednesday night/Thursday morning so will likely need a frost or freeze headline. Dry and milder conditions are then expected during the day Thursday. The upper flow de- amplifies into Friday with a series of waves traversing the flow bringing additional rain chances Friday and Saturday. The warming trend will continue through the weekend with highs into the 50s to around 60, though flow off the lake to varying degrees will temper highs along the lakeshore each day. Additional warming is expected early next week as ensemble guidance shows upper ridging being in place which would support above normal high temps with a return to drier weather.

MDB

AVIATION. For the 18Z TAFs .

Aviation Forecast Concerns:

* Band of light rain mainly affecting MDW and moreso GYY through the afternoon. Intermittent MVFR cigs possible, mainly GYY.

* Snow/rain mix developing early Tuesday morning. MVFR cigs expected with some IFR visibility possible with periods of all snow, mainly before early Tuesday afternoon.

* Snow/rain showers may linger through Tuesday afternoon.

A cold front continues to sag south of the terminals early this afternoon with a band of light rain set up in its wake. The bulk of this band will impact MDW and GYY with some intermittent light rain still possible at ORD/DPA. GYY should see light rain showers linger through much of the evening with a lesser chance at ORD/MDW/DPA. West to northwest winds persist with occasional gusts to 20 kt in the Chicago area and a bit higher towards RFD. Mainly VFR cigs are expected through the afternoon but some occasional MVFR is possible with the rain band.

Another system will move into the area early Tuesday morning with colder air continuing to spread in. A mix of rain and snow is expected to develop prior to daybreak and affect the terminals through midday. Expect that there will be periods of all snow at times which may bring IFR visibility. Some slushy accumulation is possible, mainly on grassy and other non-paved surfaces. Still some questions as to how long precipitation will last into the afternoon, but latest signals point to some lingering shower activity with improving ceilings but there is still some chance that steadier precipitation may continue into at least part of the afternoon. Winds will turn north and northeasterly Tuesday morning but be from the northwest inland of Lake Michigan toward RFD.

MDB

LOT WATCHES/WARNINGS/ADVISORIES. IL . Freeze Warning . ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-ILZ010- ILZ011-ILZ012-ILZ013-ILZ019-ILZ020-ILZ021-ILZ023-ILZ032- ILZ033-ILZ039-ILZ103-ILZ104-ILZ105-ILZ106-ILZ107- ILZ108 . midnight Wednesday to 9 AM Wednesday.

IN . Freeze Warning . INZ001-INZ002-INZ010-INZ011-INZ019 . midnight Wednesday to 9 AM Wednesday.

LM . None.

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Weather Reporting Stations
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Stations Dist Age Wind Air TempWater Temp WavesPressureDewPt
WHRI2 - Waukegan Harbor, IL 9 mi100 min NW 11 G 19 45°F
FSTI2 21 mi100 min 39°F
KNSW3 - Kenosha, WI 24 mi40 min WNW 12 G 19 45°F 1012.2 hPa (+1.0)
OKSI2 26 mi100 min NNW 5.1 G 8 50°F
CHII2 - Chicago, IL 27 mi50 min WNW 15 G 19 47°F 30°F
CNII2 30 mi40 min WNW 11 48°F 26°F
CMTI2 - 9087044 - Calumet, IL 39 mi52 min SW 6 G 12 1012 hPa

Wind History for Calumet Harbor, IL
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Airport Reports
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AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
Chicago / Wheeling, Pal-Waukee Airport, IL9 mi48 minWNW 1210.00 miOvercast49°F25°F39%1012.8 hPa
Chicago/Waukegan Regional Airport, IL12 mi45 minWNW 810.00 miOvercast46°F27°F47%1012.3 hPa
Chicago, Chicago-O'Hare International Airport, IL18 mi49 minNW 1010.00 miOvercast49°F26°F41%1012.1 hPa

Link to 5 minute data for KPWK

Wind History from PWK (wind in knots)
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Last 24hrW10W7CalmW3S3SW3SW5SW5SW6SW7SW10SW10
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1 day agoNE7NE5NE3CalmCalmCalmCalmCalmCalmCalmCalmCalmCalmCalmS3S74435W6W6W10
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2 days agoE6NE5NE5E3CalmCalmCalmN3N4N4N3N5N4N6N56NE8NE7
G15
6NE6NE9E9E8NE8

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NOTE: This section has been updated as of 1/26/2021. If the image you are expecting is not showing, please let me know. You may use the EDIT function to update your location.
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