Saturday, July4, 2020
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Marine Weather and Tides
Chicago, IL

Version 3.4
NOTICE
12/16/2019 NOAA is having trouble with requests that include wind gusts. I am posting graphs without wind gusts until it gets fixed.
10/9/2019 Updated the Marine Zones.
9/4/2019 Fixed the weather maps due to NOAA moving them.
7/25/2019 New feature in the Airports section gives a link to 5 minute updates for data reports.

Sunrise 5:19AMSunset 8:30PM Saturday July 4, 2020 8:48 PM CDT (01:48 UTC) Moonrise 8:23PMMoonset 4:37AM Illumination 100% Phase: Full Moon; Moon at 14 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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LMZ742 Expires:202007050330;;316807 Fzus53 Klot 041947 Nshlot Nearshore Marine Forecast National Weather Service Chicago/romeoville Il 247 Pm Cdt Sat Jul 4 2020 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>742-050330- Winthrop Harbor To Wilmette Harbor- Wilmette Harbor To Northerly Island- Northerly Island To Calumet Harbor- 247 Pm Cdt Sat Jul 4 2020
Tonight..Northeast winds 10 to 15 kt early becoming north at 5 to 10 kt overnight. Hazy. Waves 1 to 2 ft.
Sunday..North winds 5 to 10 kt becoming east around 10 kt by afternoon. Sunny. Waves 1 to 2 ft.
Sunday night..East winds 5 to 10 kt becoming south after midnight. Mostly clear. Waves around 1 ft.
Monday..South winds 5 to 10 kt becoming southeast around 10 kt in the afternoon. Sunny. Waves around 1 ft.
LMZ742


7 Day Forecast for Marine Location Near Chicago, IL
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location: 41.85, -87.6     debug


Area Discussion for - Chicago, IL
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FXUS63 KLOT 042320 AFDLOT

Area Forecast Discussion National Weather Service Chicago/Romeoville, IL 620 PM CDT Sat Jul 4 2020

SHORT TERM. 208 PM CDT

Through Sunday night .

Weak surface high pressure will remain in place across the western Great Lakes region through the remainder of the Independence Day weekend. Hot and slightly more humid weather will persist, with lake breezes cooling areas near Lake Michigan. An isolated afternoon shower or thunderstorm can't be completely ruled out, though the likelihood remains quite low.

Early afternoon GOES water vapor imagery depicts a weak mid-level short wave propagating southeast across southern Lake Michigan and adjacent portions of lower Michigan and northern Indiana. RAP initialized soundings indicate fairly dry thermodynamic profiles above the boundary layer, which along with relatively warm mid-level temps and poor mid-level lapse rates should limit development of any extensive cloud cover. Regional surface obs do show that boundary layer dew points have crept up a bit, especially within the marine layer off of Lake Michigan where dew points in the upper 60s/around 70 were noted, as well as hazy conditions over the cooler lake waters. Thus while temps across the region are fairly similar to this time yesterday, the heat index has nudged up a bit, with some low-mid 90s observed early this afternoon. Warm/dry sounding profiles are generally not favorable for convective development, an isolated afternoon shower or thunderstorm can't be completely ruled out in the vicinity of the lake breeze boundary, where slightly higher marine-influenced dew points and localized convergence could perhaps produce deeper convective updrafts during peak heating. Better chances will exist farther east/southeast into Indiana however, where slightly cooler mid-level temps will be found beneath the aforementioned mid-level short wave.

More of the same appears to be in store for the region Sunday, though with a slight increase in low level warmth. Temps in the 925- 850 mb layer are progged to warm a Celsius degree or so on Sunday, supporting temps solidly into the lower 90s away from the Lake Michigan shore, and probably a mid-90 reading in a spot or two. With surface dew point temps again in the mid-upper 60s during peak heating, the heat index will likely top out in the mid 90s for the most part, with a few upper 90s possible. Similarly to today, an isolated shower or thunderstorm is not completely out of the question, with the afternoon lake breeze boundary again the primary focus for initiation, though as today the potential for any isolated storms looks to be greater off to the east of the cwa across southwest Michigan and north central Indiana. Nighttime conditions both tonight and Sunday night will be mostly clear/partly cloudy, with mild overnight temps from the mid-60s to lower 70s.

Ratzer

LONG TERM. 249 PM CDT

Monday through Saturday .

Hot and increasingly humid weather continues to be the key message for the long term period as the area remains locked within a persistent summertime pattern. This continues to be the primary forecast concern, especially considering we could be approaching heat advisory criteria (Heat indices around 105 degrees) in some areas Wednesday and Thursday.

Monday still is appearing to be a precipitation free day across most of the area, as we continue to only carry some slight chances for afternoon isolated storms. Humidity will increase a bit Monday, but heat indices should remain at or below 100, with actual temps in the low 90s inland from the lake. Cooler afternoon temperatures (in the lower 80s) are likely near the lake due to the likelihood of an lake breeze.

The heat and humidity will ramp up by mid week as heights aloft build across the Mississippi Valley and lower Great Lakes concurrently with the northward flux of the humid airmass currently residing to our south. The net result of this will be hot and humid conditions Tuesday through at least Thursday, with Wednesday and Thursday potentially being the most oppressive. Temperatures on these days are forecast to be into the mid 90s, with dew points into the lower 70s, which would support heat indices in the 100 to 105 range.

Unlike the last few days, we will have some occasional diurnal thunderstorm chances with the arrival of this very humid airmass. Capping should become minimal, so we cannot rule out the possibility for some isolated to widely scattered afternoon storms at times Tuesday through Thursday. While this is the case, the best potential for a higher coverage of thunderstorms is looking to be late Thursday into Friday as a more substantial mid-level disturbance and surface cold front approaches.

KJB

AVIATION. For the 00Z TAFs .

Some minor VSBY restrictions in smoke from fireworks could occur later this evening, particularly at MDW, though with far fewer firework shows than normal, confidence is low. Cannot rule out some brief MVFR VSBY at RFD with BR/HZ pre-dawn Sunday. Otherwise, look for VFR conditions and light winds through the TAF cycle.

- Izzi

LOT WATCHES/WARNINGS/ADVISORIES. IL . None. IN . None. LM . None.

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Weather Reporting Stations
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Stations Dist Age Wind Air TempWater Temp WavesPressureDewPt
CNII2 1 mi33 min N 5.1 G 8.9 74°F 68°F
CHII2 - Chicago, IL 5 mi48 min N 7 G 7 76°F 74°F
CMTI2 - 9087044 - Calumet, IL 9 mi54 min N 5.1 G 7 76°F 1014.8 hPa72°F
45174 20 mi18 min NNW 3.9 G 5.8 74°F 75°F1 ft1015 hPa72°F
45170 34 mi18 min 3.9 G 7.8 76°F 76°F1 ft74°F
45187 45 mi28 min NNE 3.9 G 3.9 75°F 74°F1 ft

Wind History for Calumet Harbor, IL
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Airport Reports
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AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
Chicago, Chicago Midway Airport, IL9 mi55 minNE 710.00 miA Few Clouds82°F66°F60%1013.8 hPa
Chicago, Chicago-O'Hare International Airport, IL18 mi57 minNE 810.00 miA Few Clouds83°F64°F55%1014.6 hPa
Gary Regional Airport, IN19 mi63 minNNE 410.00 miClear77°F75°F94%1015.6 hPa
Lansing Municipal Airport, IL22 mi53 minNE 510.00 miFair78°F68°F72%1015.2 hPa
Chicago / Wheeling, Pal-Waukee Airport, IL24 mi56 minNE 510.00 miFair82°F62°F51%1015.1 hPa

Link to 5 minute data for KMDW

Wind History from MDW (wind in knots)
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Last 24hrE7E5CalmCalmCalmNW3N3NW3NW3CalmNW5N5N53CalmNE6NE5N7NE11NE10E10E10NE11NE7
1 day agoNE4E4E4E4CalmW3CalmNW4CalmCalmNW3CalmW3NW53SE6NE9NE9E94E11
G16
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2 days agoE6E7CalmN4N3NE3NE3CalmN3N3NE4E5E6E7E8E8
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E8NE11NE11NE9NE9

Tide / Current Tables for
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Tide / Current Tables for
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Weather Map
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wmap_A
GEOS Local Image of    EDIT
NOTE: East coast views moved to GEOS-16. They are experimental and not well supported by NOAA so they may not be correct so be warned. This change required redoing a large amount of the GOES code. If the image you are expecting is not showing, please let me know. You may need to use the EDIT function to update your location.
Link to Loop

Other links: Northern Pacific     Contential US     Full GOES-East
Wind Forecast for Chicago, IL (21,6,7,8)
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Ground Weather Radar Station Chicago, IL
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Disclaimer:
The information on this web site has not been checked for accuracy. It is for entertainment purposes only and should be independently verified before using for any other reason. There are five sources. 1) Documents and manuals from a variety of sources. These have not been checked for accuracy and in many cases have not even been read by anyone associated with L-36.com. I have no idea of they are useful or accurate, I leave that to the reader. 2) Articles others have written and submitted. If you have questions on these, please contact the author. 3) Articles that represent my personal opinions. These are intended to promote thought and for entertainment. These are not intended to be fact, they are my opinions. 4) Small programs that generate result presented on a web page. Like any computer program, these may and in some cases do have errors. Almost all of these also make simplifying assumptions so they are not totally accurate even if there are no errors. Please verify all results. 5) Weather information is from numerous of sources and is presented automatically. It is not checked for accuracy either by anyone at L-36.com or by the source which is typically the US Government. See the NOAA web site for their disclaimer. Finally, tide and current data on this site is from 2007 and 2008 data bases, which may contain even older data. Changes in harbors due to building or dredging change tides and currents and for that reason many of the locations presented are no longer supported by newer data bases. For example, there is very little tidal current data in newer data bases so current data is likely wrong to some extent. This data is NOT FOR NAVIGATION. See the XTide disclaimer for details. In addition, tide and current are influenced by storms, river flow, and other factors beyond the ability of any predictive program.