Monday, July6, 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 5:21AMSunset 8:29PM Monday July 6, 2020 7:01 PM CDT (00:01 UTC) Moonrise 10:01PMMoonset 6:37AM Illumination 98% Phase: Waning Gibbous; Moon at 16 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:202007070330;;424205 Fzus53 Klot 061949 Nshlot Nearshore Marine Forecast National Weather Service Chicago/romeoville Il 249 Pm Cdt Mon Jul 6 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>742-070330- Winthrop Harbor To Wilmette Harbor- Wilmette Harbor To Northerly Island- Northerly Island To Calumet Harbor- 249 Pm Cdt Mon Jul 6 2020
Tonight..East to southeast winds 10 to 15 kt early, diminishing to 5 to 10 kt and becoming southwest overnight. Mostly clear. Waves around 1 ft.
Tuesday..Southwest winds 5 to 10 kt becoming southeast 10 to 15 kt in the afternoon. Chance of showers and Thunderstorms in the afternoon. Waves around 1 ft.
Tuesday night..Southeast winds 5 to 10 kt becoming south after midnight. Slight chance of showers and Thunderstorms in the evening. Waves 1 ft or less.
Wednesday..Southeast winds 5 to 10 kt. Sunny. Waves 1 ft or less.
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 062339 AFDLOT

Area Forecast Discussion National Weather Service Chicago/Romeoville, IL 639 PM CDT Mon Jul 6 2020

SHORT TERM. 227 PM CDT

Through Tuesday night .

Hot and gradually more humid weather will continue early this week, with slightly better chances of isolated to scattered afternoon thunderstorms Tuesday. With continued heat and generally light winds, air quality action days have also been extended through Tuesday for Chicago and northwest Indiana.

Stagnant pattern persists in the lower levels across the Midwest region early this afternoon. Temperatures continue to warm slowly into the lower and middle 90s, except for along Lake Michigan where the lake breeze has pushed inland a bit. Aloft, morning RAOB analysis and current GOES vapor imagery depict a subtle mid-level short wave tracking across the Upper Mississippi Valley from Minnesota into western Wisconsin. Ascent associated with this feature was cooing mid-level temps slightly, along with slight moistening in the 750-500 mb layer noted in DVN's morning sounding and an upward creep in surface dew point temps, has made for a slightly more extensive diurnal cumulus field across the region. GOES 1-min visible imagery has shown growth of towering cu along a few low level convergent zones early this afternoon, notably along the IL portion of the lake breeze boundary, and across our far southern tier of counties where a moisture discontinuity resides. Isolated deeper convective updrafts will be most likely along these boundaries late this afternoon into early this evening, though a few more subtle convergent features (such as over northeast DeKalb county) may also be able to support a few sustained deeper updrafts as well. While mid-level RH is slightly higher than previous days, it's still fairly dry aloft, and dry air entrainment into developing updrafts aloft will likely cause them to struggle for the most part. Thus convection will generally remain isolated, and only the deepest updrafts will likely produce lightning. As has been the case over the past few days, these convective cells will be largely diurnally forced and should diminish/dissipate with the approach of sunset.

Tuesday looks to be another basic repeat, though with a continued subtle increase in surface dew point temps leading to slightly more uncomfortable humidity and also increasing instability for diurnal thunderstorm development. CAM guidance depicts organized convection developing tonight well to our north across Minnesota and Wisconsin, with some indication in the high-res guidance that an outflow boundary may track southeast across southern Wisconsin into northern Illinois by early Tuesday morning. While none of the current CAM runs explicitly develop convection into our cwa early Tuesday, this boundary may very well become a focus for diurnal development of new convection across the area by midday, as well as the developing lake breeze boundary. Forecast soundings indicate mlcape values around 2000 J/kg by midday/early afternoon with upper 60s surface dew points and cooler mid-level temps, which would likely support greater coverage and strength for diurnal afternoon/early evening thunderstorms. Will continue to carry chance pops area-wide Tuesday afternoon, and while deep layer shear will remain fairly weak and thus limit any real severe potential some storms may be able to produce sub-severe wind gusts and heavy downpours. Scattered storms should diminish again during the evening with loss of diurnal heating and instability.

Temperature forecast for Tuesday is a little trickier than the past few days, due to the prospect for more cloud cover and scattered convection. Low level thermal fields are not much different however, and would still support lower 90s for afternoon highs in most areas away from the Lake Michigan shore. The slightly higher low level moisture levels should yield slightly warmer heat index values as well, with mid-upper 90s during the warmest part of the day.

Ratzer

LONG TERM. 314 PM CDT

Wednesday through Monday .

After a brief break from the upper ridge across the area on Tuesday, ridging will build back over the western Great Lakes from the southwest by Wednesday. The resultant subsidence inversion should be sufficiently strong to prevent deep convection, though as has been the case for several days, a rogue shower to brief thunderstorm cannot be ruled out where convergence is locally enhanced (i.e. lake breeze or stronger HCRs. Poor mixing with light winds and a capped environment will support an increase in dew points compared to recent days. With max temps generally in the 92-94F range, afternoon heat index values will approach or locally surpass 100F away from the Lake Michigan shoreline. With the more humid conditions, Wednesday night may be the warmest night of the year for most locations as min temps remain in the mid 70s across at least the Chicago heat island.

A convectively enhanced mid-level wave generated across the central Great Plains is then progged to drift across or near the CWA sometime Thursday into Thursday night, favoring a consensus timeframe around Thursday evening. This does create some uncertainty in max temps on Thursday, but if convection does hold off (including isolated afternoon diurnal convection), Thursday will likely be the warmest day of this recent stretch in terms of air temps and heat indices. In the absence on convection, max temps into the mid 90s and heat index values surpassing 100F are possible.

If the arrival of the wave is on the earlier side late Thursday afternoon and early evening, a modest increase in deep-layer shear to 20-25 knots across at least the north half of the CWA combined with a highly unstable environment would support strong to marginally severe convection.

Some relief from the heat is expected by Friday as a cold front shifts across the area behind the convection, with more seasonable temps in store for the weekend. Small chances of showers/storms will remain across the area with guidance indicating a small ripple or two traversing the western Great Lakes in broad northwest flow, but much of the period should remain dry.

Kluber

AVIATION. For the 00Z TAFs .

A couple isolated showers developing along the lake breeze in the VC of ORD/MDW should fade by sunset. Otherwise, look for more isold-sctd SHRA/TSRA to develop Tuesday afternoon, with greatest coverage likely around the lake breeze. Isold SHRA/TSRA possible Tuesday afternoon farther inland at DPA/RFD as well, though confidence is lower, so kept them dry for now.

- 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 mi16 min E 1.9 G 8.9 81°F 70°F
CHII2 - Chicago, IL 5 mi31 min E 11 G 12 82°F 74°F
CMTI2 - 9087044 - Calumet, IL 9 mi43 min E 6 G 8.9 83°F 1013.9 hPa71°F
45174 20 mi101 min ESE 7.8 G 9.7 80°F 78°F1 ft1014.3 hPa72°F
45170 34 mi61 min 7.8 G 7.8 81°F 79°F74°F
MCYI3 - Michigan City, IN 37 mi101 min NE 9.9 G 9.9 82°F 71°F
45187 45 mi41 min SW 3.9 G 3.9 79°F 76°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 mi68 minESE 810.00 miPartly Cloudy90°F63°F41%1012.8 hPa
Chicago, Chicago-O'Hare International Airport, IL18 mi70 minE 910.00 miMostly Cloudy91°F64°F42%1013.4 hPa
Gary Regional Airport, IN19 mi76 minENE 810.00 miA Few Clouds90°F66°F46%1014.6 hPa
Lansing Municipal Airport, IL22 mi66 minE 810.00 miFair90°F65°F45%1014.2 hPa
Chicago / Wheeling, Pal-Waukee Airport, IL24 mi69 minESE 610.00 miMostly Cloudy89°F64°F43%1014.1 hPa

Link to 5 minute data for KMDW

Wind History from MDW (wind in knots)
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Last 24hrE9E7SE6S4SE4S3W4W3CalmCalmCalmCalmCalmNE3CalmCalmCalmCalmW5NW5W6E10E10E8
1 day agoNE11NE7E4NE4E6NE5NE5NE3N4NE4CalmCalmCalmCalmCalmNE4E8E7E10
G15
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2 days agoE8E7E7E5CalmCalmCalmNW3N3NW3NW3CalmNW5N5N53CalmNE6NE5N7NE11NE10E10E10

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 Midwest    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.
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Other links: Northern Pacific     Contential US     Full GOES-East
Wind Forecast for Chicago, IL (20,4,5,8)
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Ground Weather Radar Station Chicago, IL
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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.