Thursday, February22, 2018 L-36.com


Marine Weather and Tides
Chicago, IL

Version 3.4
What's New / NOTES
6/25/2017 - NOAA is having a major issue that impact the 7 day forecast load times. Many users are reporting problems. The issue has been reported.
5/23/2017 - Worked with NOAA again to speed up the 7 day forecast load times. Thanks to them for being responsive.
5/19/2016 - There were issues with the 3 day airport observation history. I switched to another data source. Let me know if you see any issues with the data feeds.

Sunrise 6:33AMSunset 5:34PM Thursday February 22, 2018 8:33 PM CST (02:33 UTC) Moonrise 11:27AMMoonset 12:41AM Illumination 53% 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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LMZ742 Winthrop Harbor To Wilmette Harbor- Wilmette Harbor To Northerly Island- Northerly Island To Calumet Harbor- 800 Pm Cst Thu Feb 22 2018
Rest of tonight..Southeast winds 10 to 20 kt. Areas of fog. Rain likely. Waves 3 to 5 ft.
Friday..Southwest winds 10 to 20 kt becoming west in the afternoon. Chance of rain in the morning. Waves 2 to 4 ft subsiding to 1 ft or less in the afternoon.
Friday night..Northwest winds 10 to 15 kt becoming north after midnight. Mostly cloudy. Waves 1 ft or less building to 1 to 3 ft after midnight.
Saturday..East winds 15 to 25 kt. Chance of snow and light freezing rain in the morning. Chance of rain through the day. Waves 2 to 4 ft building to 3 to 5 ft in the afternoon. Wave forecast is for ice free areas
LMZ742 Expires:201802231015;;400199 FZUS53 KLOT 230200 NSHLOT NEARSHORE MARINE FORECAST National Weather Service Chicago/Romeoville IL 800 PM CST Thu Feb 22 2018 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>742-231015-

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 230158
afdlot
area forecast discussion
national weather service chicago romeoville, il
758 pm cst Thu feb 22 2018

Update
757 pm cst
the main forecast changes were slowing rain timing and adjusting
fog coverage tonight. Rain over much of iowa and southern il will
slowly shift east and north. We could see scattered light rain
showers closer to midnight, but steadier rain won't reach the i-39
corridor until after midnight. The showers will shift east
through early Friday morning. Steady above freezing temperatures
support liquid precipitation. Rainfall amounts of 0.1-0.2 inches
are expected, but the rain will not have a significant impact on
area rivers.

Areas of fog will develop after midnight, but only isolated areas
will see dense fog. Again, temperatures will be above freezing, so
freezing fog is not expected. Fog will dissipate mid Friday
morning.

Jee

Short term
138 pm cst
through Friday...

another round of precipitation in this active weather pattern will
arrive gradually through the evening, and more so overnight.

Fortunately for this go around, forecast profiles suggest the
p-type will be rain.

Dry surface easterly flow has kept conditions largely dry across
the area this afternoon. A surface warm front is well south of
the area, but southwest flow over the sloped frontal surface
closer to our neck of the woods is advecting more extensive low
clouds northward. Several disturbances will traverse the frontal
surface lead to occasional rain. The first batch which will be
less organized will come later this evening where moisture will be
a bit more shallow. Precipitation chances ramp up more so
overnight as the lower level frontal zone will get closer to the
area, and more pronounced lower level convergence occurs.

Dewpoints will head above freezing area wide, so p-type will be
rain. Expect rain to generally be on the lighter side, but brief
spurts of moderate rain are possible. QPF totals will peak up to
one quarter of an inch, though most areas will have much less.

After some morning clouds and fog, west-southwest winds will
become breezy with gusts to 20 maybe 25 mph. This should help to
bring some gradual clearing or at least lifting of clouds, though
at this point low level moisture may be stubborn enough to limit
much clearing until late in the day. In spite of that, slightly
above normal highs in the 40s (to near 50 south) will occur.

Kmd

Long term
220 pm cst
Friday night through Thursday...

main forecast concerns challenges are with a potentially more
robust system over the weekend that could bring both a period of
winter weather and a period of showers and thunderstorms.

High pressure that builds across the region at the start of the
period quickly departs, and quickly turn attention to mid upper
level trough expected to push through the central CONUS into the
weekend. Low pressure expected to develop over the central plains
Friday night into Saturday and then lift northeast throughout the
day. As this occurs anticipate precip to develop ahead of an
associated warm front. Still some uncertainty as to the placement
of this precip shield but guidance is beginning to indicate this
precip reaching as far north as i-80, or just slightly north, by
early Saturday morning. Still monitoring the potential of a wintry
mix across parts of the area, that does include a period of all
snow. Cold surface temps, widely varying thermal profiles, and the
presence of dry air will support the possibility for a wintry
mix. For locations from around i-80 south to the kankakee river
valley, a wintry mix of snow, sleet, and freezing rain will be
possible. The period of this chance of a wintry mix does not
appear to be overly long, maybe in the 3-6 hour time frame.

Warming surface temps and column will help transition this to all
rain by mid late Saturday morning. South of the kankakee river
valley, all rain is appearing likely. Rainfall in this location
should be on the lighter side, but a steadier rain is possible and
will need to monitor rainfall amounts.

A lull in the precip may occur during the day Saturday but as
this highly amplified trough and deepening surface low move into
the region late Saturday into Saturday night, additional periods
of all rain will be possible area wide. A couple of items to
monitor with this time frame will be with potentially higher
amounts of rainfall that could affect ongoing river flooding, as
well as the threat of thunderstorms. Given the strength of this
system, strong LLJ waa, and increasing instability, felt confident
to include slight chance thunder area wide early Saturday
evening. At this time, the threat of strong severe storms looks to
remain just south of the area. Precip will end during the
overnight hours Saturday night, with the arrival of colder and
drier air. On the backside of this system, winds do quickly
increase with strong winds gusts possibly becoming a concern late
Saturday night into Sunday morning.

Rodriguez

Aviation
For the 00z tafs...

the main forecast concern tonight into Friday morning is the
increasing potential for lifr CIGS and visibilities across the
area.

East-northeasterly winds across the area early this evening will
gradually veer south-southeastward overnight in association with
an area of low pressure over the plains shifting northeastward
into wisconsin. This low will shift a frontal boundary across the
area early Friday morning, with winds becoming westerly in its
wake during the day. Ample low-level moisture over the area ahead
of this boundary will lead to deteriorating CIGS through this
evening across the terminal sites. Overall, expect ifr CIGS to set
up over the area by, or shortly after 03z. CIGS are then likely
to fall into the lifr category overnight into early Friday morning
ahead of the approaching boundary. There is also increasing
concern for a period of low visibilities overnight in fog and some
light rain showers. It current appears that the lowest
visibilities could fall down around 1 2 mile overnight, mainly
west of the main chicago area terminals. For this reason, I have
hit the lower visibility potential a bit harder in the 00z tafs.

Conditions should gradually improve across the area during the mid
to late morning hours, though some MVFR CIGS may hold on over the
area into the afternoon.

Kjb

Marine
356 pm cst
the current east northeast winds will become all easterly early
this evening while winds increase, as low pressure approaches the
great lakes region. At the start of the weekend, high pressure
will move through the region and expect winds to be on the lighter
side. This quickly changes though as deepening low pressure is
expected to move across the region Saturday into Sunday. Continue
to monitor this period, Saturday night through Sunday, as gales
with varying direction will be possible over much of the
lake nearshore. Included with this are the possibility for higher
end gales to 45 kt. Also will need to monitor the possibility for
storm force winds for a time Sunday morning, mainly for the north
half of the lake. Do have growing confidence for gales, with lower
confidence on storm force winds. Given the time frame of these
gales and possible storm force winds, have not issued a watch yet.

Rodriguez

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 ESE 11 G 11 36°F 33°F
OKSI2 4 mi93 min ESE 4.1 38°F
CHII2 - Chicago, IL 5 mi43 min E 15 G 16 37°F 34°F
FSTI2 9 mi93 min ESE 12 37°F
CMTI2 - 9087044 - Calumet, IL 9 mi45 min E 7 G 9.9 37°F 1028.3 hPa35°F
BHRI3 - Burns Harbor, IN 28 mi53 min E 9.9 G 16 40°F 1029.8 hPa
WHRI2 - Waukegan Harbor, IL 37 mi53 min E 12 G 13 35°F
MCYI3 - Michigan City, IN 37 mi43 min E 11 G 16 39°F 33°F

Wind History for Calumet Harbor, IL
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Last
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1 day
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W10
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G31
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Airport Reports
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AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
Chicago, Chicago Midway Airport, IL9 mi40 minE 910.00 miOvercast40°F34°F79%1029.3 hPa
Chicago, Chicago-O'Hare International Airport, IL18 mi42 minE 13 G 1810.00 miOvercast40°F32°F73%1028.4 hPa
Gary Regional Airport, IN19 mi48 minE 1410.00 miOvercast43°F35°F76%1029.5 hPa
Lansing Municipal Airport, IL22 mi38 minE 10 G 1510.00 miOvercast40°F37°F89%1028.8 hPa
Chicago / Wheeling, Pal-Waukee Airport, IL24 mi41 minE 8 G 1710.00 miOvercast39°F32°F76%1029.2 hPa

Wind History from MDW (wind in knots)
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Last 24hrNE13NE11NE10NE15NE13NE11NE11NE12NE13NE12NE12NE9E9NE15E15E14E15
G21
E15NE15E17E11NE9E10E9
1 day agoNW8W8NW9NW10N10NW11N10NW14NW12NW13NW11N12N8N9N7NE10NE10NE11N10NE11NE10NE12NE11NE14
2 days agoS15
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SW11W5SW12SW8SW14
G20
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G25
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W16
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W7SW8W10W12W12NW7

Tide / Current Tables for
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Tide / Current Tables for
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Weather Map and Satellite Images
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Weather Map
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IR Satellite Image from GEOS
east_satellite

GOES Local Image of Midwest    EDIT
Geos

Wind Forecast for Chicago, IL (21,6,7,8)
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Ground Weather Radar Station Chicago, IL
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weather_mapweather_map weather_map

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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 numerious 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.