Monday, September25, 2017 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 6:41AMSunset 6:42PM Monday September 25, 2017 3:44 PM CDT (20:44 UTC) Moonrise 11:56AMMoonset 10:07PM Illumination 27% Phase: Waxing Crescent; Moon at 5 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- 301 Pm Cdt Mon Sep 25 2017
Tonight..Southeast winds around 10 kt becoming south 5 to 10 kt in the late evening and overnight. Mostly clear. Waves 1 to 2 ft.
Tuesday..Southwest winds 5 to 10 kt. Mostly Sunny. Waves 1 ft or less.
Tuesday night..Northwest winds 10 to 15 kt increasing to 15 to 20 kt after midnight. Slight chance of showers and Thunderstorms in the evening. Waves 1 ft or less building to 2 to 4 ft after midnight.
Wednesday..North winds 15 to 20 kt. Mostly Sunny. Waves 2 to 4 ft.
LMZ742 Expires:201709260345;;923297 FZUS53 KLOT 252001 NSHLOT NEARSHORE MARINE FORECAST National Weather Service Chicago/Romeoville IL 301 PM CDT Mon Sep 25 2017 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>742-260345-

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 251922
afdlot
area forecast discussion
national weather service chicago romeoville, il
222 pm cdt Mon sep 25 2017

Short term
222 pm cdt
through Tuesday...

looking at hot but quiet conditions through this afternoon.

Cumulus clouds have sprouted across the region, but not expecting
any precip given 30 degree dewpoint depressions at the surface. A
lake breeze is pushing inland lowering 90 degree temps into the
upper 70s to low 80s. Low temps tonight will be in the mid 60s,
while chicago will be around 70.

Winds become southwest ahead of a front Tuesday morning, and
cloud cover increases. Kept high temps in the upper 80s, but cloud
cover will likely limit warming. 90s are more likely along and
east of i-55 where clouds will take longer to arrive.

I have low confidence in measurable precip Tuesday as the front
moves through the region. The main upper level wave will separate
itself from the front as the wave shifts northwest over minnesota.

Forcing along the front is forecast to weaken as the front moves
through. When I also factor in the recent dry spell, I think
showers and storms will struggle to form.

The best chance for showers and storms will be around rockford
Tuesday afternoon, but isolated showers and storms may occur from
a waukegan to amboy, il line. Severe storms are not expected as
cape will be less than 500 j kg and shear will be around 30 kt.

Jee

Long term
222 pm cdt
Tuesday night through Monday...

a return to more seasonably average temps is expected mid-week,
before a brief push of colder air arrives Friday and lingers into
the start of the weekend. Other than fairly minimal chances of
showers with the two cold fronts (Tuesday night and early Friday
morning), our dry spell looks to persist through the coming week.

However, a few lake effect showers may bring some spotty rain
mainly to parts of northwest indiana with the cooler weather at
the end of the week.

Guidance remains in good agreement in moving a cold front east
across the forecast area Tuesday evening overnight. While the
presence of a boundary moving into our unseasonably warm air mass
would suggest the threat of showers thunderstorms, the mid-level
short wave associated with low pressure moving through the
northern great lakes is well to our north, with the stronger and
better focused forcing for large scale ascent. In addition, while
surface dew points pool in the mid-60's ahead of the front,
southwesterly winds aloft maintain deeper moisture transport well
north of the cwa. Forecast soundings indicate relatively weak
lapse rates above the immediate boundary layer as well, yielding
weak instability with a bit of weak capping as well. Earlier
sunset times and loss of this diurnal instability will also be
working against significant convective shower thunderstorm
coverage, and model QPF is light and decreasing with eastward
progress of the front as well. All of this points to maintaining
only low slight chances pops along the front for Tuesday
evening night.

Cooler air spreads in behind the front on Wednesday and Thursday,
as high pressure ridge spreads east southeast across the area.

Low level thermal fields support daytime temps in the low-mid 70's
Wednesday with decreasing cloud cover on breezy north-northwest
winds. Mainly clear skies and light winds in the vicinity of the
surface ridge axis will likely allow for fairly cool min temps
across parts of the forecast area dipping into the low-mid 40's by
sunrise Thursday. NAM depicts dew point temps in the mid-upper
30's across northwest north central il within the surface ridge
axis early Thursday, suggesting some cooler spots may be possible
there. Thursday should see temps similar to Wednesday. With the
cooler air over warm lake waters, lake effect stratocu is likely
downwind of lake michigan into northwest indiana, through shallow
convective cloud depth and dry air may not support precip with
this first push of cooler air.

Medium range guidance solutions continue to indicate another
digging mid-level short wave will amplify the trough across the
great lakes region Thursday night, with a reinforcing push of
colder air arriving behind an associated cold front which arrives
very late Thursday night early Friday morning. Forecast soundings
depict fairly dry thermodynamic profiles with rain shower
potential looking fairly minimal with the front, and little no qpf
generated. While guidance has trended a little more
progressive less closed off with amplifying mid-level trough, h8
temps still drop into the +3 to +4c range across the region. This
sets the stage for daytime temps only in the 60's fri-sat (and
perhaps only low-mid 60's in many spots Saturday). Colder air
aloft should support lake effect cloud cover into northwest
indiana and perhaps some showers, as lake surface to h8 delta-t
increases to 15 16c, and convective cloud depth is significantly
deeper. Flow turns more northeasterly Saturday as surface high
builds in from the northwest, which may bring some lake clouds
into northeast il.

With amplified but progressive upper pattern indicated,
moderation in temps occurs back to around average for early
october for Sunday and Monday. Return flow becomes more
established across the plains and mississippi late in the period,
which along with moderation in temps would potentially bring the
next chance for more organized rain Monday, or more likely
Tuesday.

Ratzer

Aviation
For the 18z tafs...

light winds andVFR conditions are being reported across the area
on the backside of departing high pressure.VFR CU will continue
to form this afternoon. A lake breeze is pushing inland, and looks
like it will reach ord and mdw btwn 21z and 22z. I have medium-
high confidence in when the lake breeze will turn winds easterly
at ord and mdw. At least the initial push of wind should be around
10 kt.

Winds become southwest ahead of a front Tuesday morning.VFR
clouds increase, but I have low confidence in precip occurring.

The main wave of upper level energy will lift northwest over
minnesota and southern ontario. Meanwhile energy along the front
is forecast to weaken as it moves through the region. Throw in the
dry spell, and I think showers will struggle to form. However, if
any isolated showers or storms form, they will be near rfd after
18z. I doubt that any of the eastern sites will receive precip.

Jee

Marine
222 pm cdt
the western edge of a high pressure ridge will extend over the
western great lakes while a front will extend from northwest wi
through western ia. Southerly winds will become northwest to
north 15-25 kt behind the cold front Tuesday night. A small craft
advisory may be needed for the in nearshore waters. Another strong
push of northerly winds is expected Friday morning behind another
cold front. While low end gales will be possible, northerly winds
will be at least 25-30 kt through Friday evening, and a small
craft may be needed. High pressure will spread over the lake
Saturday. Winds will diminish and become southernly by Sunday
morning.

Jee

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 mi30 min 79°F
OKSI2 4 mi105 min ESE 2.9 82°F
CHII2 - Chicago, IL 5 mi45 min ESE 16 G 17 79°F 67°F
JAKI2 5 mi105 min ESE 6 78°F
FSTI2 9 mi105 min ESE 5.1 76°F
CMTI2 - 9087044 - Calumet, IL 9 mi45 min ENE 9.9 G 13 82°F 1013.6 hPa (-1.7)65°F
45174 20 mi25 min ESE 9.7 G 14 76°F 72°F1 ft69°F
BHRI3 - Burns Harbor, IN 28 mi65 min SSE 7 G 12 89°F 1014.9 hPa
45170 34 mi25 min ENE 3.9 G 5.8 79°F 76°F69°F
WHRI2 - Waukegan Harbor, IL 37 mi65 min S 5.1 G 7 81°F
MCYI3 - Michigan City, IN 37 mi45 min NNW 2.9 G 5.1 87°F 56°F

Wind History for Calumet Harbor, IL
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Airport Reports
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AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
Chicago, Chicago Midway Airport, IL9 mi52 minE 1010.00 miPartly Cloudy91°F57°F32%1012.4 hPa
Chicago, Chicago-O'Hare International Airport, IL18 mi54 minSE 1010.00 miPartly Cloudy92°F55°F29%1012.8 hPa
Gary Regional Airport, IN19 mi60 minE 610.00 miPartly Cloudy90°F48°F24%1014.6 hPa
Lansing Municipal Airport, IL22 mi50 minS 510.00 miFair89°F61°F40%1014.2 hPa
Chicago / Wheeling, Pal-Waukee Airport, IL24 mi53 minESE 910.00 miFair91°F60°F35%1013.7 hPa

Wind History from MDW (wind in knots)
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Last 24hrSE7E11E10E7E6E4SE3CalmS5S5S5S4S5S3S5S4S4S6S5S6SE6CalmE5E10
1 day agoE12E11E10E7E6E6E5E3E4SE5SE5SE4SE3S3S3S4S5S5SW5SW4SW6S10
G15
S6S9
2 days agoS7S9S6S6SE7E8SE7SE5SE3S6SW3CalmCalmS4S4S5S4S4SW3S43E4SE3E11

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
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GOES Local Image of Midwest    EDIT
Geos

Wind Forecast for Chicago, IL (16,3,4,5)
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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 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.