Saturday, February23, 2019 L-36.com


Marine Weather and Tides
Chicago, IL

Version 3.4
What's New / NOTES
10/6/2018 Colors of tide XTide graphs changed to emphasize that they were upgraded. See next note. Comments welcome.
10/4/2018 I have fixed XTide and updated the harmonic files. There were some name changes so you might have to click EDIT to find the new station name.

Sunrise 6:33AMSunset 5:34PM Saturday February 23, 2019 6:47 PM CST (00:47 UTC) Moonrise 11:36PMMoonset 10:11AM Illumination 79% Phase: Waning Gibbous; Moon at 19 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:201902240400;;407106 Fzus53 Klot 232223 Aaa Nshlot Nearshore Marine Forecast...updated National Weather Service Chicago/romeoville Il 423 Pm Cst Sat Feb 23 2019 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>742-240400- Winthrop Harbor To Wilmette Harbor- Wilmette Harbor To Northerly Island- Northerly Island To Calumet Harbor- 423 Pm Cst Sat Feb 23 2019
.dense fog advisory in effect until 10 pm cst this evening...
.gale warning in effect from 3 am cst Sunday through Sunday morning...
.storm warning in effect from Sunday morning through Sunday evening...
.gale warning in effect from Sunday evening through late Sunday night...
Tonight..East winds 10 to 20 kt becoming southeast to 30 kt this evening, then becoming south by late evening, then becoming southwest gales to 40 kt late. Areas of dense fog this evening. Showers. Slight chance of Thunderstorms. Waves 2 to 4 ft building to 4 to 6 ft occasionally to 8 ft.
Sunday..West storm force winds to 50 kt. Scattered snow showers in the morning. Freezing spray in the afternoon. Waves 5 to 8 ft occasionally to 10 ft.
Sunday night..West gales to 45 kt diminishing to gales to 35 kt after midnight. Heavy freezing spray. Waves 4 to 7 ft occasionally to 9 ft subsiding to 4 to 6 ft occasionally to 8 ft after midnight.
Monday..West winds 15 to 25 kt becoming northwest 10 to 15 kt in the afternoon. Freezing spray in the morning. Slight chance of snow in the afternoon. Waves 3 to 5 ft subsiding to 1 to 3 ft in the afternoon. Wave forecast is for ice free areas
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 240004
afdlot
area forecast discussion
national weather service chicago romeoville, il
604 pm cst Sat feb 23 2019

Short term
255 pm cst
through tonight...

a plethora of weather over the area the next 24 hours as can be
common when a deep low pressure center passes directly over an
area during a transition season. For tonight, the overall threat
of high impact weather for most of the night looks lower, but
several things to keep an eye on. A high wind warning GOES into
effect at 3 a.M., with strong winds advancing from west to east
across the area during the pre-dawn sunrise period.

The elevated warm sector continues to overspread the area, with a
somewhat diffuse but assisting coupled upper jet providing
forcing for areas of showers. The showers have been frequent
enough to allow churning mixing of the lowest levels and prevent
much dense fog along an otherwise favorable warm frontal trough
over northern central illinois. These arcs of showers should
continue to lift over the area through the evening, with pockets
of drizzle in-between. With stronger forcing overspreading during
the evening and MUCAPE values of 300-700 j kg, would expect some
deeper updrafts for february with isolated to scattered storms.

Convective-allowing models such as the hrrr have indicated this
throughout today. A few could have small hail and some will have
brief heavy rain that may allow for spotty nuisance ponding on
roads. As for anything lower-level based later this evening, this
continues to look like a very limited possibility. The surface
triple point will struggle to have an effective air mass in the
immediate low-levels with it, given surface temperatures peaking
in the mid 50s in the southeast CWA this evening and robust
convection in the upstream flow. Will still be something to keep
an eye on for the mid-evening time given the synoptic pattern and
dynamics, and there could still be a few more robust storms in the
southeast cwa, but the trend has been favorable to keep an
isolated wind brief tornado threat south.

With the upper wave becoming increasingly negatively tiled this
evening, the surface low will deepen to below 990 mb by midnight.

The dry slot will overspread the CWA near that time and winds will
shift southwesterly in direction. The commahead structure of the
cyclone in this mature phase should continue to become more
defined and grow, and given the forecast path of the 700mb low
and wraparound moisture and deformation near that level, would
expect at least the northern half of the CWA to be under this
late. So have precipitation chances increasing back into the
western northern CWA late tonight, with a propensity to become
more snow showers near daybreak.

Mtf

Long term
244 pm cst
Sunday through Saturday...

a very active weather pattern is still expected for much of the long
term forecast period. Multiple concerns are expected, including,
strong winds and scattered snow showers on Sunday and couple periods
of rain snow mid to late next week.

By early Sunday morning, the deepening sfc low should be lifting
newd through the upper great lakes and the strong cold front will
have pushed to the east of the area. Strong pressure rises of 10-12
mb per 3 hrs will be in place across the CWA as the deepening sfc
low lifts away from the region and strong high pressure builds into
the central plains. In combination with very strong cold advection
following the passage of the cold front and winds at the top of the
boundary layer of 50-60 kt, rapidly strengthening west winds should
be under way shortly before day break, reaching sustained speeds up
to 40 mph with gusts up to 60 mph. The strong west winds will
likely persist through much of the day and a high wind warning has
been issued for early Sunday morning until early Sunday evening.

Some scattered wrap-around snow showers will also be possible during
the morning hours. While little or no accumulation is expected, the
strong winds combined with the scattered snow showers may produce
short period of white-out conditions.

With persistent cold advection setting up following the fropa,
temperatures are expected to fall through the day. Temperatures
should start out Sunday morning in the lower 30s west of the fox
valley and i-55 corridor, with mid to upper 30s to the east. By
Sunday evening temperatures should be dropping in to the middle
teens in the rockford area and the lower 20s south and east of a
chicago to peru line. The cold advection will continue overnight,
driving temperatures down into the lower single digits above zero over
the nwrn portions of the CWA to the lower teens for the southeast
sections. While winds are expected to gradually diminish
overnight, speeds should still be around 15 to 25 mph, driving wind
chill readings as low as -10 to -20 f north of a chicago to peru
line and -5 to -10 f to the south of that line.

For the remainder of Monday until the end of the period, the upper
level pattern will transition from high amplitude to a more zonal
flow pattern. Weak embedded shortwaves rippling through fast flow
aloft will supporting occasional periods of light snow. However,
given the inherent uncertainty to the timing of short waves tracking
through fast zonal flow aloft, associated pops and potential
accumulations are a very low confidence forecast. Following the
cold Monday with highs in the teens northwest to middle 20s
southeast, temperatures for the remainder of the period should be
below seasonal normals.

Aviation
For the 00z tafs...

604 pm... Multiple forecast concerns including...

fog low clouds this evening.

Chance of thunderstorms mid late this evening.

Southeast to southwest wind shift around midnight.

Very strong winds gusts developing by sunrise Sunday.

Snow showers snow squalls Sunday morning.

An area of light rain is moving across the terminals early this
evening with prevailing visibilities generally in the 1-2sm range.

Once this activity ends... There will be a brief period were vis
may drop below 1sm. Additional showers and possibly isolated
thunderstorms are then expected to develop during the mid evening
which should help improve any lower visibilities. In addition...

low level wind shear will steadily increase over the next few
hours and this may mix the low levels just enough to prevent any
significant dense fog. Confidence is low for thunder coverage this
evening and maintained vicinity mention for a 2-3 hour period. By
late evening early morning... There should be a break in the
precipitation as the area is dry slotted. This should allow cigs
and vis to improve to at least MVFR... PossiblyVFR.

Easterly winds will become southeasterly this evening with gusts
to 20kts developing. These winds will continue shifting to the
southwest around shortly after midnight with gusts increasing into
the mid 20kt range. Another period of rain showers will move
across the area during the overnight hours with low MVFR and
possibly brief ifr CIGS moving back across the terminals. This
precipitation may mix with light snow or possibly change to all
light snow prior to sunrise.

As the surface low pressure lifts northeast across eastern wi
early Sunday morning... A strong cold front will move across the
terminals shifting winds westerly. Strong pressure rises combined
with the deepening low and a tightening gradient will result in
prevailing wind speeds in the 30-35kt range with gusts into the
45-50kt range. There remains some uncertainty regarding how long
the strongest wind gusts will prevail and while gusts to 40-45kts
are expected through late Sunday afternoon... The period of gusts
to 50kts may end up being shorter than currently indicated. As
these stronger winds arrive... There will likely be a period of
scattered snow showers that should end by mid morning and have
included this potential as tempo mention. Cms

Marine
258 pm cst
following the passage of a strong cold front late tonight, winds
over lake michigan are expected to shift to westerly and rapidly
strengthen. Expect a short period of gale force winds during the
early morning hours should increase to storm force by late morning.

Storm force gusts will remain possible until early Sunday evening.

Therefore, the portion of the gale warning for the il in nearshore
waters from 09z Sunday until 00z Monday has been upgraded to a storm
warning. After the end of storm force gust potential, winds should
still be gale force until early Monday morning. With very cold air
filtering in behind the cold front, a period of moderate to heavy
freezing spray will be likely from Sunday afternoon through Monday
afternoon. Given some uncertainty to the duration of heavy freezing
spray, will hold off on issuing a heavy freezing spray warning for
the nearshore waters at this time.

Lot watches warnings advisories
Il... High wind warning... Ilz003-ilz004-ilz005-ilz006-ilz008-ilz010-
ilz011-ilz012-ilz013-ilz014-ilz019-ilz020-ilz021-ilz022-
ilz023-ilz032-ilz033-ilz039... 3 am Sunday to 6 pm Sunday.

In... High wind warning... Inz001-inz002-inz010-inz011-inz019... 3 am
Sunday to 6 pm Sunday.

Lm... Dense fog advisory... Nearshore waters until 10 pm Saturday.

Gale warning... Lmz740-lmz741-lmz742-lmz743-lmz744-lmz745... 3 am
Sunday to 8 am Sunday.

Gale warning... Lmz740-lmz741-lmz742-lmz743-lmz744-lmz745... 10 pm
Sunday to 3 am Monday.

Storm warning... Lmz740-lmz741-lmz742-lmz743-lmz744-lmz745... 8 am
Sunday to 10 pm Sunday.

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Weather Reporting Stations
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Stations Dist Age Wind Air TempWater Temp WavesPressureDewPt
CNII2 1 mi17 min NE 4.1 G 4.1 35°F 33°F
CHII2 - Chicago, IL 5 mi27 min ESE 12 G 13 37°F 37°F
JAKI2 5 mi107 min ESE 4.1 G 5.1 36°F
CMTI2 - 9087044 - Calumet, IL 9 mi47 min E 7 G 8.9 37°F 1002.9 hPa (-5.6)37°F
FSTI2 9 mi107 min SE 17 37°F
BHRI3 - Burns Harbor, IN 28 mi39 min SE 7 G 12 42°F 1004.4 hPa
MCYI3 - Michigan City, IN 37 mi27 min ESE 12 G 16 41°F 40°F
WHRI2 - Waukegan Harbor, IL 37 mi47 min ENE 7 G 9.9 34°F

Wind History for Calumet Harbor, IL
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SW13
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G11

Airport Reports
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AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
Chicago, Chicago Midway Airport, IL9 mi54 minE 81.75 miRain Fog/Mist39°F39°F100%1004.1 hPa
Chicago, Chicago-O'Hare International Airport, IL18 mi56 minE 41.25 miRain Fog/Mist38°F35°F89%1004 hPa
Gary Regional Airport, IN19 mi62 minSE 81.50 miRain43°F42°F100%1004.1 hPa
Lansing Municipal Airport, IL22 mi52 minESE 73.00 miRain40°F40°F100%1004.1 hPa
Chicago / Wheeling, Pal-Waukee Airport, IL24 mi55 minN 01.00 miFog/Mist36°F34°F93%1005.1 hPa

Wind History from MDW (wind in knots)
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Last 24hrE10E8E9E8E7E9E6E7E7E8E7E7E9SE9SE7S3N7NE9E9E9SE9E8SE6E8
1 day agoW6W6NW4NW5NW3NW5NW5N6N5N6N5N4N6N3E11E8
G16
E6E7NE5E6NE10E8E7E7
2 days agoW13
G22
SW17
G25
W14
G24
W12
G23
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G25
W16
G28
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G24
W14
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W10W8W8W12
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W9W13W14W13W10W12W11W8W9

Tide / Current Tables for
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Weather Map and Satellite Images
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GOES 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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Wind Forecast for Chicago, IL (19,4,5,8)
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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 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.