Monday, June26, 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 5:15AMSunset 8:31PM Monday June 26, 2017 7:20 AM CDT (12:20 UTC) Moonrise 8:14AMMoonset 10:43PM Illumination 6% Phase: Waxing Crescent; Moon at 2 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-calumet Harbor To Gary- 307 Am Cdt Mon Jun 26 2017
.small craft advisory in effect from 10 am cdt this morning through this evening...
Today..West winds 15 to 25 kt becoming northwest late in the afternoon...then north toward evening. Slight chance of showers and Thunderstorms late in the afternoon. Waves 1 to 3 ft building to 3 to 6 ft.
Tonight..North winds 15 to 20 kt early becoming west 10 to 15 kt after midnight. Slight chance of showers and Thunderstorms in the evening. Waves 3 to 6 ft subsiding to 2 to 4 ft.
Tuesday..West winds 10 to 15 kt becoming southeast at around 10 kt in the afternoon. Sunny. Waves 2 to 4 ft subsiding to 1 to 3 ft in the afternoon.
Tuesday night..South winds 10 to 15 kt. Mostly clear. Waves 1 to 3 ft.
LMZ742 Expires:201706261530;;837467 FZUS53 KLOT 260807 NSHLOT NEARSHORE MARINE FORECAST National Weather Service Chicago/Romeoville IL 307 AM CDT Mon Jun 26 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>743-261530-

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 261051
afdlot
area forecast discussion
national weather service chicago romeoville, il
551 am cdt Mon jun 26 2017

Short term
330 am cdt
today and tonight...

short term portion of the forecast continues to feature cooler than
normal temperatures for late june, with the potential for isolated
to scattered showers and thunderstorms later today in association
with a pair of mid-level disturbances and a weak frontal trough.

Broad upper level trough remains across much of the eastern conus
this morning. A fairly vigorous short wave is noted over western
lake superior and far northwestern wi in GOES vapor imagery, and
this feature is progged to dig southeast across the western great
lakes region through this evening. High res guidance is in decent
agreement in depicting a surface trough cold front in association
with this wave, which pushes south into far northern il and
northwest in by late afternoon and early this evening. Weak
instability, generally less than 200 j kg of MLCAPE is indicated in
forecast soundings, which should be enough to support isolated to
scattered showers thunder given the available forcing, as indicated
by the 3km WRF and hinted at in some of the other cam output.

Farther west, another mid-level speed maxima is noted across the
northern plains, also propagating to the southeast. An area of
precipitation was already occurring with this second wave across
parts of iowa early this morning, and will spread southeast into
western central il today, primarily affecting southern parts of the
cwa during the midday afternoon hours. In between, there may be a
corridor, roughly from rochelle to south of valparaiso, where precip
potential remains minimal, with better chances over far northern and
southern parts of the forecast area. Both mid-level features push
southeast of the area this evening, with subsidence developing
overnight. This, combined with loss of diurnal instability
component, should allow showers to dissipate or settle south of the
area by later this evening.

Similar to the past couple of days, breezy west-northwest winds will
develop after sunrise this morning, with steep low level lapse rates
leading to gusts around 25 kt and a stratocu deck by mid-late
morning. Low level temps (around +12c at 925 mb) should support high
temps from near 70 far north to the lower 70's most other areas.

The late afternoon cold frontal trough will likely turn winds
north to northeast along the lake, making for a quick cool down
along the shore early this evening. High pressure builds in later
tonight with clearing skies and diminishing winds, setting the
stage for chilly overnight temps in the upper 40's to around 50
away from the core of the chicago urban heat island.

Ratzer

Long term
330 am cdt
Tuesday through Sunday...

the anomalous mid upper trough that has been bringing the cool
weather will kick east on Tuesday, with height rises favoring fair
weather conditions. After a chilly start to the day, plenty of
sunshine and the onset of low level warm advection with still
unseasonably dry 40s dew points in many areas will enable
temperatures to warm well into the 70s. Surface high pressure
around 1020 mb will be over the area through mid day and then
slide east during the afternoon, with light to moderate synoptic
south-southwest winds developing. Sufficiently weak 950 mb flow
on northwest side of the surface high and land lake thermal
differential should enable a lake breeze to form and bring some
cooling to the illinois shore and possibly along portions of
immediate indiana shore.

A pattern change to zonal will quickly occur in the midst of a
quiet overnight Tuesday night. Broad lower than average heights
will be in place over the intermountain west and plains by
Wednesday, with subtropical ridging setting up off the southeast
and mid atlantic coast on Thursday and Friday. Ensembles are in
decent agreement in the large scale pattern, so confidence
continues to be decent in this.

The zonal westerly mid-upper level flow pattern will favor
multiple convectively modified short-wave disturbances traversing
the region Wednesday-Friday and a return to more seasonable
temperatures, moist dewpoints and high column moisture content.

Therefore, the mid to late week period still looks to be fairly
active with periodic precipitation thunder potential. The synoptic
set-up will also be one to monitor for a strong severe
thunderstorm potential, as guidance is indicating relatively
strong wind fields supportive of favorable bulk shear. As alluded
to above, models are also indicating the potential for
anomalously high precipitable water values around 2" at times late
Wednesday through Friday, so a risk for heavy downpours and at
least localized flooding may also evolve.

On Wednesday, an uncertain factor will be the likelihood of an
ongoing MCS over the plains, with respect to possible mcv
formation from this, the trajectory and timing of the wave, cloud
cover limiting destabilization, impact on mid-level lapse rates
and influence of outflow boundaries. Furthermore, a warm front
will be lifting north in response to pressure falls from strong
low pressure moving from the dakotas into minnesota. An earlier
arrival of the MCS modified short-wave prior to the arrival of
better moisture with the front and resulting destabilization could
limit the magnitude of thunderstorms over the area, with possible
subsidence behind this wave until later in the evening. On the
other hand, a more favorable timing could certainly yield a
notable severe flooding risk somewhere in the region. Confidence
is low on exactly how things will play out, so have not made big
changes to the going forecast, with general idea of increasing
pops shower and thunderstorm coverage during the afternoon and
evening.

Another item of note for Wednesday is the strong south-southwest
wind potential. If cloud cover issues are not too much of a
limiting factor on mixing depth and tapping into higher momentum
air aloft, gusts could reach or even exceed 35 mph during the
afternoon per forecast soundings. The cold front trailing from
the surface low will progress toward the area Wednesday night into
Thursday and then appears probable to stall out near or over the
area on Thursday. Needless to say, confidence is also fairly low
on the position of the likely stationary frontal boundary. Current
forecast favors areas especially along and south of i-80 for
potential shower and thunderstorm redevelopment Thursday afternoon
and evening. Another convectively modified wave may try to
impinge on the warm sector late in the day or in the evening and
the timing of this will impact whether coverage is only
isolated scattered or more widespread.

The amount of cloud cover on Thursday from convective debris and
new convection will play a significant role in high temperatures.

Progged 925 mb temperatures in the lower 20s celsius at peak
heating supports highs in the upper 80s based off local
climatology in late june. In the grids went with somewhat of a
middle ground between the warming potential and most of the
deterministic guidance, which is cooler, with a forecast of
solidly mid 80s highs. With forecast dew points in the upper 60s
to lower 70s, current forecast yields MAX heat index values in
upper 80s to lower 90s. If warmth is maximized, these values could
easily reach the mid 90s (and vice versa if temps are cooler).

Additional upstream MCS activity appears likely on Thursday night
over the plains. A surface low is expected to take shape from a
short-wave emanating from this activity, with the low tracking
over the area on Friday, though there is uncertainty on exact
track. Global guidance is indicating a significant QPF signal
moving over the area Friday morning with this wave, so given time
of day and likelihood of plenty of cloud cover it's possible that
the biggest threat Friday could be heavy rainfall and flooding.

If any pockets of heating and destabilization can take place
Friday afternoon in more subsident regime behind lead wave, would
need to monitor for a strong severe risk in any convective
redevelopment given supportive wind fields bulk shear.

A cold front passage should end thunderstorm threat Friday night
and possibly set the stage for a somewhat drier quieter Saturday.

This will be determined by the timing of a fast moving trough
moving across the great lakes region either Saturday or Sunday.

With confidence very low this far out, have only partial covering
of slight chance pops over the weekend. The main message for the
Wednesday-Friday period is this: while confidence in medium- high
in large scale pattern as mentioned previously, confidence in the
day to day sensible weather details is low as is common this time
of year with mesoscale convective uncertainties that will need to
be sorted out. Should things come together, a period or two of
more widespread severe and or flooding potential may evolve. Stay
tuned for later updates.

Castro

Aviation
For the 12z tafs...

main aviation concerns remain gusty west-northwest winds today,
decreasing later with a wind shift to nne late this
afternoon early this evening. Isolated scattered shra or tsra
possible late too.

Surface low pressure was over the northern great lakes early this
morning, with forecast area on the southwestern edge of the
tighter surface pressure gradient. Mixing of the boundary layer
after sunrise will result in west-northwest winds gusting near 25
kts. Vigorous mid-level wave digging across northern wi is
expected to lead to a wind shift more to the north-northwest late
this afternoon, which typically flops to 010-020 deg. Latest esrl
hrrr hints at this, adding some confidence to earlier forecasts.

This also appears to be coincident with a weak surface trough
which may be aided by outflow from showers farther north later
this afternoon... Which may spread into the terminals in isolated
to scattered fashion by late afternoon. Weak instability may also
support isolated ts. Overall, confidence in wind shift to nne and
shower coverage timing is a bit on the low side.

Of greater confidence, is clearing skies and winds shifting back
to light west tonight, as mid-level disturbance moves off to the
east of the area and weak surface high pressure develops into the
region by early Tuesday.

Ratzer

Marine
407 am cdt
brisk west-northwest flow will be in place across the lake today.

A cold front trailing from weak low pressure over the northern
lakes this morning will shift winds to more north-northwest this
afternoon, earliest on the north half. Have issued a small craft
advisory for the entire illinois and northwest indiana nearshore,
starting at 10am for illinois and already in effect for indiana
given hazardous waves observed at the mi city buoy. Winds are
expected to shift north-northeast by the early evening in the
nearshore, but speeds will likely come down fairly quickly. High
pressure will move over the region on Tuesday, with the high
center moving over the southern portion of the lake and then
shifting east late in the day. Lighter west-northwest winds than
Monday will shift to southerly in the afternoon.

Focus then turns to the next period of strong wind concern. This
will be Wednesday through Wednesday night. As unseasonably strong
low pressure moves toward the northwestern lakes region by
Wednesday evening, southerly winds will increase to 30 kt. With
the approach of the trailing cold frontal zone Wednesday night,
the strongest winds will focus into the central and southern
portion of the lake with direction becoming southwest. Brisk
west-southwest winds will continue on Thursday, especially south,
with uncertainty on wind direction north given potential for a
wind shift. Wind direction uncertainty increases on Friday, though
speeds are likely to be lighter. A weak low pressure may pass
near or over the southern tip of the lake. Finally, a few periods
of fairly widespread thunderstorms are probable in the Wednesday-
Friday timeframe. Wednesday in particular could also see a risk
for strong to severe thunderstorms reach the lake.

Castro

Lot watches warnings advisories
Il... None.

In... Beach hazards statement... Inz002 until 4 am Tuesday.

Beach hazards statement... Inz001... 4 pm Monday to 4 am Tuesday.

Lm... Small craft advisory... Lmz740-lmz741-lmz742-lmz743... 10 am
Monday to 10 pm Monday.

Small craft advisory... Gary to michigan city in until 4 am Tuesday.

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Weather Reporting Stations
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Stations Dist Age Wind Air TempWater Temp WavesPressureDewPt
CNII2 1 mi21 min 60°F
45177 3 mi141 min 63°F
OKSI2 4 mi141 min WNW 1.9 61°F
CHII2 - Chicago, IL 5 mi31 min W 11 G 11 60°F 50°F
JAKI2 5 mi141 min W 6 58°F
FSTI2 9 mi141 min W 9.9 58°F
CMTI2 - 9087044 - Calumet, IL 9 mi51 min WSW 2.9 G 6 58°F 1019.4 hPa51°F
45174 20 mi31 min WSW 9.7 G 12 58°F 64°F1 ft52°F
BHRI3 - Burns Harbor, IN 28 mi40 min WSW 12 G 15 60°F 1020.3 hPa
45170 34 mi31 min W 12 G 16 62°F 66°F3 ft54°F
WHRI2 - Waukegan Harbor, IL 37 mi41 min W 7 G 8.9 58°F
MCYI3 - Michigan City, IN 37 mi31 min WSW 15 G 17 61°F 53°F

Wind History for Calumet Harbor, IL
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N2
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Airport Reports
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AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
Chicago, Chicago Midway Airport, IL9 mi28 minW 610.00 miMostly Cloudy59°F50°F72%1019.5 hPa
Chicago, Chicago-O'Hare International Airport, IL18 mi30 minW 810.00 miMostly Cloudy58°F48°F70%1019.6 hPa
Gary Regional Airport, IN19 mi36 minW 815.00 miMostly Cloudy57°F50°F77%1020.3 hPa
Lansing Municipal Airport, IL22 mi26 minW 610.00 miFair56°F48°F78%1020.7 hPa
Chicago / Wheeling, Pal-Waukee Airport, IL24 mi29 minW 710.00 miFair58°F51°F78%1020 hPa

Wind History from MDW (wind in knots)
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Last 24hrW13
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W10W7W9NW9W3W5W4W4NW4W7W6
1 day agoNW10W9W9W13W12
G18
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G23
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G25
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W6NW10W3W6W4W9W9W7SW6SW7W11
2 days agoNW7N5N7NW11N12N8N11
G15
NW19
G24
W8W15
G22
W14
G18
W10NW17
G21
NW10NW12NW9NW10NW9W11W9W7W6W6W9

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 (8,2,3,4)
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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.