Monday, January22, 2018 L-36.com


Marine Weather and Tides
Wilmette, 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 7:10AMSunset 4:55PM Monday January 22, 2018 9:35 PM CST (03:35 UTC) Moonrise 11:15AMMoonset 11:33PM Illumination 38% Phase: Waxing Crescent; Moon at 6 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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LMZ741 Winthrop Harbor To Wilmette Harbor- Wilmette Harbor To Northerly Island- Northerly Island To Calumet Harbor- 853 Pm Cst Mon Jan 22 2018
.small craft advisory in effect from 6 am cst Tuesday through late Tuesday night...
Rest of tonight..West winds 10 to 20 kt. Rain and snow likely. Waves 1 to 3 ft.
Tuesday..Northwest winds 20 to 25 kt. Chance of snow through the day. Waves 2 to 4 ft early, building to 6 to 9 ft occasionally to 12 ft in the afternoon.
Tuesday night..Northwest winds 15 to 25 kt. Mostly cloudy. Waves 4 to 7 ft occasionally to 9 ft subsiding to 3 to 5 ft after midnight.
Wednesday..Northwest winds 10 to 15 kt becoming west 5 to 10 kt in the afternoon. Mostly cloudy in the morning then becoming mostly Sunny. Waves 2 to 4 ft subsiding to 1 to 3 ft in the afternoon.
LMZ741 Expires:201801231015;;856481 FZUS53 KLOT 230253 NSHLOT NEARSHORE MARINE FORECAST National Weather Service Chicago/Romeoville IL 853 PM CST Mon Jan 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 Wilmette, IL
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location: 42.08, -87.73     debug


Area Discussion for - Chicago, IL
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Fxus63 klot 230324
afdlot
area forecast discussion
national weather service chicago romeoville, il
924 pm cst Mon jan 22 2018

Update
924 pm cst
the main forecast concern for later tonight is the potential for
a band of snow to develop across portions of far northern il into
early Tuesday morning.

Water vapor imagery early this evening indicates that the main
mid-level circulation is now beginning to shift northeastward
into far west-central il (just north of quincey, il). The surface
low over eastern iowa has become occluded over the past several
hours, with a new center of low pressure now developing over far
northeastern il and southeast wi this evening. Given the occlusion
of the main storm system, a well defined trowal (trough of warm
air aloft) structure has developed to the north of the main
circulation into southern wi. Ultimately this is setting up prime
conditions for the development of a rather intense area of mid-
level frontogenesis along the southern periphery of this trowal
where mid-level deformation is strengthening in association with
the arrival of the mid-level low. Radar trends across far northern
illinois and far southern wisconsin already indicate that this
process is underway as a nearly stationary band of precipitation
resides.

The main concern is that as dynamic adiabatic cooling continues
and colder air begins to wrap back into northern il tonight that
this will result in the change over to a band of potentially heavy
snow into early Tuesday morning. Overall confidence on the trends
of this change over to snow remains low at this time, but guidance
indicates that the column should become sufficiently cold to
support a change over to snow around midnight over northern il.

Given the presence of steep mid-level lapse rates above the
trowal, heavy snow will be possible across far northern il later
tonight. The main question that remains is how much snow will
fall. There certainly is the potential to get a quick few inches
of wet snow near the wi state line, but amounts would likely
rapidly drop off to the south towards the i-88 corridor. I tossed
around the idea of putting an advisory up for my far northern
counties, but have opted to hold off for now and go with a
special weather statement. Given the potential impacts to the
morning rush, an advisory could be needed later tonight.

Given the above, I have increased snow amounts far north to around
2-3 inches, with a change over to snow expected around, or shortly
after midnight.

Kjb

Short term
200 pm cst
through Tuesday...

low pressure is centered near des moines, iowa this afternoon with
a warm front draped across far northern illinois. In the
vicinity of the front, fog and drizzle will continue this
afternoon across far northern illinois while farther south dry air
wrapping in from the southwest has allowed partial clearing west
of the i-57 corridor. Temperatures and dew points are into the
upper 40s to low 50s within the warm sector and are superimposed
by steep low to mid level lapse rates this afternoon which are
contributing to a corridor of seasonably strong instability.

Midday soundings from dvn and ilx show MLCAPE values around 150
j kg while SBCAPE is closer to 600 j kg. Latest run of the rap
picks up on this axis of instability and shifts it east across the
cwa through the late afternoon and early evening ahead of an
advancing cold front, albeit with weakening instability as we get
past peak heating. Very strong winds aloft with 0-1km shear in
excess of 20kt and favorable effective SRH continue to prompt some
concern for a severe threat for any thunderstorms that make it
into the area this afternoon and evening, and an isolated tornado
remains a possibility. Convective initiation is already ongoing
near springfield, il with agitated CU field south towards st
louis. These storms will move north-northeast through the late
afternoon and evening hours within the aforementioned instability
axis though confidence in how well they will maintain their
intensity is fairly low by the time they reach the local cwa.

Late this evening and overnight, 500mb closed low will move across
the region and allow deeper moisture to return resulting in
periods of light rain. Forecast soundings eventually cool enough
for precipitation to transition to snow during the predawn and
early morning hours Tuesday. Models have been fairly consistent
showing axis of highest QPF near and north of the il wi state
line. As precipitation changes to snow, could see a dusting few
tenths of snow area-wide, but the best chance for any light
accumulations will be across the northern tier of counties where
up to an inch of snow is possible. Winds turn northwest behind
the departing low Tuesday morning and mid level moisture scours
out once more. Steep low level lapse rates redevelop in the
northwest flow and could result in a few additional flurries
during the late morning and afternoon. Temps will fall into the
low to mid 30s behind the cold front tonight and likely hold
fairly steady through the day tomorrow.

Deubelbeiss

Long term
140 pm cst
Tuesday night through Monday...

closed upper low continues to pull away from the region Tuesday
evening, with mid-level short wave ridging building briefly across
the area early in the night. Partial clearing of lower clouds is
possible during the evening in response to mid-level drying and
subsidence associated with strong h5 height falls (nearly 150
meters), though forecast soundings depict redevelopment of mid-
level clouds overnight as another mid-level short wave quickly
approaches. Clouds linger through the day Wednesday as the wave
propagates across the region, with a weak surface cold frontal
trough. Model soundings depict a relatively dry 900-700 mb layer
however, which suggests little precip threat despite cloudy skies.

Model 950 mb temps generally support daytime highs in the low-mid
30's.

Mid-level short wave and larger scale upper trough axis moves
east of the area Wednesday night. Medium range guidance is in good
agreement in building broad upper ridging east across the region,
with dry and milder conditions Thursday and Friday. Pattern is
progressive, with an upper trough developing eastward across the
central and northern plains, and an area of surface low pressure
which tracks into western ontario and trails a cold front through
the local area Friday night or early Saturday. Surface high
initially blocking gulf moisture return, and relatively quick
progression of upper flow, suggests somewhat limited precipitation
potential, especially with quicker cold frontal passage depicted
by the gfs. Slower ECMWF gem solutions would support a little
greater potential for rain especially across the southeastern part
of the CWA into Saturday. After 40's Thursday, and temps likely
near 50 Friday, timing differences with the cold front add lower
confidence to the high temp forecast Saturday, with 45-50 degree
highs likely east southeast of the advancing front.

Colder air spreads back in behind the front Saturday night,
though by the time precipitation ends in the southeast, model
partial thickness values would suggest precip type would likely
remain all rain. By Monday, even the slowest guidance (ecmwf)
moves the upper trough east of the area, with broad upper ridging
moving in aloft with weak high pressure ridge at the surface. Some
detail differences exist as expected by that time, though
generally it appears our colder air will result in temps around
average for late january. Pattern looks to remain progressive as
well, with milder air again early-mid next week.

Ratzer

Aviation
For the 00z tafs...

several forecast concerns challenges this forecast period:
* showers and thunder this evening
* a band of light moderate, possibly heavy, snow tonight thru tue
am
* returning ifr ceilings, with lifr possible
* wind shift to the northwest Tue am
* continued scattered snow showers tue
latest radar imagery showing area of showers and thunderstorms
continuing to move across much of northern illinois. Rfd currently
being impacted but expect the remaining terminals to see this
precip over the next hour, with thunder still a possibility.

However, ord dpa have the highest chances of observing this
thunder along with a possibility of small hail. Showers will then
linger for 2-3 hours but should diminish in coverage after that
point, while conditions remain mainlyVFR. The arrival of colder
air and stronger forcing later tonight will support a window of
light to moderate snow, and have adjusted tafs to account for
latest trends. This will start earlier at rfd, but then spread
east southeast soon there after. Have higher confidence of snow
now occurring, but do think there could be a window of heavier
snow. Have lowest vis falling to 1sm, but vis below 1sm is
possible. Will need to monitor this period and potential snow,
especially as snow accumulation will be possible at the terminals.

Ceilings will fall under this snow, with ifr a definite
possibility. Lifr will also be possible. Conditions should improve
by early Tuesday morning, but with winds shifting to the
northwest and with periodic snow showers continuing throughout the
day.

Rodriguez

Marine
155 pm cst
main marine forecast concerns focus on deep area of low pressure
which will move across southern lake michigan tonight. In
addition, areas of locally dense fog were in place across southern
parts of the lake, where 40-50 degree dew point air has spread
north over the colder waters. Strong northeast winds currently
occurring across northern parts of the lake will gradually back
northerly and increase more solidly into gale range through early
Tuesday morning as the low moves through, and will increase to
gale strength over the southern portion of the lake Tuesday
morning as the low pulls off to the east. Gale warning headlines
are already up for the north half, though there winds are largely
just below gale force this afternoon. A gale warning is in effect
for the southern part of the lake starting early Tuesday morning,
and headlines for the entire lake will run through 00z 6 pm cst
tomorrow. A dense fog advisory remains in effect into this evening
on the south end of the lake.

The low will eventually move off across the st. Lawrence valley
Tuesday night, with weak high pressure ridging spreading across
the western lakes Wednesday. This will allow winds to diminish to
less than 20 kts, and eventually back to the south-southwest by
early Thursday. Deep low pressure is expected to develop in the
lee of the northern rockies Thursday night, which will induce
increasing south-southeast winds. A period of southerly gales is
possible Friday through perhaps early Saturday, after which a cold
front will shift winds to the west.

Ratzer

Lot watches warnings advisories
Il... None.

In... None.

Lm... Dense fog advisory... Lmz777-lmz779 until 3 am Tuesday.

Gale warning... Lmz777-lmz779... 3 am Tuesday to 6 pm Tuesday.

Small craft advisory... Lmz740-lmz741-lmz742... 6 am Tuesday to 4
am Wednesday.

Small craft advisory... Lmz743-lmz744-lmz745... 6 am Tuesday to 10
am Wednesday.

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Weather Reporting Stations
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Stations Dist Age Wind Air TempWater Temp WavesPressureDewPt
FSTI2 8 mi96 min W 20 42°F
OKSI2 13 mi96 min WNW 4.1 44°F
CHII2 - Chicago, IL 14 mi46 min W 22 G 25 43°F 36°F
CNII2 17 mi36 min WSW 11 G 18 42°F 33°F
WHRI2 - Waukegan Harbor, IL 20 mi36 min W 16 41°F
JAKI2 22 mi96 min W 9.9 43°F
CMTI2 - 9087044 - Calumet, IL 26 mi48 min SW 8 G 16 42°F 998.8 hPa36°F
KNSW3 - Kenosha, WI 35 mi36 min SW 13 G 18 42°F 998 hPa (+0.4)
BHRI3 - Burns Harbor, IN 43 mi56 min W 19 40°F 1000 hPa

Wind History for Calumet Harbor, IL
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Airport Reports
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AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
Chicago / Wheeling, Pal-Waukee Airport, IL9 mi44 minW 710.00 miOvercast42°F37°F82%999 hPa
Chicago, Chicago-O'Hare International Airport, IL11 mi45 minW 710.00 miOvercast41°F36°F82%998.5 hPa
Chicago, Chicago Midway Airport, IL20 mi43 minW 12 G 2110.00 miLight Rain42°F34°F73%999.3 hPa

Wind History from PWK (wind in knots)
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Last 24hrE3NE3CalmCalmCalmN7CalmNE4CalmSE8E8S9S14S14
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1 day ago--SW3CalmCalmCalmE3CalmCalmS4S5CalmSE4S3CalmSE3CalmNE3Calm3CalmN3CalmCalmCalm
2 days agoSW12
G20
SW8SW9SW8SW8SW7SW8SW6SW4CalmSW6SW7W7SW8SW6SW7SW8SW8SW7S3CalmSW5SW4S4

Tide / Current Tables for
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Weather Map and Satellite Images
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IR Satellite Image from GEOS
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GOES Local Image of Midwest    EDIT
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Wind Forecast for Chicago, IL (22,6,7,8)
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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.